/*
 * Copyright 2011-2015 Branimir Karadzic. All rights reserved.
 * License: http://www.opensource.org/licenses/BSD-2-Clause
 */

#include "common.h"
#include "bgfx_utils.h"
#include "imgui/imgui.h"
#include "camera.h"
#include "bounds.h"

#define RENDER_PASS_GEOMETRY_ID       0
#define RENDER_PASS_LIGHT_ID          1
#define RENDER_PASS_COMBINE_ID        2
#define RENDER_PASS_DEBUG_LIGHTS_ID   3
#define RENDER_PASS_DEBUG_GBUFFER_ID  4

static bool s_originBottomLeft = false;

inline void mtxProj(float* _result, float _fovy, float _aspect, float _near, float _far)
{
	bx::mtxProj(_result, _fovy, _aspect, _near, _far, s_originBottomLeft);
}

struct PosNormalTangentTexcoordVertex
{
	float m_x;
	float m_y;
	float m_z;
	uint32_t m_normal;
	uint32_t m_tangent;
	int16_t m_u;
	int16_t m_v;

	static void init()
	{
		ms_decl
			.begin()
			.add(bgfx::Attrib::Position,  3, bgfx::AttribType::Float)
			.add(bgfx::Attrib::Normal,    4, bgfx::AttribType::Uint8, true, true)
			.add(bgfx::Attrib::Tangent,   4, bgfx::AttribType::Uint8, true, true)
			.add(bgfx::Attrib::TexCoord0, 2, bgfx::AttribType::Int16, true, true)
			.end();
	}

	static bgfx::VertexDecl ms_decl;
};

bgfx::VertexDecl PosNormalTangentTexcoordVertex::ms_decl;

struct PosTexCoord0Vertex
{
	float m_x;
	float m_y;
	float m_z;
	float m_u;
	float m_v;

	static void init()
	{
		ms_decl
			.begin()
			.add(bgfx::Attrib::Position,  3, bgfx::AttribType::Float)
			.add(bgfx::Attrib::TexCoord0, 2, bgfx::AttribType::Float)
			.end();
	}

	static bgfx::VertexDecl ms_decl;
};

bgfx::VertexDecl PosTexCoord0Vertex::ms_decl;

struct DebugVertex
{
	float m_x;
	float m_y;
	float m_z;
	uint32_t m_abgr;

	static void init()
	{
		ms_decl
			.begin()
			.add(bgfx::Attrib::Position, 3, bgfx::AttribType::Float)
			.add(bgfx::Attrib::Color0,   4, bgfx::AttribType::Uint8, true)
			.end();
	}

	static bgfx::VertexDecl ms_decl;
};

bgfx::VertexDecl DebugVertex::ms_decl;

uint32_t packUint32(uint8_t _x, uint8_t _y, uint8_t _z, uint8_t _w)
{
	union
	{
		uint32_t ui32;
		uint8_t arr[4];
	} un;

	un.arr[0] = _x;
	un.arr[1] = _y;
	un.arr[2] = _z;
	un.arr[3] = _w;

	return un.ui32;
}

uint32_t packF4u(float _x, float _y = 0.0f, float _z = 0.0f, float _w = 0.0f)
{
	const uint8_t xx = uint8_t(_x*127.0f + 128.0f);
	const uint8_t yy = uint8_t(_y*127.0f + 128.0f);
	const uint8_t zz = uint8_t(_z*127.0f + 128.0f);
	const uint8_t ww = uint8_t(_w*127.0f + 128.0f);
	return packUint32(xx, yy, zz, ww);
}

static PosNormalTangentTexcoordVertex s_cubeVertices[24] =
{
	{-1.0f,  1.0f,  1.0f, packF4u( 0.0f,  0.0f,  1.0f), 0,      0,      0 },
	{ 1.0f,  1.0f,  1.0f, packF4u( 0.0f,  0.0f,  1.0f), 0, 0x7fff,      0 },
	{-1.0f, -1.0f,  1.0f, packF4u( 0.0f,  0.0f,  1.0f), 0,      0, 0x7fff },
	{ 1.0f, -1.0f,  1.0f, packF4u( 0.0f,  0.0f,  1.0f), 0, 0x7fff, 0x7fff },
	{-1.0f,  1.0f, -1.0f, packF4u( 0.0f,  0.0f, -1.0f), 0,      0,      0 },
	{ 1.0f,  1.0f, -1.0f, packF4u( 0.0f,  0.0f, -1.0f), 0, 0x7fff,      0 },
	{-1.0f, -1.0f, -1.0f, packF4u( 0.0f,  0.0f, -1.0f), 0,      0, 0x7fff },
	{ 1.0f, -1.0f, -1.0f, packF4u( 0.0f,  0.0f, -1.0f), 0, 0x7fff, 0x7fff },
	{-1.0f,  1.0f,  1.0f, packF4u( 0.0f,  1.0f,  0.0f), 0,      0,      0 },
	{ 1.0f,  1.0f,  1.0f, packF4u( 0.0f,  1.0f,  0.0f), 0, 0x7fff,      0 },
	{-1.0f,  1.0f, -1.0f, packF4u( 0.0f,  1.0f,  0.0f), 0,      0, 0x7fff },
	{ 1.0f,  1.0f, -1.0f, packF4u( 0.0f,  1.0f,  0.0f), 0, 0x7fff, 0x7fff },
	{-1.0f, -1.0f,  1.0f, packF4u( 0.0f, -1.0f,  0.0f), 0,      0,      0 },
	{ 1.0f, -1.0f,  1.0f, packF4u( 0.0f, -1.0f,  0.0f), 0, 0x7fff,      0 },
	{-1.0f, -1.0f, -1.0f, packF4u( 0.0f, -1.0f,  0.0f), 0,      0, 0x7fff },
	{ 1.0f, -1.0f, -1.0f, packF4u( 0.0f, -1.0f,  0.0f), 0, 0x7fff, 0x7fff },
	{ 1.0f, -1.0f,  1.0f, packF4u( 1.0f,  0.0f,  0.0f), 0,      0,      0 },
	{ 1.0f,  1.0f,  1.0f, packF4u( 1.0f,  0.0f,  0.0f), 0, 0x7fff,      0 },
	{ 1.0f, -1.0f, -1.0f, packF4u( 1.0f,  0.0f,  0.0f), 0,      0, 0x7fff },
	{ 1.0f,  1.0f, -1.0f, packF4u( 1.0f,  0.0f,  0.0f), 0, 0x7fff, 0x7fff },
	{-1.0f, -1.0f,  1.0f, packF4u(-1.0f,  0.0f,  0.0f), 0,      0,      0 },
	{-1.0f,  1.0f,  1.0f, packF4u(-1.0f,  0.0f,  0.0f), 0, 0x7fff,      0 },
	{-1.0f, -1.0f, -1.0f, packF4u(-1.0f,  0.0f,  0.0f), 0,      0, 0x7fff },
	{-1.0f,  1.0f, -1.0f, packF4u(-1.0f,  0.0f,  0.0f), 0, 0x7fff, 0x7fff },
};

static const uint16_t s_cubeIndices[36] =
{
	 0,  2,  1,
	 1,  2,  3,
	 4,  5,  6,
	 5,  7,  6,

	 8, 10,  9,
	 9, 10, 11,
	12, 13, 14,
	13, 15, 14,

	16, 18, 17,
	17, 18, 19,
	20, 21, 22,
	21, 23, 22,
};

void screenSpaceQuad(float _textureWidth, float _textureHeight, float _texelHalf, bool _originBottomLeft, float _width = 1.0f, float _height = 1.0f)
{
	if (bgfx::checkAvailTransientVertexBuffer(3, PosTexCoord0Vertex::ms_decl) )
	{
		bgfx::TransientVertexBuffer vb;
		bgfx::allocTransientVertexBuffer(&vb, 3, PosTexCoord0Vertex::ms_decl);
		PosTexCoord0Vertex* vertex = (PosTexCoord0Vertex*)vb.data;

		const float minx = -_width;
		const float maxx =  _width;
		const float miny = 0.0f;
		const float maxy = _height*2.0f;

		const float texelHalfW = _texelHalf/_textureWidth;
		const float texelHalfH = _texelHalf/_textureHeight;
		const float minu = -1.0f + texelHalfW;
		const float maxu =  1.0f + texelHalfH;

		const float zz = 0.0f;

		float minv = texelHalfH;
		float maxv = 2.0f + texelHalfH;

		if (_originBottomLeft)
		{
			float temp = minv;
			minv = maxv;
			maxv = temp;

			minv -= 1.0f;
			maxv -= 1.0f;
		}

		vertex[0].m_x = minx;
		vertex[0].m_y = miny;
		vertex[0].m_z = zz;
		vertex[0].m_u = minu;
		vertex[0].m_v = minv;

		vertex[1].m_x = maxx;
		vertex[1].m_y = miny;
		vertex[1].m_z = zz;
		vertex[1].m_u = maxu;
		vertex[1].m_v = minv;

		vertex[2].m_x = maxx;
		vertex[2].m_y = maxy;
		vertex[2].m_z = zz;
		vertex[2].m_u = maxu;
		vertex[2].m_v = maxv;

		bgfx::setVertexBuffer(&vb);
	}
}

int _main_(int /*_argc*/, char** /*_argv*/)
{
	uint32_t width = 1280;
	uint32_t height = 720;
	uint32_t debug = BGFX_DEBUG_TEXT;
	uint32_t reset = BGFX_RESET_VSYNC;

	bgfx::init();
	bgfx::reset(width, height, reset);

	// Enable debug text.
	bgfx::setDebug(debug);

	// Set clear color palette for index 0
	bgfx::setClearColor(0, UINT32_C(0x00000000) );

	// Set clear color palette for index 1
	bgfx::setClearColor(1, UINT32_C(0x303030ff) );

	// Set geometry pass view clear state.
	bgfx::setViewClear(RENDER_PASS_GEOMETRY_ID
		, BGFX_CLEAR_COLOR|BGFX_CLEAR_DEPTH
		, 1.0f
		, 0
		, 1
		);

	// Set light pass view clear state.
	bgfx::setViewClear(RENDER_PASS_LIGHT_ID
		, BGFX_CLEAR_COLOR|BGFX_CLEAR_DEPTH
		, 1.0f
		, 0
		, 0
		);

	// Create vertex stream declaration.
	PosNormalTangentTexcoordVertex::init();
	PosTexCoord0Vertex::init();
	DebugVertex::init();

	calcTangents(s_cubeVertices
		, BX_COUNTOF(s_cubeVertices)
		, PosNormalTangentTexcoordVertex::ms_decl
		, s_cubeIndices
		, BX_COUNTOF(s_cubeIndices)
		);

	// Create static vertex buffer.
	bgfx::VertexBufferHandle vbh = bgfx::createVertexBuffer(
		  bgfx::makeRef(s_cubeVertices, sizeof(s_cubeVertices) )
		, PosNormalTangentTexcoordVertex::ms_decl
		);

	// Create static index buffer.
	bgfx::IndexBufferHandle ibh = bgfx::createIndexBuffer(bgfx::makeRef(s_cubeIndices, sizeof(s_cubeIndices) ) );

	// Create texture sampler uniforms.
	bgfx::UniformHandle s_texColor  = bgfx::createUniform("s_texColor",  bgfx::UniformType::Uniform1iv);
	bgfx::UniformHandle s_texNormal = bgfx::createUniform("s_texNormal", bgfx::UniformType::Uniform1iv);

	bgfx::UniformHandle s_albedo = bgfx::createUniform("s_albedo", bgfx::UniformType::Uniform1iv);
	bgfx::UniformHandle s_normal = bgfx::createUniform("s_normal", bgfx::UniformType::Uniform1iv);
	bgfx::UniformHandle s_depth  = bgfx::createUniform("s_depth",  bgfx::UniformType::Uniform1iv);
	bgfx::UniformHandle s_light  = bgfx::createUniform("s_light",  bgfx::UniformType::Uniform1iv);

	bgfx::UniformHandle u_mtx            = bgfx::createUniform("u_mtx",            bgfx::UniformType::Uniform4x4fv);
	bgfx::UniformHandle u_lightPosRadius = bgfx::createUniform("u_lightPosRadius", bgfx::UniformType::Uniform4fv);
	bgfx::UniformHandle u_lightRgbInnerR = bgfx::createUniform("u_lightRgbInnerR", bgfx::UniformType::Uniform4fv);

	// Create program from shaders.
	bgfx::ProgramHandle geomProgram    = loadProgram("vs_deferred_geom",       "fs_deferred_geom");
	bgfx::ProgramHandle lightProgram   = loadProgram("vs_deferred_light",      "fs_deferred_light");
	bgfx::ProgramHandle combineProgram = loadProgram("vs_deferred_combine",    "fs_deferred_combine");
	bgfx::ProgramHandle debugProgram   = loadProgram("vs_deferred_debug",      "fs_deferred_debug");
	bgfx::ProgramHandle lineProgram    = loadProgram("vs_deferred_debug_line", "fs_deferred_debug_line");

	// Load diffuse texture.
	bgfx::TextureHandle textureColor  = loadTexture("fieldstone-rgba.dds");

	// Load normal texture.
	bgfx::TextureHandle textureNormal = loadTexture("fieldstone-n.dds");

	bgfx::TextureHandle gbufferTex[3] = { BGFX_INVALID_HANDLE, BGFX_INVALID_HANDLE, BGFX_INVALID_HANDLE };
	bgfx::FrameBufferHandle gbuffer = BGFX_INVALID_HANDLE;
	bgfx::FrameBufferHandle lightBuffer = BGFX_INVALID_HANDLE;

	// Imgui.
	imguiCreate();

	const int64_t timeOffset = bx::getHPCounter();
	const bgfx::RendererType::Enum renderer = bgfx::getRendererType();
	const float texelHalf = bgfx::RendererType::Direct3D9 == renderer ? 0.5f : 0.0f;
	s_originBottomLeft = bgfx::RendererType::OpenGL == renderer || bgfx::RendererType::OpenGLES == renderer;

	// Get renderer capabilities info.
	const bgfx::Caps* caps = bgfx::getCaps();

	uint32_t oldWidth  = 0;
	uint32_t oldHeight = 0;
	uint32_t oldReset  = reset;

	int32_t scrollArea = 0;
	int32_t numLights = 512;
	float lightAnimationSpeed = 0.3f;
	bool animateMesh = true;
	bool showScissorRects = false;
	bool showGBuffer = true;

	float view[16];
	float initialPos[3] = { 0.0f, 0.0f, -15.0f };
	cameraCreate();
	cameraSetPosition(initialPos);
	cameraSetVerticalAngle(0.0f);
	cameraGetViewMtx(view);

	entry::MouseState mouseState;
	while (!entry::processEvents(width, height, debug, reset, &mouseState) )
	{
		int64_t now = bx::getHPCounter();
		static int64_t last = now;
		const int64_t frameTime = now - last;
		last = now;
		const double freq = double(bx::getHPFrequency() );
		const double toMs = 1000.0/freq;
		const float deltaTime = float(frameTime/freq);

		float time = (float)( (now-timeOffset)/freq);

		// Use debug font to print information about this example.
		bgfx::dbgTextClear();
		bgfx::dbgTextPrintf(0, 1, 0x4f, "bgfx/examples/21-deferred");
		bgfx::dbgTextPrintf(0, 2, 0x6f, "Description: MRT rendering and deferred shading.");
		bgfx::dbgTextPrintf(0, 3, 0x0f, "Frame: % 7.3f[ms]", double(frameTime)*toMs);

		if (2 > caps->maxFBAttachments)
		{
			// When multiple render targets (MRT) is not supported by GPU,
			// implement alternative code path that doesn't use MRT.
			bool blink = uint32_t(time*3.0f)&1;
			bgfx::dbgTextPrintf(0, 5, blink ? 0x1f : 0x01, " MRT not supported by GPU. ");

			// Set view 0 default viewport.
			bgfx::setViewRect(0, 0, 0, width, height);

			// This dummy draw call is here to make sure that view 0 is cleared
			// if no other draw calls are submitted to view 0.
			bgfx::submit(0);
		}
		else
		{
			if (oldWidth  != width
			||  oldHeight != height
			||  oldReset  != reset
			||  !bgfx::isValid(gbuffer) )
			{
				// Recreate variable size render targets when resolution changes.
				oldWidth  = width;
				oldHeight = height;
				oldReset  = reset;

				if (bgfx::isValid(gbuffer) )
				{
					bgfx::destroyFrameBuffer(gbuffer);
				}

				const uint32_t samplerFlags = 0
					| BGFX_TEXTURE_RT
					| BGFX_TEXTURE_MIN_POINT
					| BGFX_TEXTURE_MAG_POINT
					| BGFX_TEXTURE_MIP_POINT
					| BGFX_TEXTURE_U_CLAMP
					| BGFX_TEXTURE_V_CLAMP
					;
				gbufferTex[0] = bgfx::createTexture2D(width, height, 1, bgfx::TextureFormat::BGRA8, samplerFlags);
				gbufferTex[1] = bgfx::createTexture2D(width, height, 1, bgfx::TextureFormat::BGRA8, samplerFlags);
				gbufferTex[2] = bgfx::createTexture2D(width, height, 1, bgfx::TextureFormat::D24,   samplerFlags);
				gbuffer = bgfx::createFrameBuffer(BX_COUNTOF(gbufferTex), gbufferTex, true);

				if (bgfx::isValid(lightBuffer) )
				{
					bgfx::destroyFrameBuffer(lightBuffer);
				}

				lightBuffer = bgfx::createFrameBuffer(width, height, bgfx::TextureFormat::BGRA8, samplerFlags);
			}

			imguiBeginFrame(mouseState.m_mx
				, mouseState.m_my
				, (mouseState.m_buttons[entry::MouseButton::Left  ] ? IMGUI_MBUT_LEFT  : 0)
				| (mouseState.m_buttons[entry::MouseButton::Right ] ? IMGUI_MBUT_RIGHT : 0)
				, 0
				, width
				, height
				);

			imguiBeginScrollArea("Settings", width - width / 5 - 10, 10, width / 5, height / 3, &scrollArea);
			imguiSeparatorLine();

			imguiSlider("Num lights", numLights, 1, 2048);

			if (imguiCheck("Show G-Buffer.", showGBuffer) )
			{
				showGBuffer = !showGBuffer;
			}

			if (imguiCheck("Show light scissor.", showScissorRects) )
			{
				showScissorRects = !showScissorRects;
			}

			if (imguiCheck("Animate mesh.", animateMesh) )
			{
				animateMesh = !animateMesh;
			}

			imguiSlider("Lights animation speed", lightAnimationSpeed, 0.0f, 0.4f, 0.01f);

			imguiEndScrollArea();
			imguiEndFrame();

			// Update camera.
			cameraUpdate(deltaTime, mouseState);
			cameraGetViewMtx(view);

			// Setup views
			float vp[16];
			float invMvp[16];
			{
				bgfx::setViewRect(RENDER_PASS_GEOMETRY_ID,      0, 0, width, height);
				bgfx::setViewRect(RENDER_PASS_LIGHT_ID,         0, 0, width, height);
				bgfx::setViewRect(RENDER_PASS_COMBINE_ID,       0, 0, width, height);
				bgfx::setViewRect(RENDER_PASS_DEBUG_LIGHTS_ID,  0, 0, width, height);
				bgfx::setViewRect(RENDER_PASS_DEBUG_GBUFFER_ID, 0, 0, width, height);

				bgfx::setViewFrameBuffer(RENDER_PASS_LIGHT_ID, lightBuffer);

				float proj[16];
				mtxProj(proj, 60.0f, float(width)/float(height), 0.1f, 100.0f);

				bgfx::setViewFrameBuffer(RENDER_PASS_GEOMETRY_ID, gbuffer);
				bgfx::setViewTransform(RENDER_PASS_GEOMETRY_ID, view, proj);

				bx::mtxMul(vp, view, proj);
				bx::mtxInverse(invMvp, vp);

				bx::mtxOrtho(proj, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 100.0f);
				bgfx::setViewTransform(RENDER_PASS_LIGHT_ID,   NULL, proj);
				bgfx::setViewTransform(RENDER_PASS_COMBINE_ID, NULL, proj);

				const float aspectRatio = float(height)/float(width);
				const float size = 10.0f;
				bx::mtxOrtho(proj, -size, size, size*aspectRatio, -size*aspectRatio, 0.0f, 1000.0f);
				bgfx::setViewTransform(RENDER_PASS_DEBUG_GBUFFER_ID, NULL, proj);

				bx::mtxOrtho(proj, 0.0f, (float)width, 0.0f, (float)height, 0.0f, 1000.0f);
				bgfx::setViewTransform(RENDER_PASS_DEBUG_LIGHTS_ID, NULL, proj);
			}

			const uint32_t dim = 11;
			const float offset = (float(dim-1) * 3.0f) * 0.5f;

			// Draw into geometry pass.
			for (uint32_t yy = 0; yy < dim; ++yy)
			{
				for (uint32_t xx = 0; xx < dim; ++xx)
				{
					float mtx[16];
					if (animateMesh)
					{
						bx::mtxRotateXY(mtx, time*1.023f + xx*0.21f, time*0.03f + yy*0.37f);
					}
					else
					{
						bx::mtxIdentity(mtx);
					}
					mtx[12] = -offset + float(xx)*3.0f;
					mtx[13] = -offset + float(yy)*3.0f;
					mtx[14] = 0.0f;

					// Set transform for draw call.
					bgfx::setTransform(mtx);

					// Set vertex and fragment shaders.
					bgfx::setProgram(geomProgram);

					// Set vertex and index buffer.
					bgfx::setVertexBuffer(vbh);
					bgfx::setIndexBuffer(ibh);

					// Bind textures.
					bgfx::setTexture(0, s_texColor,  textureColor);
					bgfx::setTexture(1, s_texNormal, textureNormal);

					// Set render states.
					bgfx::setState(0
						| BGFX_STATE_RGB_WRITE
						| BGFX_STATE_ALPHA_WRITE
						| BGFX_STATE_DEPTH_WRITE
						| BGFX_STATE_DEPTH_TEST_LESS
						| BGFX_STATE_MSAA
						);

					// Submit primitive for rendering to view 0.
					bgfx::submit(RENDER_PASS_GEOMETRY_ID);
				}
			}

			// Draw lights into light buffer.
			for (int32_t light = 0; light < numLights; ++light)
			{
				Sphere lightPosRadius;

				float lightTime = time * lightAnimationSpeed * (sinf(light/float(numLights) * bx::piHalf ) * 0.5f + 0.5f);
				lightPosRadius.m_center[0] = sinf( ( (lightTime + light*0.47f) + bx::piHalf*1.37f ) )*offset;
				lightPosRadius.m_center[1] = cosf( ( (lightTime + light*0.69f) + bx::piHalf*1.49f ) )*offset;
				lightPosRadius.m_center[2] = sinf( ( (lightTime + light*0.37f) + bx::piHalf*1.57f ) )*2.0f;
				lightPosRadius.m_radius = 2.0f;

				Aabb aabb;
				sphereToAabb(aabb, lightPosRadius);

				float box[8][3] =
				{
					{ aabb.m_min[0], aabb.m_min[1], aabb.m_min[2] },
					{ aabb.m_min[0], aabb.m_min[1], aabb.m_max[2] },
					{ aabb.m_min[0], aabb.m_max[1], aabb.m_min[2] },
					{ aabb.m_min[0], aabb.m_max[1], aabb.m_max[2] },
					{ aabb.m_max[0], aabb.m_min[1], aabb.m_min[2] },
					{ aabb.m_max[0], aabb.m_min[1], aabb.m_max[2] },
					{ aabb.m_max[0], aabb.m_max[1], aabb.m_min[2] },
					{ aabb.m_max[0], aabb.m_max[1], aabb.m_max[2] },
				};

				float xyz[3];
				bx::vec3MulMtxH(xyz, box[0], vp);
				float minx = xyz[0];
				float miny = xyz[1];
				float maxx = xyz[0];
				float maxy = xyz[1];
				float maxz = xyz[2];

				for (uint32_t ii = 1; ii < 8; ++ii)
				{
					bx::vec3MulMtxH(xyz, box[ii], vp);
					minx = bx::fmin(minx, xyz[0]);
					miny = bx::fmin(miny, xyz[1]);
					maxx = bx::fmax(maxx, xyz[0]);
					maxy = bx::fmax(maxy, xyz[1]);
					maxz = bx::fmax(maxz, xyz[2]);
				}

				// Cull light if it's fully behind camera.
				if (maxz >= 0.0f)
				{
					float x0 = bx::fclamp( (minx * 0.5f + 0.5f) * width,  0.0f, (float)width);
					float y0 = bx::fclamp( (miny * 0.5f + 0.5f) * height, 0.0f, (float)height);
					float x1 = bx::fclamp( (maxx * 0.5f + 0.5f) * width,  0.0f, (float)width);
					float y1 = bx::fclamp( (maxy * 0.5f + 0.5f) * height, 0.0f, (float)height);

					if (showScissorRects)
					{
						bgfx::TransientVertexBuffer tvb;
						bgfx::TransientIndexBuffer tib;
						if (bgfx::allocTransientBuffers(&tvb, DebugVertex::ms_decl, 4, &tib, 8) )
						{
							uint32_t abgr = 0x8000ff00;

							DebugVertex* vertex = (DebugVertex*)tvb.data;
							vertex->m_x = x0;
							vertex->m_y = y0;
							vertex->m_z = 0.0f;
							vertex->m_abgr = abgr;
							++vertex;

							vertex->m_x = x1;
							vertex->m_y = y0;
							vertex->m_z = 0.0f;
							vertex->m_abgr = abgr;
							++vertex;

							vertex->m_x = x1;
							vertex->m_y = y1;
							vertex->m_z = 0.0f;
							vertex->m_abgr = abgr;
							++vertex;

							vertex->m_x = x0;
							vertex->m_y = y1;
							vertex->m_z = 0.0f;
							vertex->m_abgr = abgr;

							uint16_t* indices = (uint16_t*)tib.data;
							*indices++ = 0;
							*indices++ = 1;
							*indices++ = 1;
							*indices++ = 2;
							*indices++ = 2;
							*indices++ = 3;
							*indices++ = 3;
							*indices++ = 0;

							bgfx::setProgram(lineProgram);
							bgfx::setVertexBuffer(&tvb);
							bgfx::setIndexBuffer(&tib);
							bgfx::setState(0
								| BGFX_STATE_RGB_WRITE
								| BGFX_STATE_PT_LINES
								| BGFX_STATE_BLEND_ALPHA
								);
							bgfx::submit(RENDER_PASS_DEBUG_LIGHTS_ID);
						}
					}

					uint8_t val = light&7;
					float lightRgbInnerR[4] =
					{
						val & 0x1 ? 1.0f : 0.25f,
						val & 0x2 ? 1.0f : 0.25f,
						val & 0x4 ? 1.0f : 0.25f,
						0.8f,
					};

					// Draw light.
					bgfx::setUniform(u_lightPosRadius, &lightPosRadius);
					bgfx::setUniform(u_lightRgbInnerR, lightRgbInnerR);
					bgfx::setUniform(u_mtx, invMvp);
					const uint16_t scissorHeight = uint16_t(y1-y0);
					bgfx::setScissor(uint16_t(x0), height-scissorHeight-uint16_t(y0), uint16_t(x1-x0), scissorHeight);
					bgfx::setTexture(0, s_normal, gbuffer, 1);
					bgfx::setTexture(1, s_depth,  gbuffer, 2);
					bgfx::setProgram(lightProgram);
					bgfx::setState(0
						| BGFX_STATE_RGB_WRITE
						| BGFX_STATE_ALPHA_WRITE
						| BGFX_STATE_BLEND_ADD
						);
					screenSpaceQuad( (float)width, (float)height, texelHalf, s_originBottomLeft);
					bgfx::submit(RENDER_PASS_LIGHT_ID);
				}
			}

			// Combine color and light buffers.
			bgfx::setTexture(0, s_albedo, gbuffer,     0);
			bgfx::setTexture(1, s_light,  lightBuffer, 0);
			bgfx::setProgram(combineProgram);
			bgfx::setState(0
				| BGFX_STATE_RGB_WRITE
				| BGFX_STATE_ALPHA_WRITE
				);
			screenSpaceQuad( (float)width, (float)height, texelHalf, s_originBottomLeft);
			bgfx::submit(RENDER_PASS_COMBINE_ID);

			if (showGBuffer)
			{
				const float aspectRatio = float(width)/float(height);

				// Draw debug GBuffer.
				for (uint32_t ii = 0; ii < BX_COUNTOF(gbufferTex); ++ii)
				{
					float mtx[16];
					bx::mtxSRT(mtx
						, aspectRatio, 1.0f, 1.0f
						, 0.0f, 0.0f, 0.0f
						, -7.9f - BX_COUNTOF(gbufferTex)*0.1f*0.5f + ii*2.1f*aspectRatio, 4.0f, 0.0f
						);

					bgfx::setTransform(mtx);
					bgfx::setProgram(debugProgram);
					bgfx::setVertexBuffer(vbh);
					bgfx::setIndexBuffer(ibh, 0, 6);
					bgfx::setTexture(0, s_texColor, gbufferTex[ii]);
					bgfx::setState(BGFX_STATE_RGB_WRITE);
					bgfx::submit(RENDER_PASS_DEBUG_GBUFFER_ID);
				}
			}
		}

		// Advance to next frame. Rendering thread will be kicked to
		// process submitted rendering primitives.
		bgfx::frame();
	}

	// Cleanup.
	cameraDestroy();
	imguiDestroy();

	if (bgfx::isValid(gbuffer) )
	{
		bgfx::destroyFrameBuffer(gbuffer);
		bgfx::destroyFrameBuffer(lightBuffer);
	}

	bgfx::destroyIndexBuffer(ibh);
	bgfx::destroyVertexBuffer(vbh);

	bgfx::destroyProgram(geomProgram);
	bgfx::destroyProgram(lightProgram);
	bgfx::destroyProgram(combineProgram);
	bgfx::destroyProgram(debugProgram);
	bgfx::destroyProgram(lineProgram);

	bgfx::destroyTexture(textureColor);
	bgfx::destroyTexture(textureNormal);
	bgfx::destroyUniform(s_texColor);
	bgfx::destroyUniform(s_texNormal);

	bgfx::destroyUniform(s_albedo);
	bgfx::destroyUniform(s_normal);
	bgfx::destroyUniform(s_depth);
	bgfx::destroyUniform(s_light);

	bgfx::destroyUniform(u_lightPosRadius);
	bgfx::destroyUniform(u_lightRgbInnerR);
	bgfx::destroyUniform(u_mtx);

	// Shutdown bgfx.
	bgfx::shutdown();

	return 0;
}