bgfx/examples/41-tess/tess.cpp

/*
 * Copyright 2019 Daniel Gavin. All rights reserved.
 * License: https://github.com/bkaradzic/bgfx#license-bsd-2-clause
 */

 /*
  * Reference(s):
  *
  * - Adaptive GPU Tessellation with Compute Shaders by Jad Khoury, Jonathan Dupuy, and Christophe Riccio
  *   http://onrendering.com/data/papers/isubd/isubd.pdf
  *   https://github.com/jdupuy/opengl-framework/tree/master/demo-isubd-terrain#implicit-subdivision-on-the-gpu
  */

#include <bx/allocator.h>
#include <bx/debug.h>
#include <bx/file.h>
#include <bx/math.h>

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

namespace
{
	static const char* s_shaderOptions[] =
	{
		"Normal",
		"Diffuse"
	};

	static const float s_verticesL0[] =
	{
		0.0f, 0.0f,
		1.0f, 0.0f,
		0.0f, 1.0f,
	};

	static const uint32_t s_indexesL0[] = { 0u, 1u, 2u };

	static const float s_verticesL1[] =
	{
		0.0f, 1.0f,
		0.5f, 0.5f,
		0.0f, 0.5f,
		0.0f, 0.0f,
		0.5f, 0.0f,
		1.0f, 0.0f,
	};

	static const uint32_t s_indexesL1[] =
	{
		1u, 0u, 2u,
		1u, 2u, 3u,
		1u, 3u, 4u,
		1u, 4u, 5u,
	};

	static const float s_verticesL2[] =
	{
		0.25f, 0.75f,
		0.0f,  1.0f,
		0.0f,  0.75f,
		0.0f,  0.5f,
		0.25f, 0.5f,
		0.5f,  0.5f,

		0.25f, 0.25f,
		0.0f,  0.25f,
		0.0f,  0.0f,
		0.25f, 0.0f,
		0.5f,  0.0f,
		0.5f,  0.25f,
		0.75f, 0.25f,
		0.75f, 0.0f,
		1.0f,  0.0f,
	};

	static const uint32_t s_indexesL2[] =
	{
		0u, 1u, 2u,
		0u, 2u, 3u,
		0u, 3u, 4u,
		0u, 4u, 5u,

		6u, 5u, 4u,
		6u, 4u, 3u,
		6u, 3u, 7u,
		6u, 7u, 8u,

		6u, 8u, 9u,
		6u, 9u, 10u,
		6u, 10u, 11u,
		6u, 11u, 5u,

		12u, 5u, 11u,
		12u, 11u, 10u,
		12u, 10u, 13u,
		12u, 13u, 14u,
	};

	static const float s_verticesL3[] =
	{
		0.25f*0.5f, 0.75f*0.5f + 0.5f,
		0.0f*0.5f, 1.0f*0.5f + 0.5f,
		0.0f*0.5f, 0.75f*0.5f + 0.5f,
		0.0f*0.5f , 0.5f*0.5f + 0.5f,
		0.25f*0.5f, 0.5f*0.5f + 0.5f,
		0.5f*0.5f, 0.5f*0.5f + 0.5f,
		0.25f*0.5f, 0.25f*0.5f + 0.5f,
		0.0f*0.5f, 0.25f*0.5f + 0.5f,
		0.0f*0.5f, 0.0f*0.5f + 0.5f,
		0.25f*0.5f, 0.0f*0.5f + 0.5f,
		0.5f*0.5f, 0.0f*0.5f + 0.5f,
		0.5f*0.5f, 0.25f*0.5f + 0.5f,
		0.75f*0.5f, 0.25f*0.5f + 0.5f,
		0.75f*0.5f, 0.0f*0.5f + 0.5f,
		1.0f*0.5f, 0.0f*0.5f + 0.5f,        //14

		0.375f, 0.375f,
		0.25f, 0.375f,
		0.25f, 0.25f,
		0.375f, 0.25f,
		0.5f, 0.25f,
		0.5f, 0.375f,    //20

		0.125f, 0.375f,
		0.0f, 0.375f,
		0.0f, 0.25f,
		0.125f, 0.25f,    //24

		0.125f, 0.125f,
		0.0f, 0.125f,
		0.0f, 0.0f,
		0.125f, 0.0f,
		0.25f, 0.0f,
		0.25f, 0.125f,    //30

		0.375f, 0.125f,
		0.375f, 0.0f,
		0.5f, 0.0f,
		0.5f, 0.125f,    //34

		0.625f, 0.375f,
		0.625f, 0.25f,
		0.75f, 0.25f,    //37

		0.625f, 0.125f,
		0.625f, 0.0f,
		0.75f, 0.0f,
		0.75f, 0.125f,    //41

		0.875f, 0.125f,
		0.875f, 0.0f,
		1.0f, 0.0f,    //44
	};

	static const uint32_t s_indexesL3[] =
	{
		0u, 1u, 2u,
		0u, 2u, 3u,
		0u, 3u, 4u,
		0u, 4u, 5u,

		6u, 5u, 4u,
		6u, 4u, 3u,
		6u, 3u, 7u,
		6u, 7u, 8u,

		6u, 8u, 9u,
		6u, 9u, 10u,
		6u, 10u, 11u,
		6u, 11u, 5u,

		12u, 5u, 11u,
		12u, 11u, 10u,
		12u, 10u, 13u,
		12u, 13u, 14u,        //End fo first big triangle

		15u, 14u, 13u,
		15u, 13u, 10u,
		15u, 10u, 16u,
		15u, 16u, 17u,
		15u, 17u, 18u,
		15u, 18u, 19u,
		15u, 19u, 20u,
		15u, 20u, 14u,

		21u, 10u, 9u,
		21u, 9u, 8u,
		21u, 8u, 22u,
		21u, 22u, 23u,
		21u, 23u, 24u,
		21u, 24u, 17u,
		21u, 17u, 16u,
		21u, 16u, 10u,

		25u, 17u, 24u,
		25u, 24u, 23u,
		25u, 23u, 26u,
		25u, 26u, 27u,
		25u, 27u, 28u,
		25u, 28u, 29u,
		25u, 29u, 30u,
		25u, 30u, 17u,

		31u, 19u, 18u,
		31u, 18u, 17u,
		31u, 17u, 30u,
		31u, 30u, 29u,
		31u, 29u, 32u,
		31u, 32u, 33u,
		31u, 33u, 34u,
		31u, 34u, 19u,

		35u, 14u, 20u,
		35u, 20u, 19u,
		35u, 19u, 36u,
		35u, 36u, 37u,

		38u, 37u, 36u,
		38u, 36u, 19u,
		38u, 19u, 34u,
		38u, 34u, 33u,
		38u, 33u, 39u,
		38u, 39u, 40u,
		38u, 40u, 41u,
		38u, 41u, 37u,

		42u, 37u, 41u,
		42u, 41u, 40u,
		42u, 40u, 43u,
		42u, 43u, 44u,
	};

	enum
	{
		PROGRAM_TERRAIN_NORMAL,
		PROGRAM_TERRAIN,

		SHADING_COUNT
	};

	enum
	{
		BUFFER_SUBD
	};

	enum
	{
		PROGRAM_SUBD_CS_LOD,
		PROGRAM_UPDATE_INDIRECT,
		PROGRAM_INIT_INDIRECT,
		PROGRAM_UPDATE_DRAW,

		PROGRAM_COUNT
	};

	enum
	{
		TERRAIN_DMAP_SAMPLER,
		TERRAIN_SMAP_SAMPLER,

		SAMPLER_COUNT
	};

	enum
	{
		TEXTURE_DMAP,
		TEXTURE_SMAP,

		TEXTURE_COUNT
	};

	constexpr int32_t kNumVec4 = 2;

	struct Uniforms
	{
		void init()
		{
			u_params = bgfx::createUniform("u_params", bgfx::UniformType::Vec4, kNumVec4);

			cull = 1;
			freeze = 0;
			gpuSubd = 3;

		}

		void submit()
		{
			bgfx::setUniform(u_params, params, kNumVec4);
		}

		void destroy()
		{
			bgfx::destroy(u_params);
		}

		union
		{
			struct
			{
				float dmapFactor;
				float lodFactor;
				float cull;
				float freeze;

				float gpuSubd;
				float padding0;
				float padding1;
				float padding2;
			};

			float params[kNumVec4 * 4];
		};

		bgfx::UniformHandle u_params;
	};
	class ExampleTessellation : public entry::AppI
	{
	public:
		ExampleTessellation(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_NONE;

			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);

			m_dmap = { "textures/dmap.png", 0.45f };
			m_computeThreadCount = 5;
			m_shading = PROGRAM_TERRAIN;
			m_primitivePixelLengthTarget = 7.0f;
			m_fovy = 60.0f;
			m_pingPong = 0;
			m_restart = true;

			// Enable m_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(1
				, BGFX_CLEAR_COLOR | BGFX_CLEAR_DEPTH
				, 0x303030ff
				, 1.0f
				, 0
				);

			// Imgui.
			imguiCreate();

			m_timeOffset = bx::getHPCounter();

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

			cameraCreate();
			cameraSetPosition({ 0.0f, 0.5f, 0.0f });
			cameraSetVerticalAngle(0);

			m_wireframe = false;
			m_freeze = false;
			m_cull = true;

			loadPrograms();
			loadBuffers();
			loadTextures();

			createAtomicCounters();

			m_dispatchIndirect = bgfx::createIndirectBuffer(2);
		}

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

			m_uniforms.destroy();

			bgfx::destroy(m_bufferCounter);
			bgfx::destroy(m_bufferCulledSubd);
			bgfx::destroy(m_bufferSubd[0]);
			bgfx::destroy(m_bufferSubd[1]);
			bgfx::destroy(m_dispatchIndirect);
			bgfx::destroy(m_geometryIndices);
			bgfx::destroy(m_geometryVertices);
			bgfx::destroy(m_instancedGeometryIndices);
			bgfx::destroy(m_instancedGeometryVertices);

			for (uint32_t i = 0; i < PROGRAM_COUNT; ++i)
			{
				bgfx::destroy(m_programsCompute[i]);
			}

			for (uint32_t i = 0; i < SHADING_COUNT; ++i)
			{
				bgfx::destroy(m_programsDraw[i]);
			}

			for (uint32_t i = 0; i < SAMPLER_COUNT; ++i)
			{
				bgfx::destroy(m_samplers[i]);
			}

			for (uint32_t i = 0; i < TEXTURE_COUNT; ++i)
			{
				bgfx::destroy(m_textures[i]);
			}

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

			return 0;
		}

		bool update() override
		{
			if (!entry::processEvents(m_width, m_height, m_debug, m_reset, &m_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 float deltaTime = float(frameTime / freq);

				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 - 10.0f, 10.0f)
					, ImGuiCond_FirstUseEver
					);
				ImGui::SetNextWindowSize(
					  ImVec2(m_width / 5.0f, m_height / 3.0f)
					, ImGuiCond_FirstUseEver
					);
				ImGui::Begin("Settings", NULL, 0);

				if (ImGui::Checkbox("Debug wireframe", &m_wireframe) )
				{
					bgfx::setDebug(m_wireframe
						? BGFX_DEBUG_WIREFRAME
						: BGFX_DEBUG_NONE
						);
				}

				ImGui::SameLine();

				if (ImGui::Checkbox("Cull", &m_cull) )
				{
					m_uniforms.cull = m_cull ? 1.0f : 0.0f;
				}

				ImGui::SameLine();

				if (ImGui::Checkbox("Freeze subdividing", &m_freeze) )
				{
					m_uniforms.freeze = m_freeze ? 1.0f : 0.0f;
				}


				ImGui::SliderFloat("Pixels per edge", &m_primitivePixelLengthTarget, 1, 20);

				int gpuSlider = (int)m_uniforms.gpuSubd;

				if (ImGui::SliderInt("Triangle Patch level", &gpuSlider, 0, 3) )
				{
					m_restart = true;
					m_uniforms.gpuSubd = float(gpuSlider);
				}

				ImGui::Combo("Shading", &m_shading, s_shaderOptions, 2);

				ImGui::Text("Some variables require rebuilding the subdivide buffers and causes a stutter.");

				ImGui::End();

				// Update camera.
				cameraUpdate(deltaTime*0.01f, m_mouseState, ImGui::MouseOverArea() );

				bgfx::touch(0);
				bgfx::touch(1);

				configureUniforms();

				cameraGetViewMtx(m_viewMtx);

				float model[16];

				bx::mtxRotateX(model, bx::toRad(90) );

				bx::mtxProj(m_projMtx, m_fovy, float(m_width) / float(m_height), 0.0001f, 2000.0f, bgfx::getCaps()->homogeneousDepth);

				// Set view 0
				bgfx::setViewTransform(0, m_viewMtx, m_projMtx);

				// Set view 1
				bgfx::setViewRect(1, 0, 0, uint16_t(m_width), uint16_t(m_height) );
				bgfx::setViewTransform(1, m_viewMtx, m_projMtx);

				m_uniforms.submit();

				// update the subd buffers
				if (m_restart)
				{
					m_pingPong = 1;

					bgfx::destroy(m_instancedGeometryVertices);
					bgfx::destroy(m_instancedGeometryIndices);

					bgfx::destroy(m_bufferSubd[BUFFER_SUBD]);
					bgfx::destroy(m_bufferSubd[BUFFER_SUBD + 1]);
					bgfx::destroy(m_bufferCulledSubd);

					loadInstancedGeometryBuffers();
					loadSubdivisionBuffers();

					//init indirect
					bgfx::setBuffer(1, m_bufferSubd[m_pingPong], bgfx::Access::ReadWrite);
					bgfx::setBuffer(2, m_bufferCulledSubd, bgfx::Access::ReadWrite);
					bgfx::setBuffer(3, m_dispatchIndirect, bgfx::Access::ReadWrite);
					bgfx::setBuffer(4, m_bufferCounter, bgfx::Access::ReadWrite);
					bgfx::setBuffer(8, m_bufferSubd[1 - m_pingPong], bgfx::Access::ReadWrite);
					bgfx::dispatch(0, m_programsCompute[PROGRAM_INIT_INDIRECT], 1, 1, 1);


					m_restart = false;
				}
				else
				{
					// update batch
					bgfx::setBuffer(3, m_dispatchIndirect, bgfx::Access::ReadWrite);
					bgfx::setBuffer(4, m_bufferCounter, bgfx::Access::ReadWrite);
					bgfx::dispatch(0, m_programsCompute[PROGRAM_UPDATE_INDIRECT], 1, 1, 1);
				}

				bgfx::setBuffer(1, m_bufferSubd[m_pingPong], bgfx::Access::ReadWrite);
				bgfx::setBuffer(2, m_bufferCulledSubd, bgfx::Access::ReadWrite);
				bgfx::setBuffer(4, m_bufferCounter, bgfx::Access::ReadWrite);
				bgfx::setBuffer(6, m_geometryVertices, bgfx::Access::Read);
				bgfx::setBuffer(7, m_geometryIndices, bgfx::Access::Read);
				bgfx::setBuffer(8, m_bufferSubd[1 - m_pingPong], bgfx::Access::Read);
				bgfx::setTransform(model);

				bgfx::setTexture(0, m_samplers[TERRAIN_DMAP_SAMPLER], m_textures[TEXTURE_DMAP], BGFX_SAMPLER_U_CLAMP | BGFX_SAMPLER_V_CLAMP);

				m_uniforms.submit();

				// update the subd buffer
				bgfx::dispatch(0, m_programsCompute[PROGRAM_SUBD_CS_LOD], m_dispatchIndirect, 1);

				// update draw
				bgfx::setBuffer(3, m_dispatchIndirect, bgfx::Access::ReadWrite);
				bgfx::setBuffer(4, m_bufferCounter, bgfx::Access::ReadWrite);

				m_uniforms.submit();

				bgfx::dispatch(1, m_programsCompute[PROGRAM_UPDATE_DRAW], 1, 1, 1);

				// render the terrain
				bgfx::setTexture(0, m_samplers[TERRAIN_DMAP_SAMPLER], m_textures[TEXTURE_DMAP], BGFX_SAMPLER_U_CLAMP | BGFX_SAMPLER_V_CLAMP);
				bgfx::setTexture(1, m_samplers[TERRAIN_SMAP_SAMPLER], m_textures[TEXTURE_SMAP], BGFX_SAMPLER_MIN_ANISOTROPIC | BGFX_SAMPLER_MAG_ANISOTROPIC);

				bgfx::setTransform(model);
				bgfx::setVertexBuffer(0, m_instancedGeometryVertices);
				bgfx::setIndexBuffer(m_instancedGeometryIndices);
				bgfx::setBuffer(2, m_bufferCulledSubd, bgfx::Access::Read);
				bgfx::setBuffer(3, m_geometryVertices, bgfx::Access::Read);
				bgfx::setBuffer(4, m_geometryIndices, bgfx::Access::Read);
				bgfx::setState(BGFX_STATE_WRITE_RGB | BGFX_STATE_WRITE_Z | BGFX_STATE_DEPTH_TEST_LESS);

				m_uniforms.submit();

				bgfx::submit(1, m_programsDraw[m_shading], m_dispatchIndirect);

				m_pingPong = 1 - m_pingPong;

				imguiEndFrame();

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

				return true;
			}

			return false;
		}

		void createAtomicCounters()
		{
			m_bufferCounter = bgfx::createDynamicIndexBuffer(3, BGFX_BUFFER_INDEX32 | BGFX_BUFFER_COMPUTE_READ_WRITE);
		}

		void configureUniforms()
		{
			float lodFactor = 2.0f * bx::tan(bx::toRad(m_fovy) / 2.0f)
				/ m_width * (1 << (int)m_uniforms.gpuSubd)
				* m_primitivePixelLengthTarget;

			m_uniforms.lodFactor = lodFactor;
			m_uniforms.dmapFactor = m_dmap.scale;
		}

		/**
		* Load the Terrain Program
		*
		* This program renders an adaptive terrain using the implicit subdivision
		* technique discribed in GPU Zen 2.
		**/
		void loadPrograms()
		{
			m_samplers[TERRAIN_DMAP_SAMPLER] = bgfx::createUniform("u_DmapSampler", bgfx::UniformType::Sampler);
			m_samplers[TERRAIN_SMAP_SAMPLER] = bgfx::createUniform("u_SmapSampler", bgfx::UniformType::Sampler);

			m_uniforms.init();

			m_programsDraw[PROGRAM_TERRAIN] = loadProgram("vs_terrain_render", "fs_terrain_render");
			m_programsDraw[PROGRAM_TERRAIN_NORMAL] = loadProgram("vs_terrain_render", "fs_terrain_render_normal");

			m_programsCompute[PROGRAM_SUBD_CS_LOD] = bgfx::createProgram(loadShader("cs_terrain_lod"), true);
			m_programsCompute[PROGRAM_UPDATE_INDIRECT] = bgfx::createProgram(loadShader("cs_terrain_update_indirect"), true);
			m_programsCompute[PROGRAM_UPDATE_DRAW] = bgfx::createProgram(loadShader("cs_terrain_update_draw"), true);
			m_programsCompute[PROGRAM_INIT_INDIRECT] = bgfx::createProgram(loadShader("cs_terrain_init"), true);
		}

		void loadSmapTexture()
		{
			int w = dmap->m_width;
			int h = dmap->m_height;

			const uint16_t *texels = (const uint16_t *)dmap->m_data;

			int mipcnt = dmap->m_numMips;

			const bgfx::Memory* mem = bgfx::alloc(w * h * 2 * sizeof(float) );
			float* smap = (float*)mem->data;

			for (int j = 0; j < h; ++j)
			{
				for (int i = 0; i < w; ++i)
				{
					int i1 = bx::max(0, i - 1);
					int i2 = bx::min(w - 1, i + 1);
					int j1 = bx::max(0, j - 1);
					int j2 = bx::min(h - 1, j + 1);
					uint16_t px_l = texels[i1 + w * j]; // in [0,2^16-1]
					uint16_t px_r = texels[i2 + w * j]; // in [0,2^16-1]
					uint16_t px_b = texels[i + w * j1]; // in [0,2^16-1]
					uint16_t px_t = texels[i + w * j2]; // in [0,2^16-1]
					float z_l = (float)px_l / 65535.0f; // in [0, 1]
					float z_r = (float)px_r / 65535.0f; // in [0, 1]
					float z_b = (float)px_b / 65535.0f; // in [0, 1]
					float z_t = (float)px_t / 65535.0f; // in [0, 1]
					float slope_x = (float)w * 0.5f * (z_r - z_l);
					float slope_y = (float)h * 0.5f * (z_t - z_b);

					smap[2 * (i + w * j)] = slope_x;
					smap[1 + 2 * (i + w * j)] = slope_y;
				}
			}

			m_textures[TEXTURE_SMAP] = bgfx::createTexture2D(
				  (uint16_t)w
				, (uint16_t)h
				, mipcnt > 1
				, 1
				, bgfx::TextureFormat::RG32F
				, BGFX_TEXTURE_NONE
				, mem
				);
		}

		/**
		 * Load the Displacement Texture
		 *
		 * This loads an R16 texture used as a displacement map
		 */
		void loadDmapTexture()
		{
			dmap = imageLoad(m_dmap.pathToFile.getCPtr(), bgfx::TextureFormat::R16);

			m_textures[TEXTURE_DMAP] = bgfx::createTexture2D(
				  (uint16_t)dmap->m_width
				, (uint16_t)dmap->m_height
				, false
				, 1
				, bgfx::TextureFormat::R16
				, BGFX_TEXTURE_NONE
				, bgfx::makeRef(dmap->m_data, dmap->m_size)
				);
		}

		/**
		 * Load All Textures
		 */
		void loadTextures()
		{
			loadDmapTexture();
			loadSmapTexture();
		}

		/**
		 * Load the Geometry Buffer
		 *
		 * This procedure loads the scene geometry into an index and
		 * vertex buffer. Here, we only load 2 triangles to define the
		 * terrain.
		 **/
		void loadGeometryBuffers()
		{
			const float vertices[] =
			{
				-1.0f, -1.0f, 0.0f, 1.0f,
				+1.0f, -1.0f, 0.0f, 1.0f,
				+1.0f, +1.0f, 0.0f, 1.0f,
				-1.0f, +1.0f, 0.0f, 1.0f,
			};

			const uint32_t indices[] = { 0, 1, 3, 2, 3, 1 };

			m_geometryLayout.begin().add(bgfx::Attrib::Position, 4, bgfx::AttribType::Float).end();

			m_geometryVertices = bgfx::createVertexBuffer(
				  bgfx::copy(vertices, sizeof(vertices) )
				, m_geometryLayout
				, BGFX_BUFFER_COMPUTE_READ
				);
			m_geometryIndices = bgfx::createIndexBuffer(
				  bgfx::copy(indices, sizeof(indices) )
				, BGFX_BUFFER_COMPUTE_READ | BGFX_BUFFER_INDEX32
				);
		}

		void loadSubdivisionBuffers()
		{
			const uint32_t bufferCapacity = 1 << 27;

			m_bufferSubd[BUFFER_SUBD] = bgfx::createDynamicIndexBuffer(
				  bufferCapacity
				, BGFX_BUFFER_COMPUTE_READ_WRITE | BGFX_BUFFER_INDEX32
				);

			m_bufferSubd[BUFFER_SUBD + 1] = bgfx::createDynamicIndexBuffer(
				  bufferCapacity
				, BGFX_BUFFER_COMPUTE_READ_WRITE | BGFX_BUFFER_INDEX32
				);

			m_bufferCulledSubd = bgfx::createDynamicIndexBuffer(
				  bufferCapacity
				, BGFX_BUFFER_COMPUTE_READ_WRITE | BGFX_BUFFER_INDEX32
				);
		}

		/**
		 * Load All Buffers
		 *
		 */
		void loadBuffers()
		{
			loadSubdivisionBuffers();
			loadGeometryBuffers();
			loadInstancedGeometryBuffers();
		}

		/**
		* This will be used to instantiate a triangle grid for each subdivision
		* key present in the subd buffer.
		*/
		void loadInstancedGeometryBuffers()
		{
			const float* vertices;
			const uint32_t* indexes;

			switch (int32_t(m_uniforms.gpuSubd) )
			{
			case 0:
				m_instancedMeshVertexCount = 3;
				m_instancedMeshPrimitiveCount = 1;
				vertices = s_verticesL0;
				indexes  = s_indexesL0;
				break;

			case 1:
				m_instancedMeshVertexCount = 6;
				m_instancedMeshPrimitiveCount = 4;
				vertices = s_verticesL1;
				indexes  = s_indexesL1;
				break;

			case 2:
				m_instancedMeshVertexCount = 15;
				m_instancedMeshPrimitiveCount = 16;
				vertices = s_verticesL2;
				indexes  = s_indexesL2;
				break;

			default:
				m_instancedMeshVertexCount = 45;
				m_instancedMeshPrimitiveCount = 64;
				vertices = s_verticesL3;
				indexes  = s_indexesL3;
				break;
			}

			m_instancedGeometryLayout
				.begin()
				.add(bgfx::Attrib::TexCoord0, 2, bgfx::AttribType::Float)
				.end();

			m_instancedGeometryVertices = bgfx::createVertexBuffer(
				  bgfx::makeRef(vertices, sizeof(float) * 2 * m_instancedMeshVertexCount)
				, m_instancedGeometryLayout
				);

			m_instancedGeometryIndices  = bgfx::createIndexBuffer(
				  bgfx::makeRef(indexes, sizeof(uint32_t) * m_instancedMeshPrimitiveCount * 3)
				, BGFX_BUFFER_INDEX32
				);
		}

		Uniforms m_uniforms;

		bgfx::ProgramHandle m_programsCompute[PROGRAM_COUNT];
		bgfx::ProgramHandle m_programsDraw[SHADING_COUNT];
		bgfx::TextureHandle m_textures[TEXTURE_COUNT];
		bgfx::UniformHandle m_samplers[SAMPLER_COUNT];

		bgfx::DynamicIndexBufferHandle m_bufferSubd[2];
		bgfx::DynamicIndexBufferHandle m_bufferCulledSubd;

		bgfx::DynamicIndexBufferHandle m_bufferCounter;

		bgfx::IndexBufferHandle m_geometryIndices;
		bgfx::VertexBufferHandle m_geometryVertices;
		bgfx::VertexLayout m_geometryLayout;

		bgfx::IndexBufferHandle m_instancedGeometryIndices;
		bgfx::VertexBufferHandle m_instancedGeometryVertices;
		bgfx::VertexLayout m_instancedGeometryLayout;

		bgfx::IndirectBufferHandle m_dispatchIndirect;

		bimg::ImageContainer* dmap;

		float m_viewMtx[16];
		float m_projMtx[16];

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

		uint32_t m_oldWidth;
		uint32_t m_oldHeight;
		uint32_t m_oldReset;

		uint32_t m_instancedMeshVertexCount;
		uint32_t m_instancedMeshPrimitiveCount;

		entry::MouseState m_mouseState;

		int64_t m_timeOffset;

		struct DMap
		{
			bx::FilePath pathToFile;
			float scale;
		};

		DMap m_dmap;

		int m_computeThreadCount;
		int m_shading;
		int m_gpuSubd;
		int m_pingPong;

		float m_primitivePixelLengthTarget;
		float m_fovy;

		bool m_restart;
		bool m_wireframe;
		bool m_cull;
		bool m_freeze;
	};

} // namespace

ENTRY_IMPLEMENT_MAIN(
	  ExampleTessellation
	, "41-tess"
	, "Adaptive GPU Tessellation."
	, "https://bkaradzic.github.io/bgfx/examples.html#tess"
	);