bgfx/examples/09-hdr/hdr.cpp

/*
 * Copyright 2011-2025 Branimir Karadzic. All rights reserved.
 * License: https://github.com/bkaradzic/bgfx/blob/master/LICENSE
 */

#include "common.h"
#include "bgfx_utils.h"
#include "imgui/imgui.h"
#include <bx/rng.h>

namespace
{

struct PosColorTexCoord0Vertex
{
	float m_x;
	float m_y;
	float m_z;
	uint32_t m_rgba;
	float m_u;
	float m_v;

	static void init()
	{
		ms_layout
			.begin()
			.add(bgfx::Attrib::Position,  3, bgfx::AttribType::Float)
			.add(bgfx::Attrib::Color0,    4, bgfx::AttribType::Uint8, true)
			.add(bgfx::Attrib::TexCoord0, 2, bgfx::AttribType::Float)
			.end();
	}

	static bgfx::VertexLayout ms_layout;
};

bgfx::VertexLayout PosColorTexCoord0Vertex::ms_layout;

void screenSpaceQuad(bool _originBottomLeft = false, float _width = 1.0f, float _height = 1.0f)
{
	if (3 == bgfx::getAvailTransientVertexBuffer(3, PosColorTexCoord0Vertex::ms_layout) )
	{
		bgfx::TransientVertexBuffer vb;
		bgfx::allocTransientVertexBuffer(&vb, 3, PosColorTexCoord0Vertex::ms_layout);
		PosColorTexCoord0Vertex* vertex = (PosColorTexCoord0Vertex*)vb.data;

		const float zz = 0.0f;

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

		const float minu = -1.0f;
		const float maxu =  1.0f;

		float minv = 0.0f;
		float maxv = 2.0f;

		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_rgba = 0xffffffff;
		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_rgba = 0xffffffff;
		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_rgba = 0xffffffff;
		vertex[2].m_u = maxu;
		vertex[2].m_v = maxv;

		bgfx::setVertexBuffer(0, &vb);
	}
}

void setOffsets2x2Lum(bgfx::UniformHandle _handle, uint32_t _width, uint32_t _height)
{
	float offsets[16][4];

	float du = 1.0f/_width;
	float dv = 1.0f/_height;

	uint16_t num = 0;
	for (uint32_t yy = 0; yy < 3; ++yy)
	{
		for (uint32_t xx = 0; xx < 3; ++xx)
		{
			offsets[num][0] = xx * du;
			offsets[num][1] = yy * dv;
			++num;
		}
	}

	bgfx::setUniform(_handle, offsets, num);
}

void setOffsets4x4Lum(bgfx::UniformHandle _handle, uint32_t _width, uint32_t _height)
{
	float offsets[16][4];

	float du = 1.0f/_width;
	float dv = 1.0f/_height;

	uint16_t num = 0;
	for (uint32_t yy = 0; yy < 4; ++yy)
	{
		for (uint32_t xx = 0; xx < 4; ++xx)
		{
			offsets[num][0] = (xx - 1.0f) * du;
			offsets[num][1] = (yy - 1.0f) * dv;
			++num;
		}
	}

	bgfx::setUniform(_handle, offsets, num);
}

class ExampleHDR : public entry::AppI
{
public:
	ExampleHDR(const char* _name, const char* _description, const char* _url)
		: entry::AppI(_name, _description, _url)
	{
	}

	void init(int32_t _argc, const char* const* _argv, uint32_t _width, uint32_t _height) override
	{
		Args args(_argc, _argv);

		m_width  = _width;
		m_height = _height;
		m_debug  = BGFX_DEBUG_NONE;
		m_reset  = BGFX_RESET_VSYNC;

		bgfx::Init init;
		init.type     = args.m_type;
		init.vendorId = args.m_pciId;
		init.platformData.nwh  = entry::getNativeWindowHandle(entry::kDefaultWindowHandle);
		init.platformData.ndt  = entry::getNativeDisplayHandle();
		init.platformData.type = entry::getNativeWindowHandleType();
		init.resolution.width  = m_width;
		init.resolution.height = m_height;
		init.resolution.reset  = m_reset;
		bgfx::init(init);

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

		// Create vertex stream declaration.
		PosColorTexCoord0Vertex::init();

		m_uffizi = loadTexture("textures/uffizi.ktx"
				, 0
				| BGFX_SAMPLER_U_CLAMP
				| BGFX_SAMPLER_V_CLAMP
				| BGFX_SAMPLER_W_CLAMP
				);

		m_skyProgram     = loadProgram("vs_hdr_skybox",  "fs_hdr_skybox");
		m_lumProgram     = loadProgram("vs_hdr_lum",     "fs_hdr_lum");
		m_lumAvgProgram  = loadProgram("vs_hdr_lumavg",  "fs_hdr_lumavg");
		m_blurProgram    = loadProgram("vs_hdr_blur",    "fs_hdr_blur");
		m_brightProgram  = loadProgram("vs_hdr_bright",  "fs_hdr_bright");
		m_meshProgram    = loadProgram("vs_hdr_mesh",    "fs_hdr_mesh");
		m_tonemapProgram = loadProgram("vs_hdr_tonemap", "fs_hdr_tonemap");

		s_texCube   = bgfx::createUniform("s_texCube",  bgfx::UniformType::Sampler);
		s_texColor  = bgfx::createUniform("s_texColor", bgfx::UniformType::Sampler);
		s_texLum    = bgfx::createUniform("s_texLum",   bgfx::UniformType::Sampler);
		s_texBlur   = bgfx::createUniform("s_texBlur",  bgfx::UniformType::Sampler);
		u_mtx       = bgfx::createUniform("u_mtx",      bgfx::UniformType::Mat4);
		u_offset    = bgfx::createUniform("u_offset",   bgfx::UniformType::Vec4, 16);

		// Tonemap value will be updated once per frame.
		u_tonemap   = bgfx::createUniform("u_tonemap",  bgfx::UniformFreq::Frame, bgfx::UniformType::Vec4);

		m_mesh = meshLoad("meshes/bunny.bin");

		m_fbh.idx = bgfx::kInvalidHandle;

		m_lum[0] = bgfx::createFrameBuffer(128, 128, bgfx::TextureFormat::BGRA8);
		m_lum[1] = bgfx::createFrameBuffer( 64,  64, bgfx::TextureFormat::BGRA8);
		m_lum[2] = bgfx::createFrameBuffer( 16,  16, bgfx::TextureFormat::BGRA8);
		m_lum[3] = bgfx::createFrameBuffer(  4,   4, bgfx::TextureFormat::BGRA8);
		m_lum[4] = bgfx::createFrameBuffer(  1,   1, bgfx::TextureFormat::BGRA8);

		m_bright = bgfx::createFrameBuffer(bgfx::BackbufferRatio::Half,   bgfx::TextureFormat::BGRA8);
		m_blur   = bgfx::createFrameBuffer(bgfx::BackbufferRatio::Eighth, bgfx::TextureFormat::BGRA8);

		m_lumBgra8 = 0;
		if ( (BGFX_CAPS_TEXTURE_BLIT|BGFX_CAPS_TEXTURE_READ_BACK) == (bgfx::getCaps()->supported & (BGFX_CAPS_TEXTURE_BLIT|BGFX_CAPS_TEXTURE_READ_BACK) ) )
		{
			m_rb = bgfx::createTexture2D(1, 1, false, 1, bgfx::TextureFormat::BGRA8, BGFX_TEXTURE_BLIT_DST|BGFX_TEXTURE_READ_BACK);
		}
		else
		{
			m_rb.idx = bgfx::kInvalidHandle;
		}

		// Imgui.
		imguiCreate();

		m_caps = bgfx::getCaps();

		m_oldWidth  = 0;
		m_oldHeight = 0;
		m_oldReset  = m_reset;

		m_speed      = 0.37f;
		m_middleGray = 0.18f;
		m_white      = 1.1f;
		m_threshold  = 1.5f;

		m_scrollArea = 0;

		m_time = 0.0f;
	}

	virtual int shutdown() override
	{
		// Cleanup.
		imguiDestroy();

		meshUnload(m_mesh);

		for (uint32_t ii = 0; ii < BX_COUNTOF(m_lum); ++ii)
		{
			bgfx::destroy(m_lum[ii]);
		}
		bgfx::destroy(m_bright);
		bgfx::destroy(m_blur);

		if (bgfx::isValid(m_fbh) )
		{
			bgfx::destroy(m_fbh);
		}

		bgfx::destroy(m_meshProgram);
		bgfx::destroy(m_skyProgram);
		bgfx::destroy(m_tonemapProgram);
		bgfx::destroy(m_lumProgram);
		bgfx::destroy(m_lumAvgProgram);
		bgfx::destroy(m_blurProgram);
		bgfx::destroy(m_brightProgram);
		bgfx::destroy(m_uffizi);
		if (bgfx::isValid(m_rb) )
		{
			bgfx::destroy(m_rb);
		}

		bgfx::destroy(s_texCube);
		bgfx::destroy(s_texColor);
		bgfx::destroy(s_texLum);
		bgfx::destroy(s_texBlur);
		bgfx::destroy(u_mtx);
		bgfx::destroy(u_tonemap);
		bgfx::destroy(u_offset);

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

		return 0;
	}

	bool update() override
	{
		if (!entry::processEvents(m_width, m_height, m_debug, m_reset, &m_mouseState) )
		{
			if (!bgfx::isValid(m_fbh)
			||  m_oldWidth  != m_width
			||  m_oldHeight != m_height
			||  m_oldReset  != m_reset)
			{
				// Recreate variable size render targets when resolution changes.
				m_oldWidth  = m_width;
				m_oldHeight = m_height;
				m_oldReset  = m_reset;

				uint32_t msaa = (m_reset&BGFX_RESET_MSAA_MASK)>>BGFX_RESET_MSAA_SHIFT;

				if (bgfx::isValid(m_fbh) )
				{
					bgfx::destroy(m_fbh);
				}

				m_fbtextures[0] = bgfx::createTexture2D(
					  uint16_t(m_width)
					, uint16_t(m_height)
					, false
					, 1
					, bgfx::TextureFormat::BGRA8
					, (uint64_t(msaa + 1) << BGFX_TEXTURE_RT_MSAA_SHIFT) | BGFX_SAMPLER_U_CLAMP | BGFX_SAMPLER_V_CLAMP
					);

				const uint64_t textureFlags = BGFX_TEXTURE_RT_WRITE_ONLY|(uint64_t(msaa+1)<<BGFX_TEXTURE_RT_MSAA_SHIFT);

				bgfx::TextureFormat::Enum depthFormat =
					  bgfx::isTextureValid(0, false, 1, bgfx::TextureFormat::D16,   textureFlags) ? bgfx::TextureFormat::D16
					: bgfx::isTextureValid(0, false, 1, bgfx::TextureFormat::D24S8, textureFlags) ? bgfx::TextureFormat::D24S8
					: bgfx::TextureFormat::D32
					;

				m_fbtextures[1] = bgfx::createTexture2D(
					  uint16_t(m_width)
					, uint16_t(m_height)
					, false
					, 1
					, depthFormat
					, textureFlags
					);

				m_fbh = bgfx::createFrameBuffer(BX_COUNTOF(m_fbtextures), m_fbtextures, true);
			}

			imguiBeginFrame(m_mouseState.m_mx
					,  m_mouseState.m_my
					, (m_mouseState.m_buttons[entry::MouseButton::Left  ] ? IMGUI_MBUT_LEFT   : 0)
					| (m_mouseState.m_buttons[entry::MouseButton::Right ] ? IMGUI_MBUT_RIGHT  : 0)
					| (m_mouseState.m_buttons[entry::MouseButton::Middle] ? IMGUI_MBUT_MIDDLE : 0)
					,  m_mouseState.m_mz
					, uint16_t(m_width)
					, uint16_t(m_height)
					);

			showExampleDialog(this);

			ImGui::SetNextWindowPos(
				  ImVec2(m_width - m_width / 5.0f - 40.0f, 10.0f)
				, ImGuiCond_FirstUseEver
				);
			ImGui::SetNextWindowSize(
				  ImVec2(m_width / 5.0f + 30.0f, m_height / 2.0f)
				, ImGuiCond_FirstUseEver
				);
			ImGui::Begin("Settings"
				, NULL
				, 0
				);

			ImGui::SliderFloat("Speed", &m_speed, 0.0f, 1.0f);
			ImGui::Separator();

			ImGui::SliderFloat("Middle gray", &m_middleGray, 0.1f, 1.0f);
			ImGui::SliderFloat("White point", &m_white,      0.1f, 2.0f);
			ImGui::SliderFloat("Threshold",   &m_threshold,  0.1f, 2.0f);

			if (bgfx::isValid(m_rb) )
			{
				struct Packed { uint8_t bgra[4]; } arr = bx::bitCast<Packed>(m_lumBgra8);
				float exponent = arr.bgra[3] / 255.0f * 255.0f - 128.0f;
				float lumAvg = arr.bgra[2] / 255.0f * bx::exp2(exponent);

				ImGui::SliderFloat("Lum Avg", &lumAvg, 0.0f, 1.0f);
			}

			const bgfx::Caps* caps = bgfx::getCaps();

			static const char* s_shadingRateName[] =
			{
				"1x1",
				"1x2",
				"2x1",
				"2x2",
				"2x4",
				"4x2",
				"4x4",
			};
			static_assert(bgfx::ShadingRate::Count == BX_COUNTOF(s_shadingRateName) );

			static bgfx::ShadingRate::Enum shadingRate = bgfx::ShadingRate::Rate1x1;

			ImGui::BeginDisabled(0 == (caps->supported & BGFX_CAPS_VARIABLE_RATE_SHADING) );
			ImGui::Combo("Shading Rate", (int*)&shadingRate, s_shadingRateName, BX_COUNTOF(s_shadingRateName) );
			ImGui::EndDisabled();

			ImGui::End();

			imguiEndFrame();

			// 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::touch(0);

			int64_t now = bx::getHPCounter();
			static int64_t last = now;
			const int64_t frameTime = now - last;
			last = now;
			const double freq = double(bx::getHPFrequency() );

			m_time += (float)(frameTime*m_speed/freq);

			bgfx::ViewId shuffle[10] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
			bx::shuffle(&m_rng, shuffle, BX_COUNTOF(shuffle) );

			bgfx::ViewId hdrSkybox       = shuffle[0];
			bgfx::ViewId hdrMesh         = shuffle[1];
			bgfx::ViewId hdrLuminance    = shuffle[2];
			bgfx::ViewId hdrLumScale0    = shuffle[3];
			bgfx::ViewId hdrLumScale1    = shuffle[4];
			bgfx::ViewId hdrLumScale2    = shuffle[5];
			bgfx::ViewId hdrLumScale3    = shuffle[6];
			bgfx::ViewId hdrBrightness   = shuffle[7];
			bgfx::ViewId hdrVBlur        = shuffle[8];
			bgfx::ViewId hdrHBlurTonemap = shuffle[9];

			// Set views.
			bgfx::setViewName(hdrSkybox, "Skybox");
			bgfx::setViewClear(hdrSkybox, BGFX_CLEAR_COLOR | BGFX_CLEAR_DEPTH, 0x303030ff, 1.0f, 0);
			bgfx::setViewRect(hdrSkybox, 0, 0, bgfx::BackbufferRatio::Equal);
			bgfx::setViewFrameBuffer(hdrSkybox, m_fbh);
			bgfx::setViewShadingRate(hdrSkybox, shadingRate);

			bgfx::setViewName(hdrMesh, "Mesh");
			bgfx::setViewClear(hdrMesh, BGFX_CLEAR_DISCARD_DEPTH | BGFX_CLEAR_DISCARD_STENCIL);
			bgfx::setViewRect(hdrMesh, 0, 0, bgfx::BackbufferRatio::Equal);
			bgfx::setViewFrameBuffer(hdrMesh, m_fbh);
			bgfx::setViewShadingRate(hdrMesh, shadingRate);

			bgfx::setViewName(hdrLuminance, "Luminance");
			bgfx::setViewRect(hdrLuminance, 0, 0, 128, 128);
			bgfx::setViewFrameBuffer(hdrLuminance, m_lum[0]);
			bgfx::setViewShadingRate(hdrLuminance, bgfx::ShadingRate::Rate1x1);

			bgfx::setViewName(hdrLumScale0, "Downscale luminance 0");
			bgfx::setViewRect(hdrLumScale0, 0, 0, 64, 64);
			bgfx::setViewFrameBuffer(hdrLumScale0, m_lum[1]);
			bgfx::setViewShadingRate(hdrLumScale0, bgfx::ShadingRate::Rate1x1);

			bgfx::setViewName(hdrLumScale1, "Downscale luminance 1");
			bgfx::setViewRect(hdrLumScale1, 0, 0, 16, 16);
			bgfx::setViewFrameBuffer(hdrLumScale1, m_lum[2]);
			bgfx::setViewShadingRate(hdrLumScale1, bgfx::ShadingRate::Rate1x1);

			bgfx::setViewName(hdrLumScale2, "Downscale luminance 2");
			bgfx::setViewRect(hdrLumScale2, 0, 0, 4, 4);
			bgfx::setViewFrameBuffer(hdrLumScale2, m_lum[3]);
			bgfx::setViewShadingRate(hdrLumScale2, bgfx::ShadingRate::Rate1x1);

			bgfx::setViewName(hdrLumScale3, "Downscale luminance 3");
			bgfx::setViewRect(hdrLumScale3, 0, 0, 1, 1);
			bgfx::setViewFrameBuffer(hdrLumScale3, m_lum[4]);
			bgfx::setViewShadingRate(hdrLumScale3, bgfx::ShadingRate::Rate1x1);

			bgfx::setViewName(hdrBrightness, "Brightness");
			bgfx::setViewRect(hdrBrightness, 0, 0, bgfx::BackbufferRatio::Half);
			bgfx::setViewFrameBuffer(hdrBrightness, m_bright);
			bgfx::setViewShadingRate(hdrBrightness, bgfx::ShadingRate::Rate1x1);

			bgfx::setViewName(hdrVBlur, "Blur vertical");
			bgfx::setViewRect(hdrVBlur, 0, 0, bgfx::BackbufferRatio::Eighth);
			bgfx::setViewFrameBuffer(hdrVBlur, m_blur);
			bgfx::setViewShadingRate(hdrVBlur, bgfx::ShadingRate::Rate1x1);

			bgfx::setViewName(hdrHBlurTonemap, "Blur horizontal + tonemap");
			bgfx::setViewRect(hdrHBlurTonemap, 0, 0, bgfx::BackbufferRatio::Equal);
			bgfx::FrameBufferHandle invalid = BGFX_INVALID_HANDLE;
			bgfx::setViewFrameBuffer(hdrHBlurTonemap, invalid);
			bgfx::setViewShadingRate(hdrHBlurTonemap, bgfx::ShadingRate::Rate1x1);

			float proj[16];
			bx::mtxOrtho(proj, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 100.0f, 0.0f, caps->homogeneousDepth);

			bgfx::ViewId order[] =
			{
				hdrSkybox,
				hdrMesh,
				hdrLuminance,
				hdrLumScale0,
				hdrLumScale1,
				hdrLumScale2,
				hdrLumScale3,
				hdrBrightness,
				hdrVBlur,
				hdrHBlurTonemap
			};
			bgfx::setViewOrder(0, BX_COUNTOF(order), order);

			// Set view and projection matrix for view 0.
			for (uint8_t ii = 0; ii < BX_COUNTOF(order); ++ii)
			{
				bgfx::setViewTransform(ii, NULL, proj);
			}

			const bx::Vec3 at  = { 0.0f, 1.0f,  0.0f };
			const bx::Vec3 eye = { 0.0f, 1.0f, -2.5f };

			float mtx[16];
			bx::mtxRotateXY(mtx
					, 0.0f
					, m_time
					);

			const bx::Vec3 tmp = bx::mul(eye, mtx);

			float view[16];
			bx::mtxLookAt(view, tmp, at);
			bx::mtxProj(proj, 60.0f, float(m_width)/float(m_height), 0.1f, 100.0f, caps->homogeneousDepth);

			// Set view and projection matrix for view hdrMesh.
			bgfx::setViewTransform(hdrMesh, view, proj);

			const float tonemap[4] = { m_middleGray, bx::square(m_white), m_threshold, m_time };
			bgfx::setFrameUniform(u_tonemap, tonemap);

			// Render skybox into view hdrSkybox.
			bgfx::setTexture(0, s_texCube, m_uffizi);
			bgfx::setState(BGFX_STATE_WRITE_RGB|BGFX_STATE_WRITE_A);
			bgfx::setUniform(u_mtx, mtx);
			screenSpaceQuad(true);
			bgfx::submit(hdrSkybox, m_skyProgram);

			// Render m_mesh into view hdrMesh.
			bgfx::setTexture(0, s_texCube, m_uffizi);
			meshSubmit(m_mesh, hdrMesh, m_meshProgram, NULL);

			// Calculate luminance.
			setOffsets2x2Lum(u_offset, 128, 128);
			bgfx::setTexture(0, s_texColor, m_fbtextures[0]);
			bgfx::setState(BGFX_STATE_WRITE_RGB|BGFX_STATE_WRITE_A);
			screenSpaceQuad(m_caps->originBottomLeft);
			bgfx::submit(hdrLuminance, m_lumProgram);

			// Downscale luminance 0.
			setOffsets4x4Lum(u_offset, 128, 128);
			bgfx::setTexture(0, s_texColor, bgfx::getTexture(m_lum[0]) );
			bgfx::setState(BGFX_STATE_WRITE_RGB|BGFX_STATE_WRITE_A);
			screenSpaceQuad(m_caps->originBottomLeft);
			bgfx::submit(hdrLumScale0, m_lumAvgProgram);

			// Downscale luminance 1.
			setOffsets4x4Lum(u_offset, 64, 64);
			bgfx::setTexture(0, s_texColor, bgfx::getTexture(m_lum[1]) );
			bgfx::setState(BGFX_STATE_WRITE_RGB|BGFX_STATE_WRITE_A);
			screenSpaceQuad(m_caps->originBottomLeft);
			bgfx::submit(hdrLumScale1, m_lumAvgProgram);

			// Downscale luminance 2.
			setOffsets4x4Lum(u_offset, 16, 16);
			bgfx::setTexture(0, s_texColor, bgfx::getTexture(m_lum[2]) );
			bgfx::setState(BGFX_STATE_WRITE_RGB|BGFX_STATE_WRITE_A);
			screenSpaceQuad(m_caps->originBottomLeft);
			bgfx::submit(hdrLumScale2, m_lumAvgProgram);

			// Downscale luminance 3.
			setOffsets4x4Lum(u_offset, 4, 4);
			bgfx::setTexture(0, s_texColor, bgfx::getTexture(m_lum[3]) );
			bgfx::setState(BGFX_STATE_WRITE_RGB|BGFX_STATE_WRITE_A);
			screenSpaceQuad(m_caps->originBottomLeft);
			bgfx::submit(hdrLumScale3, m_lumAvgProgram);

			// m_bright pass m_threshold is tonemap[3].
			setOffsets4x4Lum(u_offset, m_width/2, m_height/2);
			bgfx::setTexture(0, s_texColor, m_fbtextures[0]);
			bgfx::setTexture(1, s_texLum, bgfx::getTexture(m_lum[4]) );
			bgfx::setState(BGFX_STATE_WRITE_RGB|BGFX_STATE_WRITE_A);
			screenSpaceQuad(m_caps->originBottomLeft);
			bgfx::submit(hdrBrightness, m_brightProgram);

			// m_blur m_bright pass vertically.
			bgfx::setTexture(0, s_texColor, bgfx::getTexture(m_bright) );
			bgfx::setState(BGFX_STATE_WRITE_RGB|BGFX_STATE_WRITE_A);
			screenSpaceQuad(m_caps->originBottomLeft);
			bgfx::submit(hdrVBlur, m_blurProgram);

			// m_blur m_bright pass horizontally, do tonemaping and combine.
			bgfx::setTexture(0, s_texColor, m_fbtextures[0]);
			bgfx::setTexture(1, s_texLum, bgfx::getTexture(m_lum[4]) );
			bgfx::setTexture(2, s_texBlur, bgfx::getTexture(m_blur) );
			bgfx::setState(BGFX_STATE_WRITE_RGB|BGFX_STATE_WRITE_A);
			screenSpaceQuad(m_caps->originBottomLeft);
			bgfx::submit(hdrHBlurTonemap, m_tonemapProgram);

			if (bgfx::isValid(m_rb) )
			{
				bgfx::blit(hdrHBlurTonemap, m_rb, 0, 0, bgfx::getTexture(m_lum[4]) );
				bgfx::readTexture(m_rb, &m_lumBgra8);
			}

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

			return true;
		}

		return false;
	}

	entry::MouseState m_mouseState;

	bgfx::ProgramHandle m_skyProgram;
	bgfx::ProgramHandle m_lumProgram;
	bgfx::ProgramHandle m_lumAvgProgram;
	bgfx::ProgramHandle m_blurProgram;
	bgfx::ProgramHandle m_brightProgram;
	bgfx::ProgramHandle m_meshProgram;
	bgfx::ProgramHandle m_tonemapProgram;

	bgfx::TextureHandle m_uffizi;
	bgfx::UniformHandle s_texCube;
	bgfx::UniformHandle s_texColor;
	bgfx::UniformHandle s_texLum;
	bgfx::UniformHandle s_texBlur;
	bgfx::UniformHandle u_mtx;
	bgfx::UniformHandle u_tonemap;
	bgfx::UniformHandle u_offset;

	Mesh* m_mesh;

	bgfx::TextureHandle m_fbtextures[2];
	bgfx::TextureHandle m_rb;
	bgfx::FrameBufferHandle m_fbh;
	bgfx::FrameBufferHandle m_lum[5];
	bgfx::FrameBufferHandle m_bright;
	bgfx::FrameBufferHandle m_blur;

	bx::RngMwc m_rng;

	uint32_t m_width;
	uint32_t m_height;
	uint32_t m_debug;
	uint32_t m_reset;
	uint32_t m_lumBgra8;

	uint32_t m_oldWidth;
	uint32_t m_oldHeight;
	uint32_t m_oldReset;

	float m_speed;
	float m_middleGray;
	float m_white;
	float m_threshold;

	int32_t m_scrollArea;

	const bgfx::Caps* m_caps;
	float m_time;
};

} // namespace

ENTRY_IMPLEMENT_MAIN(
	  ExampleHDR
	, "09-hdr"
	, "Using multiple views with frame buffers, and view order remapping."
	, "https://bkaradzic.github.io/bgfx/examples.html#hdr"
	);