text: /*
   * Copyright 2011-2018 Branimir Karadzic. All rights reserved.
   * License: https://github.com/bkaradzic/bgfx#license-bsd-2-clause
   */
  
  #include "common.h"
  #include "bgfx_utils.h"
  #include "imgui/imgui.h"
  
  namespace
  {
  
  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 ExampleInstancing : public entry::AppI
  {
  public:
  	ExampleInstancing(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_TEXT;
  		m_reset  = BGFX_RESET_VSYNC;
  
  		bgfx::Init init;
  		init.type     = args.m_type;
  		init.vendorId = args.m_pciId;
  		init.resolution.width  = m_width;
  		init.resolution.height = m_height;
  		init.resolution.reset  = m_reset;
  		bgfx::init(init);
  
  		// 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
  			);
  
  		// Create vertex stream declaration.
  		PosColorVertex::init();
  
  		// Create static vertex buffer.
  		m_vbh = bgfx::createVertexBuffer(
  					  bgfx::makeRef(s_cubeVertices, sizeof(s_cubeVertices) )
  					, PosColorVertex::ms_decl
  					);
  
  		// Create static index buffer.
  		m_ibh = bgfx::createIndexBuffer(
  					bgfx::makeRef(s_cubeIndices, sizeof(s_cubeIndices) )
  					);
  
  		// Create program from shaders.
  		m_program = loadProgram("vs_instancing", "fs_instancing");
  
  		m_timeOffset = bx::getHPCounter();
  
  		imguiCreate();
  	}
  
  	int shutdown() override
  	{
  		imguiDestroy();
  
  		// Cleanup.
  		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);
  
  			imguiEndFrame();
  
  			// Set view 0 default viewport.
  			bgfx::setViewRect(0, 0, 0, uint16_t(m_width), uint16_t(m_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::touch(0);
  
  			float time = (float)( (bx::getHPCounter() - m_timeOffset)/double(bx::getHPFrequency() ) );
  
  			// Get renderer capabilities info.
  			const bgfx::Caps* caps = bgfx::getCaps();
  
  			// Check if instancing is supported.
  			if (0 == (BGFX_CAPS_INSTANCING & caps->supported) )
  			{
  				// When instancing is not supported by GPU, implement alternative
  				// code path that doesn't use instancing.
  				bool blink = uint32_t(time*3.0f)&1;
  				bgfx::dbgTextPrintf(0, 0, blink ? 0x4f : 0x04, " Instancing is not supported by GPU. ");
  			}
  			else
  			{
  				const bx::Vec3 at  = { 0.0f, 0.0f,   0.0f };
  				const bx::Vec3 eye = { 0.0f, 0.0f, -35.0f };
  
  				// Set view and projection matrix for view 0.
  				{
  					float view[16];
  					bx::mtxLookAt(view, eye, at);
  
  					float proj[16];
  					bx::mtxProj(proj, 60.0f, float(m_width)/float(m_height), 0.1f, 100.0f, bgfx::getCaps()->homogeneousDepth);
  					bgfx::setViewTransform(0, view, proj);
  
  					// Set view 0 default viewport.
  					bgfx::setViewRect(0, 0, 0, uint16_t(m_width), uint16_t(m_height) );
  				}
  
  				// 80 bytes stride = 64 bytes for 4x4 matrix + 16 bytes for RGBA color.
  				const uint16_t instanceStride = 80;
  				// 11x11 cubes
  				const uint32_t numInstances   = 121;
  
  				if (numInstances == bgfx::getAvailInstanceDataBuffer(numInstances, instanceStride) )
  				{
  					bgfx::InstanceDataBuffer idb;
  					bgfx::allocInstanceDataBuffer(&idb, numInstances, instanceStride);
  
  					uint8_t* data = idb.data;
  
  					// Write instance data for 11x11 cubes.
  					for (uint32_t yy = 0; yy < 11; ++yy)
  					{
  						for (uint32_t xx = 0; xx < 11; ++xx)
  						{
  							float* mtx = (float*)data;
  							bx::mtxRotateXY(mtx, time + xx*0.21f, time + yy*0.37f);
  							mtx[12] = -15.0f + float(xx)*3.0f;
  							mtx[13] = -15.0f + float(yy)*3.0f;
  							mtx[14] = 0.0f;
  
  							float* color = (float*)&data[64];
  							color[0] = bx::sin(time+float(xx)/11.0f)*0.5f+0.5f;
  							color[1] = bx::cos(time+float(yy)/11.0f)*0.5f+0.5f;
  							color[2] = bx::sin(time*3.0f)*0.5f+0.5f;
  							color[3] = 1.0f;
  
  							data += instanceStride;
  						}
  					}
  
  					// Set vertex and index buffer.
  					bgfx::setVertexBuffer(0, m_vbh);
  					bgfx::setIndexBuffer(m_ibh);
  
  					// Set instance data buffer.
  					bgfx::setInstanceDataBuffer(&idb);
  
  					// Set render states.
  					bgfx::setState(BGFX_STATE_DEFAULT);
  
  					// Submit primitive for rendering to view 0.
  					bgfx::submit(0, m_program);
  				}
  			}
  
  			// 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;
  };
  
  } // namespace
  
  ENTRY_IMPLEMENT_MAIN(ExampleInstancing, "05-instancing", "Geometry instancing.");
  