diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index b75f3559c..49153f574 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -963,6 +963,7 @@ set( FASTMATH_SOURCES
 	gl/shaders/gl_presentshader.cpp
 	gl/shaders/gl_present3dRowshader.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 6d080434d..f35071854 100644
--- a/src/gl/renderer/gl_postprocess.cpp
+++ b/src/gl/renderer/gl_postprocess.cpp
@@ -54,6 +54,7 @@
 #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"
@@ -106,6 +107,32 @@ CUSTOM_CVAR(Int, gl_fxaa, 0, CVAR_ARCHIVE | CVAR_GLOBALCONFIG)
 	}
 }
 
+CUSTOM_CVAR(Int, gl_ssao, 0, CVAR_ARCHIVE | CVAR_GLOBALCONFIG)
+{
+	if (self < 0 || self > 3)
+		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(Int, gl_ssao_debug, 0, 0)
+CVAR(Float, gl_ssao_bias, 0.2f, 0)
+CVAR(Float, gl_ssao_radius, 80.0f, 0)
+CUSTOM_CVAR(Float, gl_ssao_blur, 16.0f, 0)
+{
+	if (self < 0.1f) self = 0.1f;
+}
+
+CUSTOM_CVAR(Float, gl_ssao_exponent, 1.8f, 0)
+{
+	if (self < 0.1f) self = 0.1f;
+}
+
 EXTERN_CVAR(Float, vid_brightness)
 EXTERN_CVAR(Float, vid_contrast)
 
@@ -117,6 +144,153 @@ void FGLRenderer::RenderScreenQuad()
 	GLRenderer->mVBO->RenderArray(GL_TRIANGLE_STRIP, FFlatVertexBuffer::PRESENT_INDEX, 4);
 }
 
+void FGLRenderer::PostProcessScene()
+{
+	mBuffers->BlitSceneToTexture();
+	UpdateCameraExposure();
+	BloomScene();
+	TonemapScene();
+	ColormapScene();
+	LensDistortScene();
+	ApplyFXAA();
+}
+
+//-----------------------------------------------------------------------------
+//
+// Adds ambient occlusion to the scene
+//
+//-----------------------------------------------------------------------------
+
+void FGLRenderer::AmbientOccludeScene()
+{
+	FGLDebug::PushGroup("AmbientOccludeScene");
+
+	FGLPostProcessState savedState;
+	savedState.SaveTextureBindings(3);
+
+	float bias = gl_ssao_bias;
+	float aoRadius = gl_ssao_radius;
+	const float blurAmount = gl_ssao_blur;
+	float aoStrength = gl_ssao_strength;
+
+	//float tanHalfFovy = tan(fovy * (M_PI / 360.0f));
+	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);
+	float r2 = aoRadius * aoRadius;
+
+	float blurSharpness = 1.0f / blurAmount;
+
+	float sceneScaleX = mSceneViewport.width / (float)mScreenViewport.width;
+	float sceneScaleY = mSceneViewport.height / (float)mScreenViewport.height;
+	float sceneOffsetX = mSceneViewport.left / (float)mScreenViewport.width;
+	float sceneOffsetY = mSceneViewport.top / (float)mScreenViewport.height;
+
+	int randomTexture = clamp(gl_ssao - 1, 0, FGLRenderBuffers::NumAmbientRandomTextures - 1);
+
+	// Calculate linear depth values
+	glBindFramebuffer(GL_FRAMEBUFFER, mBuffers->LinearDepthFB);
+	glViewport(0, 0, mBuffers->AmbientWidth, mBuffers->AmbientHeight);
+	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();
+	mLinearDepthShader->DepthTexture.Set(0);
+	mLinearDepthShader->ColorTexture.Set(1);
+	if (gl_multisample > 1) mLinearDepthShader->SampleIndex.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);
+	mLinearDepthShader->Scale.Set(sceneScaleX, sceneScaleY);
+	mLinearDepthShader->Offset.Set(sceneOffsetX, sceneOffsetY);
+	RenderScreenQuad();
+
+	// Apply ambient occlusion
+	glBindFramebuffer(GL_FRAMEBUFFER, mBuffers->AmbientFB1);
+	glBindTexture(GL_TEXTURE_2D, mBuffers->LinearDepthTexture);
+	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[randomTexture]);
+	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);
+	mBuffers->BindSceneNormalTexture(2);
+	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->NormalTexture.Set(2);
+	if (gl_multisample > 1) mSSAOShader->SampleIndex.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));
+	mSSAOShader->AOStrength.Set(aoStrength);
+	mSSAOShader->Scale.Set(sceneScaleX, sceneScaleY);
+	mSSAOShader->Offset.Set(sceneOffsetX, sceneOffsetY);
+	RenderScreenQuad();
+
+	// Blur SSAO texture
+	if (gl_ssao_debug < 2)
+	{
+		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(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(blurSharpness);
+		mDepthBlurShader->InvFullResolution[true].Set(1.0f / mBuffers->AmbientWidth, 1.0f / mBuffers->AmbientHeight);
+		mDepthBlurShader->PowExponent[true].Set(gl_ssao_exponent);
+		RenderScreenQuad();
+	}
+
+	// Add SSAO back to scene texture:
+	mBuffers->BindSceneFB(false);
+	glViewport(mSceneViewport.left, mSceneViewport.top, mSceneViewport.width, mSceneViewport.height);
+	glEnable(GL_BLEND);
+	glBlendEquation(GL_FUNC_ADD);
+	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+	if (gl_ssao_debug != 0)
+	{
+		glClearColor(1.0f, 1.0f, 1.0f, 1.0f);
+		glClear(GL_COLOR_BUFFER_BIT);
+	}
+	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);
+	mBuffers->BindSceneFogTexture(1);
+	mSSAOCombineShader->Bind();
+	mSSAOCombineShader->AODepthTexture.Set(0);
+	mSSAOCombineShader->SceneFogTexture.Set(1);
+	if (gl_multisample > 1) mSSAOCombineShader->SampleCount.Set(gl_multisample);
+	mSSAOCombineShader->Scale.Set(sceneScaleX, sceneScaleY);
+	mSSAOCombineShader->Offset.Set(sceneOffsetX, sceneOffsetY);
+	RenderScreenQuad();
+
+	FGLDebug::PopGroup();
+}
+
 //-----------------------------------------------------------------------------
 //
 // Extracts light average from the scene and updates the camera exposure texture
@@ -131,7 +305,7 @@ void FGLRenderer::UpdateCameraExposure()
 	FGLDebug::PushGroup("UpdateCameraExposure");
 
 	FGLPostProcessState savedState;
-	savedState.SaveTextureBinding1();
+	savedState.SaveTextureBindings(2);
 
 	// Extract light level from scene texture:
 	const auto &level0 = mBuffers->ExposureLevels[0];
@@ -198,13 +372,13 @@ 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");
 
 	FGLPostProcessState savedState;
-	savedState.SaveTextureBinding1();
+	savedState.SaveTextureBindings(2);
 
 	const float blurAmount = gl_bloom_amount;
 	int sampleCount = gl_bloom_kernel_size;
@@ -293,7 +467,10 @@ void FGLRenderer::TonemapScene()
 
 	FGLDebug::PushGroup("TonemapScene");
 
+	CreateTonemapPalette();
+
 	FGLPostProcessState savedState;
+	savedState.SaveTextureBindings(2);
 
 	mBuffers->BindNextFB();
 	mBuffers->BindCurrentTexture(0);
@@ -302,12 +479,18 @@ void FGLRenderer::TonemapScene()
 
 	if (mTonemapShader->IsPaletteMode())
 	{
+		glActiveTexture(GL_TEXTURE1);
+		glBindTexture(GL_TEXTURE_2D, mTonemapPalette->GetTextureHandle(0));
+		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_CLAMP_TO_EDGE);
+		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+		glActiveTexture(GL_TEXTURE0);
+
 		mTonemapShader->PaletteLUT.Set(1);
-		BindTonemapPalette(1);
 	}
 	else
 	{
-		savedState.SaveTextureBinding1();
 		glActiveTexture(GL_TEXTURE1);
 		glBindTexture(GL_TEXTURE_2D, mBuffers->ExposureTexture);
 		glActiveTexture(GL_TEXTURE0);
@@ -321,13 +504,9 @@ void FGLRenderer::TonemapScene()
 	FGLDebug::PopGroup();
 }
 
-void FGLRenderer::BindTonemapPalette(int texunit)
+void FGLRenderer::CreateTonemapPalette()
 {
-	if (mTonemapPalette)
-	{
-		mTonemapPalette->Bind(texunit, 0, false);
-	}
-	else
+	if (!mTonemapPalette)
 	{
 		TArray<unsigned char> lut;
 		lut.Resize(512 * 512 * 4);
@@ -348,14 +527,7 @@ void FGLRenderer::BindTonemapPalette(int texunit)
 		}
 
 		mTonemapPalette = new FHardwareTexture(512, 512, true);
-		mTonemapPalette->CreateTexture(&lut[0], 512, 512, texunit, false, 0, "mTonemapPalette");
-
-		glActiveTexture(GL_TEXTURE0 + texunit);
-		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_CLAMP_TO_EDGE);
-		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
-		glActiveTexture(GL_TEXTURE0);
+		mTonemapPalette->CreateTexture(&lut[0], 512, 512, 0, false, 0, "mTonemapPalette");
 	}
 }
 
@@ -425,7 +597,7 @@ void FGLRenderer::LensDistortScene()
 		0.0f
 	};
 
-	float aspect = mSceneViewport.width / mSceneViewport.height;
+	float aspect = mSceneViewport.width / (float)mSceneViewport.height;
 
 	// Scale factor to keep sampling within the input texture
 	float r2 = aspect * aspect * 0.25 + 0.25f;
diff --git a/src/gl/renderer/gl_postprocessstate.cpp b/src/gl/renderer/gl_postprocessstate.cpp
index 57b7862f5..fead1435a 100644
--- a/src/gl/renderer/gl_postprocessstate.cpp
+++ b/src/gl/renderer/gl_postprocessstate.cpp
@@ -45,17 +45,7 @@ FGLPostProcessState::FGLPostProcessState()
 {
 	glGetIntegerv(GL_ACTIVE_TEXTURE, &activeTex);
 	glActiveTexture(GL_TEXTURE0);
-	glGetIntegerv(GL_TEXTURE_BINDING_2D, &textureBinding[0]);
-	glBindTexture(GL_TEXTURE_2D, 0);
-	if (gl.flags & RFL_SAMPLER_OBJECTS)
-	{
-		glGetIntegerv(GL_SAMPLER_BINDING, &samplerBinding[0]);
-		glBindSampler(0, 0);
-		glActiveTexture(GL_TEXTURE0 + 1);
-		glGetIntegerv(GL_SAMPLER_BINDING, &samplerBinding[1]);
-		glBindSampler(1, 0);
-		glActiveTexture(GL_TEXTURE0);
-	}
+	SaveTextureBindings(1);
 
 	glGetBooleanv(GL_BLEND, &blendEnabled);
 	glGetBooleanv(GL_SCISSOR_TEST, &scissorEnabled);
@@ -75,12 +65,26 @@ FGLPostProcessState::FGLPostProcessState()
 	glDisable(GL_BLEND);
 }
 
-void FGLPostProcessState::SaveTextureBinding1()
+void FGLPostProcessState::SaveTextureBindings(unsigned int numUnits)
 {
-	glActiveTexture(GL_TEXTURE1);
-	glGetIntegerv(GL_TEXTURE_BINDING_2D, &textureBinding[1]);
-	glBindTexture(GL_TEXTURE_2D, 0);
-	textureBinding1Saved = true;
+	while (textureBinding.Size() < numUnits)
+	{
+		unsigned int i = textureBinding.Size();
+
+		GLint texture;
+		glActiveTexture(GL_TEXTURE0 + i);
+		glGetIntegerv(GL_TEXTURE_BINDING_2D, &texture);
+		glBindTexture(GL_TEXTURE_2D, 0);
+		textureBinding.Push(texture);
+
+		if (gl.flags & RFL_SAMPLER_OBJECTS)
+		{
+			GLint sampler;
+			glGetIntegerv(GL_SAMPLER_BINDING, &sampler);
+			glBindSampler(i, 0);
+			samplerBinding.Push(sampler);
+		}
+	}
 	glActiveTexture(GL_TEXTURE0);
 }
 
@@ -117,25 +121,22 @@ FGLPostProcessState::~FGLPostProcessState()
 
 	glUseProgram(currentProgram);
 
-	if (textureBinding1Saved)
+	// Fully unbind to avoid incomplete texture warnings from Nvidia's driver when gl_debug_level 4 is active
+	for (unsigned int i = 0; i < textureBinding.Size(); i++)
 	{
-		glActiveTexture(GL_TEXTURE1);
+		glActiveTexture(GL_TEXTURE0 + i);
 		glBindTexture(GL_TEXTURE_2D, 0);
 	}
 
-	glActiveTexture(GL_TEXTURE0);
-	glBindTexture(GL_TEXTURE_2D, 0);
-	if (gl.flags & RFL_SAMPLER_OBJECTS)
+	for (unsigned int i = 0; i < samplerBinding.Size(); i++)
 	{
-		glBindSampler(0, samplerBinding[0]);
-		glBindSampler(1, samplerBinding[1]);
+		glBindSampler(i, samplerBinding[i]);
 	}
-	glBindTexture(GL_TEXTURE_2D, textureBinding[0]);
 
-	if (textureBinding1Saved)
+	for (unsigned int i = 0; i < textureBinding.Size(); i++)
 	{
-		glActiveTexture(GL_TEXTURE1);
-		glBindTexture(GL_TEXTURE_2D, textureBinding[1]);
+		glActiveTexture(GL_TEXTURE0 + i);
+		glBindTexture(GL_TEXTURE_2D, textureBinding[i]);
 	}
 
 	glActiveTexture(activeTex);
diff --git a/src/gl/renderer/gl_postprocessstate.h b/src/gl/renderer/gl_postprocessstate.h
index bf53aa7de..795a7d4ba 100644
--- a/src/gl/renderer/gl_postprocessstate.h
+++ b/src/gl/renderer/gl_postprocessstate.h
@@ -14,15 +14,15 @@ public:
 	FGLPostProcessState();
 	~FGLPostProcessState();
 
-	void SaveTextureBinding1();
+	void SaveTextureBindings(unsigned int numUnits);
 
 private:
 	FGLPostProcessState(const FGLPostProcessState &) = delete;
 	FGLPostProcessState &operator=(const FGLPostProcessState &) = delete;
 
 	GLint activeTex;
-	GLint textureBinding[2];
-	GLint samplerBinding[2];
+	TArray<GLint> textureBinding;
+	TArray<GLint> samplerBinding;
 	GLboolean blendEnabled;
 	GLboolean scissorEnabled;
 	GLboolean depthEnabled;
@@ -34,7 +34,6 @@ private:
 	GLint blendSrcAlpha;
 	GLint blendDestRgb;
 	GLint blendDestAlpha;
-	bool textureBinding1Saved = false;
 };
 
 #endif
diff --git a/src/gl/renderer/gl_renderbuffers.cpp b/src/gl/renderer/gl_renderbuffers.cpp
index b2471e4b9..b14ee9852 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)
@@ -58,6 +59,11 @@ FGLRenderBuffers::FGLRenderBuffers()
 		mPipelineFB[i] = 0;
 	}
 
+	for (int i = 0; i < NumAmbientRandomTextures; i++)
+	{
+		AmbientRandomTexture[i] = 0;
+	}
+
 	glGetIntegerv(GL_FRAMEBUFFER_BINDING, (GLint*)&mOutputFB);
 	glGetIntegerv(GL_MAX_SAMPLES, &mMaxSamples);
 }
@@ -75,15 +81,27 @@ FGLRenderBuffers::~FGLRenderBuffers()
 	ClearEyeBuffers();
 	ClearBloom();
 	ClearExposureLevels();
+	ClearAmbientOcclusion();
 }
 
 void FGLRenderBuffers::ClearScene()
 {
 	DeleteFrameBuffer(mSceneFB);
-	DeleteRenderBuffer(mSceneMultisample);
-	DeleteRenderBuffer(mSceneDepthStencil);
-	DeleteRenderBuffer(mSceneDepth);
-	DeleteRenderBuffer(mSceneStencil);
+	DeleteFrameBuffer(mSceneDataFB);
+	if (mSceneUsesTextures)
+	{
+		DeleteTexture(mSceneMultisample);
+		DeleteTexture(mSceneFog);
+		DeleteTexture(mSceneNormal);
+		DeleteTexture(mSceneDepthStencil);
+	}
+	else
+	{
+		DeleteRenderBuffer(mSceneMultisample);
+		DeleteRenderBuffer(mSceneFog);
+		DeleteRenderBuffer(mSceneNormal);
+		DeleteRenderBuffer(mSceneDepthStencil);
+	}
 }
 
 void FGLRenderBuffers::ClearPipeline()
@@ -132,6 +150,18 @@ void FGLRenderBuffers::ClearEyeBuffers()
 	mEyeFBs.Clear();
 }
 
+void FGLRenderBuffers::ClearAmbientOcclusion()
+{
+	DeleteFrameBuffer(LinearDepthFB);
+	DeleteFrameBuffer(AmbientFB0);
+	DeleteFrameBuffer(AmbientFB1);
+	DeleteTexture(LinearDepthTexture);
+	DeleteTexture(AmbientTexture0);
+	DeleteTexture(AmbientTexture1);
+	for (int i = 0; i < NumAmbientRandomTextures; i++)
+		DeleteTexture(AmbientRandomTexture[i]);
+}
+
 void FGLRenderBuffers::DeleteTexture(GLuint &handle)
 {
 	if (handle != 0)
@@ -177,6 +207,7 @@ bool FGLRenderBuffers::Setup(int width, int height, int sceneWidth, int sceneHei
 		I_FatalError("Requested invalid render buffer sizes: screen = %dx%d", width, height);
 
 	int samples = clamp((int)gl_multisample, 0, mMaxSamples);
+	bool needsSceneTextures = (gl_ssao != 0);
 
 	GLint activeTex;
 	GLint textureBinding;
@@ -184,25 +215,23 @@ bool FGLRenderBuffers::Setup(int width, int height, int sceneWidth, int sceneHei
 	glActiveTexture(GL_TEXTURE0);
 	glGetIntegerv(GL_TEXTURE_BINDING_2D, &textureBinding);
 
-	if (width == mWidth && height == mHeight && mSamples != samples)
-	{
-		CreateScene(mWidth, mHeight, samples);
-		mSamples = samples;
-	}
-	else if (width != mWidth || height != mHeight)
-	{
+	if (width != mWidth || height != mHeight)
 		CreatePipeline(width, height);
-		CreateScene(width, height, samples);
-		mWidth = width;
-		mHeight = height;
-		mSamples = samples;
-	}
+
+	if (width != mWidth || height != mHeight || mSamples != samples || mSceneUsesTextures != needsSceneTextures)
+		CreateScene(width, height, samples, needsSceneTextures);
+
+	mWidth = width;
+	mHeight = height;
+	mSamples = samples;
+	mSceneUsesTextures = needsSceneTextures;
 
 	// Bloom bluring buffers need to match the scene to avoid bloom bleeding artifacts
 	if (mSceneWidth != sceneWidth || mSceneHeight != sceneHeight)
 	{
 		CreateBloom(sceneWidth, sceneHeight);
 		CreateExposureLevels(sceneWidth, sceneHeight);
+		CreateAmbientOcclusion(sceneWidth, sceneHeight);
 		mSceneWidth = sceneWidth;
 		mSceneHeight = sceneHeight;
 	}
@@ -235,15 +264,46 @@ bool FGLRenderBuffers::Setup(int width, int height, int sceneWidth, int sceneHei
 //
 //==========================================================================
 
-void FGLRenderBuffers::CreateScene(int width, int height, int samples)
+void FGLRenderBuffers::CreateScene(int width, int height, int samples, bool needsSceneTextures)
 {
 	ClearScene();
 
 	if (samples > 1)
-		mSceneMultisample = CreateRenderBuffer("SceneMultisample", GL_RGBA16F, samples, width, height);
-
-	mSceneDepthStencil = CreateRenderBuffer("SceneDepthStencil", GL_DEPTH24_STENCIL8, samples, width, height);
-	mSceneFB = CreateFrameBuffer("SceneFB", samples > 1 ? mSceneMultisample : mPipelineTexture[0], mSceneDepthStencil, samples > 1);
+	{
+		if (needsSceneTextures)
+		{
+			mSceneMultisample = Create2DMultisampleTexture("SceneMultisample", GL_RGBA16F, width, height, samples, false);
+			mSceneDepthStencil = Create2DMultisampleTexture("SceneDepthStencil", GL_DEPTH24_STENCIL8, width, height, samples, false);
+			mSceneFog = Create2DMultisampleTexture("SceneFog", GL_RGBA8, width, height, samples, false);
+			mSceneNormal = Create2DMultisampleTexture("SceneNormal", GL_RGB10_A2, width, height, samples, false);
+			mSceneFB = CreateFrameBuffer("SceneFB", mSceneMultisample, 0, 0, mSceneDepthStencil, true);
+			mSceneDataFB = CreateFrameBuffer("SceneGBufferFB", mSceneMultisample, mSceneFog, mSceneNormal, mSceneDepthStencil, true);
+		}
+		else
+		{
+			mSceneMultisample = CreateRenderBuffer("SceneMultisample", GL_RGBA16F, width, height, samples);
+			mSceneDepthStencil = CreateRenderBuffer("SceneDepthStencil", GL_DEPTH24_STENCIL8, width, height, samples);
+			mSceneFB = CreateFrameBuffer("SceneFB", mSceneMultisample, mSceneDepthStencil, true);
+			mSceneDataFB = CreateFrameBuffer("SceneGBufferFB", mSceneMultisample, mSceneDepthStencil, true);
+		}
+	}
+	else
+	{
+		if (needsSceneTextures)
+		{
+			mSceneDepthStencil = Create2DTexture("SceneDepthStencil", GL_DEPTH24_STENCIL8, width, height);
+			mSceneFog = Create2DTexture("SceneFog", GL_RGBA8, width, height);
+			mSceneNormal = Create2DTexture("SceneNormal", GL_RGB10_A2, width, height);
+			mSceneFB = CreateFrameBuffer("SceneFB", mPipelineTexture[0], 0, 0, mSceneDepthStencil, false);
+			mSceneDataFB = CreateFrameBuffer("SceneGBufferFB", mPipelineTexture[0], mSceneFog, mSceneNormal, mSceneDepthStencil, false);
+		}
+		else
+		{
+			mSceneDepthStencil = CreateRenderBuffer("SceneDepthStencil", GL_DEPTH24_STENCIL8, width, height);
+			mSceneFB = CreateFrameBuffer("SceneFB", mPipelineTexture[0], mSceneDepthStencil, false);
+			mSceneDataFB = CreateFrameBuffer("SceneGBufferFB", mPipelineTexture[0], mSceneDepthStencil, false);
+		}
+	}
 }
 
 //==========================================================================
@@ -278,13 +338,13 @@ void FGLRenderBuffers::CreateBloom(int width, int height)
 	if (width <= 0 || height <= 0)
 		return;
 
-	int bloomWidth = MAX(width / 2, 1);
-	int bloomHeight = MAX(height / 2, 1);
+	int bloomWidth = (width + 1) / 2;
+	int bloomHeight = (height + 1) / 2;
 	for (int i = 0; i < NumBloomLevels; i++)
 	{
 		auto &level = BloomLevels[i];
-		level.Width = MAX(bloomWidth / 2, 1);
-		level.Height = MAX(bloomHeight / 2, 1);
+		level.Width = (bloomWidth + 1) / 2;
+		level.Height = (bloomHeight + 1) / 2;
 
 		level.VTexture = Create2DTexture("Bloom.VTexture", GL_RGBA16F, level.Width, level.Height);
 		level.HTexture = Create2DTexture("Bloom.HTexture", GL_RGBA16F, level.Width, level.Height);
@@ -296,6 +356,55 @@ 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 + 1) / 2;
+	AmbientHeight = (height + 1) / 2;
+	LinearDepthTexture = Create2DTexture("LinearDepthTexture", GL_R32F, AmbientWidth, AmbientHeight);
+	AmbientTexture0 = Create2DTexture("AmbientTexture0", GL_RG16F, AmbientWidth, AmbientHeight);
+	AmbientTexture1 = Create2DTexture("AmbientTexture1", GL_RG16F, AmbientWidth, AmbientHeight);
+	LinearDepthFB = CreateFrameBuffer("LinearDepthFB", LinearDepthTexture);
+	AmbientFB0 = CreateFrameBuffer("AmbientFB0", AmbientTexture0);
+	AmbientFB1 = CreateFrameBuffer("AmbientFB1", AmbientTexture1);
+
+	// Must match quality enum in FSSAOShader::GetDefines
+	double numDirections[NumAmbientRandomTextures] = { 2.0, 4.0, 8.0 };
+
+	std::mt19937 generator(1337);
+	std::uniform_real_distribution<double> distribution(0.0, 1.0);
+	for (int quality = 0; quality < NumAmbientRandomTextures; quality++)
+	{
+		int16_t randomValues[16 * 4];
+
+		for (int i = 0; i < 16; i++)
+		{
+			double angle = 2.0 * M_PI * distribution(generator) / numDirections[quality];
+			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[quality] = Create2DTexture("AmbientRandomTexture", GL_RGBA16_SNORM, 4, 4, randomValues);
+	}
+}
+
 //==========================================================================
 //
 // Creates camera exposure level buffers
@@ -368,12 +477,31 @@ 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_RGBA16_SNORM:		dataformat = GL_RGBA; datatype = GL_SHORT; break;
+	case GL_R32F:				dataformat = GL_RED; datatype = GL_FLOAT; break;
+	case GL_R16F:				dataformat = GL_RED; datatype = GL_FLOAT; break;
+	case GL_RG32F:				dataformat = GL_RG; datatype = GL_FLOAT; break;
+	case GL_RG16F:				dataformat = GL_RG; datatype = GL_FLOAT; break;
+	case GL_RGB10_A2:			dataformat = GL_RGBA; datatype = GL_UNSIGNED_INT_10_10_10_2; 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;
+	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 +509,17 @@ 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
@@ -397,7 +536,7 @@ GLuint FGLRenderBuffers::CreateRenderBuffer(const FString &name, GLuint format,
 	return handle;
 }
 
-GLuint FGLRenderBuffers::CreateRenderBuffer(const FString &name, GLuint format, int samples, int width, int height)
+GLuint FGLRenderBuffers::CreateRenderBuffer(const FString &name, GLuint format, int width, int height, int samples)
 {
 	if (samples <= 1)
 		return CreateRenderBuffer(name, format, width, height);
@@ -444,18 +583,30 @@ GLuint FGLRenderBuffers::CreateFrameBuffer(const FString &name, GLuint colorbuff
 	return handle;
 }
 
-GLuint FGLRenderBuffers::CreateFrameBuffer(const FString &name, GLuint colorbuffer, GLuint depth, GLuint stencil, bool colorIsARenderBuffer)
+GLuint FGLRenderBuffers::CreateFrameBuffer(const FString &name, GLuint colorbuffer0, GLuint colorbuffer1, GLuint colorbuffer2, 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);
+		if (colorbuffer2 != 0)
+			glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT2, GL_TEXTURE_2D_MULTISAMPLE, colorbuffer2, 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_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);
+		if (colorbuffer2 != 0)
+			glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT2, GL_TEXTURE_2D, colorbuffer2, 0);
+		glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT, GL_TEXTURE_2D, depthstencil, 0);
+	}
 	if (CheckFrameBufferCompleteness())
 		ClearFrameBuffer(true, true);
 	return handle;
@@ -475,22 +626,23 @@ 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 +747,69 @@ 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 fog data texture to the specified texture unit
+//
+//==========================================================================
+
+void FGLRenderBuffers::BindSceneFogTexture(int index)
+{
+	glActiveTexture(GL_TEXTURE0 + index);
+	if (mSamples > 1)
+		glBindTexture(GL_TEXTURE_2D_MULTISAMPLE, mSceneFog);
+	else
+		glBindTexture(GL_TEXTURE_2D, mSceneFog);
+}
+
+//==========================================================================
+//
+// Binds the scene normal data texture to the specified texture unit
+//
+//==========================================================================
+
+void FGLRenderBuffers::BindSceneNormalTexture(int index)
+{
+	glActiveTexture(GL_TEXTURE0 + index);
+	if (mSamples > 1)
+		glBindTexture(GL_TEXTURE_2D_MULTISAMPLE, mSceneNormal);
+	else
+		glBindTexture(GL_TEXTURE_2D, mSceneNormal);
+}
+
+//==========================================================================
+//
+// 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..f2f7b7cb9 100644
--- a/src/gl/renderer/gl_renderbuffers.h
+++ b/src/gl/renderer/gl_renderbuffers.h
@@ -31,7 +31,11 @@ public:
 
 	bool Setup(int width, int height, int sceneWidth, int sceneHeight);
 
-	void BindSceneFB();
+	void BindSceneFB(bool sceneData);
+	void BindSceneColorTexture(int index);
+	void BindSceneFogTexture(int index);
+	void BindSceneNormalTexture(int index);
+	void BindSceneDepthTexture(int index);
 	void BlitSceneToTexture();
 
 	void BindCurrentTexture(int index);
@@ -53,28 +57,46 @@ public:
 	GLuint ExposureFB = 0;
 	bool FirstExposureFrame = true;
 
+	// Ambient occlusion buffers
+	GLuint LinearDepthTexture = 0;
+	GLuint LinearDepthFB = 0;
+	GLuint AmbientTexture0 = 0;
+	GLuint AmbientTexture1 = 0;
+	GLuint AmbientFB0 = 0;
+	GLuint AmbientFB1 = 0;
+	int AmbientWidth = 0;
+	int AmbientHeight = 0;
+	enum { NumAmbientRandomTextures = 3 };
+	GLuint AmbientRandomTexture[NumAmbientRandomTextures];
+
 	static bool IsEnabled();
 
 	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();
 	void ClearEyeBuffers();
 	void ClearBloom();
 	void ClearExposureLevels();
-	void CreateScene(int width, int height, int samples);
+	void ClearAmbientOcclusion();
+	void CreateScene(int width, int height, int samples, bool needsSceneTextures);
 	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 CreateRenderBuffer(const FString &name, GLuint format, int width, int height, int samples);
 	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 colorbuffer2, GLuint depthstencil, bool multisample);
 	bool CheckFrameBufferCompleteness();
 	void ClearFrameBuffer(bool stencil, bool depth);
 	void DeleteTexture(GLuint &handle);
@@ -94,9 +116,11 @@ private:
 	// Buffers for the scene
 	GLuint mSceneMultisample = 0;
 	GLuint mSceneDepthStencil = 0;
-	GLuint mSceneDepth = 0;
-	GLuint mSceneStencil = 0;
+	GLuint mSceneFog = 0;
+	GLuint mSceneNormal = 0;
 	GLuint mSceneFB = 0;
+	GLuint mSceneDataFB = 0;
+	bool mSceneUsesTextures = false;
 
 	// Effect/HUD buffers
 	GLuint mPipelineTexture[NumPipelineTextures];
diff --git a/src/gl/renderer/gl_renderer.cpp b/src/gl/renderer/gl_renderer.cpp
index 0ffafef49..90687bcb7 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"
@@ -118,6 +119,10 @@ FGLRenderer::FGLRenderer(OpenGLFrameBuffer *fb)
 	mTonemapPalette = nullptr;
 	mColormapShader = nullptr;
 	mLensShader = nullptr;
+	mLinearDepthShader = nullptr;
+	mDepthBlurShader = nullptr;
+	mSSAOShader = nullptr;
+	mSSAOCombineShader = nullptr;
 	mFXAAShader = nullptr;
 	mFXAALumaShader = nullptr;
 }
@@ -128,6 +133,10 @@ void gl_FlushModels();
 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();
@@ -196,6 +205,10 @@ 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 (mPresent3dCheckerShader) delete mPresent3dCheckerShader;
 	if (mPresent3dColumnShader) delete mPresent3dColumnShader;
 	if (mPresent3dRowShader) delete mPresent3dRowShader;
@@ -327,7 +340,7 @@ 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/renderer/gl_renderer.h b/src/gl/renderer/gl_renderer.h
index 6ea1e357a..869b46d2d 100644
--- a/src/gl/renderer/gl_renderer.h
+++ b/src/gl/renderer/gl_renderer.h
@@ -19,6 +19,10 @@ class FLightBuffer;
 class FSamplerManager;
 class DPSprite;
 class FGLRenderBuffers;
+class FLinearDepthShader;
+class FDepthBlurShader;
+class FSSAOShader;
+class FSSAOCombineShader;
 class FBloomExtractShader;
 class FBloomCombineShader;
 class FExposureExtractShader;
@@ -98,6 +102,10 @@ public:
 	int mOldFBID;
 
 	FGLRenderBuffers *mBuffers;
+	FLinearDepthShader *mLinearDepthShader;
+	FSSAOShader *mSSAOShader;
+	FDepthBlurShader *mDepthBlurShader;
+	FSSAOCombineShader *mSSAOCombineShader;
 	FBloomExtractShader *mBloomExtractShader;
 	FBloomCombineShader *mBloomCombineShader;
 	FExposureExtractShader *mExposureExtractShader;
@@ -182,10 +190,12 @@ 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();
-	void BindTonemapPalette(int texunit);
+	void CreateTonemapPalette();
 	void ClearTonemapPalette();
 	void LensDistortScene();
 	void ApplyFXAA();
@@ -209,6 +219,9 @@ public:
 		DAngle rotation, FDynamicColormap *colormap, int lightlevel, int bottomclip);
 
 	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/renderer/gl_renderstate.cpp b/src/gl/renderer/gl_renderstate.cpp
index a8c9c5da2..fa8237cca 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();
 	}
 
@@ -347,7 +348,7 @@ 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 6a1856910..76e2c791c 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;
@@ -112,6 +119,9 @@ class FRenderState
 
 	FShader *activeShader;
 
+	EPassType mPassType = NORMAL_PASS;
+	int mNumDrawBuffers = 1;
+
 	bool ApplyShader();
 
 public:
@@ -472,6 +482,32 @@ public:
 		return mInterpolationFactor;
 	}
 
+	void SetPassType(EPassType passType)
+	{
+		mPassType = passType;
+	}
+
+	EPassType GetPassType()
+	{
+		return mPassType;
+	}
+
+	void EnableDrawBuffers(int count)
+	{
+		count = MIN(count, 3);
+		if (mNumDrawBuffers != count)
+		{
+			static GLenum buffers[] = { GL_COLOR_ATTACHMENT0, GL_COLOR_ATTACHMENT1, GL_COLOR_ATTACHMENT2 };
+			glDrawBuffers(count, buffers);
+			mNumDrawBuffers = count;
+		}
+	}
+
+	int GetPassDrawBufferCount()
+	{
+		return mPassType == GBUFFER_PASS ? 3 : 1;
+	}
+
 	// Backwards compatibility crap follows
 	void ApplyFixedFunction();
 	void DrawColormapOverlay();
diff --git a/src/gl/scene/gl_decal.cpp b/src/gl/scene/gl_decal.cpp
index 651cb7aa9..7fb680f8e 100644
--- a/src/gl/scene/gl_decal.cpp
+++ b/src/gl/scene/gl_decal.cpp
@@ -316,6 +316,8 @@ void GLWall::DrawDecal(DBaseDecal *decal)
 		gl_RenderState.SetFog(0,-1);
 	}
 
+	gl_RenderState.SetNormal(glseg.Normal());
+
 	FQuadDrawer qd;
 	for (i = 0; i < 4; i++)
 	{
diff --git a/src/gl/scene/gl_portal.cpp b/src/gl/scene/gl_portal.cpp
index 50693d75c..02fd9b452 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/scene/gl_scene.cpp b/src/gl/scene/gl_scene.cpp
index 0cf0fa0a1..5b969d7b9 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();
+		bool useSSAO = (gl_ssao != 0);
+		mBuffers->BindSceneFB(useSSAO);
+		gl_RenderState.SetPassType(useSSAO ? GBUFFER_PASS : NORMAL_PASS);
+		gl_RenderState.EnableDrawBuffers(gl_RenderState.GetPassDrawBufferCount());
+		gl_RenderState.Apply();
 	}
 
 	// Always clear all buffers with scissor test disabled.
@@ -209,7 +213,7 @@ 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
@@ -472,6 +476,23 @@ void FGLRenderer::RenderTranslucent()
 void FGLRenderer::DrawScene(int drawmode)
 {
 	static int recursion=0;
+	static int ssao_portals_available = 0;
+
+	bool applySSAO = false;
+	if (drawmode == DM_MAINVIEW)
+	{
+		ssao_portals_available = gl_ssao_portals;
+		applySSAO = true;
+	}
+	else if (drawmode == DM_OFFSCREEN)
+	{
+		ssao_portals_available = 0;
+	}
+	else if (ssao_portals_available > 0)
+	{
+		applySSAO = true;
+		ssao_portals_available--;
+	}
 
 	if (camera != nullptr)
 	{
@@ -491,6 +512,16 @@ void FGLRenderer::DrawScene(int drawmode)
 
 	RenderScene(recursion);
 
+	if (applySSAO && gl_RenderState.GetPassType() == GBUFFER_PASS)
+	{
+		gl_RenderState.EnableDrawBuffers(1);
+		AmbientOccludeScene();
+		mBuffers->BindSceneFB(true);
+		gl_RenderState.EnableDrawBuffers(gl_RenderState.GetPassDrawBufferCount());
+		gl_RenderState.Apply();
+		gl_RenderState.ApplyMatrices();
+	}
+
 	// Handle all portals after rendering the opaque objects but before
 	// doing all translucent stuff
 	recursion++;
@@ -830,13 +861,7 @@ 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();
-			ApplyFXAA();
+			PostProcessScene();
 
 			// This should be done after postprocessing, not before.
 			mBuffers->BindCurrentFB();
diff --git a/src/gl/scene/gl_walls_draw.cpp b/src/gl/scene/gl_walls_draw.cpp
index f166a2ce1..81164e434 100644
--- a/src/gl/scene/gl_walls_draw.cpp
+++ b/src/gl/scene/gl_walls_draw.cpp
@@ -228,6 +228,7 @@ void GLWall::RenderFogBoundary()
 		{
 			int rel = rellight + getExtraLight();
 			gl_SetFog(lightlevel, rel, &Colormap, false);
+			gl_RenderState.EnableDrawBuffers(1);
 			gl_RenderState.SetEffect(EFF_FOGBOUNDARY);
 			gl_RenderState.AlphaFunc(GL_GEQUAL, 0.f);
 			glEnable(GL_POLYGON_OFFSET_FILL);
@@ -236,6 +237,7 @@ void GLWall::RenderFogBoundary()
 			glPolygonOffset(0.0f, 0.0f);
 			glDisable(GL_POLYGON_OFFSET_FILL);
 			gl_RenderState.SetEffect(EFF_NONE);
+			gl_RenderState.EnableDrawBuffers(gl_RenderState.GetPassDrawBufferCount());
 		}
 		else
 		{
diff --git a/src/gl/shaders/gl_ambientshader.cpp b/src/gl/shaders/gl_ambientshader.cpp
new file mode 100644
index 000000000..effde2496
--- /dev/null
+++ b/src/gl/shaders/gl_ambientshader.cpp
@@ -0,0 +1,160 @@
+// 
+//---------------------------------------------------------------------------
+//
+// 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"
+#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()
+{
+	bool multisample = (gl_multisample > 1);
+	if (mMultisample != multisample)
+		mShader.reset();
+
+	if (!mShader)
+	{
+		mShader = std::make_unique<FShaderProgram>();
+		mShader->Compile(FShaderProgram::Vertex, "shaders/glsl/screenquad.vp", "", 330);
+		mShader->Compile(FShaderProgram::Fragment, "shaders/glsl/lineardepth.fp", multisample ? "#define MULTISAMPLE\n" : "", 330);
+		mShader->SetFragDataLocation(0, "FragColor");
+		mShader->Link("shaders/glsl/lineardepth");
+		mShader->SetAttribLocation(0, "PositionInProjection");
+		DepthTexture.Init(*mShader, "DepthTexture");
+		ColorTexture.Init(*mShader, "ColorTexture");
+		SampleIndex.Init(*mShader, "SampleIndex");
+		LinearizeDepthA.Init(*mShader, "LinearizeDepthA");
+		LinearizeDepthB.Init(*mShader, "LinearizeDepthB");
+		InverseDepthRangeA.Init(*mShader, "InverseDepthRangeA");
+		InverseDepthRangeB.Init(*mShader, "InverseDepthRangeB");
+		Scale.Init(*mShader, "Scale");
+		Offset.Init(*mShader, "Offset");
+		mMultisample = multisample;
+	}
+	mShader->Bind();
+}
+
+void FSSAOShader::Bind()
+{
+	bool multisample = (gl_multisample > 1);
+	if (mCurrentQuality != gl_ssao || mMultisample != multisample)
+		mShader.reset();
+
+	if (!mShader)
+	{
+		mShader = std::make_unique<FShaderProgram>();
+		mShader->Compile(FShaderProgram::Vertex, "shaders/glsl/screenquad.vp", "", 330);
+		mShader->Compile(FShaderProgram::Fragment, "shaders/glsl/ssao.fp", GetDefines(gl_ssao, multisample), 330);
+		mShader->SetFragDataLocation(0, "FragColor");
+		mShader->Link("shaders/glsl/ssao");
+		mShader->SetAttribLocation(0, "PositionInProjection");
+		DepthTexture.Init(*mShader, "DepthTexture");
+		NormalTexture.Init(*mShader, "NormalTexture");
+		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");
+		Scale.Init(*mShader, "Scale");
+		Offset.Init(*mShader, "Offset");
+		SampleIndex.Init(*mShader, "SampleIndex");
+		mMultisample = multisample;
+	}
+	mShader->Bind();
+}
+
+FString FSSAOShader::GetDefines(int mode, bool multisample)
+{
+	// Must match quality values in FGLRenderBuffers::CreateAmbientOcclusion
+	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);
+
+	if (multisample)
+		defines += "\n#define MULTISAMPLE\n";
+	return defines;
+}
+
+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()
+{
+	bool multisample = (gl_multisample > 1);
+	if (mMultisample != multisample)
+		mShader.reset();
+
+	if (!mShader)
+	{
+		mShader = std::make_unique<FShaderProgram>();
+		mShader->Compile(FShaderProgram::Vertex, "shaders/glsl/screenquad.vp", "", 330);
+		mShader->Compile(FShaderProgram::Fragment, "shaders/glsl/ssaocombine.fp", multisample ? "#define MULTISAMPLE\n" : "", 330);
+		mShader->SetFragDataLocation(0, "FragColor");
+		mShader->Link("shaders/glsl/ssaocombine");
+		mShader->SetAttribLocation(0, "PositionInProjection");
+		AODepthTexture.Init(*mShader, "AODepthTexture");
+		SceneFogTexture.Init(*mShader, "SceneFogTexture");
+		SampleCount.Init(*mShader, "SampleCount");
+		Scale.Init(*mShader, "Scale");
+		Offset.Init(*mShader, "Offset");
+		mMultisample = multisample;
+	}
+	mShader->Bind();
+}
diff --git a/src/gl/shaders/gl_ambientshader.h b/src/gl/shaders/gl_ambientshader.h
new file mode 100644
index 000000000..d3310c3d6
--- /dev/null
+++ b/src/gl/shaders/gl_ambientshader.h
@@ -0,0 +1,93 @@
+#ifndef __GL_AMBIENTSHADER_H
+#define __GL_AMBIENTSHADER_H
+
+#include "gl_shaderprogram.h"
+
+class FLinearDepthShader
+{
+public:
+	void Bind();
+
+	FBufferedUniformSampler DepthTexture;
+	FBufferedUniformSampler ColorTexture;
+	FBufferedUniform1i SampleIndex;
+	FBufferedUniform1f LinearizeDepthA;
+	FBufferedUniform1f LinearizeDepthB;
+	FBufferedUniform1f InverseDepthRangeA;
+	FBufferedUniform1f InverseDepthRangeB;
+	FBufferedUniform2f Scale;
+	FBufferedUniform2f Offset;
+
+private:
+	std::unique_ptr<FShaderProgram> mShader;
+	bool mMultisample = false;
+};
+
+class FSSAOShader
+{
+public:
+	void Bind();
+
+	FBufferedUniformSampler DepthTexture;
+	FBufferedUniformSampler NormalTexture;
+	FBufferedUniformSampler RandomTexture;
+	FBufferedUniform2f UVToViewA;
+	FBufferedUniform2f UVToViewB;
+	FBufferedUniform2f InvFullResolution;
+	FBufferedUniform1f NDotVBias;
+	FBufferedUniform1f NegInvR2;
+	FBufferedUniform1f RadiusToScreen;
+	FBufferedUniform1f AOMultiplier;
+	FBufferedUniform1f AOStrength;
+	FBufferedUniform2f Scale;
+	FBufferedUniform2f Offset;
+	FBufferedUniform1i SampleIndex;
+
+private:
+	enum Quality
+	{
+		Off,
+		LowQuality,
+		MediumQuality,
+		HighQuality,
+		NumQualityModes
+	};
+
+	FString GetDefines(int mode, bool multisample);
+
+	std::unique_ptr<FShaderProgram> mShader;
+	Quality mCurrentQuality = Off;
+	bool mMultisample = false;
+};
+
+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;
+	FBufferedUniformSampler SceneFogTexture;
+	FBufferedUniform1i SampleCount;
+	FBufferedUniform2f Scale;
+	FBufferedUniform2f Offset;
+
+private:
+	std::unique_ptr<FShaderProgram> mShader;
+	bool mMultisample = false;
+};
+
+#endif
\ No newline at end of file
diff --git a/src/gl/shaders/gl_shader.cpp b/src/gl/shaders/gl_shader.cpp
index 8f78e22e4..b7d8335f8 100644
--- a/src/gl/shaders/gl_shader.cpp
+++ b/src/gl/shaders/gl_shader.cpp
@@ -181,6 +181,10 @@ bool FShader::Load(const char * name, const char * vert_prog_lump, const char *
 	glBindAttribLocation(hShader, VATTR_VERTEX2, "aVertex2");
 	glBindAttribLocation(hShader, VATTR_NORMAL, "aNormal");
 
+	glBindFragDataLocation(hShader, 0, "FragColor");
+	glBindFragDataLocation(hShader, 1, "FragFog");
+	glBindFragDataLocation(hShader, 2, "FragNormal");
+
 	glLinkProgram(hShader);
 
 	glGetShaderInfoLog(hVertProg, 10000, NULL, buffer);
@@ -300,12 +304,13 @@ 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
@@ -388,27 +393,75 @@ 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();
 }
 
 //==========================================================================
@@ -417,10 +470,30 @@ 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++)
@@ -430,11 +503,11 @@ 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);
 		}
 	}
@@ -444,7 +517,7 @@ 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);
 	}
 
@@ -466,11 +539,8 @@ 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];
@@ -494,7 +564,7 @@ void FShaderManager::Clean()
 //
 //==========================================================================
 
-int FShaderManager::Find(const char * shn)
+int FShaderCollection::Find(const char * shn)
 {
 	FName sfn = shn;
 
@@ -508,21 +578,6 @@ int FShaderManager::Find(const char * shn)
 	return -1;
 }
 
-//==========================================================================
-//
-//
-//
-//==========================================================================
-
-void FShaderManager::SetActiveShader(FShader *sh)
-{
-	if (mActiveShader != sh)
-	{
-		glUseProgram(sh!= NULL? sh->GetHandle() : 0);
-		mActiveShader = sh;
-	}
-}
-
 
 //==========================================================================
 //
@@ -530,7 +585,7 @@ void FShaderManager::SetActiveShader(FShader *sh)
 //
 //==========================================================================
 
-FShader *FShaderManager::BindEffect(int effect)
+FShader *FShaderCollection::BindEffect(int effect)
 {
 	if (effect >= 0 && effect < MAX_EFFECTS && mEffectShaders[effect] != NULL)
 	{
@@ -548,39 +603,28 @@ 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)
-	{
-		glMatrixMode(GL_PROJECTION);
-		glLoadMatrixf(proj->get());
-		glMatrixMode(GL_MODELVIEW);
-		glLoadMatrixf(view->get());
-	}
-	else
-	{
-		VSMatrix norm;
-		norm.computeNormalMatrix(*view);
+	VSMatrix norm;
+	norm.computeNormalMatrix(*view);
 
-		for (int i = 0; i < 4; i++)
-		{
-			mTextureEffects[i]->ApplyMatrices(proj, view, &norm);
-			mTextureEffectsNAT[i]->ApplyMatrices(proj, view, &norm);
-		}
-		mTextureEffects[4]->ApplyMatrices(proj, view, &norm);
-		if (gl_fuzztype != 0)
-		{
-			mTextureEffects[4 + gl_fuzztype]->ApplyMatrices(proj, view, &norm);
-		}
-		for (unsigned i = 12; i < mTextureEffects.Size(); i++)
-		{
-			mTextureEffects[i]->ApplyMatrices(proj, view, &norm);
-		}
-		for (int i = 0; i < MAX_EFFECTS; i++)
-		{
-			mEffectShaders[i]->ApplyMatrices(proj, view, &norm);
-		}
-		if (mActiveShader != NULL) mActiveShader->Bind();
+	for (int i = 0; i < 4; i++)
+	{
+		mTextureEffects[i]->ApplyMatrices(proj, view, &norm);
+		mTextureEffectsNAT[i]->ApplyMatrices(proj, view, &norm);
+	}
+	mTextureEffects[4]->ApplyMatrices(proj, view, &norm);
+	if (gl_fuzztype != 0)
+	{
+		mTextureEffects[4 + gl_fuzztype]->ApplyMatrices(proj, view, &norm);
+	}
+	for (unsigned i = 12; i < mTextureEffects.Size(); i++)
+	{
+		mTextureEffects[i]->ApplyMatrices(proj, view, &norm);
+	}
+	for (int i = 0; i < MAX_EFFECTS; i++)
+	{
+		mEffectShaders[i]->ApplyMatrices(proj, view, &norm);
 	}
 }
 
diff --git a/src/gl/shaders/gl_shader.h b/src/gl/shaders/gl_shader.h
index 679ae1172..acdd530aa 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;
@@ -324,7 +325,6 @@ public:
 
 };
 
-
 //==========================================================================
 //
 // The global shader manager
@@ -332,26 +332,40 @@ 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/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/src/gl/stereo3d/scoped_color_mask.h b/src/gl/stereo3d/scoped_color_mask.h
index 42c02db3a..e55772092 100644
--- a/src/gl/stereo3d/scoped_color_mask.h
+++ b/src/gl/stereo3d/scoped_color_mask.h
@@ -41,8 +41,10 @@ public:
 		gl_RenderState.GetColorMask(saved[0], saved[1], saved[2], saved[3]);
 		gl_RenderState.SetColorMask(r, g, b, a);
 		gl_RenderState.ApplyColorMask();
+		gl_RenderState.EnableDrawBuffers(1);
 	}
 	~ScopedColorMask() {
+		gl_RenderState.EnableDrawBuffers(gl_RenderState.GetPassDrawBufferCount());
 		gl_RenderState.SetColorMask(saved[0], saved[1], saved[2], saved[3]);
 		gl_RenderState.ApplyColorMask();
 	}
diff --git a/src/gl/system/gl_cvars.h b/src/gl/system/gl_cvars.h
index 4cda3657d..3b425d261 100644
--- a/src/gl/system/gl_cvars.h
+++ b/src/gl/system/gl_cvars.h
@@ -50,6 +50,13 @@ 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(Int, gl_ssao)
+EXTERN_CVAR(Int, gl_ssao_portals)
+EXTERN_CVAR(Float, gl_ssao_strength)
+EXTERN_CVAR(Int, 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/src/gl/textures/gl_hwtexture.cpp b/src/gl/textures/gl_hwtexture.cpp
index edcda4398..477d1986b 100644
--- a/src/gl/textures/gl_hwtexture.cpp
+++ b/src/gl/textures/gl_hwtexture.cpp
@@ -374,6 +374,11 @@ unsigned int FHardwareTexture::Bind(int texunit, int translation, bool needmipma
 	return 0;
 }
 
+unsigned int FHardwareTexture::GetTextureHandle(int translation)
+{
+	TranslatedTexture *pTex = GetTexID(translation);
+	return pTex->glTexID;
+}
 
 void FHardwareTexture::Unbind(int texunit)
 {
diff --git a/src/gl/textures/gl_hwtexture.h b/src/gl/textures/gl_hwtexture.h
index 96eff0264..59fc98169 100644
--- a/src/gl/textures/gl_hwtexture.h
+++ b/src/gl/textures/gl_hwtexture.h
@@ -83,6 +83,7 @@ public:
 
 	unsigned int Bind(int texunit, int translation, bool needmipmap);
 	unsigned int CreateTexture(unsigned char * buffer, int w, int h, int texunit, bool mipmap, int translation, const FString &name);
+	unsigned int GetTextureHandle(int translation);
 
 	void Clean(bool all);
 	void CleanUnused(SpriteHits &usedtranslations);
diff --git a/wadsrc/static/language.enu b/wadsrc/static/language.enu
index 448506727..fc611b3c0 100644
--- a/wadsrc/static/language.enu
+++ b/wadsrc/static/language.enu
@@ -2171,6 +2171,9 @@ 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";
@@ -2640,6 +2643,8 @@ GLPREFMNU_MULTISAMPLE			= "Multisample";
 GLPREFMNU_TONEMAP				= "Tonemap Mode";
 GLPREFMNU_BLOOM					= "Bloom effect";
 GLPREFMNU_LENS					= "Lens distortion effect";
+GLPREFMNU_SSAO					= "Ambient occlusion quality";
+GLPREFMNU_SSAO_PORTALS			= "Portals with AO";
 GLPREFMNU_FXAA					= "FXAA Quality";
 
 // Option Values
diff --git a/wadsrc/static/menudef.zz b/wadsrc/static/menudef.zz
index 1261286d6..599c28a2d 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 "FXAAQuality"
 {
 	0, "$OPTVAL_OFF"
@@ -238,5 +246,7 @@ OptionMenu "GLPrefOptions"
 	Option "$GLPREFMNU_TONEMAP", 				gl_tonemap,						"TonemapModes"
 	Option "$GLPREFMNU_BLOOM",		 			gl_bloom,						"OnOff"
 	Option "$GLPREFMNU_LENS",		 			gl_lens,						"OnOff"
+	Option "$GLPREFMNU_SSAO",		 			gl_ssao,						"SSAOModes"
+	Slider "$GLPREFMNU_SSAO_PORTALS",			gl_ssao_portals,				0.0, 4.0, 1.0, 0
 	Option "$GLPREFMNU_FXAA",		 			gl_fxaa,						"FXAAQuality"
 }
diff --git a/wadsrc/static/shaders/glsl/depthblur.fp b/wadsrc/static/shaders/glsl/depthblur.fp
new file mode 100644
index 000000000..7e3dad074
--- /dev/null
+++ b/wadsrc/static/shaders/glsl/depthblur.fp
@@ -0,0 +1,69 @@
+
+in vec2 TexCoord;
+out vec4 FragColor;
+
+uniform sampler2D AODepthTexture;
+uniform float BlurSharpness;
+uniform vec2 InvFullResolution;
+uniform float PowExponent;
+
+#define KERNEL_RADIUS 3.0
+
+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 - centerDepth) * BlurSharpness;
+
+	return exp2(-r * r * blurFalloff - deltaZ * deltaZ);
+}
+
+void ProcessSample(float ao, float z, float r, float centerDepth, inout float totalAO, inout float totalW)
+{
+	float w = CrossBilateralWeight(r, z, centerDepth);
+	totalAO += w * ao;
+	totalW += w;
+}
+
+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 + TexCoord;
+		vec2 aoZ = texture(AODepthTexture, uv).xy;
+		ProcessSample(aoZ.x, aoZ.y, r, centerDepth, totalAO, totalW);
+	}
+}
+
+vec2 ComputeBlur(vec2 deltaUV)
+{
+	vec2 aoZ = texture(AODepthTexture, TexCoord).xy;
+
+	float totalAO = aoZ.x;
+	float totalW = 1.0;
+
+	ProcessRadius(deltaUV, aoZ.y, totalAO, totalW);
+	ProcessRadius(-deltaUV, aoZ.y, 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/lineardepth.fp b/wadsrc/static/shaders/glsl/lineardepth.fp
new file mode 100644
index 000000000..3e2b3eb95
--- /dev/null
+++ b/wadsrc/static/shaders/glsl/lineardepth.fp
@@ -0,0 +1,46 @@
+
+in vec2 TexCoord;
+out vec4 FragColor;
+
+#if defined(MULTISAMPLE)
+uniform sampler2DMS DepthTexture;
+uniform sampler2DMS ColorTexture;
+uniform int SampleIndex;
+#else
+uniform sampler2D DepthTexture;
+uniform sampler2D ColorTexture;
+#endif
+
+uniform float LinearizeDepthA;
+uniform float LinearizeDepthB;
+uniform float InverseDepthRangeA;
+uniform float InverseDepthRangeB;
+uniform vec2 Scale;
+uniform vec2 Offset;
+
+float normalizeDepth(float depth)
+{
+	float normalizedDepth = clamp(InverseDepthRangeA * depth + InverseDepthRangeB, 0.0, 1.0);
+	return 1.0 / (normalizedDepth * LinearizeDepthA + LinearizeDepthB);
+}
+
+void main()
+{
+	vec2 uv = Offset + TexCoord * Scale;
+
+#if defined(MULTISAMPLE)
+	ivec2 texSize = textureSize(DepthTexture);
+#else
+	ivec2 texSize = textureSize(DepthTexture, 0);
+#endif
+
+	ivec2 ipos = ivec2(max(uv * vec2(texSize), vec2(0.0)));
+
+#if defined(MULTISAMPLE)
+	float depth = normalizeDepth(texelFetch(ColorTexture, ipos, SampleIndex).a != 0.0 ? texelFetch(DepthTexture, ipos, SampleIndex).x : 1.0);
+#else
+	float depth = normalizeDepth(texelFetch(ColorTexture, ipos, 0).a != 0.0 ? texelFetch(DepthTexture, ipos, 0).x : 1.0);
+#endif
+
+	FragColor = vec4(depth, 0.0, 0.0, 1.0);
+}
diff --git a/wadsrc/static/shaders/glsl/main.fp b/wadsrc/static/shaders/glsl/main.fp
index 36db31f68..5834dcf5d 100644
--- a/wadsrc/static/shaders/glsl/main.fp
+++ b/wadsrc/static/shaders/glsl/main.fp
@@ -7,6 +7,10 @@ in vec4 vTexCoord;
 in vec4 vColor;
 
 out vec4 FragColor;
+#ifdef GBUFFER_PASS
+out vec4 FragFog;
+out vec4 FragNormal;
+#endif
 
 #ifdef SHADER_STORAGE_LIGHTS
 	layout(std430, binding = 1) buffer LightBufferSSO
@@ -266,6 +270,32 @@ 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, distance(pixelpos.xyz, uCameraPos.xyz));
+	}
+	fogfactor = exp2 (uFogDensity * fogdist);
+			
+	return mix(uFogColor.rgb, vec3(0.0), fogfactor);
+}
 
 //===========================================================================
 //
@@ -381,5 +411,9 @@ void main()
 		}
 	}
 	FragColor = frag;
+#ifdef GBUFFER_PASS
+	FragFog = vec4(AmbientOcclusionColor(), 1.0);
+	FragNormal = vec4(vEyeNormal.xyz * 0.5 + 0.5, 1.0);
+#endif
 }
 
diff --git a/wadsrc/static/shaders/glsl/ssao.fp b/wadsrc/static/shaders/glsl/ssao.fp
new file mode 100644
index 000000000..3b2db6005
--- /dev/null
+++ b/wadsrc/static/shaders/glsl/ssao.fp
@@ -0,0 +1,138 @@
+
+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 float AOStrength;
+
+uniform vec2 Scale;
+uniform vec2 Offset;
+
+uniform sampler2D DepthTexture;
+
+#if defined(MULTISAMPLE)
+uniform sampler2DMS NormalTexture;
+uniform int SampleIndex;
+#else
+uniform sampler2D NormalTexture;
+#endif
+
+#if defined(USE_RANDOM_TEXTURE)
+uniform sampler2D RandomTexture;
+#endif
+
+#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);
+}
+
+#if defined(MULTISAMPLE)
+vec3 SampleNormal(vec2 uv)
+{
+	ivec2 texSize = textureSize(NormalTexture);
+	ivec2 ipos = ivec2(uv * vec2(texSize));
+	return texelFetch(NormalTexture, ipos, SampleIndex).xyz * 2.0 - 1.0;
+}
+#else
+vec3 SampleNormal(vec2 uv)
+{
+	ivec2 texSize = textureSize(NormalTexture, 0);
+	ivec2 ipos = ivec2(uv * vec2(texSize));
+	return texelFetch(NormalTexture, ipos, 0).xyz * 2.0 - 1.0;
+}
+#endif
+
+// Look up the eye space normal for the specified texture coordinate
+vec3 FetchNormal(vec2 uv)
+{
+	vec3 normal = SampleNormal(Offset + uv * Scale);
+	if (length(normal) > 0.1)
+	{
+		normal = normalize(normal);
+		normal.z = -normal.z;
+		return normal;
+	}
+	else
+	{
+		return vec3(0.0);
+	}
+}
+
+// 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 !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
+    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 = FetchNormal(TexCoord);
+	float occlusion = viewNormal != vec3(0.0) ? ComputeAO(viewPosition, viewNormal) * AOStrength + (1.0 - AOStrength) : 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..4ca64421b
--- /dev/null
+++ b/wadsrc/static/shaders/glsl/ssaocombine.fp
@@ -0,0 +1,39 @@
+
+in vec2 TexCoord;
+out vec4 FragColor;
+
+uniform sampler2D AODepthTexture;
+
+#if defined(MULTISAMPLE)
+uniform sampler2DMS SceneFogTexture;
+uniform int SampleCount;
+#else
+uniform sampler2D SceneFogTexture;
+#endif
+
+uniform vec2 Scale;
+uniform vec2 Offset;
+
+void main()
+{
+	vec2 uv = Offset + TexCoord * Scale;
+
+#if defined(MULTISAMPLE)
+	ivec2 texSize = textureSize(SceneFogTexture);
+#else
+	ivec2 texSize = textureSize(SceneFogTexture, 0);
+#endif
+	ivec2 ipos = ivec2(uv * vec2(texSize));
+
+#if defined(MULTISAMPLE)
+	vec3 fogColor = vec3(0.0);
+	for (int i = 0; i < SampleCount; i++)
+		fogColor += texelFetch(SceneFogTexture, ipos, i).rgb;
+	fogColor /= float(SampleCount);
+#else
+	vec3 fogColor = texelFetch(SceneFogTexture, ipos, 0).rgb;
+#endif
+
+	float attenutation = texture(AODepthTexture, TexCoord).x;
+	FragColor = vec4(fogColor, 1.0 - attenutation);
+}
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);
 }