From 9076d462619a5c9a4020c28477365c2efa568ce1 Mon Sep 17 00:00:00 2001
From: Magnus Norddahl <dpjudas@users.noreply.github.com>
Date: Mon, 29 Aug 2016 13:10:22 +0200
Subject: [PATCH 01/18] Added SSAO pass

---
 src/CMakeLists.txt                        |   1 +
 src/gl/renderer/gl_postprocess.cpp        | 107 ++++++++++-
 src/gl/renderer/gl_renderbuffers.cpp      | 221 +++++++++++++++++-----
 src/gl/renderer/gl_renderbuffers.h        |  24 ++-
 src/gl/renderer/gl_renderer.cpp           |   5 +
 src/gl/renderer/gl_renderer.h             |   9 +
 src/gl/scene/gl_scene.cpp                 |   9 +-
 src/gl/shaders/gl_ambientshader.cpp       |  89 +++++++++
 src/gl/shaders/gl_ambientshader.h         |  39 ++++
 src/gl/stereo3d/gl_stereo3d.cpp           |   2 +-
 wadsrc/static/language.enu                |   1 +
 wadsrc/static/menudef.zz                  |   1 +
 wadsrc/static/shaders/glsl/lineardepth.fp |  16 ++
 wadsrc/static/shaders/glsl/ssao.fp        | 117 ++++++++++++
 14 files changed, 580 insertions(+), 61 deletions(-)
 create mode 100644 src/gl/shaders/gl_ambientshader.cpp
 create mode 100644 src/gl/shaders/gl_ambientshader.h
 create mode 100644 wadsrc/static/shaders/glsl/lineardepth.fp
 create mode 100644 wadsrc/static/shaders/glsl/ssao.fp

diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 73dba07c4..039a03b52 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -1125,6 +1125,7 @@ set( FASTMATH_SOURCES
 	gl/shaders/gl_shaderprogram.cpp
 	gl/shaders/gl_presentshader.cpp
 	gl/shaders/gl_bloomshader.cpp
+	gl/shaders/gl_ambientshader.cpp
 	gl/shaders/gl_blurshader.cpp
 	gl/shaders/gl_colormapshader.cpp
 	gl/shaders/gl_tonemapshader.cpp
diff --git a/src/gl/renderer/gl_postprocess.cpp b/src/gl/renderer/gl_postprocess.cpp
index 7ce8be0ad..9df28ce5b 100644
--- a/src/gl/renderer/gl_postprocess.cpp
+++ b/src/gl/renderer/gl_postprocess.cpp
@@ -55,6 +55,7 @@
 #include "gl/renderer/gl_postprocessstate.h"
 #include "gl/data/gl_data.h"
 #include "gl/data/gl_vertexbuffer.h"
+#include "gl/shaders/gl_ambientshader.h"
 #include "gl/shaders/gl_bloomshader.h"
 #include "gl/shaders/gl_blurshader.h"
 #include "gl/shaders/gl_tonemapshader.h"
@@ -98,6 +99,20 @@ CVAR(Float, gl_lens_k, -0.12f, 0)
 CVAR(Float, gl_lens_kcube, 0.1f, 0)
 CVAR(Float, gl_lens_chromatic, 1.12f, 0)
 
+CVAR(Bool, gl_ssao, false, CVAR_ARCHIVE | CVAR_GLOBALCONFIG)
+CVAR(Bool, gl_ssao_debug, false, 0)
+CVAR(Float, gl_ssao_bias, 0.5f, 0)
+CVAR(Float, gl_ssao_radius, 100.0f, 0)
+CUSTOM_CVAR(Float, gl_ssao_blur_amount, 6.0f, 0)
+{
+	if (self < 0.1f) self = 0.1f;
+}
+CUSTOM_CVAR(Int, gl_ssao_blur_samples, 9, 0)
+{
+	if (self < 3 || self > 15 || self % 2 == 0)
+		self = 9;
+}
+
 EXTERN_CVAR(Float, vid_brightness)
 EXTERN_CVAR(Float, vid_contrast)
 
@@ -109,6 +124,96 @@ void FGLRenderer::RenderScreenQuad()
 	GLRenderer->mVBO->RenderArray(GL_TRIANGLE_STRIP, FFlatVertexBuffer::PRESENT_INDEX, 4);
 }
 
+void FGLRenderer::PostProcessScene()
+{
+	if (FGLRenderBuffers::IsEnabled()) mBuffers->BlitSceneToTexture();
+	AmbientOccludeScene();
+	UpdateCameraExposure();
+	BloomScene();
+	TonemapScene();
+	LensDistortScene();
+}
+
+//-----------------------------------------------------------------------------
+//
+// Adds ambient occlusion to the scene
+//
+//-----------------------------------------------------------------------------
+
+void FGLRenderer::AmbientOccludeScene()
+{
+	if (!gl_ssao || !FGLRenderBuffers::IsEnabled())
+		return;
+
+	FGLDebug::PushGroup("AmbientOccludeScene");
+
+	FGLPostProcessState savedState;
+
+	float bias = gl_ssao_bias;
+	float aoRadius = gl_ssao_radius;
+	const float blurAmount = gl_ssao_blur_amount;
+	int blurSampleCount = gl_ssao_blur_samples;
+
+	//float tanHalfFovy = tan(fovy * (M_PI / 360.0f));
+	float tanHalfFovy = 1.0f / 1.33333302f; //gl_RenderState.mProjectionMatrix.get()[5];
+	float invFocalLenX = tanHalfFovy * (mBuffers->AmbientWidth / (float)mBuffers->AmbientHeight);
+	float invFocalLenY = tanHalfFovy;
+	float nDotVBias = clamp(bias, 0.0f, 1.0f);
+	float r2 = aoRadius * aoRadius;
+
+	// Calculate linear depth values
+	glBindFramebuffer(GL_FRAMEBUFFER, mBuffers->AmbientFB0);
+	glViewport(0, 0, mBuffers->AmbientWidth, mBuffers->AmbientHeight);
+	mBuffers->BindSceneDepthTexture(0);
+	mLinearDepthShader->Bind();
+	mLinearDepthShader->DepthTexture.Set(0);
+	mLinearDepthShader->LinearizeDepthA.Set(1.0f / GetZFar() - 1.0f / GetZNear());
+	mLinearDepthShader->LinearizeDepthB.Set(MAX(1.0f / GetZNear(), 1.e-8f));
+	mLinearDepthShader->InverseDepthRangeA.Set(1.0f);
+	mLinearDepthShader->InverseDepthRangeB.Set(0.0f);
+	RenderScreenQuad();
+
+	// Apply ambient occlusion
+	glBindFramebuffer(GL_FRAMEBUFFER, mBuffers->AmbientFB1);
+	glBindTexture(GL_TEXTURE_2D, mBuffers->AmbientTexture0);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+	mSSAOShader->Bind();
+	mSSAOShader->DepthTexture.Set(0);
+	mSSAOShader->UVToViewA.Set(2.0f * invFocalLenX, -2.0f * invFocalLenY);
+	mSSAOShader->UVToViewB.Set(-invFocalLenX, invFocalLenY);
+	mSSAOShader->InvFullResolution.Set(1.0f / mBuffers->AmbientWidth, 1.0f / mBuffers->AmbientHeight);
+	mSSAOShader->NDotVBias.Set(nDotVBias);
+	mSSAOShader->NegInvR2.Set(-1.0f / r2);
+	mSSAOShader->RadiusToScreen.Set(aoRadius * 0.5 / tanHalfFovy * mBuffers->AmbientHeight);
+	mSSAOShader->AOMultiplier.Set(1.0f / (1.0f - nDotVBias));
+	RenderScreenQuad();
+
+	// Blur SSAO texture
+	mBlurShader->BlurHorizontal(this, blurAmount, blurSampleCount, mBuffers->AmbientTexture1, mBuffers->AmbientFB0, mBuffers->AmbientWidth, mBuffers->AmbientHeight);
+	mBlurShader->BlurVertical(this, blurAmount, blurSampleCount, mBuffers->AmbientTexture0, mBuffers->AmbientFB1, mBuffers->AmbientWidth, mBuffers->AmbientHeight);
+
+	// Add SSAO back to scene texture:
+	mBuffers->BindCurrentFB();
+	glViewport(mSceneViewport.left, mSceneViewport.top, mSceneViewport.width, mSceneViewport.height);
+	glEnable(GL_BLEND);
+	glBlendEquation(GL_FUNC_ADD);
+	if (gl_ssao_debug)
+		glBlendFunc(GL_ONE, GL_ZERO);
+	else
+		glBlendFunc(GL_ZERO, GL_SRC_COLOR);
+	glActiveTexture(GL_TEXTURE0);
+	glBindTexture(GL_TEXTURE_2D, mBuffers->AmbientTexture1);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+	mBloomCombineShader->Bind();
+	mBloomCombineShader->BloomTexture.Set(0);
+	RenderScreenQuad();
+	glViewport(mScreenViewport.left, mScreenViewport.top, mScreenViewport.width, mScreenViewport.height);
+
+	FGLDebug::PopGroup();
+}
+
 //-----------------------------------------------------------------------------
 //
 // Extracts light average from the scene and updates the camera exposure texture
@@ -190,7 +295,7 @@ void FGLRenderer::UpdateCameraExposure()
 void FGLRenderer::BloomScene()
 {
 	// Only bloom things if enabled and no special fixed light mode is active
-	if (!gl_bloom || gl_fixedcolormap != CM_DEFAULT)
+	if (!gl_bloom || gl_fixedcolormap != CM_DEFAULT || gl_ssao_debug)
 		return;
 
 	FGLDebug::PushGroup("BloomScene");
diff --git a/src/gl/renderer/gl_renderbuffers.cpp b/src/gl/renderer/gl_renderbuffers.cpp
index b2471e4b9..54d597c4d 100644
--- a/src/gl/renderer/gl_renderbuffers.cpp
+++ b/src/gl/renderer/gl_renderbuffers.cpp
@@ -40,6 +40,7 @@
 #include "w_wad.h"
 #include "i_system.h"
 #include "doomerrors.h"
+#include <random>
 
 CVAR(Int, gl_multisample, 1, CVAR_ARCHIVE|CVAR_GLOBALCONFIG);
 CVAR(Bool, gl_renderbuffers, true, CVAR_ARCHIVE | CVAR_GLOBALCONFIG | CVAR_NOINITCALL)
@@ -75,15 +76,16 @@ FGLRenderBuffers::~FGLRenderBuffers()
 	ClearEyeBuffers();
 	ClearBloom();
 	ClearExposureLevels();
+	ClearAmbientOcclusion();
 }
 
 void FGLRenderBuffers::ClearScene()
 {
 	DeleteFrameBuffer(mSceneFB);
-	DeleteRenderBuffer(mSceneMultisample);
-	DeleteRenderBuffer(mSceneDepthStencil);
-	DeleteRenderBuffer(mSceneDepth);
-	DeleteRenderBuffer(mSceneStencil);
+	DeleteFrameBuffer(mSceneDataFB);
+	DeleteTexture(mSceneMultisample);
+	DeleteTexture(mSceneData);
+	DeleteTexture(mSceneDepthStencil);
 }
 
 void FGLRenderBuffers::ClearPipeline()
@@ -132,6 +134,15 @@ void FGLRenderBuffers::ClearEyeBuffers()
 	mEyeFBs.Clear();
 }
 
+void FGLRenderBuffers::ClearAmbientOcclusion()
+{
+	DeleteFrameBuffer(AmbientFB0);
+	DeleteFrameBuffer(AmbientFB1);
+	DeleteTexture(AmbientTexture0);
+	DeleteTexture(AmbientTexture1);
+	DeleteTexture(AmbientRandomTexture);
+}
+
 void FGLRenderBuffers::DeleteTexture(GLuint &handle)
 {
 	if (handle != 0)
@@ -203,6 +214,7 @@ bool FGLRenderBuffers::Setup(int width, int height, int sceneWidth, int sceneHei
 	{
 		CreateBloom(sceneWidth, sceneHeight);
 		CreateExposureLevels(sceneWidth, sceneHeight);
+		CreateAmbientOcclusion(sceneWidth, sceneHeight);
 		mSceneWidth = sceneWidth;
 		mSceneHeight = sceneHeight;
 	}
@@ -240,10 +252,19 @@ void FGLRenderBuffers::CreateScene(int width, int height, int samples)
 	ClearScene();
 
 	if (samples > 1)
-		mSceneMultisample = CreateRenderBuffer("SceneMultisample", GL_RGBA16F, samples, width, height);
+	{
+		mSceneMultisample = Create2DMultisampleTexture("SceneMultisample", GL_RGBA16F, width, height, samples, false);
+		mSceneDepthStencil = Create2DMultisampleTexture("SceneDepthStencil", GL_DEPTH24_STENCIL8, width, height, samples, false);
+		mSceneData = Create2DMultisampleTexture("SceneSSAOData", GL_RGBA8, width, height, samples, false);
+	}
+	else
+	{
+		mSceneDepthStencil = Create2DTexture("SceneDepthStencil", GL_DEPTH24_STENCIL8, width, height);
+		mSceneData = Create2DTexture("SceneSSAOData", GL_RGBA8, width, height);
+	}
 
-	mSceneDepthStencil = CreateRenderBuffer("SceneDepthStencil", GL_DEPTH24_STENCIL8, samples, width, height);
-	mSceneFB = CreateFrameBuffer("SceneFB", samples > 1 ? mSceneMultisample : mPipelineTexture[0], mSceneDepthStencil, samples > 1);
+	mSceneFB = CreateFrameBuffer("SceneFB", samples > 1 ? mSceneMultisample : mPipelineTexture[0], 0, mSceneDepthStencil, samples > 1);
+	mSceneDataFB = CreateFrameBuffer("SSAOSceneFB", samples > 1 ? mSceneMultisample : mPipelineTexture[0], mSceneData, mSceneDepthStencil, samples > 1);
 }
 
 //==========================================================================
@@ -296,6 +317,47 @@ void FGLRenderBuffers::CreateBloom(int width, int height)
 	}
 }
 
+//==========================================================================
+//
+// Creates ambient occlusion working buffers
+//
+//==========================================================================
+
+void FGLRenderBuffers::CreateAmbientOcclusion(int width, int height)
+{
+	ClearAmbientOcclusion();
+
+	if (width <= 0 || height <= 0)
+		return;
+
+	AmbientWidth = width / 2;
+	AmbientHeight = height / 2;
+	AmbientTexture0 = Create2DTexture("AmbientTexture0", GL_RG32F, AmbientWidth, AmbientHeight);
+	AmbientTexture1 = Create2DTexture("AmbientTexture1", GL_RG32F, AmbientWidth, AmbientHeight);
+	AmbientFB0 = CreateFrameBuffer("AmbientFB0", AmbientTexture0);
+	AmbientFB1 = CreateFrameBuffer("AmbientFB1", AmbientTexture1);
+
+	int16_t randomValues[16 * 4];
+	std::mt19937 generator(1337);
+	std::uniform_real_distribution<double> distribution(-1.0, 1.0);
+	for (int i = 0; i < 16; i++)
+	{
+		double num_directions = 8.0; // Must be same as the define in ssao.fp
+		double angle = 2.0 * M_PI * distribution(generator) / num_directions;
+		double x = cos(angle);
+		double y = sin(angle);
+		double z = distribution(generator);
+		double w = distribution(generator);
+
+		randomValues[i * 4 + 0] = (int16_t)clamp(x * 32767.0, -32768.0, 32767.0);
+		randomValues[i * 4 + 1] = (int16_t)clamp(y * 32767.0, -32768.0, 32767.0);
+		randomValues[i * 4 + 2] = (int16_t)clamp(z * 32767.0, -32768.0, 32767.0);
+		randomValues[i * 4 + 3] = (int16_t)clamp(w * 32767.0, -32768.0, 32767.0);
+	}
+
+	AmbientRandomTexture = Create2DTexture("AmbientRandomTexture", GL_RGBA16_SNORM, 4, 4, randomValues);
+}
+
 //==========================================================================
 //
 // Creates camera exposure level buffers
@@ -368,12 +430,28 @@ void FGLRenderBuffers::CreateEyeBuffers(int eye)
 
 GLuint FGLRenderBuffers::Create2DTexture(const FString &name, GLuint format, int width, int height, const void *data)
 {
-	GLuint type = (format == GL_RGBA16F || format == GL_R32F) ? GL_FLOAT : GL_UNSIGNED_BYTE;
 	GLuint handle = 0;
 	glGenTextures(1, &handle);
 	glBindTexture(GL_TEXTURE_2D, handle);
 	FGLDebug::LabelObject(GL_TEXTURE, handle, name);
-	glTexImage2D(GL_TEXTURE_2D, 0, format, width, height, 0, format != GL_R32F ? GL_RGBA : GL_RED, type, data);
+
+	GLenum dataformat, datatype;
+	switch (format)
+	{
+	case GL_RGBA8:				dataformat = GL_RGBA; datatype = GL_UNSIGNED_BYTE; break;
+	case GL_RGBA16:				dataformat = GL_RGBA; datatype = GL_UNSIGNED_SHORT; break;
+	case GL_RGBA16F:			dataformat = GL_RGBA; datatype = GL_FLOAT; break;
+	case GL_RGBA32F:			dataformat = GL_RGBA; datatype = GL_FLOAT; break;
+	case GL_R32F:				dataformat = GL_RED; datatype = GL_FLOAT; break;
+	case GL_RG32F:				dataformat = GL_RG; datatype = GL_FLOAT; break;
+	case GL_DEPTH_COMPONENT24:	dataformat = GL_DEPTH_COMPONENT; datatype = GL_FLOAT; break;
+	case GL_STENCIL_INDEX8:		dataformat = GL_STENCIL_INDEX; datatype = GL_INT; break;
+	case GL_DEPTH24_STENCIL8:	dataformat = GL_DEPTH_STENCIL; datatype = GL_UNSIGNED_INT_24_8; break;
+	case GL_RGBA16_SNORM:		dataformat = GL_RGBA; datatype = GL_SHORT; break;
+	default: I_FatalError("Unknown format passed to FGLRenderBuffers.Create2DTexture");
+	}
+
+	glTexImage2D(GL_TEXTURE_2D, 0, format, width, height, 0, dataformat, datatype, data);
 	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
 	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
 	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
@@ -381,6 +459,17 @@ GLuint FGLRenderBuffers::Create2DTexture(const FString &name, GLuint format, int
 	return handle;
 }
 
+GLuint FGLRenderBuffers::Create2DMultisampleTexture(const FString &name, GLuint format, int width, int height, int samples, bool fixedSampleLocations)
+{
+	GLuint handle = 0;
+	glGenTextures(1, &handle);
+	glBindTexture(GL_TEXTURE_2D_MULTISAMPLE, handle);
+	FGLDebug::LabelObject(GL_TEXTURE, handle, name);
+	glTexImage2DMultisample(GL_TEXTURE_2D_MULTISAMPLE, samples, format, width, height, fixedSampleLocations);
+	glBindTexture(GL_TEXTURE_2D_MULTISAMPLE, 0);
+	return handle;
+}
+
 //==========================================================================
 //
 // Creates a render buffer
@@ -428,34 +517,26 @@ GLuint FGLRenderBuffers::CreateFrameBuffer(const FString &name, GLuint colorbuff
 	return handle;
 }
 
-GLuint FGLRenderBuffers::CreateFrameBuffer(const FString &name, GLuint colorbuffer, GLuint depthstencil, bool colorIsARenderBuffer)
+GLuint FGLRenderBuffers::CreateFrameBuffer(const FString &name, GLuint colorbuffer0, GLuint colorbuffer1, GLuint depthstencil, bool multisample)
 {
 	GLuint handle = 0;
 	glGenFramebuffers(1, &handle);
 	glBindFramebuffer(GL_FRAMEBUFFER, handle);
 	FGLDebug::LabelObject(GL_FRAMEBUFFER, handle, name);
-	if (colorIsARenderBuffer)
-		glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, colorbuffer);
+	if (multisample)
+	{
+		glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D_MULTISAMPLE, colorbuffer0, 0);
+		if (colorbuffer1 != 0)
+			glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT1, GL_TEXTURE_2D_MULTISAMPLE, colorbuffer1, 0);
+		glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT, GL_TEXTURE_2D_MULTISAMPLE, depthstencil, 0);
+	}
 	else
-		glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, colorbuffer, 0);
-	glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT, GL_RENDERBUFFER, depthstencil);
-	if (CheckFrameBufferCompleteness())
-		ClearFrameBuffer(true, true);
-	return handle;
-}
-
-GLuint FGLRenderBuffers::CreateFrameBuffer(const FString &name, GLuint colorbuffer, GLuint depth, GLuint stencil, bool colorIsARenderBuffer)
-{
-	GLuint handle = 0;
-	glGenFramebuffers(1, &handle);
-	glBindFramebuffer(GL_FRAMEBUFFER, handle);
-	FGLDebug::LabelObject(GL_FRAMEBUFFER, handle, name);
-	if (colorIsARenderBuffer)
-		glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, colorbuffer);
-	else
-		glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, colorbuffer, 0);
-	glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, depth);
-	glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT, GL_RENDERBUFFER, stencil);
+	{
+		glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, colorbuffer0, 0);
+		if (colorbuffer1 != 0)
+			glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT1, GL_TEXTURE_2D, colorbuffer1, 0);
+		glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT, GL_TEXTURE_2D, depthstencil, 0);
+	}
 	if (CheckFrameBufferCompleteness())
 		ClearFrameBuffer(true, true);
 	return handle;
@@ -475,22 +556,23 @@ bool FGLRenderBuffers::CheckFrameBufferCompleteness()
 
 	FailedCreate = true;
 
-#if 0
-	FString error = "glCheckFramebufferStatus failed: ";
-	switch (result)
+	if (gl_debug_level > 0)
 	{
-	default: error.AppendFormat("error code %d", (int)result); break;
-	case GL_FRAMEBUFFER_UNDEFINED: error << "GL_FRAMEBUFFER_UNDEFINED"; break;
-	case GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT: error << "GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT"; break;
-	case GL_FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT: error << "GL_FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT"; break;
-	case GL_FRAMEBUFFER_INCOMPLETE_DRAW_BUFFER: error << "GL_FRAMEBUFFER_INCOMPLETE_DRAW_BUFFER"; break;
-	case GL_FRAMEBUFFER_INCOMPLETE_READ_BUFFER: error << "GL_FRAMEBUFFER_INCOMPLETE_READ_BUFFER"; break;
-	case GL_FRAMEBUFFER_UNSUPPORTED: error << "GL_FRAMEBUFFER_UNSUPPORTED"; break;
-	case GL_FRAMEBUFFER_INCOMPLETE_MULTISAMPLE: error << "GL_FRAMEBUFFER_INCOMPLETE_MULTISAMPLE"; break;
-	case GL_FRAMEBUFFER_INCOMPLETE_LAYER_TARGETS: error << "GL_FRAMEBUFFER_INCOMPLETE_LAYER_TARGETS"; break;
+		FString error = "glCheckFramebufferStatus failed: ";
+		switch (result)
+		{
+		default: error.AppendFormat("error code %d", (int)result); break;
+		case GL_FRAMEBUFFER_UNDEFINED: error << "GL_FRAMEBUFFER_UNDEFINED"; break;
+		case GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT: error << "GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT"; break;
+		case GL_FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT: error << "GL_FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT"; break;
+		case GL_FRAMEBUFFER_INCOMPLETE_DRAW_BUFFER: error << "GL_FRAMEBUFFER_INCOMPLETE_DRAW_BUFFER"; break;
+		case GL_FRAMEBUFFER_INCOMPLETE_READ_BUFFER: error << "GL_FRAMEBUFFER_INCOMPLETE_READ_BUFFER"; break;
+		case GL_FRAMEBUFFER_UNSUPPORTED: error << "GL_FRAMEBUFFER_UNSUPPORTED"; break;
+		case GL_FRAMEBUFFER_INCOMPLETE_MULTISAMPLE: error << "GL_FRAMEBUFFER_INCOMPLETE_MULTISAMPLE"; break;
+		case GL_FRAMEBUFFER_INCOMPLETE_LAYER_TARGETS: error << "GL_FRAMEBUFFER_INCOMPLETE_LAYER_TARGETS"; break;
+		}
+		Printf("%s\n", error.GetChars());
 	}
-	I_FatalError(error);
-#endif
 
 	return false;
 }
@@ -595,9 +677,54 @@ void FGLRenderBuffers::BindEyeFB(int eye, bool readBuffer)
 //
 //==========================================================================
 
-void FGLRenderBuffers::BindSceneFB()
+void FGLRenderBuffers::BindSceneFB(bool sceneData)
 {
-	glBindFramebuffer(GL_FRAMEBUFFER, mSceneFB);
+	glBindFramebuffer(GL_FRAMEBUFFER, sceneData ? mSceneDataFB : mSceneFB);
+}
+
+//==========================================================================
+//
+// Binds the scene color texture to the specified texture unit
+//
+//==========================================================================
+
+void FGLRenderBuffers::BindSceneColorTexture(int index)
+{
+	glActiveTexture(GL_TEXTURE0 + index);
+	if (mSamples > 1)
+		glBindTexture(GL_TEXTURE_2D_MULTISAMPLE, mSceneMultisample);
+	else
+		glBindTexture(GL_TEXTURE_2D, mPipelineTexture[0]);
+}
+
+//==========================================================================
+//
+// Binds the scene data texture to the specified texture unit
+//
+//==========================================================================
+
+void FGLRenderBuffers::BindSceneDataTexture(int index)
+{
+	glActiveTexture(GL_TEXTURE0 + index);
+	if (mSamples > 1)
+		glBindTexture(GL_TEXTURE_2D_MULTISAMPLE, mSceneData);
+	else
+		glBindTexture(GL_TEXTURE_2D, mSceneData);
+}
+
+//==========================================================================
+//
+// Binds the depth texture to the specified texture unit
+//
+//==========================================================================
+
+void FGLRenderBuffers::BindSceneDepthTexture(int index)
+{
+	glActiveTexture(GL_TEXTURE0 + index);
+	if (mSamples > 1)
+		glBindTexture(GL_TEXTURE_2D_MULTISAMPLE, mSceneDepthStencil);
+	else
+		glBindTexture(GL_TEXTURE_2D, mSceneDepthStencil);
 }
 
 //==========================================================================
diff --git a/src/gl/renderer/gl_renderbuffers.h b/src/gl/renderer/gl_renderbuffers.h
index 4477718f4..351a0ed0c 100644
--- a/src/gl/renderer/gl_renderbuffers.h
+++ b/src/gl/renderer/gl_renderbuffers.h
@@ -31,7 +31,10 @@ public:
 
 	bool Setup(int width, int height, int sceneWidth, int sceneHeight);
 
-	void BindSceneFB();
+	void BindSceneFB(bool sceneData);
+	void BindSceneColorTexture(int index);
+	void BindSceneDataTexture(int index);
+	void BindSceneDepthTexture(int index);
 	void BlitSceneToTexture();
 
 	void BindCurrentTexture(int index);
@@ -53,6 +56,15 @@ public:
 	GLuint ExposureFB = 0;
 	bool FirstExposureFrame = true;
 
+	// Ambient occlusion buffers
+	GLuint AmbientTexture0 = 0;
+	GLuint AmbientTexture1 = 0;
+	GLuint AmbientFB0 = 0;
+	GLuint AmbientFB1 = 0;
+	int AmbientWidth = 0;
+	int AmbientHeight = 0;
+	GLuint AmbientRandomTexture = 0;
+
 	static bool IsEnabled();
 
 	int GetWidth() const { return mWidth; }
@@ -64,17 +76,19 @@ private:
 	void ClearEyeBuffers();
 	void ClearBloom();
 	void ClearExposureLevels();
+	void ClearAmbientOcclusion();
 	void CreateScene(int width, int height, int samples);
 	void CreatePipeline(int width, int height);
 	void CreateBloom(int width, int height);
 	void CreateExposureLevels(int width, int height);
 	void CreateEyeBuffers(int eye);
+	void CreateAmbientOcclusion(int width, int height);
 	GLuint Create2DTexture(const FString &name, GLuint format, int width, int height, const void *data = nullptr);
+	GLuint Create2DMultisampleTexture(const FString &name, GLuint format, int width, int height, int samples, bool fixedSampleLocations);
 	GLuint CreateRenderBuffer(const FString &name, GLuint format, int width, int height);
 	GLuint CreateRenderBuffer(const FString &name, GLuint format, int samples, int width, int height);
 	GLuint CreateFrameBuffer(const FString &name, GLuint colorbuffer);
-	GLuint CreateFrameBuffer(const FString &name, GLuint colorbuffer, GLuint depthstencil, bool colorIsARenderBuffer);
-	GLuint CreateFrameBuffer(const FString &name, GLuint colorbuffer, GLuint depth, GLuint stencil, bool colorIsARenderBuffer);
+	GLuint CreateFrameBuffer(const FString &name, GLuint colorbuffer0, GLuint colorbuffer1, GLuint depthstencil, bool multisample);
 	bool CheckFrameBufferCompleteness();
 	void ClearFrameBuffer(bool stencil, bool depth);
 	void DeleteTexture(GLuint &handle);
@@ -94,9 +108,9 @@ private:
 	// Buffers for the scene
 	GLuint mSceneMultisample = 0;
 	GLuint mSceneDepthStencil = 0;
-	GLuint mSceneDepth = 0;
-	GLuint mSceneStencil = 0;
+	GLuint mSceneData = 0;
 	GLuint mSceneFB = 0;
+	GLuint mSceneDataFB = 0;
 
 	// Effect/HUD buffers
 	GLuint mPipelineTexture[NumPipelineTextures];
diff --git a/src/gl/renderer/gl_renderer.cpp b/src/gl/renderer/gl_renderer.cpp
index 42b4a8e1b..829b2500b 100644
--- a/src/gl/renderer/gl_renderer.cpp
+++ b/src/gl/renderer/gl_renderer.cpp
@@ -51,6 +51,7 @@
 #include "gl/data/gl_vertexbuffer.h"
 #include "gl/scene/gl_drawinfo.h"
 #include "gl/shaders/gl_shader.h"
+#include "gl/shaders/gl_ambientshader.h"
 #include "gl/shaders/gl_bloomshader.h"
 #include "gl/shaders/gl_blurshader.h"
 #include "gl/shaders/gl_tonemapshader.h"
@@ -121,6 +122,8 @@ void gl_FlushModels();
 void FGLRenderer::Initialize(int width, int height)
 {
 	mBuffers = new FGLRenderBuffers();
+	mLinearDepthShader = new FLinearDepthShader();
+	mSSAOShader = new FSSAOShader();
 	mBloomExtractShader = new FBloomExtractShader();
 	mBloomCombineShader = new FBloomCombineShader();
 	mExposureExtractShader = new FExposureExtractShader();
@@ -184,6 +187,8 @@ FGLRenderer::~FGLRenderer()
 	}
 	if (mBuffers) delete mBuffers;
 	if (mPresentShader) delete mPresentShader;
+	if (mLinearDepthShader) delete mLinearDepthShader;
+	if (mSSAOShader) delete mSSAOShader;
 	if (mBloomExtractShader) delete mBloomExtractShader;
 	if (mBloomCombineShader) delete mBloomCombineShader;
 	if (mExposureExtractShader) delete mExposureExtractShader;
diff --git a/src/gl/renderer/gl_renderer.h b/src/gl/renderer/gl_renderer.h
index 71c52474a..2ec35b4a8 100644
--- a/src/gl/renderer/gl_renderer.h
+++ b/src/gl/renderer/gl_renderer.h
@@ -19,6 +19,8 @@ class FLightBuffer;
 class FSamplerManager;
 class DPSprite;
 class FGLRenderBuffers;
+class FLinearDepthShader;
+class FSSAOShader;
 class FBloomExtractShader;
 class FBloomCombineShader;
 class FExposureExtractShader;
@@ -93,6 +95,8 @@ public:
 	int mOldFBID;
 
 	FGLRenderBuffers *mBuffers;
+	FLinearDepthShader *mLinearDepthShader;
+	FSSAOShader *mSSAOShader;
 	FBloomExtractShader *mBloomExtractShader;
 	FBloomCombineShader *mBloomCombineShader;
 	FExposureExtractShader *mExposureExtractShader;
@@ -172,6 +176,8 @@ public:
 	void WriteSavePic (player_t *player, FileWriter *file, int width, int height);
 	void EndDrawScene(sector_t * viewsector);
 	void UpdateCameraExposure();
+	void PostProcessScene();
+	void AmbientOccludeScene();
 	void BloomScene();
 	void TonemapScene();
 	void ColormapScene();
@@ -198,6 +204,9 @@ public:
 		DAngle rotation, FDynamicColormap *colormap, int lightlevel);
 
 	int PTM_BestColor (const uint32 *pal_in, int r, int g, int b, int first, int num);
+
+	static float GetZNear() { return 5.f; }
+	static float GetZFar() { return 65536.f; }
 };
 
 // Global functions. Make them members of GLRenderer later?
diff --git a/src/gl/scene/gl_scene.cpp b/src/gl/scene/gl_scene.cpp
index 0c76b4bb1..27772a0ca 100644
--- a/src/gl/scene/gl_scene.cpp
+++ b/src/gl/scene/gl_scene.cpp
@@ -209,7 +209,7 @@ void FGLRenderer::SetProjection(float fov, float ratio, float fovratio)
 {
 
 	float fovy = 2 * RAD2DEG(atan(tan(DEG2RAD(fov) / 2) / fovratio));
-	gl_RenderState.mProjectionMatrix.perspective(fovy, ratio, 5.f, 65536.f);
+	gl_RenderState.mProjectionMatrix.perspective(fovy, ratio, GetZNear(), GetZFar());
 }
 
 // raw matrix input from stereo 3d modes
@@ -826,12 +826,7 @@ sector_t * FGLRenderer::RenderViewpoint (AActor * camera, GL_IRECT * bounds, flo
 		if (mainview && toscreen) EndDrawScene(lviewsector); // do not call this for camera textures.
 		if (mainview && FGLRenderBuffers::IsEnabled())
 		{
-			mBuffers->BlitSceneToTexture();
-			UpdateCameraExposure();
-			BloomScene();
-			TonemapScene();
-			ColormapScene();
-			LensDistortScene();
+			PostProcessScene();
 
 			// This should be done after postprocessing, not before.
 			mBuffers->BindCurrentFB();
diff --git a/src/gl/shaders/gl_ambientshader.cpp b/src/gl/shaders/gl_ambientshader.cpp
new file mode 100644
index 000000000..d9d4a3425
--- /dev/null
+++ b/src/gl/shaders/gl_ambientshader.cpp
@@ -0,0 +1,89 @@
+/*
+** gl_bloomshader.cpp
+** Shaders used for screen space ambient occlusion
+**
+**---------------------------------------------------------------------------
+** Copyright 2016 Magnus Norddahl
+** All rights reserved.
+**
+** Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions
+** are met:
+**
+** 1. Redistributions of source code must retain the above copyright
+**    notice, this list of conditions and the following disclaimer.
+** 2. Redistributions in binary form must reproduce the above copyright
+**    notice, this list of conditions and the following disclaimer in the
+**    documentation and/or other materials provided with the distribution.
+** 3. The name of the author may not be used to endorse or promote products
+**    derived from this software without specific prior written permission.
+** 4. When not used as part of GZDoom or a GZDoom derivative, this code will be
+**    covered by the terms of the GNU Lesser General Public License as published
+**    by the Free Software Foundation; either version 2.1 of the License, or (at
+**    your option) any later version.
+** 5. Full disclosure of the entire project's source code, except for third
+**    party libraries is mandatory. (NOTE: This clause is non-negotiable!)
+**
+** THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+** IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+** OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+** IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+** NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+** THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+**---------------------------------------------------------------------------
+**
+*/
+
+#include "gl/system/gl_system.h"
+#include "files.h"
+#include "m_swap.h"
+#include "v_video.h"
+#include "gl/gl_functions.h"
+#include "vectors.h"
+#include "gl/system/gl_interface.h"
+#include "gl/system/gl_framebuffer.h"
+#include "gl/system/gl_cvars.h"
+#include "gl/shaders/gl_ambientshader.h"
+
+void FLinearDepthShader::Bind()
+{
+	if (!mShader)
+	{
+		mShader.Compile(FShaderProgram::Vertex, "shaders/glsl/screenquad.vp", "", 330);
+		mShader.Compile(FShaderProgram::Fragment, "shaders/glsl/lineardepth.fp", "", 330);
+		mShader.SetFragDataLocation(0, "FragColor");
+		mShader.Link("shaders/glsl/lineardepth");
+		mShader.SetAttribLocation(0, "PositionInProjection");
+		DepthTexture.Init(mShader, "DepthTexture");
+		LinearizeDepthA.Init(mShader, "LinearizeDepthA");
+		LinearizeDepthB.Init(mShader, "LinearizeDepthB");
+		InverseDepthRangeA.Init(mShader, "InverseDepthRangeA");
+		InverseDepthRangeB.Init(mShader, "InverseDepthRangeB");
+	}
+	mShader.Bind();
+}
+
+void FSSAOShader::Bind()
+{
+	if (!mShader)
+	{
+		mShader.Compile(FShaderProgram::Vertex, "shaders/glsl/screenquad.vp", "", 330);
+		mShader.Compile(FShaderProgram::Fragment, "shaders/glsl/ssao.fp", "", 330);
+		mShader.SetFragDataLocation(0, "FragColor");
+		mShader.Link("shaders/glsl/ssao");
+		mShader.SetAttribLocation(0, "PositionInProjection");
+		DepthTexture.Init(mShader, "DepthTexture");
+		UVToViewA.Init(mShader, "UVToViewA");
+		UVToViewB.Init(mShader, "UVToViewB");
+		InvFullResolution.Init(mShader, "InvFullResolution");
+		NDotVBias.Init(mShader, "NDotVBias");
+		NegInvR2.Init(mShader, "NegInvR2");
+		RadiusToScreen.Init(mShader, "RadiusToScreen");
+		AOMultiplier.Init(mShader, "AOMultiplier");
+	}
+	mShader.Bind();
+}
diff --git a/src/gl/shaders/gl_ambientshader.h b/src/gl/shaders/gl_ambientshader.h
new file mode 100644
index 000000000..44f916596
--- /dev/null
+++ b/src/gl/shaders/gl_ambientshader.h
@@ -0,0 +1,39 @@
+#ifndef __GL_AMBIENTSHADER_H
+#define __GL_AMBIENTSHADER_H
+
+#include "gl_shaderprogram.h"
+
+class FLinearDepthShader
+{
+public:
+	void Bind();
+
+	FBufferedUniformSampler DepthTexture;
+	FBufferedUniform1f LinearizeDepthA;
+	FBufferedUniform1f LinearizeDepthB;
+	FBufferedUniform1f InverseDepthRangeA;
+	FBufferedUniform1f InverseDepthRangeB;
+
+private:
+	FShaderProgram mShader;
+};
+
+class FSSAOShader
+{
+public:
+	void Bind();
+
+	FBufferedUniformSampler DepthTexture;
+	FBufferedUniform2f UVToViewA;
+	FBufferedUniform2f UVToViewB;
+	FBufferedUniform2f InvFullResolution;
+	FBufferedUniform1f NDotVBias;
+	FBufferedUniform1f NegInvR2;
+	FBufferedUniform1f RadiusToScreen;
+	FBufferedUniform1f AOMultiplier;
+
+private:
+	FShaderProgram mShader;
+};
+
+#endif
\ No newline at end of file
diff --git a/src/gl/stereo3d/gl_stereo3d.cpp b/src/gl/stereo3d/gl_stereo3d.cpp
index 9403d4751..6b1623ba6 100644
--- a/src/gl/stereo3d/gl_stereo3d.cpp
+++ b/src/gl/stereo3d/gl_stereo3d.cpp
@@ -41,7 +41,7 @@ VSMatrix EyePose::GetProjection(float fov, float aspectRatio, float fovRatio) co
 
 	// Lifted from gl_scene.cpp FGLRenderer::SetProjection()
 	float fovy = (float)(2 * RAD2DEG(atan(tan(DEG2RAD(fov) / 2) / fovRatio)));
-	result.perspective(fovy, aspectRatio, 5.f, 65536.f);
+	result.perspective(fovy, aspectRatio, FGLRenderer::GetZNear(), FGLRenderer::GetZFar());
 
 	return result;
 }
diff --git a/wadsrc/static/language.enu b/wadsrc/static/language.enu
index 50526a75b..197e262f5 100644
--- a/wadsrc/static/language.enu
+++ b/wadsrc/static/language.enu
@@ -2633,6 +2633,7 @@ GLPREFMNU_MULTISAMPLE			= "Multisample";
 GLPREFMNU_TONEMAP				= "Tonemap Mode";
 GLPREFMNU_BLOOM					= "Bloom effect";
 GLPREFMNU_LENS					= "Lens distortion effect";
+GLPREFMNU_SSAO					= "Ambient occlusion";
 
 // Option Values
 OPTVAL_SMART 				= "Smart";
diff --git a/wadsrc/static/menudef.zz b/wadsrc/static/menudef.zz
index 1ab4f1a6d..68523ea83 100644
--- a/wadsrc/static/menudef.zz
+++ b/wadsrc/static/menudef.zz
@@ -226,4 +226,5 @@ OptionMenu "GLPrefOptions"
 	Option "$GLPREFMNU_TONEMAP", 				gl_tonemap,						"TonemapModes"
 	Option "$GLPREFMNU_BLOOM",		 			gl_bloom,						"OnOff"
 	Option "$GLPREFMNU_LENS",		 			gl_lens,						"OnOff"
+	Option "$GLPREFMNU_SSAO",		 			gl_ssao,						"OnOff"
 }
diff --git a/wadsrc/static/shaders/glsl/lineardepth.fp b/wadsrc/static/shaders/glsl/lineardepth.fp
new file mode 100644
index 000000000..f61bb3995
--- /dev/null
+++ b/wadsrc/static/shaders/glsl/lineardepth.fp
@@ -0,0 +1,16 @@
+
+in vec2 TexCoord;
+out vec4 FragColor;
+
+uniform sampler2D DepthTexture;
+uniform float LinearizeDepthA;
+uniform float LinearizeDepthB;
+uniform float InverseDepthRangeA;
+uniform float InverseDepthRangeB;
+
+void main()
+{
+	float depth = texture(DepthTexture, TexCoord).x;
+	float normalizedDepth = clamp(InverseDepthRangeA * depth + InverseDepthRangeB, 0.0, 1.0);
+	FragColor = vec4(1.0 / (normalizedDepth * LinearizeDepthA + LinearizeDepthB), 0.0, 0.0, 1.0);
+}
diff --git a/wadsrc/static/shaders/glsl/ssao.fp b/wadsrc/static/shaders/glsl/ssao.fp
new file mode 100644
index 000000000..c9f8534d9
--- /dev/null
+++ b/wadsrc/static/shaders/glsl/ssao.fp
@@ -0,0 +1,117 @@
+
+in vec2 TexCoord;
+out vec4 FragColor;
+
+uniform vec2 UVToViewA;
+uniform vec2 UVToViewB;
+uniform vec2 InvFullResolution;
+
+uniform float NDotVBias;
+uniform float NegInvR2;
+uniform float RadiusToScreen;
+uniform float AOMultiplier;
+
+uniform sampler2D DepthTexture;
+
+#if USE_RANDOM_TEXTURE
+uniform sampler2D RandomTexture;
+#endif
+
+#define NUM_DIRECTIONS 8.0
+#define NUM_STEPS 4.0
+
+#define PI 3.14159265358979323846
+
+// Calculate eye space position for the specified texture coordinate
+vec3 FetchViewPos(vec2 uv)
+{
+    float z = texture(DepthTexture, uv).x;
+    return vec3((UVToViewA * uv + UVToViewB) * z, z);
+}
+
+vec3 MinDiff(vec3 p, vec3 pr, vec3 pl)
+{
+    vec3 v1 = pr - p;
+    vec3 v2 = p - pl;
+    return (dot(v1, v1) < dot(v2, v2)) ? v1 : v2;
+}
+
+// Reconstruct eye space normal from nearest neighbors
+vec3 ReconstructNormal(vec3 p)
+{
+    vec3 pr = FetchViewPos(TexCoord + vec2(InvFullResolution.x, 0));
+    vec3 pl = FetchViewPos(TexCoord + vec2(-InvFullResolution.x, 0));
+    vec3 pt = FetchViewPos(TexCoord + vec2(0, InvFullResolution.y));
+    vec3 pb = FetchViewPos(TexCoord + vec2(0, -InvFullResolution.y));
+    return normalize(cross(MinDiff(p, pr, pl), MinDiff(p, pt, pb)));
+}
+
+// Compute normalized 2D direction
+vec2 RotateDirection(vec2 dir, vec2 cossin)
+{
+    return vec2(dir.x * cossin.x - dir.y * cossin.y, dir.x * cossin.y + dir.y * cossin.x);
+}
+
+vec4 GetJitter()
+{
+#if !USE_RANDOM_TEXTURE
+    return vec4(1,0,1,1);
+	//vec3 rand = noise3(TexCoord.x + TexCoord.y);
+	//float angle = 2.0 * PI * rand.x / NUM_DIRECTIONS;
+	//return vec4(cos(angle), sin(angle), rand.y, rand.z);
+#else
+	#define RANDOM_TEXTURE_WIDTH 4.0
+    return texture(RandomTexture, gl_FragCoord.xy / RANDOM_TEXTURE_WIDTH);
+#endif
+}
+
+// Calculates the ambient occlusion of a sample
+float ComputeSampleAO(vec3 kernelPos, vec3 normal, vec3 samplePos)
+{
+	vec3 v = samplePos - kernelPos;
+	float distanceSquare = dot(v, v);
+	float nDotV = dot(normal, v) * inversesqrt(distanceSquare);
+	return clamp(nDotV - NDotVBias, 0.0, 1.0) * clamp(distanceSquare * NegInvR2 + 1.0, 0.0, 1.0);
+}
+
+// Calculates the total ambient occlusion for the entire fragment
+float ComputeAO(vec3 viewPosition, vec3 viewNormal)
+{
+    vec4 rand = GetJitter();
+
+	float radiusPixels = RadiusToScreen / viewPosition.z;
+	float stepSizePixels = radiusPixels / (NUM_STEPS + 1.0);
+
+	const float directionAngleStep = 2.0 * PI / NUM_DIRECTIONS;
+	float ao = 0.0;
+
+    for (float directionIndex = 0.0; directionIndex < NUM_DIRECTIONS; ++directionIndex)
+    {
+        float angle = directionAngleStep * directionIndex;
+
+        vec2 direction = RotateDirection(vec2(cos(angle), sin(angle)), rand.xy);
+        float rayPixels = (rand.z * stepSizePixels + 1.0);
+
+        for (float StepIndex = 0.0; StepIndex < NUM_STEPS; ++StepIndex)
+        {
+            vec2 sampleUV = round(rayPixels * direction) * InvFullResolution + TexCoord;
+            vec3 samplePos = FetchViewPos(sampleUV);
+            ao += ComputeSampleAO(viewPosition, viewNormal, samplePos);
+            rayPixels += stepSizePixels;
+        }
+    }
+
+    ao *= AOMultiplier / (NUM_DIRECTIONS * NUM_STEPS);
+    return clamp(1.0 - ao * 2.0, 0.0, 1.0);
+}
+
+void main()
+{
+    vec3 viewPosition = FetchViewPos(TexCoord);
+    vec3 viewNormal = ReconstructNormal(viewPosition);
+	float occlusion = ComputeAO(viewPosition, viewNormal);
+	//FragColor = vec4(viewPosition.x * 0.001 + 0.5, viewPosition.y * 0.001 + 0.5, viewPosition.z * 0.001, 1.0);
+	//FragColor = vec4(viewNormal.x * 0.5 + 0.5, viewNormal.y * 0.5 + 0.5, viewNormal.z * 0.5 + 0.5, 1.0);
+	//FragColor = vec4(occlusion, viewPosition.z, 0.0, 1.0);
+	FragColor = vec4(occlusion, occlusion, occlusion, 1.0);
+}

From 723eb746f660d8ee63b63fff7a515ad27fb4264f Mon Sep 17 00:00:00 2001
From: Magnus Norddahl <dpjudas@users.noreply.github.com>
Date: Tue, 30 Aug 2016 01:09:21 +0200
Subject: [PATCH 02/18] Add ssao random texture

---
 src/gl/renderer/gl_postprocess.cpp  | 10 ++++++++++
 src/gl/shaders/gl_ambientshader.cpp | 11 ++++++++++-
 src/gl/shaders/gl_ambientshader.h   |  2 ++
 wadsrc/static/shaders/glsl/ssao.fp  | 16 +++++++++-------
 4 files changed, 31 insertions(+), 8 deletions(-)

diff --git a/src/gl/renderer/gl_postprocess.cpp b/src/gl/renderer/gl_postprocess.cpp
index 9df28ce5b..4fb83c642 100644
--- a/src/gl/renderer/gl_postprocess.cpp
+++ b/src/gl/renderer/gl_postprocess.cpp
@@ -100,6 +100,7 @@ CVAR(Float, gl_lens_kcube, 0.1f, 0)
 CVAR(Float, gl_lens_chromatic, 1.12f, 0)
 
 CVAR(Bool, gl_ssao, false, CVAR_ARCHIVE | CVAR_GLOBALCONFIG)
+CVAR(Float, gl_ssao_strength, 0.7, CVAR_ARCHIVE | CVAR_GLOBALCONFIG)
 CVAR(Bool, gl_ssao_debug, false, 0)
 CVAR(Float, gl_ssao_bias, 0.5f, 0)
 CVAR(Float, gl_ssao_radius, 100.0f, 0)
@@ -148,11 +149,13 @@ void FGLRenderer::AmbientOccludeScene()
 	FGLDebug::PushGroup("AmbientOccludeScene");
 
 	FGLPostProcessState savedState;
+	savedState.SaveTextureBinding1();
 
 	float bias = gl_ssao_bias;
 	float aoRadius = gl_ssao_radius;
 	const float blurAmount = gl_ssao_blur_amount;
 	int blurSampleCount = gl_ssao_blur_samples;
+	float aoStrength = gl_ssao_strength;
 
 	//float tanHalfFovy = tan(fovy * (M_PI / 360.0f));
 	float tanHalfFovy = 1.0f / 1.33333302f; //gl_RenderState.mProjectionMatrix.get()[5];
@@ -178,8 +181,14 @@ void FGLRenderer::AmbientOccludeScene()
 	glBindTexture(GL_TEXTURE_2D, mBuffers->AmbientTexture0);
 	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
 	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+	glActiveTexture(GL_TEXTURE1);
+	glBindTexture(GL_TEXTURE_2D, mBuffers->AmbientRandomTexture);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+	glActiveTexture(GL_TEXTURE0);
 	mSSAOShader->Bind();
 	mSSAOShader->DepthTexture.Set(0);
+	mSSAOShader->RandomTexture.Set(1);
 	mSSAOShader->UVToViewA.Set(2.0f * invFocalLenX, -2.0f * invFocalLenY);
 	mSSAOShader->UVToViewB.Set(-invFocalLenX, invFocalLenY);
 	mSSAOShader->InvFullResolution.Set(1.0f / mBuffers->AmbientWidth, 1.0f / mBuffers->AmbientHeight);
@@ -187,6 +196,7 @@ void FGLRenderer::AmbientOccludeScene()
 	mSSAOShader->NegInvR2.Set(-1.0f / r2);
 	mSSAOShader->RadiusToScreen.Set(aoRadius * 0.5 / tanHalfFovy * mBuffers->AmbientHeight);
 	mSSAOShader->AOMultiplier.Set(1.0f / (1.0f - nDotVBias));
+	mSSAOShader->AOStrength.Set(aoStrength);
 	RenderScreenQuad();
 
 	// Blur SSAO texture
diff --git a/src/gl/shaders/gl_ambientshader.cpp b/src/gl/shaders/gl_ambientshader.cpp
index d9d4a3425..55682a91e 100644
--- a/src/gl/shaders/gl_ambientshader.cpp
+++ b/src/gl/shaders/gl_ambientshader.cpp
@@ -71,12 +71,20 @@ void FSSAOShader::Bind()
 {
 	if (!mShader)
 	{
+		const char *defines = R"(
+			#define USE_RANDOM_TEXTURE
+			#define RANDOM_TEXTURE_WIDTH 4.0
+			#define NUM_DIRECTIONS 8.0
+			#define NUM_STEPS 4.0
+		)";
+
 		mShader.Compile(FShaderProgram::Vertex, "shaders/glsl/screenquad.vp", "", 330);
-		mShader.Compile(FShaderProgram::Fragment, "shaders/glsl/ssao.fp", "", 330);
+		mShader.Compile(FShaderProgram::Fragment, "shaders/glsl/ssao.fp", defines, 330);
 		mShader.SetFragDataLocation(0, "FragColor");
 		mShader.Link("shaders/glsl/ssao");
 		mShader.SetAttribLocation(0, "PositionInProjection");
 		DepthTexture.Init(mShader, "DepthTexture");
+		RandomTexture.Init(mShader, "RandomTexture");
 		UVToViewA.Init(mShader, "UVToViewA");
 		UVToViewB.Init(mShader, "UVToViewB");
 		InvFullResolution.Init(mShader, "InvFullResolution");
@@ -84,6 +92,7 @@ void FSSAOShader::Bind()
 		NegInvR2.Init(mShader, "NegInvR2");
 		RadiusToScreen.Init(mShader, "RadiusToScreen");
 		AOMultiplier.Init(mShader, "AOMultiplier");
+		AOStrength.Init(mShader, "AOStrength");
 	}
 	mShader.Bind();
 }
diff --git a/src/gl/shaders/gl_ambientshader.h b/src/gl/shaders/gl_ambientshader.h
index 44f916596..fdff178ec 100644
--- a/src/gl/shaders/gl_ambientshader.h
+++ b/src/gl/shaders/gl_ambientshader.h
@@ -24,6 +24,7 @@ public:
 	void Bind();
 
 	FBufferedUniformSampler DepthTexture;
+	FBufferedUniformSampler RandomTexture;
 	FBufferedUniform2f UVToViewA;
 	FBufferedUniform2f UVToViewB;
 	FBufferedUniform2f InvFullResolution;
@@ -31,6 +32,7 @@ public:
 	FBufferedUniform1f NegInvR2;
 	FBufferedUniform1f RadiusToScreen;
 	FBufferedUniform1f AOMultiplier;
+	FBufferedUniform1f AOStrength;
 
 private:
 	FShaderProgram mShader;
diff --git a/wadsrc/static/shaders/glsl/ssao.fp b/wadsrc/static/shaders/glsl/ssao.fp
index c9f8534d9..f143e913f 100644
--- a/wadsrc/static/shaders/glsl/ssao.fp
+++ b/wadsrc/static/shaders/glsl/ssao.fp
@@ -11,15 +11,14 @@ uniform float NegInvR2;
 uniform float RadiusToScreen;
 uniform float AOMultiplier;
 
+uniform float AOStrength;
+
 uniform sampler2D DepthTexture;
 
-#if USE_RANDOM_TEXTURE
+#if defined(USE_RANDOM_TEXTURE)
 uniform sampler2D RandomTexture;
 #endif
 
-#define NUM_DIRECTIONS 8.0
-#define NUM_STEPS 4.0
-
 #define PI 3.14159265358979323846
 
 // Calculate eye space position for the specified texture coordinate
@@ -54,13 +53,12 @@ vec2 RotateDirection(vec2 dir, vec2 cossin)
 
 vec4 GetJitter()
 {
-#if !USE_RANDOM_TEXTURE
+#if !defined(USE_RANDOM_TEXTURE)
     return vec4(1,0,1,1);
 	//vec3 rand = noise3(TexCoord.x + TexCoord.y);
 	//float angle = 2.0 * PI * rand.x / NUM_DIRECTIONS;
 	//return vec4(cos(angle), sin(angle), rand.y, rand.z);
 #else
-	#define RANDOM_TEXTURE_WIDTH 4.0
     return texture(RandomTexture, gl_FragCoord.xy / RANDOM_TEXTURE_WIDTH);
 #endif
 }
@@ -109,7 +107,11 @@ void main()
 {
     vec3 viewPosition = FetchViewPos(TexCoord);
     vec3 viewNormal = ReconstructNormal(viewPosition);
-	float occlusion = ComputeAO(viewPosition, viewNormal);
+	float occlusion = ComputeAO(viewPosition, viewNormal) * AOStrength + (1.0 - AOStrength);
+
+	// GZDoom does not use linear buffers at the moment, apply some gamma to get it closer to correct
+	occlusion = occlusion * occlusion;
+
 	//FragColor = vec4(viewPosition.x * 0.001 + 0.5, viewPosition.y * 0.001 + 0.5, viewPosition.z * 0.001, 1.0);
 	//FragColor = vec4(viewNormal.x * 0.5 + 0.5, viewNormal.y * 0.5 + 0.5, viewNormal.z * 0.5 + 0.5, 1.0);
 	//FragColor = vec4(occlusion, viewPosition.z, 0.0, 1.0);

From a6fdaca6337cc2226dafb3a26e38273a2bb0e909 Mon Sep 17 00:00:00 2001
From: Magnus Norddahl <dpjudas@users.noreply.github.com>
Date: Thu, 1 Sep 2016 07:15:40 +0200
Subject: [PATCH 03/18] Fix precision issue in SSAO shader

---
 src/gl/renderer/gl_postprocess.cpp | 8 ++++----
 src/gl/renderer/gl_renderbuffers.h | 3 +++
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/src/gl/renderer/gl_postprocess.cpp b/src/gl/renderer/gl_postprocess.cpp
index 4fb83c642..2356eaee7 100644
--- a/src/gl/renderer/gl_postprocess.cpp
+++ b/src/gl/renderer/gl_postprocess.cpp
@@ -104,11 +104,11 @@ CVAR(Float, gl_ssao_strength, 0.7, CVAR_ARCHIVE | CVAR_GLOBALCONFIG)
 CVAR(Bool, gl_ssao_debug, false, 0)
 CVAR(Float, gl_ssao_bias, 0.5f, 0)
 CVAR(Float, gl_ssao_radius, 100.0f, 0)
-CUSTOM_CVAR(Float, gl_ssao_blur_amount, 6.0f, 0)
+CUSTOM_CVAR(Float, gl_ssao_blur_amount, 4.0f, 0)
 {
 	if (self < 0.1f) self = 0.1f;
 }
-CUSTOM_CVAR(Int, gl_ssao_blur_samples, 9, 0)
+CUSTOM_CVAR(Int, gl_ssao_blur_samples, 5, 0)
 {
 	if (self < 3 || self > 15 || self % 2 == 0)
 		self = 9;
@@ -158,8 +158,8 @@ void FGLRenderer::AmbientOccludeScene()
 	float aoStrength = gl_ssao_strength;
 
 	//float tanHalfFovy = tan(fovy * (M_PI / 360.0f));
-	float tanHalfFovy = 1.0f / 1.33333302f; //gl_RenderState.mProjectionMatrix.get()[5];
-	float invFocalLenX = tanHalfFovy * (mBuffers->AmbientWidth / (float)mBuffers->AmbientHeight);
+	float tanHalfFovy = 1.0f / 1.33333302f; // 1.0f / gl_RenderState.mProjectionMatrix.get()[5];
+	float invFocalLenX = tanHalfFovy * (mBuffers->GetSceneWidth() / (float)mBuffers->GetSceneHeight());
 	float invFocalLenY = tanHalfFovy;
 	float nDotVBias = clamp(bias, 0.0f, 1.0f);
 	float r2 = aoRadius * aoRadius;
diff --git a/src/gl/renderer/gl_renderbuffers.h b/src/gl/renderer/gl_renderbuffers.h
index 351a0ed0c..080593881 100644
--- a/src/gl/renderer/gl_renderbuffers.h
+++ b/src/gl/renderer/gl_renderbuffers.h
@@ -70,6 +70,9 @@ public:
 	int GetWidth() const { return mWidth; }
 	int GetHeight() const { return mHeight; }
 
+	int GetSceneWidth() const { return mSceneWidth; }
+	int GetSceneHeight() const { return mSceneHeight; }
+
 private:
 	void ClearScene();
 	void ClearPipeline();

From a246b586733613f318897d64a0f65df092c058c6 Mon Sep 17 00:00:00 2001
From: Magnus Norddahl <dpjudas@users.noreply.github.com>
Date: Fri, 2 Sep 2016 05:45:00 +0200
Subject: [PATCH 04/18] Change SSAO blur to be depth aware

---
 src/gl/renderer/gl_postprocess.cpp        | 22 ++++--
 src/gl/renderer/gl_renderer.cpp           |  8 +++
 src/gl/renderer/gl_renderer.h             |  4 ++
 src/gl/shaders/gl_ambientshader.cpp       | 32 +++++++++
 src/gl/shaders/gl_ambientshader.h         | 25 +++++++
 wadsrc/static/shaders/glsl/depthblur.fp   | 81 +++++++++++++++++++++++
 wadsrc/static/shaders/glsl/ssao.fp        |  9 +--
 wadsrc/static/shaders/glsl/ssaocombine.fp | 11 +++
 8 files changed, 180 insertions(+), 12 deletions(-)
 create mode 100644 wadsrc/static/shaders/glsl/depthblur.fp
 create mode 100644 wadsrc/static/shaders/glsl/ssaocombine.fp

diff --git a/src/gl/renderer/gl_postprocess.cpp b/src/gl/renderer/gl_postprocess.cpp
index 2356eaee7..97491cb58 100644
--- a/src/gl/renderer/gl_postprocess.cpp
+++ b/src/gl/renderer/gl_postprocess.cpp
@@ -200,8 +200,22 @@ void FGLRenderer::AmbientOccludeScene()
 	RenderScreenQuad();
 
 	// Blur SSAO texture
-	mBlurShader->BlurHorizontal(this, blurAmount, blurSampleCount, mBuffers->AmbientTexture1, mBuffers->AmbientFB0, mBuffers->AmbientWidth, mBuffers->AmbientHeight);
-	mBlurShader->BlurVertical(this, blurAmount, blurSampleCount, mBuffers->AmbientTexture0, mBuffers->AmbientFB1, mBuffers->AmbientWidth, mBuffers->AmbientHeight);
+	glBindFramebuffer(GL_FRAMEBUFFER, mBuffers->AmbientFB0);
+	glBindTexture(GL_TEXTURE_2D, mBuffers->AmbientTexture1);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+	mDepthBlurShader->Bind(false);
+	mDepthBlurShader->BlurSharpness[false].Set(blurAmount);
+	mDepthBlurShader->InvFullResolution[false].Set(1.0f / mBuffers->AmbientWidth, 1.0f / mBuffers->AmbientHeight);
+	RenderScreenQuad();
+
+	glBindFramebuffer(GL_FRAMEBUFFER, mBuffers->AmbientFB1);
+	glBindTexture(GL_TEXTURE_2D, mBuffers->AmbientTexture0);
+	mDepthBlurShader->Bind(true);
+	mDepthBlurShader->BlurSharpness[true].Set(blurAmount);
+	mDepthBlurShader->InvFullResolution[true].Set(1.0f / mBuffers->AmbientWidth, 1.0f / mBuffers->AmbientHeight);
+	mDepthBlurShader->PowExponent[true].Set(1.8f);
+	RenderScreenQuad();
 
 	// Add SSAO back to scene texture:
 	mBuffers->BindCurrentFB();
@@ -216,8 +230,8 @@ void FGLRenderer::AmbientOccludeScene()
 	glBindTexture(GL_TEXTURE_2D, mBuffers->AmbientTexture1);
 	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
 	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
-	mBloomCombineShader->Bind();
-	mBloomCombineShader->BloomTexture.Set(0);
+	mSSAOCombineShader->Bind();
+	mSSAOCombineShader->AODepthTexture.Set(0);
 	RenderScreenQuad();
 	glViewport(mScreenViewport.left, mScreenViewport.top, mScreenViewport.width, mScreenViewport.height);
 
diff --git a/src/gl/renderer/gl_renderer.cpp b/src/gl/renderer/gl_renderer.cpp
index 829b2500b..befa330e9 100644
--- a/src/gl/renderer/gl_renderer.cpp
+++ b/src/gl/renderer/gl_renderer.cpp
@@ -114,6 +114,10 @@ FGLRenderer::FGLRenderer(OpenGLFrameBuffer *fb)
 	mTonemapPalette = nullptr;
 	mColormapShader = nullptr;
 	mLensShader = nullptr;
+	mLinearDepthShader = nullptr;
+	mDepthBlurShader = nullptr;
+	mSSAOShader = nullptr;
+	mSSAOCombineShader = nullptr;
 }
 
 void gl_LoadModels();
@@ -123,7 +127,9 @@ void FGLRenderer::Initialize(int width, int height)
 {
 	mBuffers = new FGLRenderBuffers();
 	mLinearDepthShader = new FLinearDepthShader();
+	mDepthBlurShader = new FDepthBlurShader();
 	mSSAOShader = new FSSAOShader();
+	mSSAOCombineShader = new FSSAOCombineShader();
 	mBloomExtractShader = new FBloomExtractShader();
 	mBloomCombineShader = new FBloomCombineShader();
 	mExposureExtractShader = new FExposureExtractShader();
@@ -188,7 +194,9 @@ FGLRenderer::~FGLRenderer()
 	if (mBuffers) delete mBuffers;
 	if (mPresentShader) delete mPresentShader;
 	if (mLinearDepthShader) delete mLinearDepthShader;
+	if (mDepthBlurShader) delete mDepthBlurShader;
 	if (mSSAOShader) delete mSSAOShader;
+	if (mSSAOCombineShader) delete mSSAOCombineShader;
 	if (mBloomExtractShader) delete mBloomExtractShader;
 	if (mBloomCombineShader) delete mBloomCombineShader;
 	if (mExposureExtractShader) delete mExposureExtractShader;
diff --git a/src/gl/renderer/gl_renderer.h b/src/gl/renderer/gl_renderer.h
index 2ec35b4a8..a285c9ef7 100644
--- a/src/gl/renderer/gl_renderer.h
+++ b/src/gl/renderer/gl_renderer.h
@@ -20,7 +20,9 @@ class FSamplerManager;
 class DPSprite;
 class FGLRenderBuffers;
 class FLinearDepthShader;
+class FDepthBlurShader;
 class FSSAOShader;
+class FSSAOCombineShader;
 class FBloomExtractShader;
 class FBloomCombineShader;
 class FExposureExtractShader;
@@ -97,6 +99,8 @@ public:
 	FGLRenderBuffers *mBuffers;
 	FLinearDepthShader *mLinearDepthShader;
 	FSSAOShader *mSSAOShader;
+	FDepthBlurShader *mDepthBlurShader;
+	FSSAOCombineShader *mSSAOCombineShader;
 	FBloomExtractShader *mBloomExtractShader;
 	FBloomCombineShader *mBloomCombineShader;
 	FExposureExtractShader *mExposureExtractShader;
diff --git a/src/gl/shaders/gl_ambientshader.cpp b/src/gl/shaders/gl_ambientshader.cpp
index 55682a91e..6b8c9cc48 100644
--- a/src/gl/shaders/gl_ambientshader.cpp
+++ b/src/gl/shaders/gl_ambientshader.cpp
@@ -96,3 +96,35 @@ void FSSAOShader::Bind()
 	}
 	mShader.Bind();
 }
+
+void FDepthBlurShader::Bind(bool vertical)
+{
+	auto &shader = mShader[vertical];
+	if (!shader)
+	{
+		shader.Compile(FShaderProgram::Vertex, "shaders/glsl/screenquad.vp", "", 330);
+		shader.Compile(FShaderProgram::Fragment, "shaders/glsl/depthblur.fp", vertical ? "#define BLUR_VERTICAL\n" : "#define BLUR_HORIZONTAL\n", 330);
+		shader.SetFragDataLocation(0, "FragColor");
+		shader.Link("shaders/glsl/depthblur");
+		shader.SetAttribLocation(0, "PositionInProjection");
+		AODepthTexture[vertical].Init(shader, "AODepthTexture");
+		BlurSharpness[vertical].Init(shader, "BlurSharpness");
+		InvFullResolution[vertical].Init(shader, "InvFullResolution");
+		PowExponent[vertical].Init(shader, "PowExponent");
+	}
+	shader.Bind();
+}
+
+void FSSAOCombineShader::Bind()
+{
+	if (!mShader)
+	{
+		mShader.Compile(FShaderProgram::Vertex, "shaders/glsl/screenquad.vp", "", 330);
+		mShader.Compile(FShaderProgram::Fragment, "shaders/glsl/ssaocombine.fp", "", 330);
+		mShader.SetFragDataLocation(0, "FragColor");
+		mShader.Link("shaders/glsl/ssaocombine");
+		mShader.SetAttribLocation(0, "PositionInProjection");
+		AODepthTexture.Init(mShader, "AODepthTexture");
+	}
+	mShader.Bind();
+}
diff --git a/src/gl/shaders/gl_ambientshader.h b/src/gl/shaders/gl_ambientshader.h
index fdff178ec..419ca939e 100644
--- a/src/gl/shaders/gl_ambientshader.h
+++ b/src/gl/shaders/gl_ambientshader.h
@@ -38,4 +38,29 @@ private:
 	FShaderProgram mShader;
 };
 
+class FDepthBlurShader
+{
+public:
+	void Bind(bool vertical);
+
+	FBufferedUniformSampler AODepthTexture[2];
+	FBufferedUniform1f BlurSharpness[2];
+	FBufferedUniform2f InvFullResolution[2];
+	FBufferedUniform1f PowExponent[2];
+
+private:
+	FShaderProgram mShader[2];
+};
+
+class FSSAOCombineShader
+{
+public:
+	void Bind();
+
+	FBufferedUniformSampler AODepthTexture;
+
+private:
+	FShaderProgram mShader;
+};
+
 #endif
\ No newline at end of file
diff --git a/wadsrc/static/shaders/glsl/depthblur.fp b/wadsrc/static/shaders/glsl/depthblur.fp
new file mode 100644
index 000000000..bd464d03d
--- /dev/null
+++ b/wadsrc/static/shaders/glsl/depthblur.fp
@@ -0,0 +1,81 @@
+
+in vec2 TexCoord;
+out vec4 FragColor;
+
+uniform sampler2D AODepthTexture;
+uniform float BlurSharpness;
+uniform vec2 InvFullResolution;
+uniform float PowExponent;
+
+#define KERNEL_RADIUS 3.0
+
+struct CenterPixelData
+{
+	vec2 UV;
+	float Depth;
+	float Sharpness;
+};
+
+float CrossBilateralWeight(float r, float sampleDepth, CenterPixelData center)
+{
+	const float blurSigma = KERNEL_RADIUS * 0.5;
+	const float blurFalloff = 1.0 / (2.0 * blurSigma * blurSigma);
+
+	float deltaZ = (sampleDepth - center.Depth) * center.Sharpness;
+
+	return exp2(-r * r * blurFalloff - deltaZ * deltaZ);
+}
+
+void ProcessSample(float ao, float z, float r, CenterPixelData center, inout float totalAO, inout float totalW)
+{
+	float w = CrossBilateralWeight(r, z, center);
+	totalAO += w * ao;
+	totalW += w;
+}
+
+void ProcessRadius(vec2 deltaUV, CenterPixelData center, inout float totalAO, inout float totalW)
+{
+	for (float r = 1; r <= KERNEL_RADIUS; r += 1.0)
+	{
+		vec2 uv = r * deltaUV + center.UV;
+		vec2 aoZ = texture(AODepthTexture, uv).xy;
+		ProcessSample(aoZ.x, aoZ.y, r, center, totalAO, totalW);
+	}
+}
+
+vec2 ComputeBlur(vec2 deltaUV)
+{
+	vec2 aoZ = texture(AODepthTexture, TexCoord).xy;
+
+	CenterPixelData center;
+	center.UV = TexCoord;
+	center.Depth = aoZ.y;
+	center.Sharpness = BlurSharpness;
+
+	float totalAO = aoZ.x;
+	float totalW = 1.0;
+
+	ProcessRadius(deltaUV, center, totalAO, totalW);
+	ProcessRadius(-deltaUV, center, totalAO, totalW);
+
+	return vec2(totalAO / totalW, aoZ.y);
+}
+
+vec2 BlurX()
+{
+	return ComputeBlur(vec2(InvFullResolution.x, 0.0));
+}
+
+float BlurY()
+{
+	return pow(clamp(ComputeBlur(vec2(0.0, InvFullResolution.y)).x, 0.0, 1.0), PowExponent);
+}
+
+void main()
+{
+#if defined(BLUR_HORIZONTAL)
+	FragColor = vec4(BlurX(), 0.0, 1.0);
+#else
+	FragColor = vec4(BlurY(), 0.0, 0.0, 1.0);
+#endif
+}
diff --git a/wadsrc/static/shaders/glsl/ssao.fp b/wadsrc/static/shaders/glsl/ssao.fp
index f143e913f..e0d972c57 100644
--- a/wadsrc/static/shaders/glsl/ssao.fp
+++ b/wadsrc/static/shaders/glsl/ssao.fp
@@ -108,12 +108,5 @@ void main()
     vec3 viewPosition = FetchViewPos(TexCoord);
     vec3 viewNormal = ReconstructNormal(viewPosition);
 	float occlusion = ComputeAO(viewPosition, viewNormal) * AOStrength + (1.0 - AOStrength);
-
-	// GZDoom does not use linear buffers at the moment, apply some gamma to get it closer to correct
-	occlusion = occlusion * occlusion;
-
-	//FragColor = vec4(viewPosition.x * 0.001 + 0.5, viewPosition.y * 0.001 + 0.5, viewPosition.z * 0.001, 1.0);
-	//FragColor = vec4(viewNormal.x * 0.5 + 0.5, viewNormal.y * 0.5 + 0.5, viewNormal.z * 0.5 + 0.5, 1.0);
-	//FragColor = vec4(occlusion, viewPosition.z, 0.0, 1.0);
-	FragColor = vec4(occlusion, occlusion, occlusion, 1.0);
+	FragColor = vec4(occlusion, viewPosition.z, 0.0, 1.0);
 }
diff --git a/wadsrc/static/shaders/glsl/ssaocombine.fp b/wadsrc/static/shaders/glsl/ssaocombine.fp
new file mode 100644
index 000000000..21fdff102
--- /dev/null
+++ b/wadsrc/static/shaders/glsl/ssaocombine.fp
@@ -0,0 +1,11 @@
+
+in vec2 TexCoord;
+out vec4 FragColor;
+
+uniform sampler2D AODepthTexture;
+
+void main()
+{
+	float attenutation = texture(AODepthTexture, TexCoord).x;
+	FragColor = vec4(attenutation, attenutation, attenutation, 0.0);
+}

From 09bec67821f6ac1a78aab3bfbd037b1397721b2a Mon Sep 17 00:00:00 2001
From: Magnus Norddahl <dpjudas@users.noreply.github.com>
Date: Sat, 3 Sep 2016 04:12:00 +0200
Subject: [PATCH 05/18] Resolve multisampling depth in shader

---
 src/gl/renderer/gl_postprocess.cpp        | 21 +++++++++--------
 src/gl/shaders/gl_ambientshader.cpp       | 28 ++++++++++++-----------
 src/gl/shaders/gl_ambientshader.h         | 15 ++++++------
 wadsrc/static/shaders/glsl/lineardepth.fp | 19 +++++++++++++++
 4 files changed, 54 insertions(+), 29 deletions(-)

diff --git a/src/gl/renderer/gl_postprocess.cpp b/src/gl/renderer/gl_postprocess.cpp
index 97491cb58..8282bc387 100644
--- a/src/gl/renderer/gl_postprocess.cpp
+++ b/src/gl/renderer/gl_postprocess.cpp
@@ -127,8 +127,7 @@ void FGLRenderer::RenderScreenQuad()
 
 void FGLRenderer::PostProcessScene()
 {
-	if (FGLRenderBuffers::IsEnabled()) mBuffers->BlitSceneToTexture();
-	AmbientOccludeScene();
+	mBuffers->BlitSceneToTexture();
 	UpdateCameraExposure();
 	BloomScene();
 	TonemapScene();
@@ -156,6 +155,7 @@ void FGLRenderer::AmbientOccludeScene()
 	const float blurAmount = gl_ssao_blur_amount;
 	int blurSampleCount = gl_ssao_blur_samples;
 	float aoStrength = gl_ssao_strength;
+	bool multisample = gl_multisample > 1;
 
 	//float tanHalfFovy = tan(fovy * (M_PI / 360.0f));
 	float tanHalfFovy = 1.0f / 1.33333302f; // 1.0f / gl_RenderState.mProjectionMatrix.get()[5];
@@ -168,12 +168,15 @@ void FGLRenderer::AmbientOccludeScene()
 	glBindFramebuffer(GL_FRAMEBUFFER, mBuffers->AmbientFB0);
 	glViewport(0, 0, mBuffers->AmbientWidth, mBuffers->AmbientHeight);
 	mBuffers->BindSceneDepthTexture(0);
-	mLinearDepthShader->Bind();
-	mLinearDepthShader->DepthTexture.Set(0);
-	mLinearDepthShader->LinearizeDepthA.Set(1.0f / GetZFar() - 1.0f / GetZNear());
-	mLinearDepthShader->LinearizeDepthB.Set(MAX(1.0f / GetZNear(), 1.e-8f));
-	mLinearDepthShader->InverseDepthRangeA.Set(1.0f);
-	mLinearDepthShader->InverseDepthRangeB.Set(0.0f);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+	mLinearDepthShader->Bind(multisample);
+	mLinearDepthShader->DepthTexture[multisample].Set(0);
+	if (multisample) mLinearDepthShader->SampleCount[multisample].Set(gl_multisample);
+	mLinearDepthShader->LinearizeDepthA[multisample].Set(1.0f / GetZFar() - 1.0f / GetZNear());
+	mLinearDepthShader->LinearizeDepthB[multisample].Set(MAX(1.0f / GetZNear(), 1.e-8f));
+	mLinearDepthShader->InverseDepthRangeA[multisample].Set(1.0f);
+	mLinearDepthShader->InverseDepthRangeB[multisample].Set(0.0f);
 	RenderScreenQuad();
 
 	// Apply ambient occlusion
@@ -218,7 +221,7 @@ void FGLRenderer::AmbientOccludeScene()
 	RenderScreenQuad();
 
 	// Add SSAO back to scene texture:
-	mBuffers->BindCurrentFB();
+	mBuffers->BindSceneFB();
 	glViewport(mSceneViewport.left, mSceneViewport.top, mSceneViewport.width, mSceneViewport.height);
 	glEnable(GL_BLEND);
 	glBlendEquation(GL_FUNC_ADD);
diff --git a/src/gl/shaders/gl_ambientshader.cpp b/src/gl/shaders/gl_ambientshader.cpp
index 6b8c9cc48..f3b6eced6 100644
--- a/src/gl/shaders/gl_ambientshader.cpp
+++ b/src/gl/shaders/gl_ambientshader.cpp
@@ -49,22 +49,24 @@
 #include "gl/system/gl_cvars.h"
 #include "gl/shaders/gl_ambientshader.h"
 
-void FLinearDepthShader::Bind()
+void FLinearDepthShader::Bind(bool multisample)
 {
-	if (!mShader)
+	auto &shader = mShader[multisample];
+	if (!shader)
 	{
-		mShader.Compile(FShaderProgram::Vertex, "shaders/glsl/screenquad.vp", "", 330);
-		mShader.Compile(FShaderProgram::Fragment, "shaders/glsl/lineardepth.fp", "", 330);
-		mShader.SetFragDataLocation(0, "FragColor");
-		mShader.Link("shaders/glsl/lineardepth");
-		mShader.SetAttribLocation(0, "PositionInProjection");
-		DepthTexture.Init(mShader, "DepthTexture");
-		LinearizeDepthA.Init(mShader, "LinearizeDepthA");
-		LinearizeDepthB.Init(mShader, "LinearizeDepthB");
-		InverseDepthRangeA.Init(mShader, "InverseDepthRangeA");
-		InverseDepthRangeB.Init(mShader, "InverseDepthRangeB");
+		shader.Compile(FShaderProgram::Vertex, "shaders/glsl/screenquad.vp", "", 330);
+		shader.Compile(FShaderProgram::Fragment, "shaders/glsl/lineardepth.fp", multisample ? "#define MULTISAMPLE\n" : "", 330);
+		shader.SetFragDataLocation(0, "FragColor");
+		shader.Link("shaders/glsl/lineardepth");
+		shader.SetAttribLocation(0, "PositionInProjection");
+		DepthTexture[multisample].Init(shader, "DepthTexture");
+		SampleCount[multisample].Init(shader, "SampleCount");
+		LinearizeDepthA[multisample].Init(shader, "LinearizeDepthA");
+		LinearizeDepthB[multisample].Init(shader, "LinearizeDepthB");
+		InverseDepthRangeA[multisample].Init(shader, "InverseDepthRangeA");
+		InverseDepthRangeB[multisample].Init(shader, "InverseDepthRangeB");
 	}
-	mShader.Bind();
+	shader.Bind();
 }
 
 void FSSAOShader::Bind()
diff --git a/src/gl/shaders/gl_ambientshader.h b/src/gl/shaders/gl_ambientshader.h
index 419ca939e..5f9ef630b 100644
--- a/src/gl/shaders/gl_ambientshader.h
+++ b/src/gl/shaders/gl_ambientshader.h
@@ -6,16 +6,17 @@
 class FLinearDepthShader
 {
 public:
-	void Bind();
+	void Bind(bool multisample);
 
-	FBufferedUniformSampler DepthTexture;
-	FBufferedUniform1f LinearizeDepthA;
-	FBufferedUniform1f LinearizeDepthB;
-	FBufferedUniform1f InverseDepthRangeA;
-	FBufferedUniform1f InverseDepthRangeB;
+	FBufferedUniformSampler DepthTexture[2];
+	FBufferedUniform1i SampleCount[2];
+	FBufferedUniform1f LinearizeDepthA[2];
+	FBufferedUniform1f LinearizeDepthB[2];
+	FBufferedUniform1f InverseDepthRangeA[2];
+	FBufferedUniform1f InverseDepthRangeB[2];
 
 private:
-	FShaderProgram mShader;
+	FShaderProgram mShader[2];
 };
 
 class FSSAOShader
diff --git a/wadsrc/static/shaders/glsl/lineardepth.fp b/wadsrc/static/shaders/glsl/lineardepth.fp
index f61bb3995..31df9dc32 100644
--- a/wadsrc/static/shaders/glsl/lineardepth.fp
+++ b/wadsrc/static/shaders/glsl/lineardepth.fp
@@ -2,7 +2,12 @@
 in vec2 TexCoord;
 out vec4 FragColor;
 
+#if defined(MULTISAMPLE)
+uniform sampler2DMS DepthTexture;
+uniform int SampleCount;
+#else
 uniform sampler2D DepthTexture;
+#endif
 uniform float LinearizeDepthA;
 uniform float LinearizeDepthB;
 uniform float InverseDepthRangeA;
@@ -10,7 +15,21 @@ uniform float InverseDepthRangeB;
 
 void main()
 {
+#if defined(MULTISAMPLE)
+	ivec2 texSize = textureSize(DepthTexture);
+	ivec2 ipos = ivec2(TexCoord * vec2(texSize));
+	float depth = 0.0;
+	for (int i = 0; i < SampleCount; i++)
+		depth += texelFetch(DepthTexture, ipos, i).x;
+	depth /= float(SampleCount);
+#else
+	/*ivec2 texSize = textureSize(DepthTexture, 0);
+	ivec2 ipos = ivec2(TexCoord * vec2(texSize));
+	if (ipos.x < 0) ipos.x += texSize.x;
+	if (ipos.y < 0) ipos.y += texSize.y;
+	float depth = texelFetch(DepthTexture, ipos, 0).x;*/
 	float depth = texture(DepthTexture, TexCoord).x;
+#endif
 	float normalizedDepth = clamp(InverseDepthRangeA * depth + InverseDepthRangeB, 0.0, 1.0);
 	FragColor = vec4(1.0 / (normalizedDepth * LinearizeDepthA + LinearizeDepthB), 0.0, 0.0, 1.0);
 }

From c7c0ffadb55421a1d7723db9bb1dac46ebd1d005 Mon Sep 17 00:00:00 2001
From: Magnus Norddahl <dpjudas@users.noreply.github.com>
Date: Sat, 3 Sep 2016 04:29:50 +0200
Subject: [PATCH 06/18] Move SSAO pass to be before translucent rendering Fix
 depth sampling location when not using fullscreen scene

---
 src/gl/renderer/gl_postprocess.cpp        |  3 ++-
 src/gl/scene/gl_scene.cpp                 |  2 ++
 src/gl/shaders/gl_ambientshader.cpp       |  2 ++
 src/gl/shaders/gl_ambientshader.h         |  2 ++
 wadsrc/static/shaders/glsl/lineardepth.fp | 12 +++++++++---
 5 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/src/gl/renderer/gl_postprocess.cpp b/src/gl/renderer/gl_postprocess.cpp
index 8282bc387..3031d80ba 100644
--- a/src/gl/renderer/gl_postprocess.cpp
+++ b/src/gl/renderer/gl_postprocess.cpp
@@ -177,6 +177,8 @@ void FGLRenderer::AmbientOccludeScene()
 	mLinearDepthShader->LinearizeDepthB[multisample].Set(MAX(1.0f / GetZNear(), 1.e-8f));
 	mLinearDepthShader->InverseDepthRangeA[multisample].Set(1.0f);
 	mLinearDepthShader->InverseDepthRangeB[multisample].Set(0.0f);
+	mLinearDepthShader->Scale[multisample].Set(mSceneViewport.width / (float)mScreenViewport.width, mSceneViewport.height / (float)mScreenViewport.height);
+	mLinearDepthShader->Offset[multisample].Set(mSceneViewport.left / (float)mScreenViewport.width, mSceneViewport.top / (float)mScreenViewport.height);
 	RenderScreenQuad();
 
 	// Apply ambient occlusion
@@ -236,7 +238,6 @@ void FGLRenderer::AmbientOccludeScene()
 	mSSAOCombineShader->Bind();
 	mSSAOCombineShader->AODepthTexture.Set(0);
 	RenderScreenQuad();
-	glViewport(mScreenViewport.left, mScreenViewport.top, mScreenViewport.width, mScreenViewport.height);
 
 	FGLDebug::PopGroup();
 }
diff --git a/src/gl/scene/gl_scene.cpp b/src/gl/scene/gl_scene.cpp
index 27772a0ca..a50fe87f8 100644
--- a/src/gl/scene/gl_scene.cpp
+++ b/src/gl/scene/gl_scene.cpp
@@ -491,6 +491,8 @@ void FGLRenderer::DrawScene(int drawmode)
 
 	RenderScene(recursion);
 
+	AmbientOccludeScene();
+
 	// Handle all portals after rendering the opaque objects but before
 	// doing all translucent stuff
 	recursion++;
diff --git a/src/gl/shaders/gl_ambientshader.cpp b/src/gl/shaders/gl_ambientshader.cpp
index f3b6eced6..54a651281 100644
--- a/src/gl/shaders/gl_ambientshader.cpp
+++ b/src/gl/shaders/gl_ambientshader.cpp
@@ -65,6 +65,8 @@ void FLinearDepthShader::Bind(bool multisample)
 		LinearizeDepthB[multisample].Init(shader, "LinearizeDepthB");
 		InverseDepthRangeA[multisample].Init(shader, "InverseDepthRangeA");
 		InverseDepthRangeB[multisample].Init(shader, "InverseDepthRangeB");
+		Scale[multisample].Init(shader, "Scale");
+		Offset[multisample].Init(shader, "Offset");
 	}
 	shader.Bind();
 }
diff --git a/src/gl/shaders/gl_ambientshader.h b/src/gl/shaders/gl_ambientshader.h
index 5f9ef630b..5b18ea85f 100644
--- a/src/gl/shaders/gl_ambientshader.h
+++ b/src/gl/shaders/gl_ambientshader.h
@@ -14,6 +14,8 @@ public:
 	FBufferedUniform1f LinearizeDepthB[2];
 	FBufferedUniform1f InverseDepthRangeA[2];
 	FBufferedUniform1f InverseDepthRangeB[2];
+	FBufferedUniform2f Scale[2];
+	FBufferedUniform2f Offset[2];
 
 private:
 	FShaderProgram mShader[2];
diff --git a/wadsrc/static/shaders/glsl/lineardepth.fp b/wadsrc/static/shaders/glsl/lineardepth.fp
index 31df9dc32..7e4eee745 100644
--- a/wadsrc/static/shaders/glsl/lineardepth.fp
+++ b/wadsrc/static/shaders/glsl/lineardepth.fp
@@ -8,28 +8,34 @@ uniform int SampleCount;
 #else
 uniform sampler2D DepthTexture;
 #endif
+
 uniform float LinearizeDepthA;
 uniform float LinearizeDepthB;
 uniform float InverseDepthRangeA;
 uniform float InverseDepthRangeB;
+uniform vec2 Scale;
+uniform vec2 Offset;
 
 void main()
 {
+	vec2 uv = Offset + TexCoord * Scale;
+
 #if defined(MULTISAMPLE)
 	ivec2 texSize = textureSize(DepthTexture);
-	ivec2 ipos = ivec2(TexCoord * vec2(texSize));
+	ivec2 ipos = ivec2(uv * vec2(texSize));
 	float depth = 0.0;
 	for (int i = 0; i < SampleCount; i++)
 		depth += texelFetch(DepthTexture, ipos, i).x;
 	depth /= float(SampleCount);
 #else
 	/*ivec2 texSize = textureSize(DepthTexture, 0);
-	ivec2 ipos = ivec2(TexCoord * vec2(texSize));
+	ivec2 ipos = ivec2(uv * vec2(texSize));
 	if (ipos.x < 0) ipos.x += texSize.x;
 	if (ipos.y < 0) ipos.y += texSize.y;
 	float depth = texelFetch(DepthTexture, ipos, 0).x;*/
-	float depth = texture(DepthTexture, TexCoord).x;
+	float depth = texture(DepthTexture, uv).x;
 #endif
+
 	float normalizedDepth = clamp(InverseDepthRangeA * depth + InverseDepthRangeB, 0.0, 1.0);
 	FragColor = vec4(1.0 / (normalizedDepth * LinearizeDepthA + LinearizeDepthB), 0.0, 0.0, 1.0);
 }

From e025f6e54bbf140c584030928706e95dee2bb8a5 Mon Sep 17 00:00:00 2001
From: Magnus Norddahl <dpjudas@users.noreply.github.com>
Date: Sun, 4 Sep 2016 08:15:29 +0200
Subject: [PATCH 07/18] Mark portals in scene alpha channel for the SSAO pass

---
 src/gl/renderer/gl_postprocess.cpp        | 5 +++++
 src/gl/scene/gl_portal.cpp                | 8 +++++---
 src/gl/shaders/gl_ambientshader.cpp       | 1 +
 src/gl/shaders/gl_ambientshader.h         | 1 +
 wadsrc/static/shaders/glsl/lineardepth.fp | 8 +++++---
 wadsrc/static/shaders/glsl/stencil.fp     | 2 +-
 6 files changed, 18 insertions(+), 7 deletions(-)

diff --git a/src/gl/renderer/gl_postprocess.cpp b/src/gl/renderer/gl_postprocess.cpp
index 3031d80ba..d2b1b14c1 100644
--- a/src/gl/renderer/gl_postprocess.cpp
+++ b/src/gl/renderer/gl_postprocess.cpp
@@ -170,8 +170,13 @@ void FGLRenderer::AmbientOccludeScene()
 	mBuffers->BindSceneDepthTexture(0);
 	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
 	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+	mBuffers->BindSceneColorTexture(1);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+	glActiveTexture(GL_TEXTURE0);
 	mLinearDepthShader->Bind(multisample);
 	mLinearDepthShader->DepthTexture[multisample].Set(0);
+	mLinearDepthShader->ColorTexture[multisample].Set(1);
 	if (multisample) mLinearDepthShader->SampleCount[multisample].Set(gl_multisample);
 	mLinearDepthShader->LinearizeDepthA[multisample].Set(1.0f / GetZFar() - 1.0f / GetZNear());
 	mLinearDepthShader->LinearizeDepthB[multisample].Set(MAX(1.0f / GetZNear(), 1.e-8f));
diff --git a/src/gl/scene/gl_portal.cpp b/src/gl/scene/gl_portal.cpp
index f34b5e23f..575ef968d 100644
--- a/src/gl/scene/gl_portal.cpp
+++ b/src/gl/scene/gl_portal.cpp
@@ -423,14 +423,16 @@ void GLPortal::End(bool usestencil)
 		glDepthFunc(GL_LEQUAL);
 		glDepthRange(0, 1);
 		{
-			ScopedColorMask colorMask(0, 0, 0, 0); 
-			// glColorMask(0,0,0,0);						// no graphics
+			ScopedColorMask colorMask(0, 0, 0, 1); // mark portal in alpha channel but don't touch color
 			gl_RenderState.SetEffect(EFF_STENCIL);
 			gl_RenderState.EnableTexture(false);
+			gl_RenderState.BlendFunc(GL_ONE, GL_ZERO);
+			gl_RenderState.BlendEquation(GL_FUNC_ADD);
+			gl_RenderState.Apply();
 			DrawPortalStencil();
 			gl_RenderState.SetEffect(EFF_NONE);
 			gl_RenderState.EnableTexture(true);
-		} // glColorMask(1, 1, 1, 1);
+		}
 		glDepthFunc(GL_LESS);
 	}
 	PortalAll.Unclock();
diff --git a/src/gl/shaders/gl_ambientshader.cpp b/src/gl/shaders/gl_ambientshader.cpp
index 54a651281..3fbd03434 100644
--- a/src/gl/shaders/gl_ambientshader.cpp
+++ b/src/gl/shaders/gl_ambientshader.cpp
@@ -60,6 +60,7 @@ void FLinearDepthShader::Bind(bool multisample)
 		shader.Link("shaders/glsl/lineardepth");
 		shader.SetAttribLocation(0, "PositionInProjection");
 		DepthTexture[multisample].Init(shader, "DepthTexture");
+		ColorTexture[multisample].Init(shader, "ColorTexture");
 		SampleCount[multisample].Init(shader, "SampleCount");
 		LinearizeDepthA[multisample].Init(shader, "LinearizeDepthA");
 		LinearizeDepthB[multisample].Init(shader, "LinearizeDepthB");
diff --git a/src/gl/shaders/gl_ambientshader.h b/src/gl/shaders/gl_ambientshader.h
index 5b18ea85f..9c97791ba 100644
--- a/src/gl/shaders/gl_ambientshader.h
+++ b/src/gl/shaders/gl_ambientshader.h
@@ -9,6 +9,7 @@ public:
 	void Bind(bool multisample);
 
 	FBufferedUniformSampler DepthTexture[2];
+	FBufferedUniformSampler ColorTexture[2];
 	FBufferedUniform1i SampleCount[2];
 	FBufferedUniform1f LinearizeDepthA[2];
 	FBufferedUniform1f LinearizeDepthB[2];
diff --git a/wadsrc/static/shaders/glsl/lineardepth.fp b/wadsrc/static/shaders/glsl/lineardepth.fp
index 7e4eee745..61e5e8126 100644
--- a/wadsrc/static/shaders/glsl/lineardepth.fp
+++ b/wadsrc/static/shaders/glsl/lineardepth.fp
@@ -4,9 +4,11 @@ out vec4 FragColor;
 
 #if defined(MULTISAMPLE)
 uniform sampler2DMS DepthTexture;
+uniform sampler2DMS ColorTexture;
 uniform int SampleCount;
 #else
 uniform sampler2D DepthTexture;
+uniform sampler2D ColorTexture;
 #endif
 
 uniform float LinearizeDepthA;
@@ -25,15 +27,15 @@ void main()
 	ivec2 ipos = ivec2(uv * vec2(texSize));
 	float depth = 0.0;
 	for (int i = 0; i < SampleCount; i++)
-		depth += texelFetch(DepthTexture, ipos, i).x;
+		depth += texelFetch(ColorTexture, ipos, i).a != 0.0 ? texelFetch(DepthTexture, ipos, i).x : 1.0;
 	depth /= float(SampleCount);
 #else
 	/*ivec2 texSize = textureSize(DepthTexture, 0);
 	ivec2 ipos = ivec2(uv * vec2(texSize));
 	if (ipos.x < 0) ipos.x += texSize.x;
 	if (ipos.y < 0) ipos.y += texSize.y;
-	float depth = texelFetch(DepthTexture, ipos, 0).x;*/
-	float depth = texture(DepthTexture, uv).x;
+	float depth = texelFetch(ColorTexture, ipos, 0).a != 0.0 ? texelFetch(DepthTexture, ipos, 0).x : 1.0;*/
+	float depth = texture(ColorTexture, uv).a != 0.0 ? texture(DepthTexture, uv).x : 1.0;
 #endif
 
 	float normalizedDepth = clamp(InverseDepthRangeA * depth + InverseDepthRangeB, 0.0, 1.0);
diff --git a/wadsrc/static/shaders/glsl/stencil.fp b/wadsrc/static/shaders/glsl/stencil.fp
index d1b8745f6..65f12b405 100644
--- a/wadsrc/static/shaders/glsl/stencil.fp
+++ b/wadsrc/static/shaders/glsl/stencil.fp
@@ -3,6 +3,6 @@ out vec4 FragColor;
 
 void main()
 {
-	FragColor = vec4(1.0);
+	FragColor = vec4(1.0, 1.0, 1.0, 0.0);
 }
 

From 11725c435e623470633fc4589dc9134abd59824e Mon Sep 17 00:00:00 2001
From: Magnus Norddahl <dpjudas@users.noreply.github.com>
Date: Fri, 9 Sep 2016 09:47:46 +0200
Subject: [PATCH 08/18] Grab tanHalfFovy from the projection matrix

---
 src/gl/renderer/gl_postprocess.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/gl/renderer/gl_postprocess.cpp b/src/gl/renderer/gl_postprocess.cpp
index d2b1b14c1..232ad91ba 100644
--- a/src/gl/renderer/gl_postprocess.cpp
+++ b/src/gl/renderer/gl_postprocess.cpp
@@ -158,7 +158,7 @@ void FGLRenderer::AmbientOccludeScene()
 	bool multisample = gl_multisample > 1;
 
 	//float tanHalfFovy = tan(fovy * (M_PI / 360.0f));
-	float tanHalfFovy = 1.0f / 1.33333302f; // 1.0f / gl_RenderState.mProjectionMatrix.get()[5];
+	float tanHalfFovy = 1.0f / gl_RenderState.mProjectionMatrix.get()[5];
 	float invFocalLenX = tanHalfFovy * (mBuffers->GetSceneWidth() / (float)mBuffers->GetSceneHeight());
 	float invFocalLenY = tanHalfFovy;
 	float nDotVBias = clamp(bias, 0.0f, 1.0f);

From 24ab13f1ce6cf2ed4455f74a0d6cdc9afac9631a Mon Sep 17 00:00:00 2001
From: Magnus Norddahl <dpjudas@users.noreply.github.com>
Date: Fri, 9 Sep 2016 18:19:00 +0200
Subject: [PATCH 09/18] Fix stripes in the reconstructed normals due to down
 scaling

---
 src/gl/renderer/gl_postprocess.cpp        |  2 +-
 wadsrc/static/shaders/glsl/lineardepth.fp | 17 ++++++++++-------
 2 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/src/gl/renderer/gl_postprocess.cpp b/src/gl/renderer/gl_postprocess.cpp
index 232ad91ba..da56dc2cf 100644
--- a/src/gl/renderer/gl_postprocess.cpp
+++ b/src/gl/renderer/gl_postprocess.cpp
@@ -182,7 +182,7 @@ void FGLRenderer::AmbientOccludeScene()
 	mLinearDepthShader->LinearizeDepthB[multisample].Set(MAX(1.0f / GetZNear(), 1.e-8f));
 	mLinearDepthShader->InverseDepthRangeA[multisample].Set(1.0f);
 	mLinearDepthShader->InverseDepthRangeB[multisample].Set(0.0f);
-	mLinearDepthShader->Scale[multisample].Set(mSceneViewport.width / (float)mScreenViewport.width, mSceneViewport.height / (float)mScreenViewport.height);
+	mLinearDepthShader->Scale[multisample].Set(mBuffers->AmbientWidth * 2.0f / (float)mScreenViewport.width, mBuffers->AmbientHeight * 2.0f / (float)mScreenViewport.height);
 	mLinearDepthShader->Offset[multisample].Set(mSceneViewport.left / (float)mScreenViewport.width, mSceneViewport.top / (float)mScreenViewport.height);
 	RenderScreenQuad();
 
diff --git a/wadsrc/static/shaders/glsl/lineardepth.fp b/wadsrc/static/shaders/glsl/lineardepth.fp
index 61e5e8126..558738bd9 100644
--- a/wadsrc/static/shaders/glsl/lineardepth.fp
+++ b/wadsrc/static/shaders/glsl/lineardepth.fp
@@ -24,18 +24,21 @@ void main()
 
 #if defined(MULTISAMPLE)
 	ivec2 texSize = textureSize(DepthTexture);
-	ivec2 ipos = ivec2(uv * vec2(texSize));
+#else
+	ivec2 texSize = textureSize(DepthTexture, 0);
+#endif
+
+	// Use floor here because as we downscale the sampling error has to remain uniform to prevent
+	// noise in the depth values.
+	ivec2 ipos = ivec2(max(floor(uv * vec2(texSize) - 0.75), vec2(0.0)));
+
+#if defined(MULTISAMPLE)
 	float depth = 0.0;
 	for (int i = 0; i < SampleCount; i++)
 		depth += texelFetch(ColorTexture, ipos, i).a != 0.0 ? texelFetch(DepthTexture, ipos, i).x : 1.0;
 	depth /= float(SampleCount);
 #else
-	/*ivec2 texSize = textureSize(DepthTexture, 0);
-	ivec2 ipos = ivec2(uv * vec2(texSize));
-	if (ipos.x < 0) ipos.x += texSize.x;
-	if (ipos.y < 0) ipos.y += texSize.y;
-	float depth = texelFetch(ColorTexture, ipos, 0).a != 0.0 ? texelFetch(DepthTexture, ipos, 0).x : 1.0;*/
-	float depth = texture(ColorTexture, uv).a != 0.0 ? texture(DepthTexture, uv).x : 1.0;
+	float depth = texelFetch(ColorTexture, ipos, 0).a != 0.0 ? texelFetch(DepthTexture, ipos, 0).x : 1.0;
 #endif
 
 	float normalizedDepth = clamp(InverseDepthRangeA * depth + InverseDepthRangeB, 0.0, 1.0);

From 0a8cc1b74c8176deff39f931da68b3f698d030bd Mon Sep 17 00:00:00 2001
From: Magnus Norddahl <dpjudas@users.noreply.github.com>
Date: Sat, 10 Sep 2016 22:39:09 +0200
Subject: [PATCH 10/18] Fix depth blur

---
 src/gl/renderer/gl_postprocess.cpp      | 12 ++++------
 wadsrc/static/shaders/glsl/depthblur.fp | 32 ++++++++-----------------
 2 files changed, 14 insertions(+), 30 deletions(-)

diff --git a/src/gl/renderer/gl_postprocess.cpp b/src/gl/renderer/gl_postprocess.cpp
index da56dc2cf..c58f6ea3a 100644
--- a/src/gl/renderer/gl_postprocess.cpp
+++ b/src/gl/renderer/gl_postprocess.cpp
@@ -108,11 +108,6 @@ CUSTOM_CVAR(Float, gl_ssao_blur_amount, 4.0f, 0)
 {
 	if (self < 0.1f) self = 0.1f;
 }
-CUSTOM_CVAR(Int, gl_ssao_blur_samples, 5, 0)
-{
-	if (self < 3 || self > 15 || self % 2 == 0)
-		self = 9;
-}
 
 EXTERN_CVAR(Float, vid_brightness)
 EXTERN_CVAR(Float, vid_contrast)
@@ -153,7 +148,6 @@ void FGLRenderer::AmbientOccludeScene()
 	float bias = gl_ssao_bias;
 	float aoRadius = gl_ssao_radius;
 	const float blurAmount = gl_ssao_blur_amount;
-	int blurSampleCount = gl_ssao_blur_samples;
 	float aoStrength = gl_ssao_strength;
 	bool multisample = gl_multisample > 1;
 
@@ -164,6 +158,8 @@ void FGLRenderer::AmbientOccludeScene()
 	float nDotVBias = clamp(bias, 0.0f, 1.0f);
 	float r2 = aoRadius * aoRadius;
 
+	float blurSharpness = 1.0f / blurAmount;
+
 	// Calculate linear depth values
 	glBindFramebuffer(GL_FRAMEBUFFER, mBuffers->AmbientFB0);
 	glViewport(0, 0, mBuffers->AmbientWidth, mBuffers->AmbientHeight);
@@ -215,14 +211,14 @@ void FGLRenderer::AmbientOccludeScene()
 	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
 	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
 	mDepthBlurShader->Bind(false);
-	mDepthBlurShader->BlurSharpness[false].Set(blurAmount);
+	mDepthBlurShader->BlurSharpness[false].Set(blurSharpness);
 	mDepthBlurShader->InvFullResolution[false].Set(1.0f / mBuffers->AmbientWidth, 1.0f / mBuffers->AmbientHeight);
 	RenderScreenQuad();
 
 	glBindFramebuffer(GL_FRAMEBUFFER, mBuffers->AmbientFB1);
 	glBindTexture(GL_TEXTURE_2D, mBuffers->AmbientTexture0);
 	mDepthBlurShader->Bind(true);
-	mDepthBlurShader->BlurSharpness[true].Set(blurAmount);
+	mDepthBlurShader->BlurSharpness[true].Set(blurSharpness);
 	mDepthBlurShader->InvFullResolution[true].Set(1.0f / mBuffers->AmbientWidth, 1.0f / mBuffers->AmbientHeight);
 	mDepthBlurShader->PowExponent[true].Set(1.8f);
 	RenderScreenQuad();
diff --git a/wadsrc/static/shaders/glsl/depthblur.fp b/wadsrc/static/shaders/glsl/depthblur.fp
index bd464d03d..c4f4438d3 100644
--- a/wadsrc/static/shaders/glsl/depthblur.fp
+++ b/wadsrc/static/shaders/glsl/depthblur.fp
@@ -7,39 +7,32 @@ uniform float BlurSharpness;
 uniform vec2 InvFullResolution;
 uniform float PowExponent;
 
-#define KERNEL_RADIUS 3.0
+#define KERNEL_RADIUS 7.0
 
-struct CenterPixelData
-{
-	vec2 UV;
-	float Depth;
-	float Sharpness;
-};
-
-float CrossBilateralWeight(float r, float sampleDepth, CenterPixelData center)
+float CrossBilateralWeight(float r, float sampleDepth, float centerDepth)
 {
 	const float blurSigma = KERNEL_RADIUS * 0.5;
 	const float blurFalloff = 1.0 / (2.0 * blurSigma * blurSigma);
 
-	float deltaZ = (sampleDepth - center.Depth) * center.Sharpness;
+	float deltaZ = (sampleDepth - centerDepth) * BlurSharpness;
 
 	return exp2(-r * r * blurFalloff - deltaZ * deltaZ);
 }
 
-void ProcessSample(float ao, float z, float r, CenterPixelData center, inout float totalAO, inout float totalW)
+void ProcessSample(float ao, float z, float r, float centerDepth, inout float totalAO, inout float totalW)
 {
-	float w = CrossBilateralWeight(r, z, center);
+	float w = CrossBilateralWeight(r, z, centerDepth);
 	totalAO += w * ao;
 	totalW += w;
 }
 
-void ProcessRadius(vec2 deltaUV, CenterPixelData center, inout float totalAO, inout float totalW)
+void ProcessRadius(vec2 deltaUV, float centerDepth, inout float totalAO, inout float totalW)
 {
 	for (float r = 1; r <= KERNEL_RADIUS; r += 1.0)
 	{
-		vec2 uv = r * deltaUV + center.UV;
+		vec2 uv = r * deltaUV + TexCoord;
 		vec2 aoZ = texture(AODepthTexture, uv).xy;
-		ProcessSample(aoZ.x, aoZ.y, r, center, totalAO, totalW);
+		ProcessSample(aoZ.x, aoZ.y, r, centerDepth, totalAO, totalW);
 	}
 }
 
@@ -47,16 +40,11 @@ vec2 ComputeBlur(vec2 deltaUV)
 {
 	vec2 aoZ = texture(AODepthTexture, TexCoord).xy;
 
-	CenterPixelData center;
-	center.UV = TexCoord;
-	center.Depth = aoZ.y;
-	center.Sharpness = BlurSharpness;
-
 	float totalAO = aoZ.x;
 	float totalW = 1.0;
 
-	ProcessRadius(deltaUV, center, totalAO, totalW);
-	ProcessRadius(-deltaUV, center, totalAO, totalW);
+	ProcessRadius(deltaUV, aoZ.y, totalAO, totalW);
+	ProcessRadius(-deltaUV, aoZ.y, totalAO, totalW);
 
 	return vec2(totalAO / totalW, aoZ.y);
 }

From 37e3172c945298a95709e81752c783bc70b2f8c4 Mon Sep 17 00:00:00 2001
From: Magnus Norddahl <dpjudas@users.noreply.github.com>
Date: Sun, 11 Sep 2016 11:09:40 +0200
Subject: [PATCH 11/18] Fix random texture sampling bug

---
 src/gl/renderer/gl_postprocess.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/gl/renderer/gl_postprocess.cpp b/src/gl/renderer/gl_postprocess.cpp
index c58f6ea3a..f89776d63 100644
--- a/src/gl/renderer/gl_postprocess.cpp
+++ b/src/gl/renderer/gl_postprocess.cpp
@@ -191,6 +191,8 @@ void FGLRenderer::AmbientOccludeScene()
 	glBindTexture(GL_TEXTURE_2D, mBuffers->AmbientRandomTexture);
 	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
 	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
 	glActiveTexture(GL_TEXTURE0);
 	mSSAOShader->Bind();
 	mSSAOShader->DepthTexture.Set(0);

From 9af34bac69147d22774ac9c999dc3ef751efa86a Mon Sep 17 00:00:00 2001
From: Magnus Norddahl <dpjudas@users.noreply.github.com>
Date: Tue, 20 Sep 2016 02:57:57 +0200
Subject: [PATCH 12/18] Add gbuffer pass support to FShaderManager and
 FRenderState

---
 src/gl/renderer/gl_renderstate.cpp |   7 +-
 src/gl/renderer/gl_renderstate.h   |  19 +++
 src/gl/shaders/gl_shader.cpp       | 179 ++++++++++++++++++-----------
 src/gl/shaders/gl_shader.h         |  46 +++++---
 wadsrc/static/shaders/glsl/main.fp |   6 +
 5 files changed, 170 insertions(+), 87 deletions(-)

diff --git a/src/gl/renderer/gl_renderstate.cpp b/src/gl/renderer/gl_renderstate.cpp
index 967296cb8..17f19455e 100644
--- a/src/gl/renderer/gl_renderstate.cpp
+++ b/src/gl/renderer/gl_renderstate.cpp
@@ -105,6 +105,7 @@ void FRenderState::Reset()
 	mViewMatrix.loadIdentity();
 	mModelMatrix.loadIdentity();
 	mTextureMatrix.loadIdentity();
+	mPassType = NORMAL_PASS;
 }
 
 //==========================================================================
@@ -118,11 +119,11 @@ bool FRenderState::ApplyShader()
 	static const float nulvec[] = { 0.f, 0.f, 0.f, 0.f };
 	if (mSpecialEffect > EFF_NONE)
 	{
-		activeShader = GLRenderer->mShaderManager->BindEffect(mSpecialEffect);
+		activeShader = GLRenderer->mShaderManager->BindEffect(mSpecialEffect, mPassType);
 	}
 	else
 	{
-		activeShader = GLRenderer->mShaderManager->Get(mTextureEnabled ? mEffectState : 4, mAlphaThreshold >= 0.f);
+		activeShader = GLRenderer->mShaderManager->Get(mTextureEnabled ? mEffectState : 4, mAlphaThreshold >= 0.f, mPassType);
 		activeShader->Bind();
 	}
 
@@ -342,7 +343,7 @@ void FRenderState::ApplyMatrices()
 {
 	if (GLRenderer->mShaderManager != NULL)
 	{
-		GLRenderer->mShaderManager->ApplyMatrices(&mProjectionMatrix, &mViewMatrix);
+		GLRenderer->mShaderManager->ApplyMatrices(&mProjectionMatrix, &mViewMatrix, mPassType);
 	}
 }
 
diff --git a/src/gl/renderer/gl_renderstate.h b/src/gl/renderer/gl_renderstate.h
index 1c0a20348..7bec51be0 100644
--- a/src/gl/renderer/gl_renderstate.h
+++ b/src/gl/renderer/gl_renderstate.h
@@ -63,6 +63,13 @@ enum EEffect
 	MAX_EFFECTS
 };
 
+enum EPassType
+{
+	NORMAL_PASS,
+	GBUFFER_PASS,
+	MAX_PASS_TYPES
+};
+
 class FRenderState
 {
 	bool mTextureEnabled;
@@ -111,6 +118,8 @@ class FRenderState
 
 	FShader *activeShader;
 
+	EPassType mPassType = NORMAL_PASS;
+
 	bool ApplyShader();
 
 public:
@@ -459,6 +468,16 @@ public:
 		return mInterpolationFactor;
 	}
 
+	void SetPassType(EPassType passType)
+	{
+		mPassType = passType;
+	}
+
+	EPassType GetPassType()
+	{
+		return mPassType;
+	}
+
 	// Backwards compatibility crap follows
 	void ApplyFixedFunction();
 	void DrawColormapOverlay();
diff --git a/src/gl/shaders/gl_shader.cpp b/src/gl/shaders/gl_shader.cpp
index d4e05dfa8..59b941e86 100644
--- a/src/gl/shaders/gl_shader.cpp
+++ b/src/gl/shaders/gl_shader.cpp
@@ -180,6 +180,9 @@ bool FShader::Load(const char * name, const char * vert_prog_lump, const char *
 	glBindAttribLocation(hShader, VATTR_COLOR, "aColor");
 	glBindAttribLocation(hShader, VATTR_VERTEX2, "aVertex2");
 
+	glBindFragDataLocation(hShader, 0, "FragColor");
+	glBindFragDataLocation(hShader, 1, "FragData");
+
 	glLinkProgram(hShader);
 
 	glGetShaderInfoLog(hVertProg, 10000, NULL, buffer);
@@ -297,12 +300,13 @@ bool FShader::Bind()
 //
 //==========================================================================
 
-FShader *FShaderManager::Compile (const char *ShaderName, const char *ShaderPath, bool usediscard)
+FShader *FShaderCollection::Compile (const char *ShaderName, const char *ShaderPath, bool usediscard, EPassType passType)
 {
 	FString defines;
 	// this can't be in the shader code due to ATI strangeness.
 	if (gl.MaxLights() == 128) defines += "#define MAXLIGHTS128\n";
 	if (!usediscard) defines += "#define NO_ALPHATEST\n";
+	if (passType == GBUFFER_PASS) defines += "#define GBUFFER_PASS\n";
 
 	FShader *shader = NULL;
 	try
@@ -385,27 +389,75 @@ static const FEffectShader effectshaders[]=
 	{ "stencil", "shaders/glsl/main.vp", "shaders/glsl/stencil.fp", NULL, "#define SIMPLE\n#define NO_ALPHATEST\n" },
 };
 
-
-//==========================================================================
-//
-//
-//
-//==========================================================================
-
 FShaderManager::FShaderManager()
 {
-	if (!gl.legacyMode) CompileShaders();
+	if (!gl.legacyMode)
+	{
+		for (int passType = 0; passType < MAX_PASS_TYPES; passType++)
+			mPassShaders.Push(new FShaderCollection((EPassType)passType));
+	}
 }
 
-//==========================================================================
-//
-//
-//
-//==========================================================================
-
 FShaderManager::~FShaderManager()
 {
-	if (!gl.legacyMode) Clean();
+	if (!gl.legacyMode)
+	{
+		glUseProgram(0);
+		mActiveShader = NULL;
+
+		for (auto collection : mPassShaders)
+			delete collection;
+	}
+}
+
+void FShaderManager::SetActiveShader(FShader *sh)
+{
+	if (mActiveShader != sh)
+	{
+		glUseProgram(sh!= NULL? sh->GetHandle() : 0);
+		mActiveShader = sh;
+	}
+}
+
+FShader *FShaderManager::BindEffect(int effect, EPassType passType)
+{
+	if (passType < mPassShaders.Size())
+		return mPassShaders[passType]->BindEffect(effect);
+	else
+		return nullptr;
+}
+
+FShader *FShaderManager::Get(unsigned int eff, bool alphateston, EPassType passType)
+{
+	if (passType < mPassShaders.Size())
+		return mPassShaders[passType]->Get(eff, alphateston);
+	else
+		return nullptr;
+}
+
+void FShaderManager::ApplyMatrices(VSMatrix *proj, VSMatrix *view, EPassType passType)
+{
+	if (gl.legacyMode)
+	{
+		glMatrixMode(GL_PROJECTION);
+		glLoadMatrixf(proj->get());
+		glMatrixMode(GL_MODELVIEW);
+		glLoadMatrixf(view->get());
+	}
+	else
+	{
+		if (passType < mPassShaders.Size())
+			mPassShaders[passType]->ApplyMatrices(proj, view);
+
+		if (mActiveShader)
+			mActiveShader->Bind();
+	}
+}
+
+void FShaderManager::ResetFixedColormap()
+{
+	for (auto &collection : mPassShaders)
+		collection->ResetFixedColormap();
 }
 
 //==========================================================================
@@ -414,10 +466,30 @@ FShaderManager::~FShaderManager()
 //
 //==========================================================================
 
-void FShaderManager::CompileShaders()
+FShaderCollection::FShaderCollection(EPassType passType)
 {
-	mActiveShader = NULL;
+	CompileShaders(passType);
+}
 
+//==========================================================================
+//
+//
+//
+//==========================================================================
+
+FShaderCollection::~FShaderCollection()
+{
+	Clean();
+}
+
+//==========================================================================
+//
+//
+//
+//==========================================================================
+
+void FShaderCollection::CompileShaders(EPassType passType)
+{
 	mTextureEffects.Clear();
 	mTextureEffectsNAT.Clear();
 	for (int i = 0; i < MAX_EFFECTS; i++)
@@ -427,11 +499,11 @@ void FShaderManager::CompileShaders()
 
 	for(int i=0;defaultshaders[i].ShaderName != NULL;i++)
 	{
-		FShader *shc = Compile(defaultshaders[i].ShaderName, defaultshaders[i].gettexelfunc, true);
+		FShader *shc = Compile(defaultshaders[i].ShaderName, defaultshaders[i].gettexelfunc, true, passType);
 		mTextureEffects.Push(shc);
 		if (i <= 3)
 		{
-			FShader *shc = Compile(defaultshaders[i].ShaderName, defaultshaders[i].gettexelfunc, false);
+			FShader *shc = Compile(defaultshaders[i].ShaderName, defaultshaders[i].gettexelfunc, false, passType);
 			mTextureEffectsNAT.Push(shc);
 		}
 	}
@@ -441,7 +513,7 @@ void FShaderManager::CompileShaders()
 		FString name = ExtractFileBase(usershaders[i]);
 		FName sfn = name;
 
-		FShader *shc = Compile(sfn, usershaders[i], true);
+		FShader *shc = Compile(sfn, usershaders[i], true, passType);
 		mTextureEffects.Push(shc);
 	}
 
@@ -463,11 +535,8 @@ void FShaderManager::CompileShaders()
 //
 //==========================================================================
 
-void FShaderManager::Clean()
+void FShaderCollection::Clean()
 {
-	glUseProgram(0);
-	mActiveShader = NULL;
-
 	for (unsigned int i = 0; i < mTextureEffectsNAT.Size(); i++)
 	{
 		if (mTextureEffectsNAT[i] != NULL) delete mTextureEffectsNAT[i];
@@ -491,7 +560,7 @@ void FShaderManager::Clean()
 //
 //==========================================================================
 
-int FShaderManager::Find(const char * shn)
+int FShaderCollection::Find(const char * shn)
 {
 	FName sfn = shn;
 
@@ -505,21 +574,6 @@ int FShaderManager::Find(const char * shn)
 	return -1;
 }
 
-//==========================================================================
-//
-//
-//
-//==========================================================================
-
-void FShaderManager::SetActiveShader(FShader *sh)
-{
-	if (mActiveShader != sh)
-	{
-		glUseProgram(sh!= NULL? sh->GetHandle() : 0);
-		mActiveShader = sh;
-	}
-}
-
 
 //==========================================================================
 //
@@ -527,7 +581,7 @@ void FShaderManager::SetActiveShader(FShader *sh)
 //
 //==========================================================================
 
-FShader *FShaderManager::BindEffect(int effect)
+FShader *FShaderCollection::BindEffect(int effect)
 {
 	if (effect >= 0 && effect < MAX_EFFECTS && mEffectShaders[effect] != NULL)
 	{
@@ -545,36 +599,25 @@ FShader *FShaderManager::BindEffect(int effect)
 //==========================================================================
 EXTERN_CVAR(Int, gl_fuzztype)
 
-void FShaderManager::ApplyMatrices(VSMatrix *proj, VSMatrix *view)
+void FShaderCollection::ApplyMatrices(VSMatrix *proj, VSMatrix *view)
 {
-	if (gl.legacyMode)
+	for (int i = 0; i < 4; i++)
 	{
-		glMatrixMode(GL_PROJECTION);
-		glLoadMatrixf(proj->get());
-		glMatrixMode(GL_MODELVIEW);
-		glLoadMatrixf(view->get());
+		mTextureEffects[i]->ApplyMatrices(proj, view);
+		mTextureEffectsNAT[i]->ApplyMatrices(proj, view);
 	}
-	else
+	mTextureEffects[4]->ApplyMatrices(proj, view);
+	if (gl_fuzztype != 0)
 	{
-		for (int i = 0; i < 4; i++)
-		{
-			mTextureEffects[i]->ApplyMatrices(proj, view);
-			mTextureEffectsNAT[i]->ApplyMatrices(proj, view);
-		}
-		mTextureEffects[4]->ApplyMatrices(proj, view);
-		if (gl_fuzztype != 0)
-		{
-			mTextureEffects[4 + gl_fuzztype]->ApplyMatrices(proj, view);
-		}
-		for (unsigned i = 12; i < mTextureEffects.Size(); i++)
-		{
-			mTextureEffects[i]->ApplyMatrices(proj, view);
-		}
-		for (int i = 0; i < MAX_EFFECTS; i++)
-		{
-			mEffectShaders[i]->ApplyMatrices(proj, view);
-		}
-		if (mActiveShader != NULL) mActiveShader->Bind();
+		mTextureEffects[4 + gl_fuzztype]->ApplyMatrices(proj, view);
+	}
+	for (unsigned i = 12; i < mTextureEffects.Size(); i++)
+	{
+		mTextureEffects[i]->ApplyMatrices(proj, view);
+	}
+	for (int i = 0; i < MAX_EFFECTS; i++)
+	{
+		mEffectShaders[i]->ApplyMatrices(proj, view);
 	}
 }
 
diff --git a/src/gl/shaders/gl_shader.h b/src/gl/shaders/gl_shader.h
index 343942321..ce285c3ee 100644
--- a/src/gl/shaders/gl_shader.h
+++ b/src/gl/shaders/gl_shader.h
@@ -37,6 +37,7 @@ enum
 	VATTR_NORMAL = 4
 };
 
+class FShaderCollection;
 
 //==========================================================================
 //
@@ -248,7 +249,7 @@ public:
 
 class FShader
 {
-	friend class FShaderManager;
+	friend class FShaderCollection;
 	friend class FRenderState;
 
 	unsigned int hShader;
@@ -322,7 +323,6 @@ public:
 
 };
 
-
 //==========================================================================
 //
 // The global shader manager
@@ -330,26 +330,40 @@ public:
 //==========================================================================
 class FShaderManager
 {
-	TArray<FShader*> mTextureEffects;
-	TArray<FShader*> mTextureEffectsNAT;
-	FShader *mActiveShader;
-	FShader *mEffectShaders[MAX_EFFECTS];
-
-	void Clean();
-	void CompileShaders();
-	
 public:
 	FShaderManager();
 	~FShaderManager();
-	FShader *Compile(const char *ShaderName, const char *ShaderPath, bool usediscard);
+
+	void SetActiveShader(FShader *sh);
+	FShader *GetActiveShader() const { return mActiveShader; }
+
+	FShader *BindEffect(int effect, EPassType passType);
+	FShader *Get(unsigned int eff, bool alphateston, EPassType passType);
+	void ApplyMatrices(VSMatrix *proj, VSMatrix *view, EPassType passType);
+
+	void ResetFixedColormap();
+
+private:
+	FShader *mActiveShader = nullptr;
+	TArray<FShaderCollection*> mPassShaders;
+};
+
+class FShaderCollection
+{
+	TArray<FShader*> mTextureEffects;
+	TArray<FShader*> mTextureEffectsNAT;
+	FShader *mEffectShaders[MAX_EFFECTS];
+
+	void Clean();
+	void CompileShaders(EPassType passType);
+	
+public:
+	FShaderCollection(EPassType passType);
+	~FShaderCollection();
+	FShader *Compile(const char *ShaderName, const char *ShaderPath, bool usediscard, EPassType passType);
 	int Find(const char *mame);
 	FShader *BindEffect(int effect);
-	void SetActiveShader(FShader *sh);
 	void ApplyMatrices(VSMatrix *proj, VSMatrix *view);
-	FShader *GetActiveShader() const
-	{
-		return mActiveShader;
-	}
 
 	void ResetFixedColormap()
 	{
diff --git a/wadsrc/static/shaders/glsl/main.fp b/wadsrc/static/shaders/glsl/main.fp
index 95ac874b7..4d3531f01 100644
--- a/wadsrc/static/shaders/glsl/main.fp
+++ b/wadsrc/static/shaders/glsl/main.fp
@@ -5,6 +5,9 @@ in vec4 vTexCoord;
 in vec4 vColor;
 
 out vec4 FragColor;
+#ifdef GBUFFER_PASS
+out vec4 FragData;
+#endif
 
 #ifdef SHADER_STORAGE_LIGHTS
 	layout(std430, binding = 1) buffer LightBufferSSO
@@ -345,5 +348,8 @@ void main()
 		}
 	}
 	FragColor = frag;
+#ifdef GBUFFER_PASS
+	FragData = vec4(uFogColor.rgb, 1.0);
+#endif
 }
 

From d7741362823fbe3bca3821b20fe75d0802575379 Mon Sep 17 00:00:00 2001
From: Magnus Norddahl <dpjudas@users.noreply.github.com>
Date: Wed, 21 Sep 2016 02:04:56 +0200
Subject: [PATCH 13/18] Added SceneData texture as the second colorbuffer when
 rendering a scene and placed fog data into it

---
 src/gl/renderer/gl_postprocess.cpp        | 18 ++++++++------
 src/gl/renderer/gl_renderer.cpp           |  2 +-
 src/gl/scene/gl_scene.cpp                 | 23 ++++++++++++++++--
 src/gl/shaders/gl_ambientshader.cpp       | 23 +++++++++++-------
 src/gl/shaders/gl_ambientshader.h         | 10 +++++---
 src/gl/system/gl_cvars.h                  |  6 +++++
 wadsrc/static/shaders/glsl/main.fp        | 28 +++++++++++++++++++++-
 wadsrc/static/shaders/glsl/ssaocombine.fp | 29 ++++++++++++++++++++++-
 8 files changed, 115 insertions(+), 24 deletions(-)

diff --git a/src/gl/renderer/gl_postprocess.cpp b/src/gl/renderer/gl_postprocess.cpp
index f89776d63..3b94fd8cc 100644
--- a/src/gl/renderer/gl_postprocess.cpp
+++ b/src/gl/renderer/gl_postprocess.cpp
@@ -137,9 +137,6 @@ void FGLRenderer::PostProcessScene()
 
 void FGLRenderer::AmbientOccludeScene()
 {
-	if (!gl_ssao || !FGLRenderBuffers::IsEnabled())
-		return;
-
 	FGLDebug::PushGroup("AmbientOccludeScene");
 
 	FGLPostProcessState savedState;
@@ -226,20 +223,27 @@ void FGLRenderer::AmbientOccludeScene()
 	RenderScreenQuad();
 
 	// Add SSAO back to scene texture:
-	mBuffers->BindSceneFB();
+	mBuffers->BindSceneFB(false);
+	GLenum buffers[] = { GL_COLOR_ATTACHMENT0 };
+	glDrawBuffers(1, buffers);
 	glViewport(mSceneViewport.left, mSceneViewport.top, mSceneViewport.width, mSceneViewport.height);
 	glEnable(GL_BLEND);
 	glBlendEquation(GL_FUNC_ADD);
 	if (gl_ssao_debug)
 		glBlendFunc(GL_ONE, GL_ZERO);
 	else
-		glBlendFunc(GL_ZERO, GL_SRC_COLOR);
+		glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
 	glActiveTexture(GL_TEXTURE0);
 	glBindTexture(GL_TEXTURE_2D, mBuffers->AmbientTexture1);
 	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
 	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
-	mSSAOCombineShader->Bind();
-	mSSAOCombineShader->AODepthTexture.Set(0);
+	mBuffers->BindSceneDataTexture(1);
+	mSSAOCombineShader->Bind(multisample);
+	mSSAOCombineShader->AODepthTexture[multisample].Set(0);
+	mSSAOCombineShader->SceneDataTexture[multisample].Set(1);
+	if (multisample) mSSAOCombineShader->SampleCount[multisample].Set(gl_multisample);
+	mSSAOCombineShader->Scale[multisample].Set(mBuffers->AmbientWidth * 2.0f / (float)mScreenViewport.width, mBuffers->AmbientHeight * 2.0f / (float)mScreenViewport.height);
+	mSSAOCombineShader->Offset[multisample].Set(mSceneViewport.left / (float)mScreenViewport.width, mSceneViewport.top / (float)mScreenViewport.height);
 	RenderScreenQuad();
 
 	FGLDebug::PopGroup();
diff --git a/src/gl/renderer/gl_renderer.cpp b/src/gl/renderer/gl_renderer.cpp
index befa330e9..368db63d2 100644
--- a/src/gl/renderer/gl_renderer.cpp
+++ b/src/gl/renderer/gl_renderer.cpp
@@ -323,7 +323,7 @@ void FGLRenderer::Begin2D()
 	if (mBuffers->Setup(mScreenViewport.width, mScreenViewport.height, mSceneViewport.width, mSceneViewport.height))
 	{
 		if (mDrawingScene2D)
-			mBuffers->BindSceneFB();
+			mBuffers->BindSceneFB(false);
 		else
 			mBuffers->BindCurrentFB();
 	}
diff --git a/src/gl/scene/gl_scene.cpp b/src/gl/scene/gl_scene.cpp
index a50fe87f8..6a8c9a11a 100644
--- a/src/gl/scene/gl_scene.cpp
+++ b/src/gl/scene/gl_scene.cpp
@@ -158,7 +158,11 @@ void FGLRenderer::Set3DViewport(bool mainview)
 {
 	if (mainview && mBuffers->Setup(mScreenViewport.width, mScreenViewport.height, mSceneViewport.width, mSceneViewport.height))
 	{
-		mBuffers->BindSceneFB();
+		mBuffers->BindSceneFB(gl_ssao);
+		GLenum buffers[] = { GL_COLOR_ATTACHMENT0, GL_COLOR_ATTACHMENT1 };
+		glDrawBuffers(gl_ssao ? 2 : 1, buffers);
+		gl_RenderState.SetPassType(gl_ssao ? GBUFFER_PASS : NORMAL_PASS);
+		gl_RenderState.Apply();
 	}
 
 	// Always clear all buffers with scissor test disabled.
@@ -491,7 +495,13 @@ void FGLRenderer::DrawScene(int drawmode)
 
 	RenderScene(recursion);
 
-	AmbientOccludeScene();
+	bool applySSAO = gl_ssao && FGLRenderBuffers::IsEnabled() && drawmode != DM_PORTAL;
+	if (applySSAO)
+	{
+		AmbientOccludeScene();
+		gl_RenderState.SetPassType(GBUFFER_PASS);
+		gl_RenderState.Apply();
+	}
 
 	// Handle all portals after rendering the opaque objects but before
 	// doing all translucent stuff
@@ -499,6 +509,15 @@ void FGLRenderer::DrawScene(int drawmode)
 	GLPortal::EndFrame();
 	recursion--;
 	RenderTranslucent();
+
+	if (applySSAO)
+	{
+		mBuffers->BindSceneFB(true);
+		GLenum buffers[] = { GL_COLOR_ATTACHMENT0, GL_COLOR_ATTACHMENT1 };
+		glDrawBuffers(2, buffers);
+		gl_RenderState.SetPassType(NORMAL_PASS);
+		gl_RenderState.Apply();
+	}
 }
 
 
diff --git a/src/gl/shaders/gl_ambientshader.cpp b/src/gl/shaders/gl_ambientshader.cpp
index 3fbd03434..4fa5b0e01 100644
--- a/src/gl/shaders/gl_ambientshader.cpp
+++ b/src/gl/shaders/gl_ambientshader.cpp
@@ -120,16 +120,21 @@ void FDepthBlurShader::Bind(bool vertical)
 	shader.Bind();
 }
 
-void FSSAOCombineShader::Bind()
+void FSSAOCombineShader::Bind(bool multisample)
 {
-	if (!mShader)
+	auto &shader = mShader[multisample];
+	if (!shader)
 	{
-		mShader.Compile(FShaderProgram::Vertex, "shaders/glsl/screenquad.vp", "", 330);
-		mShader.Compile(FShaderProgram::Fragment, "shaders/glsl/ssaocombine.fp", "", 330);
-		mShader.SetFragDataLocation(0, "FragColor");
-		mShader.Link("shaders/glsl/ssaocombine");
-		mShader.SetAttribLocation(0, "PositionInProjection");
-		AODepthTexture.Init(mShader, "AODepthTexture");
+		shader.Compile(FShaderProgram::Vertex, "shaders/glsl/screenquad.vp", "", 330);
+		shader.Compile(FShaderProgram::Fragment, "shaders/glsl/ssaocombine.fp", multisample ? "#define MULTISAMPLE\n" : "", 330);
+		shader.SetFragDataLocation(0, "FragColor");
+		shader.Link("shaders/glsl/ssaocombine");
+		shader.SetAttribLocation(0, "PositionInProjection");
+		AODepthTexture[multisample].Init(shader, "AODepthTexture");
+		SceneDataTexture[multisample].Init(shader, "SceneDataTexture");
+		SampleCount[multisample].Init(shader, "SampleCount");
+		Scale[multisample].Init(shader, "Scale");
+		Offset[multisample].Init(shader, "Offset");
 	}
-	mShader.Bind();
+	shader.Bind();
 }
diff --git a/src/gl/shaders/gl_ambientshader.h b/src/gl/shaders/gl_ambientshader.h
index 9c97791ba..f36b10625 100644
--- a/src/gl/shaders/gl_ambientshader.h
+++ b/src/gl/shaders/gl_ambientshader.h
@@ -59,12 +59,16 @@ private:
 class FSSAOCombineShader
 {
 public:
-	void Bind();
+	void Bind(bool multisample);
 
-	FBufferedUniformSampler AODepthTexture;
+	FBufferedUniformSampler AODepthTexture[2];
+	FBufferedUniformSampler SceneDataTexture[2];
+	FBufferedUniform1i SampleCount[2];
+	FBufferedUniform2f Scale[2];
+	FBufferedUniform2f Offset[2];
 
 private:
-	FShaderProgram mShader;
+	FShaderProgram mShader[2];
 };
 
 #endif
\ No newline at end of file
diff --git a/src/gl/system/gl_cvars.h b/src/gl/system/gl_cvars.h
index 4cda3657d..97bd0b46c 100644
--- a/src/gl/system/gl_cvars.h
+++ b/src/gl/system/gl_cvars.h
@@ -50,6 +50,12 @@ EXTERN_CVAR(Bool, gl_lens)
 EXTERN_CVAR(Float, gl_lens_k)
 EXTERN_CVAR(Float, gl_lens_kcube)
 EXTERN_CVAR(Float, gl_lens_chromatic)
+EXTERN_CVAR(Bool, gl_ssao)
+EXTERN_CVAR(Float, gl_ssao_strength)
+EXTERN_CVAR(Bool, gl_ssao_debug)
+EXTERN_CVAR(Float, gl_ssao_bias)
+EXTERN_CVAR(Float, gl_ssao_radius)
+EXTERN_CVAR(Float, gl_ssao_blur_amount)
 
 EXTERN_CVAR(Int, gl_debug_level)
 EXTERN_CVAR(Bool, gl_debug_breakpoint)
diff --git a/wadsrc/static/shaders/glsl/main.fp b/wadsrc/static/shaders/glsl/main.fp
index 4d3531f01..0d2b419c1 100644
--- a/wadsrc/static/shaders/glsl/main.fp
+++ b/wadsrc/static/shaders/glsl/main.fp
@@ -233,6 +233,32 @@ vec4 applyFog(vec4 frag, float fogfactor)
 	return vec4(mix(uFogColor.rgb, frag.rgb, fogfactor), frag.a);
 }
 
+//===========================================================================
+//
+// The color of the fragment if it is fully occluded by ambient lighting
+//
+//===========================================================================
+
+vec3 AmbientOcclusionColor()
+{
+	float fogdist;
+	float fogfactor;
+			
+	//
+	// calculate fog factor
+	//
+	if (uFogEnabled == -1) 
+	{
+		fogdist = pixelpos.w;
+	}
+	else 
+	{
+		fogdist = max(16.0, length(pixelpos.xyz));
+	}
+	fogfactor = exp2 (uFogDensity * fogdist);
+			
+	return mix(uFogColor.rgb, vec3(0.0), fogfactor);
+}
 
 //===========================================================================
 //
@@ -349,7 +375,7 @@ void main()
 	}
 	FragColor = frag;
 #ifdef GBUFFER_PASS
-	FragData = vec4(uFogColor.rgb, 1.0);
+	FragData = vec4(AmbientOcclusionColor(), 1.0);
 #endif
 }
 
diff --git a/wadsrc/static/shaders/glsl/ssaocombine.fp b/wadsrc/static/shaders/glsl/ssaocombine.fp
index 21fdff102..7cd096276 100644
--- a/wadsrc/static/shaders/glsl/ssaocombine.fp
+++ b/wadsrc/static/shaders/glsl/ssaocombine.fp
@@ -4,8 +4,35 @@ out vec4 FragColor;
 
 uniform sampler2D AODepthTexture;
 
+#if defined(MULTISAMPLE)
+uniform sampler2DMS SceneDataTexture;
+uniform int SampleCount;
+#else
+uniform sampler2D SceneDataTexture;
+#endif
+
+uniform vec2 Scale;
+uniform vec2 Offset;
+
 void main()
 {
+	vec2 uv = Offset + TexCoord * Scale;
+#if defined(MULTISAMPLE)
+	ivec2 texSize = textureSize(SceneDataTexture);
+#else
+	ivec2 texSize = textureSize(SceneDataTexture, 0);
+#endif
+	ivec2 ipos = ivec2(max(floor(uv * vec2(texSize) - 0.75), vec2(0.0)));
+
+#if defined(MULTISAMPLE)
+	vec3 fogColor = vec3(0.0);
+	for (int i = 0; i < SampleCount; i++)
+		fogColor += texelFetch(SceneDataTexture, ipos, i).rgb;
+	fogColor /= float(SampleCount);
+#else
+	vec3 fogColor = texelFetch(SceneDataTexture, ipos, 0).rgb;
+#endif
+
 	float attenutation = texture(AODepthTexture, TexCoord).x;
-	FragColor = vec4(attenutation, attenutation, attenutation, 0.0);
+	FragColor = vec4(fogColor, 1.0 - attenutation);
 }

From 0397fe185f68d923fec0cee03faee4bc946e0126 Mon Sep 17 00:00:00 2001
From: Magnus Norddahl <dpjudas@users.noreply.github.com>
Date: Thu, 22 Sep 2016 03:49:19 +0200
Subject: [PATCH 14/18] Don't do ambient occlusion when rendering to texture

---
 src/gl/scene/gl_scene.cpp | 32 +++++++++++++++++++-------------
 1 file changed, 19 insertions(+), 13 deletions(-)

diff --git a/src/gl/scene/gl_scene.cpp b/src/gl/scene/gl_scene.cpp
index 6a8c9a11a..59d6e0987 100644
--- a/src/gl/scene/gl_scene.cpp
+++ b/src/gl/scene/gl_scene.cpp
@@ -493,14 +493,29 @@ void FGLRenderer::DrawScene(int drawmode)
 	}
 	GLRenderer->mClipPortal = NULL;	// this must be reset before any portal recursion takes place.
 
-	RenderScene(recursion);
-
-	bool applySSAO = gl_ssao && FGLRenderBuffers::IsEnabled() && drawmode != DM_PORTAL;
+	// If SSAO is active, switch to gbuffer shaders and use the gbuffer framebuffer
+	bool applySSAO = gl_ssao && FGLRenderBuffers::IsEnabled() && drawmode == DM_MAINVIEW;
 	if (applySSAO)
 	{
-		AmbientOccludeScene();
+		GLenum buffers[] = { GL_COLOR_ATTACHMENT0, GL_COLOR_ATTACHMENT1 };
+		glDrawBuffers(2, buffers);
 		gl_RenderState.SetPassType(GBUFFER_PASS);
 		gl_RenderState.Apply();
+		gl_RenderState.ApplyMatrices();
+	}
+
+	RenderScene(recursion);
+
+	// Apply ambient occlusion and switch back to shaders without gbuffer output
+	if (applySSAO)
+	{
+		GLenum buffers[] = { GL_COLOR_ATTACHMENT0 };
+		glDrawBuffers(1, buffers);
+		AmbientOccludeScene();
+		mBuffers->BindSceneFB(true);
+		gl_RenderState.SetPassType(NORMAL_PASS);
+		gl_RenderState.Apply();
+		gl_RenderState.ApplyMatrices();
 	}
 
 	// Handle all portals after rendering the opaque objects but before
@@ -509,15 +524,6 @@ void FGLRenderer::DrawScene(int drawmode)
 	GLPortal::EndFrame();
 	recursion--;
 	RenderTranslucent();
-
-	if (applySSAO)
-	{
-		mBuffers->BindSceneFB(true);
-		GLenum buffers[] = { GL_COLOR_ATTACHMENT0, GL_COLOR_ATTACHMENT1 };
-		glDrawBuffers(2, buffers);
-		gl_RenderState.SetPassType(NORMAL_PASS);
-		gl_RenderState.Apply();
-	}
 }
 
 

From 3f11c0562c446ce2c007c8a10ec99f3898ccc7fe Mon Sep 17 00:00:00 2001
From: Magnus Norddahl <dpjudas@users.noreply.github.com>
Date: Sat, 24 Sep 2016 19:26:25 +0200
Subject: [PATCH 15/18] Add ssao quality setting

---
 src/gl/renderer/gl_postprocess.cpp  |  7 +++-
 src/gl/scene/gl_scene.cpp           |  9 +++--
 src/gl/shaders/gl_ambientshader.cpp | 63 ++++++++++++++++++-----------
 src/gl/shaders/gl_ambientshader.h   | 13 +++++-
 src/gl/system/gl_cvars.h            |  2 +-
 wadsrc/static/language.enu          |  5 ++-
 wadsrc/static/menudef.zz            | 10 ++++-
 7 files changed, 76 insertions(+), 33 deletions(-)

diff --git a/src/gl/renderer/gl_postprocess.cpp b/src/gl/renderer/gl_postprocess.cpp
index 3b94fd8cc..2fcfe245a 100644
--- a/src/gl/renderer/gl_postprocess.cpp
+++ b/src/gl/renderer/gl_postprocess.cpp
@@ -99,7 +99,12 @@ CVAR(Float, gl_lens_k, -0.12f, 0)
 CVAR(Float, gl_lens_kcube, 0.1f, 0)
 CVAR(Float, gl_lens_chromatic, 1.12f, 0)
 
-CVAR(Bool, gl_ssao, false, CVAR_ARCHIVE | CVAR_GLOBALCONFIG)
+CUSTOM_CVAR(Int, gl_ssao, 0, CVAR_ARCHIVE | CVAR_GLOBALCONFIG)
+{
+	if (self < 0 || self > 3)
+		self = 0;
+}
+
 CVAR(Float, gl_ssao_strength, 0.7, CVAR_ARCHIVE | CVAR_GLOBALCONFIG)
 CVAR(Bool, gl_ssao_debug, false, 0)
 CVAR(Float, gl_ssao_bias, 0.5f, 0)
diff --git a/src/gl/scene/gl_scene.cpp b/src/gl/scene/gl_scene.cpp
index 59d6e0987..3efd22155 100644
--- a/src/gl/scene/gl_scene.cpp
+++ b/src/gl/scene/gl_scene.cpp
@@ -158,10 +158,11 @@ void FGLRenderer::Set3DViewport(bool mainview)
 {
 	if (mainview && mBuffers->Setup(mScreenViewport.width, mScreenViewport.height, mSceneViewport.width, mSceneViewport.height))
 	{
-		mBuffers->BindSceneFB(gl_ssao);
+		bool useSSAO = (gl_ssao != 0);
+		mBuffers->BindSceneFB(useSSAO);
 		GLenum buffers[] = { GL_COLOR_ATTACHMENT0, GL_COLOR_ATTACHMENT1 };
-		glDrawBuffers(gl_ssao ? 2 : 1, buffers);
-		gl_RenderState.SetPassType(gl_ssao ? GBUFFER_PASS : NORMAL_PASS);
+		glDrawBuffers(useSSAO ? 2 : 1, buffers);
+		gl_RenderState.SetPassType(useSSAO ? GBUFFER_PASS : NORMAL_PASS);
 		gl_RenderState.Apply();
 	}
 
@@ -494,7 +495,7 @@ void FGLRenderer::DrawScene(int drawmode)
 	GLRenderer->mClipPortal = NULL;	// this must be reset before any portal recursion takes place.
 
 	// If SSAO is active, switch to gbuffer shaders and use the gbuffer framebuffer
-	bool applySSAO = gl_ssao && FGLRenderBuffers::IsEnabled() && drawmode == DM_MAINVIEW;
+	bool applySSAO = gl_ssao != 0 && FGLRenderBuffers::IsEnabled() && drawmode == DM_MAINVIEW;
 	if (applySSAO)
 	{
 		GLenum buffers[] = { GL_COLOR_ATTACHMENT0, GL_COLOR_ATTACHMENT1 };
diff --git a/src/gl/shaders/gl_ambientshader.cpp b/src/gl/shaders/gl_ambientshader.cpp
index 4fa5b0e01..7d0e26a6a 100644
--- a/src/gl/shaders/gl_ambientshader.cpp
+++ b/src/gl/shaders/gl_ambientshader.cpp
@@ -74,32 +74,47 @@ void FLinearDepthShader::Bind(bool multisample)
 
 void FSSAOShader::Bind()
 {
-	if (!mShader)
+	auto &shader = mShader[gl_ssao];
+	if (!shader)
 	{
-		const char *defines = R"(
-			#define USE_RANDOM_TEXTURE
-			#define RANDOM_TEXTURE_WIDTH 4.0
-			#define NUM_DIRECTIONS 8.0
-			#define NUM_STEPS 4.0
-		)";
-
-		mShader.Compile(FShaderProgram::Vertex, "shaders/glsl/screenquad.vp", "", 330);
-		mShader.Compile(FShaderProgram::Fragment, "shaders/glsl/ssao.fp", defines, 330);
-		mShader.SetFragDataLocation(0, "FragColor");
-		mShader.Link("shaders/glsl/ssao");
-		mShader.SetAttribLocation(0, "PositionInProjection");
-		DepthTexture.Init(mShader, "DepthTexture");
-		RandomTexture.Init(mShader, "RandomTexture");
-		UVToViewA.Init(mShader, "UVToViewA");
-		UVToViewB.Init(mShader, "UVToViewB");
-		InvFullResolution.Init(mShader, "InvFullResolution");
-		NDotVBias.Init(mShader, "NDotVBias");
-		NegInvR2.Init(mShader, "NegInvR2");
-		RadiusToScreen.Init(mShader, "RadiusToScreen");
-		AOMultiplier.Init(mShader, "AOMultiplier");
-		AOStrength.Init(mShader, "AOStrength");
+		shader.Compile(FShaderProgram::Vertex, "shaders/glsl/screenquad.vp", "", 330);
+		shader.Compile(FShaderProgram::Fragment, "shaders/glsl/ssao.fp", GetDefines(gl_ssao), 330);
+		shader.SetFragDataLocation(0, "FragColor");
+		shader.Link("shaders/glsl/ssao");
+		shader.SetAttribLocation(0, "PositionInProjection");
+		DepthTexture.Init(shader, "DepthTexture");
+		RandomTexture.Init(shader, "RandomTexture");
+		UVToViewA.Init(shader, "UVToViewA");
+		UVToViewB.Init(shader, "UVToViewB");
+		InvFullResolution.Init(shader, "InvFullResolution");
+		NDotVBias.Init(shader, "NDotVBias");
+		NegInvR2.Init(shader, "NegInvR2");
+		RadiusToScreen.Init(shader, "RadiusToScreen");
+		AOMultiplier.Init(shader, "AOMultiplier");
+		AOStrength.Init(shader, "AOStrength");
 	}
-	mShader.Bind();
+	shader.Bind();
+}
+
+FString FSSAOShader::GetDefines(int mode)
+{
+	int numDirections, numSteps;
+	switch (gl_ssao)
+	{
+	default:
+	case LowQuality:    numDirections = 2; numSteps = 4; break;
+	case MediumQuality: numDirections = 4; numSteps = 4; break;
+	case HighQuality:   numDirections = 8; numSteps = 4; break;
+	}
+
+	FString defines;
+	defines.Format(R"(
+		#define USE_RANDOM_TEXTURE
+		#define RANDOM_TEXTURE_WIDTH 4.0
+		#define NUM_DIRECTIONS %d.0
+		#define NUM_STEPS %d.0
+	)", numDirections, numSteps);
+	return defines;
 }
 
 void FDepthBlurShader::Bind(bool vertical)
diff --git a/src/gl/shaders/gl_ambientshader.h b/src/gl/shaders/gl_ambientshader.h
index f36b10625..704729b24 100644
--- a/src/gl/shaders/gl_ambientshader.h
+++ b/src/gl/shaders/gl_ambientshader.h
@@ -39,7 +39,18 @@ public:
 	FBufferedUniform1f AOStrength;
 
 private:
-	FShaderProgram mShader;
+	enum Quality
+	{
+		Off,
+		LowQuality,
+		MediumQuality,
+		HighQuality,
+		NumQualityModes
+	};
+
+	FString GetDefines(int mode);
+
+	FShaderProgram mShader[NumQualityModes];
 };
 
 class FDepthBlurShader
diff --git a/src/gl/system/gl_cvars.h b/src/gl/system/gl_cvars.h
index 97bd0b46c..845f0dd22 100644
--- a/src/gl/system/gl_cvars.h
+++ b/src/gl/system/gl_cvars.h
@@ -50,7 +50,7 @@ EXTERN_CVAR(Bool, gl_lens)
 EXTERN_CVAR(Float, gl_lens_k)
 EXTERN_CVAR(Float, gl_lens_kcube)
 EXTERN_CVAR(Float, gl_lens_chromatic)
-EXTERN_CVAR(Bool, gl_ssao)
+EXTERN_CVAR(Int, gl_ssao)
 EXTERN_CVAR(Float, gl_ssao_strength)
 EXTERN_CVAR(Bool, gl_ssao_debug)
 EXTERN_CVAR(Float, gl_ssao_bias)
diff --git a/wadsrc/static/language.enu b/wadsrc/static/language.enu
index 197e262f5..fae6d871b 100644
--- a/wadsrc/static/language.enu
+++ b/wadsrc/static/language.enu
@@ -2167,6 +2167,9 @@ NETMNU_TICBALANCE				= "Latency balancing";
 // Option Values
 OPTVAL_OFF					= "Off";
 OPTVAL_ON					= "On";
+OPTVAL_LOW					= "Low";
+OPTVAL_MEDIUM				= "Medium";
+OPTVAL_HIGH					= "High";
 OPTVAL_MALE					= "Male";
 OPTVAL_FEMALE				= "Female";
 OPTVAL_OTHER				= "Other";
@@ -2633,7 +2636,7 @@ GLPREFMNU_MULTISAMPLE			= "Multisample";
 GLPREFMNU_TONEMAP				= "Tonemap Mode";
 GLPREFMNU_BLOOM					= "Bloom effect";
 GLPREFMNU_LENS					= "Lens distortion effect";
-GLPREFMNU_SSAO					= "Ambient occlusion";
+GLPREFMNU_SSAO					= "Ambient occlusion quality";
 
 // Option Values
 OPTVAL_SMART 				= "Smart";
diff --git a/wadsrc/static/menudef.zz b/wadsrc/static/menudef.zz
index 68523ea83..8b742ceff 100644
--- a/wadsrc/static/menudef.zz
+++ b/wadsrc/static/menudef.zz
@@ -42,6 +42,14 @@ OptionValue "TonemapModes"
 	5, "$OPTVAL_PALETTE"
 }
 
+OptionValue "SSAOModes"
+{
+	0, "$OPTVAL_OFF"
+	1, "$OPTVAL_LOW"
+	2, "$OPTVAL_MEDIUM"
+	3, "$OPTVAL_HIGH"
+}
+
 OptionValue "TextureFormats"
 {
 	0, "$OPTVAL_RGBA8"
@@ -226,5 +234,5 @@ OptionMenu "GLPrefOptions"
 	Option "$GLPREFMNU_TONEMAP", 				gl_tonemap,						"TonemapModes"
 	Option "$GLPREFMNU_BLOOM",		 			gl_bloom,						"OnOff"
 	Option "$GLPREFMNU_LENS",		 			gl_lens,						"OnOff"
-	Option "$GLPREFMNU_SSAO",		 			gl_ssao,						"OnOff"
+	Option "$GLPREFMNU_SSAO",		 			gl_ssao,						"SSAOModes"
 }

From 979e70ca8f9514b1f976d604e7a0a63907149238 Mon Sep 17 00:00:00 2001
From: Magnus Norddahl <dpjudas@users.noreply.github.com>
Date: Sat, 24 Sep 2016 20:09:40 +0200
Subject: [PATCH 16/18] Add gl_ssao_portals for controlling how many portals
 gets SSAO

---
 src/gl/renderer/gl_postprocess.cpp |  6 ++++++
 src/gl/scene/gl_scene.cpp          | 13 +++++++++++--
 src/gl/system/gl_cvars.h           |  1 +
 wadsrc/static/language.enu         |  1 +
 wadsrc/static/menudef.zz           |  1 +
 5 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/src/gl/renderer/gl_postprocess.cpp b/src/gl/renderer/gl_postprocess.cpp
index 2fcfe245a..23fdda2eb 100644
--- a/src/gl/renderer/gl_postprocess.cpp
+++ b/src/gl/renderer/gl_postprocess.cpp
@@ -105,6 +105,12 @@ CUSTOM_CVAR(Int, gl_ssao, 0, CVAR_ARCHIVE | CVAR_GLOBALCONFIG)
 		self = 0;
 }
 
+CUSTOM_CVAR(Int, gl_ssao_portals, 0, CVAR_ARCHIVE | CVAR_GLOBALCONFIG)
+{
+	if (self < 0)
+		self = 0;
+}
+
 CVAR(Float, gl_ssao_strength, 0.7, CVAR_ARCHIVE | CVAR_GLOBALCONFIG)
 CVAR(Bool, gl_ssao_debug, false, 0)
 CVAR(Float, gl_ssao_bias, 0.5f, 0)
diff --git a/src/gl/scene/gl_scene.cpp b/src/gl/scene/gl_scene.cpp
index 3efd22155..b6120f940 100644
--- a/src/gl/scene/gl_scene.cpp
+++ b/src/gl/scene/gl_scene.cpp
@@ -477,6 +477,7 @@ void FGLRenderer::RenderTranslucent()
 void FGLRenderer::DrawScene(int drawmode)
 {
 	static int recursion=0;
+	static int ssao_portals_available = 0;
 
 	if (camera != nullptr)
 	{
@@ -494,8 +495,16 @@ void FGLRenderer::DrawScene(int drawmode)
 	}
 	GLRenderer->mClipPortal = NULL;	// this must be reset before any portal recursion takes place.
 
-	// If SSAO is active, switch to gbuffer shaders and use the gbuffer framebuffer
-	bool applySSAO = gl_ssao != 0 && FGLRenderBuffers::IsEnabled() && drawmode == DM_MAINVIEW;
+	// Decide if we need to do ssao for this scene
+	bool applySSAO = gl_ssao != 0 && FGLRenderBuffers::IsEnabled();
+	switch (drawmode)
+	{
+	case DM_MAINVIEW: ssao_portals_available = gl_ssao_portals; break;
+	case DM_OFFSCREEN: ssao_portals_available = 0; applySSAO = false; break;
+	case DM_PORTAL: applySSAO = applySSAO && (ssao_portals_available > 0); ssao_portals_available--; break;
+	}
+
+	// If SSAO is active, switch to gbuffer shaders and use the framebuffer with gbuffers
 	if (applySSAO)
 	{
 		GLenum buffers[] = { GL_COLOR_ATTACHMENT0, GL_COLOR_ATTACHMENT1 };
diff --git a/src/gl/system/gl_cvars.h b/src/gl/system/gl_cvars.h
index 845f0dd22..836787117 100644
--- a/src/gl/system/gl_cvars.h
+++ b/src/gl/system/gl_cvars.h
@@ -51,6 +51,7 @@ EXTERN_CVAR(Float, gl_lens_k)
 EXTERN_CVAR(Float, gl_lens_kcube)
 EXTERN_CVAR(Float, gl_lens_chromatic)
 EXTERN_CVAR(Int, gl_ssao)
+EXTERN_CVAR(Int, gl_ssao_portals)
 EXTERN_CVAR(Float, gl_ssao_strength)
 EXTERN_CVAR(Bool, gl_ssao_debug)
 EXTERN_CVAR(Float, gl_ssao_bias)
diff --git a/wadsrc/static/language.enu b/wadsrc/static/language.enu
index fae6d871b..cb3af51aa 100644
--- a/wadsrc/static/language.enu
+++ b/wadsrc/static/language.enu
@@ -2637,6 +2637,7 @@ GLPREFMNU_TONEMAP				= "Tonemap Mode";
 GLPREFMNU_BLOOM					= "Bloom effect";
 GLPREFMNU_LENS					= "Lens distortion effect";
 GLPREFMNU_SSAO					= "Ambient occlusion quality";
+GLPREFMNU_SSAO_PORTALS			= "Portals with AO";
 
 // Option Values
 OPTVAL_SMART 				= "Smart";
diff --git a/wadsrc/static/menudef.zz b/wadsrc/static/menudef.zz
index 8b742ceff..4784baa93 100644
--- a/wadsrc/static/menudef.zz
+++ b/wadsrc/static/menudef.zz
@@ -235,4 +235,5 @@ OptionMenu "GLPrefOptions"
 	Option "$GLPREFMNU_BLOOM",		 			gl_bloom,						"OnOff"
 	Option "$GLPREFMNU_LENS",		 			gl_lens,						"OnOff"
 	Option "$GLPREFMNU_SSAO",		 			gl_ssao,						"SSAOModes"
+	Slider "$GLPREFMNU_SSAO_PORTALS",			gl_ssao_portals,				0.0, 4.0, 1.0, 0
 }

From 6cb9f875dd3acc102cf46be46d0a8cb38d4860c6 Mon Sep 17 00:00:00 2001
From: Magnus Norddahl <dpjudas@users.noreply.github.com>
Date: Sun, 25 Sep 2016 00:31:43 +0200
Subject: [PATCH 17/18] Fix missing call from merge

---
 src/gl/renderer/gl_postprocess.cpp | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/gl/renderer/gl_postprocess.cpp b/src/gl/renderer/gl_postprocess.cpp
index 23fdda2eb..6c18edd1e 100644
--- a/src/gl/renderer/gl_postprocess.cpp
+++ b/src/gl/renderer/gl_postprocess.cpp
@@ -137,6 +137,7 @@ void FGLRenderer::PostProcessScene()
 	UpdateCameraExposure();
 	BloomScene();
 	TonemapScene();
+	ColormapScene();
 	LensDistortScene();
 }
 

From 287acea6b46669d4192b132e84d889b4e0730c95 Mon Sep 17 00:00:00 2001
From: Magnus Norddahl <dpjudas@users.noreply.github.com>
Date: Sun, 25 Sep 2016 00:31:57 +0200
Subject: [PATCH 18/18] Update copyright

---
 src/gl/shaders/gl_ambientshader.cpp | 60 ++++++++++-------------------
 1 file changed, 21 insertions(+), 39 deletions(-)

diff --git a/src/gl/shaders/gl_ambientshader.cpp b/src/gl/shaders/gl_ambientshader.cpp
index 7d0e26a6a..43adb5c0e 100644
--- a/src/gl/shaders/gl_ambientshader.cpp
+++ b/src/gl/shaders/gl_ambientshader.cpp
@@ -1,42 +1,24 @@
-/*
-** gl_bloomshader.cpp
-** Shaders used for screen space ambient occlusion
-**
-**---------------------------------------------------------------------------
-** Copyright 2016 Magnus Norddahl
-** All rights reserved.
-**
-** Redistribution and use in source and binary forms, with or without
-** modification, are permitted provided that the following conditions
-** are met:
-**
-** 1. Redistributions of source code must retain the above copyright
-**    notice, this list of conditions and the following disclaimer.
-** 2. Redistributions in binary form must reproduce the above copyright
-**    notice, this list of conditions and the following disclaimer in the
-**    documentation and/or other materials provided with the distribution.
-** 3. The name of the author may not be used to endorse or promote products
-**    derived from this software without specific prior written permission.
-** 4. When not used as part of GZDoom or a GZDoom derivative, this code will be
-**    covered by the terms of the GNU Lesser General Public License as published
-**    by the Free Software Foundation; either version 2.1 of the License, or (at
-**    your option) any later version.
-** 5. Full disclosure of the entire project's source code, except for third
-**    party libraries is mandatory. (NOTE: This clause is non-negotiable!)
-**
-** THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
-** IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
-** OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
-** IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
-** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
-** NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
-** THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-**---------------------------------------------------------------------------
-**
-*/
+// 
+//---------------------------------------------------------------------------
+//
+// Copyright(C) 2016 Magnus Norddahl
+// All rights reserved.
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with this program.  If not, see http://www.gnu.org/licenses/
+//
+//--------------------------------------------------------------------------
+//
 
 #include "gl/system/gl_system.h"
 #include "files.h"