/*
**  Postprocessing framework
**  Copyright (c) 2016-2020 Magnus Norddahl
**
**  This software is provided 'as-is', without any express or implied
**  warranty.  In no event will the authors be held liable for any damages
**  arising from the use of this software.
**
**  Permission is granted to anyone to use this software for any purpose,
**  including commercial applications, and to alter it and redistribute it
**  freely, subject to the following restrictions:
**
**  1. The origin of this software must not be misrepresented; you must not
**     claim that you wrote the original software. If you use this software
**     in a product, an acknowledgment in the product documentation would be
**     appreciated but is not required.
**  2. Altered source versions must be plainly marked as such, and must not be
**     misrepresented as being the original software.
**  3. This notice may not be removed or altered from any source distribution.
*/

#include "gl_system.h"
#include "m_png.h"
#include "gl_buffers.h"
#include "gl_framebuffer.h"
#include "gl_debug.h"
#include "gl_renderbuffers.h"
#include "gl_renderer.h"
#include "gl_postprocessstate.h"
#include "gl_shaderprogram.h"
#include "hwrenderer/postprocessing/hw_postprocess.h"
#include "hwrenderer/postprocessing/hw_postprocess_cvars.h"
#include "flatvertices.h"
#include "r_videoscale.h"
#include "v_video.h"
#include "templates.h"
#include "hw_vrmodes.h"
#include "v_draw.h"

extern bool vid_hdr_active;

CVAR(Int, gl_dither_bpc, 0, CVAR_ARCHIVE | CVAR_GLOBALCONFIG | CVAR_NOINITCALL)

namespace OpenGLRenderer
{


void FGLRenderer::RenderScreenQuad()
{
	auto buffer = static_cast<GLVertexBuffer *>(screen->mVertexData->GetBufferObjects().first);
	buffer->Bind(nullptr);
	glDrawArrays(GL_TRIANGLE_STRIP, FFlatVertexBuffer::PRESENT_INDEX, 3);
}

void FGLRenderer::PostProcessScene(int fixedcm, float flash, const std::function<void()> &afterBloomDrawEndScene2D)
{
	int sceneWidth = mBuffers->GetSceneWidth();
	int sceneHeight = mBuffers->GetSceneHeight();

	GLPPRenderState renderstate(mBuffers);

	hw_postprocess.Pass1(&renderstate, fixedcm, sceneWidth, sceneHeight);
	mBuffers->BindCurrentFB();
	if (afterBloomDrawEndScene2D) afterBloomDrawEndScene2D();
	hw_postprocess.Pass2(&renderstate, fixedcm, flash, sceneWidth, sceneHeight);
}

//-----------------------------------------------------------------------------
//
// Adds ambient occlusion to the scene
//
//-----------------------------------------------------------------------------

void FGLRenderer::AmbientOccludeScene(float m5)
{
	int sceneWidth = mBuffers->GetSceneWidth();
	int sceneHeight = mBuffers->GetSceneHeight();

	GLPPRenderState renderstate(mBuffers);
	hw_postprocess.ssao.Render(&renderstate, m5, sceneWidth, sceneHeight);
}

void FGLRenderer::BlurScene(float gameinfobluramount)
{
	int sceneWidth = mBuffers->GetSceneWidth();
	int sceneHeight = mBuffers->GetSceneHeight();

	GLPPRenderState renderstate(mBuffers);

	auto vrmode = VRMode::GetVRMode(true);
	int eyeCount = vrmode->mEyeCount;
	for (int i = 0; i < eyeCount; ++i)
	{
		hw_postprocess.bloom.RenderBlur(&renderstate, sceneWidth, sceneHeight, gameinfobluramount);
		if (eyeCount - i > 1) mBuffers->NextEye(eyeCount);
	}
}

void FGLRenderer::ClearTonemapPalette()
{
	hw_postprocess.tonemap.ClearTonemapPalette();
}

//-----------------------------------------------------------------------------
//
// Copies the rendered screen to its final destination
//
//-----------------------------------------------------------------------------

void FGLRenderer::Flush()
{
	auto vrmode = VRMode::GetVRMode(true);
	if (vrmode->mEyeCount == 1)
	{
		CopyToBackbuffer(nullptr, true);
	}
	else
	{
		// Render 2D to eye textures
		int eyeCount = vrmode->mEyeCount;
		for (int eye_ix = 0; eye_ix < eyeCount; ++eye_ix)
		{
			screen->Draw2D();
			if (eyeCount - eye_ix > 1)
				mBuffers->NextEye(eyeCount);
		}
		twod->Clear();

		FGLPostProcessState savedState;
		FGLDebug::PushGroup("PresentEyes");
		// Note: This here is the ONLY place in the entire engine where the OpenGL dependent parts of the Stereo3D code need to be dealt with.
		// There's absolutely no need to create a overly complex class hierarchy for just this.
		PresentStereo();
		FGLDebug::PopGroup();
	}
}

//-----------------------------------------------------------------------------
//
// Gamma correct while copying to frame buffer
//
//-----------------------------------------------------------------------------

void FGLRenderer::CopyToBackbuffer(const IntRect *bounds, bool applyGamma)
{
	screen->Draw2D();	// draw all pending 2D stuff before copying the buffer
	twod->Clear();

	GLPPRenderState renderstate(mBuffers);
	hw_postprocess.customShaders.Run(&renderstate, "screen");

	FGLDebug::PushGroup("CopyToBackbuffer");
	FGLPostProcessState savedState;
	savedState.SaveTextureBindings(2);
	mBuffers->BindOutputFB();

	IntRect box;
	if (bounds)
	{
		box = *bounds;
	}
	else
	{
		ClearBorders();
		box = screen->mOutputLetterbox;
	}

	mBuffers->BindCurrentTexture(0);
	DrawPresentTexture(box, applyGamma);
	FGLDebug::PopGroup();
}

void FGLRenderer::DrawPresentTexture(const IntRect &box, bool applyGamma)
{
	glViewport(box.left, box.top, box.width, box.height);

	mBuffers->BindDitherTexture(1);

	glActiveTexture(GL_TEXTURE0);
	if (ViewportLinearScale())
	{
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	}
	else
	{
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
	}

	mPresentShader->Bind();
	if (!applyGamma || framebuffer->IsHWGammaActive())
	{
		mPresentShader->Uniforms->InvGamma = 1.0f;
		mPresentShader->Uniforms->Contrast = 1.0f;
		mPresentShader->Uniforms->Brightness = 0.0f;
		mPresentShader->Uniforms->Saturation = 1.0f;
	}
	else
	{
		mPresentShader->Uniforms->InvGamma = 1.0f / clamp<float>(vid_gamma, 0.1f, 4.f);
		mPresentShader->Uniforms->Contrast = clamp<float>(vid_contrast, 0.1f, 3.f);
		mPresentShader->Uniforms->Brightness = clamp<float>(vid_brightness, -0.8f, 0.8f);
		mPresentShader->Uniforms->Saturation = clamp<float>(vid_saturation, -15.0f, 15.f);
		mPresentShader->Uniforms->GrayFormula = static_cast<int>(gl_satformula);
	}
	if (vid_hdr_active && framebuffer->IsFullscreen())
	{
		// Full screen exclusive mode treats a rgba16f frame buffer as linear.
		// It probably will eventually in desktop mode too, but the DWM doesn't seem to support that.
		mPresentShader->Uniforms->HdrMode = 1;
		mPresentShader->Uniforms->ColorScale = (gl_dither_bpc == -1) ? 1023.0f : (float)((1 << gl_dither_bpc) - 1);
	}
	else
	{
		mPresentShader->Uniforms->HdrMode = 0;
		mPresentShader->Uniforms->ColorScale = (gl_dither_bpc == -1) ? 255.0f : (float)((1 << gl_dither_bpc) - 1);
	}
	mPresentShader->Uniforms->Scale = { screen->mScreenViewport.width / (float)mBuffers->GetWidth(), screen->mScreenViewport.height / (float)mBuffers->GetHeight() };
	mPresentShader->Uniforms->Offset = { 0.0f, 0.0f };
	mPresentShader->Uniforms.SetData();
	static_cast<GLDataBuffer*>(mPresentShader->Uniforms.GetBuffer())->BindBase();
	RenderScreenQuad();
}

//-----------------------------------------------------------------------------
//
// Fills the black bars around the screen letterbox
//
//-----------------------------------------------------------------------------

void FGLRenderer::ClearBorders()
{
	const auto &box = screen->mOutputLetterbox;

	int clientWidth = framebuffer->GetClientWidth();
	int clientHeight = framebuffer->GetClientHeight();
	if (clientWidth == 0 || clientHeight == 0)
		return;

	glViewport(0, 0, clientWidth, clientHeight);
	glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
	glEnable(GL_SCISSOR_TEST);
	if (box.top > 0)
	{
		glScissor(0, 0, clientWidth, box.top);
		glClear(GL_COLOR_BUFFER_BIT);
	}
	if (clientHeight - box.top - box.height > 0)
	{
		glScissor(0, box.top + box.height, clientWidth, clientHeight - box.top - box.height);
		glClear(GL_COLOR_BUFFER_BIT);
	}
	if (box.left > 0)
	{
		glScissor(0, box.top, box.left, box.height);
		glClear(GL_COLOR_BUFFER_BIT);
	}
	if (clientWidth - box.left - box.width > 0)
	{
		glScissor(box.left + box.width, box.top, clientWidth - box.left - box.width, box.height);
		glClear(GL_COLOR_BUFFER_BIT);
	}
	glDisable(GL_SCISSOR_TEST);
}

}