text: /*
   * Copyright 2011-2017 Branimir Karadzic. All rights reserved.
   * License: https://github.com/bkaradzic/bgfx#license-bsd-2-clause
   */
  
  #include "common.h"
  #include "bgfx_utils.h"
  #include "camera.h"
  #include "imgui/imgui.h"
  
  namespace
  {
  
  #define CUBES_DIM 10
  
  struct PosColorVertex
  {
  	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 PosColorVertex::ms_decl;
  
  static PosColorVertex s_cubeVertices[8] =
  {
  	{-1.0f,  1.0f,  1.0f, 0xff000000 },
  	{ 1.0f,  1.0f,  1.0f, 0xff0000ff },
  	{-1.0f, -1.0f,  1.0f, 0xff00ff00 },
  	{ 1.0f, -1.0f,  1.0f, 0xff00ffff },
  	{-1.0f,  1.0f, -1.0f, 0xffff0000 },
  	{ 1.0f,  1.0f, -1.0f, 0xffff00ff },
  	{-1.0f, -1.0f, -1.0f, 0xffffff00 },
  	{ 1.0f, -1.0f, -1.0f, 0xffffffff },
  };
  
  static const uint16_t s_cubeIndices[36] =
  {
  	0, 1, 2, // 0
  	1, 3, 2,
  	4, 6, 5, // 2
  	5, 6, 7,
  	0, 2, 4, // 4
  	4, 2, 6,
  	1, 5, 3, // 6
  	5, 7, 3,
  	0, 4, 1, // 8
  	4, 5, 1,
  	2, 3, 6, // 10
  	6, 3, 7,
  };
  
  class ExampleOcclusion : public entry::AppI
  {
  public:
  	ExampleOcclusion(const char* _name, const char* _description)
  		: entry::AppI(_name, _description)
  	{
  	}
  
  	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(args.m_type, args.m_pciId);
  		bgfx::reset(m_width, m_height, m_reset);
  
  		// Enable debug text.
  		bgfx::setDebug(m_debug);
  
  		// Set view 0 clear state.
  		bgfx::setViewClear(0
  				, BGFX_CLEAR_COLOR|BGFX_CLEAR_DEPTH
  				, 0x303030ff
  				, 1.0f
  				, 0
  				);
  
  		bgfx::setViewClear(2
  				, BGFX_CLEAR_COLOR|BGFX_CLEAR_DEPTH
  				, 0x202020ff
  				, 1.0f
  				, 0
  				);
  
  		// Create vertex stream declaration.
  		PosColorVertex::init();
  
  		// Create static vertex buffer.
  		m_vbh = bgfx::createVertexBuffer(
  				// Static data can be passed with bgfx::makeRef
  				bgfx::makeRef(s_cubeVertices, sizeof(s_cubeVertices) )
  				, PosColorVertex::ms_decl
  				);
  
  		// Create static index buffer.
  		m_ibh = bgfx::createIndexBuffer(
  				// Static data can be passed with bgfx::makeRef
  				bgfx::makeRef(s_cubeIndices, sizeof(s_cubeIndices) )
  				);
  
  		// Create program from shaders.
  		m_program = loadProgram("vs_cubes", "fs_cubes");
  
  		const bgfx::Caps* caps = bgfx::getCaps();
  		m_occlusionQuerySupported = !!(caps->supported & BGFX_CAPS_OCCLUSION_QUERY);
  
  		if (m_occlusionQuerySupported)
  		{
  			for (uint32_t ii = 0; ii < BX_COUNTOF(m_occlusionQueries); ++ii)
  			{
  				m_occlusionQueries[ii] = bgfx::createOcclusionQuery();
  			}
  		}
  
  		cameraCreate();
  
  		const float initialPos[3] = { 15.5f, 0.0f, -15.5f };
  		cameraSetPosition(initialPos);
  		cameraSetHorizontalAngle(bx::toRad(-45.0f) );
  
  		m_timeOffset = bx::getHPCounter();
  
  		imguiCreate();
  	}
  
  	virtual int shutdown() override
  	{
  		imguiDestroy();
  
  		// Cleanup.
  		cameraDestroy();
  
  		if (m_occlusionQuerySupported)
  		{
  			for (uint32_t ii = 0; ii < BX_COUNTOF(m_occlusionQueries); ++ii)
  			{
  				bgfx::destroy(m_occlusionQueries[ii]);
  			}
  		}
  
  		bgfx::destroy(m_ibh);
  		bgfx::destroy(m_vbh);
  		bgfx::destroy(m_program);
  
  		// Shutdown bgfx.
  		bgfx::shutdown();
  
  		return 0;
  	}
  
  	bool update() override
  	{
  		if (!entry::processEvents(m_width, m_height, m_debug, m_reset, &m_mouseState) )
  		{
  			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
  				, !m_occlusionQuerySupported
  				? "Occlusion query is not supported."
  				: NULL
  				);
  
  			imguiEndFrame();
  
  			if (m_occlusionQuerySupported)
  			{
  				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 float time = (float)( (now-m_timeOffset)/double(bx::getHPFrequency() ) );
  				const float deltaTime = float(frameTime/freq);
  
  				// Update camera.
  				float view[16];
  				cameraUpdate(deltaTime, m_state.m_mouse);
  				cameraGetViewMtx(view);
  
  				// Set view and projection matrix for view 0.
  				const bgfx::HMD* hmd = bgfx::getHMD();
  				if (NULL != hmd && 0 != (hmd->flags & BGFX_HMD_RENDERING) )
  				{
  					float viewHead[16];
  					float eye[3] = {};
  					bx::mtxQuatTranslationHMD(viewHead, hmd->eye[0].rotation, eye);
  
  					float tmp[16];
  					bx::mtxMul(tmp, view, viewHead);
  
  					bgfx::setViewTransform(0, tmp, hmd->eye[0].projection);
  					bgfx::setViewRect(0, 0, 0, hmd->width, hmd->height);
  
  					bgfx::setViewTransform(1, tmp, hmd->eye[1].projection);
  					bgfx::setViewRect(1, 0, 0, hmd->width, hmd->height);
  				}
  				else
  				{
  					float proj[16];
  					bx::mtxProj(proj, 90.0f, float(m_width)/float(m_height), 0.1f, 10000.0f, bgfx::getCaps()->homogeneousDepth);
  
  					bgfx::setViewTransform(0, view, proj);
  					bgfx::setViewRect(0, 0, 0, uint16_t(m_width), uint16_t(m_height) );
  
  					bgfx::setViewTransform(1, view, proj);
  					bgfx::setViewRect(1, 0, 0, uint16_t(m_width), uint16_t(m_height) );
  
  					float at[3]  = {  0.0f,  0.0f,   0.0f };
  					float eye[3] = { 17.5f, 10.0f, -17.5f };
  					bx::mtxLookAt(view, eye, at);
  
  					bgfx::setViewTransform(2, view, proj);
  					bgfx::setViewRect(2, 10, uint16_t(m_height - m_height/4 - 10), uint16_t(m_width/4), uint16_t(m_height/4) );
  				}
  
  				bgfx::touch(0);
  				bgfx::touch(2);
  
  				uint8_t img[CUBES_DIM*CUBES_DIM*2];
  
  				for (uint32_t yy = 0; yy < CUBES_DIM; ++yy)
  				{
  					for (uint32_t xx = 0; xx < CUBES_DIM; ++xx)
  					{
  						float mtx[16];
  						bx::mtxRotateXY(mtx, time + xx*0.21f, time + yy*0.37f);
  						mtx[12] = -(CUBES_DIM-1) * 3.0f / 2.0f + float(xx)*3.0f;
  						mtx[13] = 0.0f;
  						mtx[14] = -(CUBES_DIM-1) * 3.0f / 2.0f + float(yy)*3.0f;
  
  						bgfx::OcclusionQueryHandle occlusionQuery = m_occlusionQueries[yy*CUBES_DIM+xx];
  
  						bgfx::setTransform(mtx);
  						bgfx::setVertexBuffer(0, m_vbh);
  						bgfx::setIndexBuffer(m_ibh);
  						bgfx::setCondition(occlusionQuery, true);
  						bgfx::setState(BGFX_STATE_DEFAULT);
  						bgfx::submit(0, m_program);
  
  						bgfx::setTransform(mtx);
  						bgfx::setVertexBuffer(0, m_vbh);
  						bgfx::setIndexBuffer(m_ibh);
  						bgfx::setState(0
  							| BGFX_STATE_DEPTH_TEST_LEQUAL
  							| BGFX_STATE_CULL_CW
  							);
  						bgfx::submit(1, m_program, occlusionQuery);
  
  						bgfx::setTransform(mtx);
  						bgfx::setVertexBuffer(0, m_vbh);
  						bgfx::setIndexBuffer(m_ibh);
  						bgfx::setCondition(occlusionQuery, true);
  						bgfx::setState(BGFX_STATE_DEFAULT);
  						bgfx::submit(2, m_program);
  
  						img[(yy*CUBES_DIM+xx)*2+0] = " \xfex"[bgfx::getResult(occlusionQuery)];
  						img[(yy*CUBES_DIM+xx)*2+1] = 0xf;
  					}
  				}
  
  				for (uint16_t xx = 0; xx < CUBES_DIM; ++xx)
  				{
  					bgfx::dbgTextImage(5 + xx*2, 5, 1, CUBES_DIM, img + xx*2, CUBES_DIM*2);
  				}
  
  				int32_t numPixels = 0;
  				bgfx::getResult(m_occlusionQueries[0], &numPixels);
  				bgfx::dbgTextPrintf(5, 5 + CUBES_DIM + 1, 0xf, "%d", numPixels);
  			}
  
  			// Advance to next frame. Rendering thread will be kicked to
  			// process submitted rendering primitives.
  			bgfx::frame();
  
  			return true;
  		}
  
  		return false;
  	}
  
  	entry::MouseState m_mouseState;
  
  	uint32_t m_width;
  	uint32_t m_height;
  	uint32_t m_debug;
  	uint32_t m_reset;
  
  	bgfx::VertexBufferHandle m_vbh;
  	bgfx::IndexBufferHandle m_ibh;
  	bgfx::ProgramHandle m_program;
  	int64_t m_timeOffset;
  	bool m_occlusionQuerySupported;
  
  	bgfx::OcclusionQueryHandle m_occlusionQueries[CUBES_DIM*CUBES_DIM];
  
  	entry::WindowState m_state;
  };
  
  } // namespace
  
  ENTRY_IMPLEMENT_MAIN(ExampleOcclusion, "26-occlusion", "Using occlusion query for conditional rendering.");
  