procedural-3d-engine/raytracing/raytracing.cpp

/*
* Vulkan Example - Compute shader ray tracing
*
* Copyright (C) 2016 by Sascha Willems - www.saschawillems.de
*
* This code is licensed under the MIT license (MIT) (http://opensource.org/licenses/MIT)
*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <vector>

#define GLM_FORCE_RADIANS
#define GLM_FORCE_DEPTH_ZERO_TO_ONE
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>

#include <vulkan/vulkan.h>
#include "vulkanexamplebase.h"

#define VERTEX_BUFFER_BIND_ID 0
#define ENABLE_VALIDATION false

#if defined(__ANDROID__)
#define TEX_DIM 1024
#else
#define TEX_DIM 2048
#endif

class VulkanExample : public VulkanExampleBase
{
public:
	vkTools::VulkanTexture textureComputeTarget;

	// Resources for the graphics part of the example
	struct {
		VkDescriptorSetLayout descriptorSetLayout;	// Raytraced image display shader binding layout
		VkDescriptorSet descriptorSetPreCompute;	// Raytraced image display shader bindings before compute shader image manipulation
		VkDescriptorSet descriptorSet;				// Raytraced image display shader bindings after compute shader image manipulation
		VkPipeline pipeline;						// Raytraced image display pipeline
		VkPipelineLayout pipelineLayout;			// Layout of the graphics pipeline
	} graphics;

	// Resources for the compute part of the example
	struct {
		VkQueue queue;								// Separate queue for compute commands (queue family may differ from the one used for graphics)
		VkCommandPool commandPool;					// Use a separate command pool (queue family may differ from the one used for graphics)
		VkCommandBuffer commandBuffer;				// Command buffer storing the dispatch commands and barriers
		VkFence fence;								// Synchronization fence to avoid rewriting compute CB if still in use
		VkDescriptorSetLayout descriptorSetLayout;	// Compute shader binding layout
		VkDescriptorSet descriptorSet;				// Compute shader bindings
		VkPipelineLayout pipelineLayout;			// Layout of the compute pipeline
		VkPipeline pipeline;						// Compute raytracing pipeline
	} compute;

	vk::Buffer uniformDataCompute;

	struct {
		glm::vec3 lightPos;							
		float aspectRatio;							// Aspect ratio of the viewport
		glm::vec4 fogColor = glm::vec4(0.0f);
		struct {
			glm::vec3 pos = glm::vec3(0.0f, 1.5f, 4.0f);
			glm::vec3 lookat = glm::vec3(0.0f, 0.5f, 0.0f);
			float fov = 10.0f;
		} camera;
	} uboCompute;

	VulkanExample() : VulkanExampleBase(ENABLE_VALIDATION)
	{
		title = "Vulkan Example - Compute shader ray tracing";
		enableTextOverlay = true;
		uboCompute.aspectRatio = (float)width / (float)height;
		paused = true;
		timerSpeed *= 0.5f;
	}

	~VulkanExample()
	{
		// Graphics
		vkDestroyPipeline(device, graphics.pipeline, nullptr);
		vkDestroyPipelineLayout(device, graphics.pipelineLayout, nullptr);
		vkDestroyDescriptorSetLayout(device, graphics.descriptorSetLayout, nullptr);

		// Compute
		vkDestroyPipeline(device, compute.pipeline, nullptr);
		vkDestroyPipelineLayout(device, compute.pipelineLayout, nullptr);
		vkDestroyDescriptorSetLayout(device, compute.descriptorSetLayout, nullptr);
		vkDestroyFence(device, compute.fence, nullptr);
		vkDestroyCommandPool(device, compute.commandPool, nullptr);
		uniformDataCompute.destroy();

		textureLoader->destroyTexture(textureComputeTarget);
	}

	// Prepare a texture target that is used to store compute shader calculations
	void prepareTextureTarget(vkTools::VulkanTexture *tex, uint32_t width, uint32_t height, VkFormat format)
	{
		// Get device properties for the requested texture format
		VkFormatProperties formatProperties;
		vkGetPhysicalDeviceFormatProperties(physicalDevice, format, &formatProperties);
		// Check if requested image format supports image storage operations
		assert(formatProperties.optimalTilingFeatures & VK_FORMAT_FEATURE_STORAGE_IMAGE_BIT);

		// Prepare blit target texture
		tex->width = width;
		tex->height = height;

		VkImageCreateInfo imageCreateInfo = vkTools::initializers::imageCreateInfo();
		imageCreateInfo.imageType = VK_IMAGE_TYPE_2D;
		imageCreateInfo.format = format;
		imageCreateInfo.extent = { width, height, 1 };
		imageCreateInfo.mipLevels = 1;
		imageCreateInfo.arrayLayers = 1;
		imageCreateInfo.samples = VK_SAMPLE_COUNT_1_BIT;
		imageCreateInfo.tiling = VK_IMAGE_TILING_OPTIMAL;
		imageCreateInfo.initialLayout = VK_IMAGE_LAYOUT_UNDEFINED;
		// Image will be sampled in the fragment shader and used as storage target in the compute shader
		imageCreateInfo.usage = VK_IMAGE_USAGE_SAMPLED_BIT | VK_IMAGE_USAGE_STORAGE_BIT;
		imageCreateInfo.flags = 0;

		VkMemoryAllocateInfo memAllocInfo = vkTools::initializers::memoryAllocateInfo();
		VkMemoryRequirements memReqs;

		VK_CHECK_RESULT(vkCreateImage(device, &imageCreateInfo, nullptr, &tex->image));
		vkGetImageMemoryRequirements(device, tex->image, &memReqs);
		memAllocInfo.allocationSize = memReqs.size;
		memAllocInfo.memoryTypeIndex = vulkanDevice->getMemoryType(memReqs.memoryTypeBits, VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT);
		VK_CHECK_RESULT(vkAllocateMemory(device, &memAllocInfo, nullptr, &tex->deviceMemory));
		VK_CHECK_RESULT(vkBindImageMemory(device, tex->image, tex->deviceMemory, 0));

		VkCommandBuffer layoutCmd = VulkanExampleBase::createCommandBuffer(VK_COMMAND_BUFFER_LEVEL_PRIMARY, true);

		tex->imageLayout = VK_IMAGE_LAYOUT_GENERAL;
		vkTools::setImageLayout(
			layoutCmd, 
			tex->image,
			VK_IMAGE_ASPECT_COLOR_BIT, 
			VK_IMAGE_LAYOUT_UNDEFINED,
			tex->imageLayout);

		VulkanExampleBase::flushCommandBuffer(layoutCmd, queue, true);

		// Create sampler
		VkSamplerCreateInfo sampler = vkTools::initializers::samplerCreateInfo();
		sampler.magFilter = VK_FILTER_LINEAR;
		sampler.minFilter = VK_FILTER_LINEAR;
		sampler.mipmapMode = VK_SAMPLER_MIPMAP_MODE_LINEAR;
		sampler.addressModeU = VK_SAMPLER_ADDRESS_MODE_CLAMP_TO_BORDER;
		sampler.addressModeV = sampler.addressModeU;
		sampler.addressModeW = sampler.addressModeU;
		sampler.mipLodBias = 0.0f;
		sampler.maxAnisotropy = 0;
		sampler.compareOp = VK_COMPARE_OP_NEVER;
		sampler.minLod = 0.0f;
		sampler.maxLod = 0.0f;
		sampler.borderColor = VK_BORDER_COLOR_FLOAT_OPAQUE_WHITE;
		VK_CHECK_RESULT(vkCreateSampler(device, &sampler, nullptr, &tex->sampler));

		// Create image view
		VkImageViewCreateInfo view = vkTools::initializers::imageViewCreateInfo();
		view.viewType = VK_IMAGE_VIEW_TYPE_2D;
		view.format = format;
		view.components = { VK_COMPONENT_SWIZZLE_R, VK_COMPONENT_SWIZZLE_G, VK_COMPONENT_SWIZZLE_B, VK_COMPONENT_SWIZZLE_A };
		view.subresourceRange = { VK_IMAGE_ASPECT_COLOR_BIT, 0, 1, 0, 1 };
		view.image = tex->image;
		VK_CHECK_RESULT(vkCreateImageView(device, &view, nullptr, &tex->view));

		// Initialize a descriptor for later use
		tex->descriptor.imageLayout = tex->imageLayout;
		tex->descriptor.imageView = tex->view;
		tex->descriptor.sampler = tex->sampler;
	}

	void buildCommandBuffers()
	{
		// Destroy command buffers if already present
		if (!checkCommandBuffers())
		{
			destroyCommandBuffers();
			createCommandBuffers();
		}

		VkCommandBufferBeginInfo cmdBufInfo = vkTools::initializers::commandBufferBeginInfo();

		VkClearValue clearValues[2];
		clearValues[0].color = defaultClearColor;
		clearValues[0].color = { {0.0f, 0.0f, 0.2f, 0.0f} };
		clearValues[1].depthStencil = { 1.0f, 0 };

		VkRenderPassBeginInfo renderPassBeginInfo = vkTools::initializers::renderPassBeginInfo();
		renderPassBeginInfo.renderPass = renderPass;
		renderPassBeginInfo.renderArea.offset.x = 0;
		renderPassBeginInfo.renderArea.offset.y = 0;
		renderPassBeginInfo.renderArea.extent.width = width;
		renderPassBeginInfo.renderArea.extent.height = height;
		renderPassBeginInfo.clearValueCount = 2;
		renderPassBeginInfo.pClearValues = clearValues;

		for (int32_t i = 0; i < drawCmdBuffers.size(); ++i)
		{
			// Set target frame buffer
			renderPassBeginInfo.framebuffer = frameBuffers[i];

			VK_CHECK_RESULT(vkBeginCommandBuffer(drawCmdBuffers[i], &cmdBufInfo));

			// Image memory barrier to make sure that compute shader writes are finished before sampling from the texture
			VkImageMemoryBarrier imageMemoryBarrier = {};
			imageMemoryBarrier.sType = VK_STRUCTURE_TYPE_IMAGE_MEMORY_BARRIER;
			imageMemoryBarrier.oldLayout = VK_IMAGE_LAYOUT_GENERAL;
			imageMemoryBarrier.newLayout = VK_IMAGE_LAYOUT_GENERAL;
			imageMemoryBarrier.image = textureComputeTarget.image;
			imageMemoryBarrier.subresourceRange = { VK_IMAGE_ASPECT_COLOR_BIT, 0, 1, 0, 1 };
			imageMemoryBarrier.srcAccessMask = VK_ACCESS_SHADER_WRITE_BIT;
			imageMemoryBarrier.dstAccessMask = VK_ACCESS_SHADER_READ_BIT;
			vkCmdPipelineBarrier(
				drawCmdBuffers[i],
				VK_PIPELINE_STAGE_COMPUTE_SHADER_BIT,
				VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT,
				VK_FLAGS_NONE,
				0, nullptr,
				0, nullptr,
				1, &imageMemoryBarrier);

			vkCmdBeginRenderPass(drawCmdBuffers[i], &renderPassBeginInfo, VK_SUBPASS_CONTENTS_INLINE);

			VkViewport viewport = vkTools::initializers::viewport((float)width, (float)height, 0.0f, 1.0f);
			vkCmdSetViewport(drawCmdBuffers[i], 0, 1, &viewport);

			VkRect2D scissor = vkTools::initializers::rect2D(width, height, 0, 0);
			vkCmdSetScissor(drawCmdBuffers[i], 0, 1, &scissor);

			// Display ray traced image generated by compute shader as a full screen quad
			// Quad vertices are generated in the vertex shader
			vkCmdBindDescriptorSets(drawCmdBuffers[i], VK_PIPELINE_BIND_POINT_GRAPHICS, graphics.pipelineLayout, 0, 1, &graphics.descriptorSet, 0, NULL);
			vkCmdBindPipeline(drawCmdBuffers[i], VK_PIPELINE_BIND_POINT_GRAPHICS, graphics.pipeline);
			vkCmdDraw(drawCmdBuffers[i], 3, 1, 0, 0);

			vkCmdEndRenderPass(drawCmdBuffers[i]);

			VK_CHECK_RESULT(vkEndCommandBuffer(drawCmdBuffers[i]));
		}

	}

	void buildComputeCommandBuffer()
	{
		VkCommandBufferBeginInfo cmdBufInfo = vkTools::initializers::commandBufferBeginInfo();

		VK_CHECK_RESULT(vkBeginCommandBuffer(compute.commandBuffer, &cmdBufInfo));

		vkCmdBindPipeline(compute.commandBuffer, VK_PIPELINE_BIND_POINT_COMPUTE, compute.pipeline);
		vkCmdBindDescriptorSets(compute.commandBuffer, VK_PIPELINE_BIND_POINT_COMPUTE, compute.pipelineLayout, 0, 1, &compute.descriptorSet, 0, 0);

		vkCmdDispatch(compute.commandBuffer, textureComputeTarget.width / 16, textureComputeTarget.height / 16, 1);

		vkEndCommandBuffer(compute.commandBuffer);
	}

	void setupDescriptorPool()
	{
		std::vector<VkDescriptorPoolSize> poolSizes =
		{
			vkTools::initializers::descriptorPoolSize(VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER, 2),
			// Graphics pipeline uses image samplers for display
			vkTools::initializers::descriptorPoolSize(VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER, 4),
			// Compute pipeline uses storage images image loads and stores
			vkTools::initializers::descriptorPoolSize(VK_DESCRIPTOR_TYPE_STORAGE_IMAGE, 1),
		};

		VkDescriptorPoolCreateInfo descriptorPoolInfo =
			vkTools::initializers::descriptorPoolCreateInfo(
				poolSizes.size(),
				poolSizes.data(),
				3);

		VK_CHECK_RESULT(vkCreateDescriptorPool(device, &descriptorPoolInfo, nullptr, &descriptorPool));
	}

	void setupDescriptorSetLayout()
	{
		std::vector<VkDescriptorSetLayoutBinding> setLayoutBindings =
		{
			// Binding 0 : Fragment shader image sampler
			vkTools::initializers::descriptorSetLayoutBinding(
				VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER,
				VK_SHADER_STAGE_FRAGMENT_BIT,
				0)
		};

		VkDescriptorSetLayoutCreateInfo descriptorLayout =
			vkTools::initializers::descriptorSetLayoutCreateInfo(
				setLayoutBindings.data(),
				setLayoutBindings.size());

		VK_CHECK_RESULT(vkCreateDescriptorSetLayout(device, &descriptorLayout, nullptr, &graphics.descriptorSetLayout));

		VkPipelineLayoutCreateInfo pPipelineLayoutCreateInfo =
			vkTools::initializers::pipelineLayoutCreateInfo(
				&graphics.descriptorSetLayout,
				1);

		VK_CHECK_RESULT(vkCreatePipelineLayout(device, &pPipelineLayoutCreateInfo, nullptr, &graphics.pipelineLayout));
	}

	void setupDescriptorSet()
	{
		VkDescriptorSetAllocateInfo allocInfo =
			vkTools::initializers::descriptorSetAllocateInfo(
				descriptorPool,
				&graphics.descriptorSetLayout,
				1);

		VK_CHECK_RESULT(vkAllocateDescriptorSets(device, &allocInfo, &graphics.descriptorSet));

		std::vector<VkWriteDescriptorSet> writeDescriptorSets =
		{
			// Binding 0 : Fragment shader texture sampler
			vkTools::initializers::writeDescriptorSet(
				graphics.descriptorSet,
				VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER,
				0,
				&textureComputeTarget.descriptor)
		};

		vkUpdateDescriptorSets(device, writeDescriptorSets.size(), writeDescriptorSets.data(), 0, NULL);
	}

	void preparePipelines()
	{
		VkPipelineInputAssemblyStateCreateInfo inputAssemblyState =
			vkTools::initializers::pipelineInputAssemblyStateCreateInfo(
				VK_PRIMITIVE_TOPOLOGY_TRIANGLE_LIST,
				0,
				VK_FALSE);

		VkPipelineRasterizationStateCreateInfo rasterizationState =
			vkTools::initializers::pipelineRasterizationStateCreateInfo(
				VK_POLYGON_MODE_FILL,
				VK_CULL_MODE_FRONT_BIT,
				VK_FRONT_FACE_COUNTER_CLOCKWISE,
				0);

		VkPipelineColorBlendAttachmentState blendAttachmentState =
			vkTools::initializers::pipelineColorBlendAttachmentState(
				0xf,
				VK_FALSE);

		VkPipelineColorBlendStateCreateInfo colorBlendState =
			vkTools::initializers::pipelineColorBlendStateCreateInfo(
				1,
				&blendAttachmentState);

		VkPipelineDepthStencilStateCreateInfo depthStencilState =
			vkTools::initializers::pipelineDepthStencilStateCreateInfo(
				VK_FALSE,
				VK_FALSE,
				VK_COMPARE_OP_LESS_OR_EQUAL);

		VkPipelineViewportStateCreateInfo viewportState =
			vkTools::initializers::pipelineViewportStateCreateInfo(1, 1, 0);

		VkPipelineMultisampleStateCreateInfo multisampleState =
			vkTools::initializers::pipelineMultisampleStateCreateInfo(
				VK_SAMPLE_COUNT_1_BIT,
				0);

		std::vector<VkDynamicState> dynamicStateEnables = {
			VK_DYNAMIC_STATE_VIEWPORT,
			VK_DYNAMIC_STATE_SCISSOR
		};
		VkPipelineDynamicStateCreateInfo dynamicState =
			vkTools::initializers::pipelineDynamicStateCreateInfo(
				dynamicStateEnables.data(),
				dynamicStateEnables.size(),
				0);

		// Display pipeline
		std::array<VkPipelineShaderStageCreateInfo,2> shaderStages;

		shaderStages[0] = loadShader(getAssetPath() + "shaders/raytracing/texture.vert.spv", VK_SHADER_STAGE_VERTEX_BIT);
		shaderStages[1] = loadShader(getAssetPath() + "shaders/raytracing/texture.frag.spv", VK_SHADER_STAGE_FRAGMENT_BIT);

		VkGraphicsPipelineCreateInfo pipelineCreateInfo =
			vkTools::initializers::pipelineCreateInfo(
				graphics.pipelineLayout,
				renderPass,
				0);

		VkPipelineVertexInputStateCreateInfo emptyInputState{};
		emptyInputState.sType = VK_STRUCTURE_TYPE_PIPELINE_VERTEX_INPUT_STATE_CREATE_INFO;
		emptyInputState.vertexAttributeDescriptionCount = 0;
		emptyInputState.pVertexAttributeDescriptions = nullptr;
		emptyInputState.vertexBindingDescriptionCount = 0;
		emptyInputState.pVertexBindingDescriptions = nullptr;
		pipelineCreateInfo.pVertexInputState = &emptyInputState;

		pipelineCreateInfo.pInputAssemblyState = &inputAssemblyState;
		pipelineCreateInfo.pRasterizationState = &rasterizationState;
		pipelineCreateInfo.pColorBlendState = &colorBlendState;
		pipelineCreateInfo.pMultisampleState = &multisampleState;
		pipelineCreateInfo.pViewportState = &viewportState;
		pipelineCreateInfo.pDepthStencilState = &depthStencilState;
		pipelineCreateInfo.pDynamicState = &dynamicState;
		pipelineCreateInfo.stageCount = shaderStages.size();
		pipelineCreateInfo.pStages = shaderStages.data();
		pipelineCreateInfo.renderPass = renderPass;

		VK_CHECK_RESULT(vkCreateGraphicsPipelines(device, pipelineCache, 1, &pipelineCreateInfo, nullptr, &graphics.pipeline));
	}

	// Prepare the compute pipeline that generates the ray traced image
	void prepareCompute()
	{
		// Create a compute capable device queue
		// The VulkanDevice::createLogicalDevice functions finds a compute capable queue and prefers queue families that only support compute
		// Depending on the implementation this may result in different queue family indices for graphics and computes,
		// requiring proper synchronization (see the memory barriers in buildComputeCommandBuffer)
		VkDeviceQueueCreateInfo queueCreateInfo = {};
		queueCreateInfo.sType = VK_STRUCTURE_TYPE_DEVICE_QUEUE_CREATE_INFO;
		queueCreateInfo.pNext = NULL;
		queueCreateInfo.queueFamilyIndex = vulkanDevice->queueFamilyIndices.compute;
		queueCreateInfo.queueCount = 1;
		vkGetDeviceQueue(device, vulkanDevice->queueFamilyIndices.compute, 0, &compute.queue);

		std::vector<VkDescriptorSetLayoutBinding> setLayoutBindings = {
			// Binding 0 : Sampled image (write)
			vkTools::initializers::descriptorSetLayoutBinding(
				VK_DESCRIPTOR_TYPE_STORAGE_IMAGE,
				VK_SHADER_STAGE_COMPUTE_BIT,
				0),
			// Binding 1 : Uniform buffer block
			vkTools::initializers::descriptorSetLayoutBinding(
				VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER,
				VK_SHADER_STAGE_COMPUTE_BIT,
				1)
		};

		VkDescriptorSetLayoutCreateInfo descriptorLayout =
			vkTools::initializers::descriptorSetLayoutCreateInfo(
				setLayoutBindings.data(),
				setLayoutBindings.size());

		VK_CHECK_RESULT(vkCreateDescriptorSetLayout(device, &descriptorLayout, nullptr,	&compute.descriptorSetLayout));

		VkPipelineLayoutCreateInfo pPipelineLayoutCreateInfo =
			vkTools::initializers::pipelineLayoutCreateInfo(
				&compute.descriptorSetLayout,
				1);

		VK_CHECK_RESULT(vkCreatePipelineLayout(device, &pPipelineLayoutCreateInfo, nullptr, &compute.pipelineLayout));

		VkDescriptorSetAllocateInfo allocInfo =
			vkTools::initializers::descriptorSetAllocateInfo(
				descriptorPool,
				&compute.descriptorSetLayout,
				1);

		VK_CHECK_RESULT(vkAllocateDescriptorSets(device, &allocInfo, &compute.descriptorSet));

		std::vector<VkWriteDescriptorSet> computeWriteDescriptorSets =
		{
			// Binding 0 : Output storage image
			vkTools::initializers::writeDescriptorSet(
				compute.descriptorSet,
				VK_DESCRIPTOR_TYPE_STORAGE_IMAGE,
				0,
				&textureComputeTarget.descriptor),
			// Binding 1 : Uniform buffer block
			vkTools::initializers::writeDescriptorSet(
				compute.descriptorSet,
				VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER,
				1,
				&uniformDataCompute.descriptor)
		};

		vkUpdateDescriptorSets(device, computeWriteDescriptorSets.size(), computeWriteDescriptorSets.data(), 0, NULL);

		// Create compute shader pipelines
		VkComputePipelineCreateInfo computePipelineCreateInfo =
			vkTools::initializers::computePipelineCreateInfo(
				compute.pipelineLayout,
				0);

		computePipelineCreateInfo.stage = loadShader(getAssetPath() + "shaders/raytracing/raytracing.comp.spv", VK_SHADER_STAGE_COMPUTE_BIT);
		VK_CHECK_RESULT(vkCreateComputePipelines(device, pipelineCache, 1, &computePipelineCreateInfo, nullptr, &compute.pipeline));

		// Separate command pool as queue family for compute may be different than graphics
		VkCommandPoolCreateInfo cmdPoolInfo = {};
		cmdPoolInfo.sType = VK_STRUCTURE_TYPE_COMMAND_POOL_CREATE_INFO;
		cmdPoolInfo.queueFamilyIndex = vulkanDevice->queueFamilyIndices.compute;
		cmdPoolInfo.flags = VK_COMMAND_POOL_CREATE_RESET_COMMAND_BUFFER_BIT;
		VK_CHECK_RESULT(vkCreateCommandPool(device, &cmdPoolInfo, nullptr, &compute.commandPool));

		// Create a command buffer for compute operations
		VkCommandBufferAllocateInfo cmdBufAllocateInfo =
			vkTools::initializers::commandBufferAllocateInfo(
				compute.commandPool,
				VK_COMMAND_BUFFER_LEVEL_PRIMARY,
				1);

		VK_CHECK_RESULT(vkAllocateCommandBuffers(device, &cmdBufAllocateInfo, &compute.commandBuffer));

		// Fence for compute CB sync
		VkFenceCreateInfo fenceCreateInfo = vkTools::initializers::fenceCreateInfo(VK_FENCE_CREATE_SIGNALED_BIT);
		VK_CHECK_RESULT(vkCreateFence(device, &fenceCreateInfo, nullptr, &compute.fence));

		// Build a single command buffer containing the compute dispatch commands
		buildComputeCommandBuffer();
	}

	// Prepare and initialize uniform buffer containing shader uniforms
	void prepareUniformBuffers()
	{
		// Compute shader parameter uniform buffer block
		vulkanDevice->createBuffer(
			VK_BUFFER_USAGE_UNIFORM_BUFFER_BIT,
			VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT | VK_MEMORY_PROPERTY_HOST_COHERENT_BIT,
			&uniformDataCompute,
			sizeof(uboCompute));

		updateUniformBuffers();
	}

	void updateUniformBuffers()
	{
		uboCompute.lightPos.x = 0.0f + sin(glm::radians(timer * 360.0f)) * 2.0f;
		uboCompute.lightPos.y = 5.0f;
		uboCompute.lightPos.z = 1.0f;
		uboCompute.lightPos.z = 0.0f + cos(glm::radians(timer * 360.0f)) * 2.0f;
		VK_CHECK_RESULT(uniformDataCompute.map());
		memcpy(uniformDataCompute.mapped, &uboCompute, sizeof(uboCompute));
		uniformDataCompute.unmap();
	}

	void draw()
	{
		VulkanExampleBase::prepareFrame();

		// Command buffer to be sumitted to the queue
		submitInfo.commandBufferCount = 1;
		submitInfo.pCommandBuffers = &drawCmdBuffers[currentBuffer];
		VK_CHECK_RESULT(vkQueueSubmit(queue, 1, &submitInfo, VK_NULL_HANDLE));

		VulkanExampleBase::submitFrame();

		// Submit compute commands
		// Use a fence to ensure that compute command buffer has finished executin before using it again
		vkWaitForFences(device, 1, &compute.fence, VK_TRUE, UINT64_MAX);
		vkResetFences(device, 1, &compute.fence);

		VkSubmitInfo computeSubmitInfo = vkTools::initializers::submitInfo();
		computeSubmitInfo.commandBufferCount = 1;
		computeSubmitInfo.pCommandBuffers = &compute.commandBuffer;

		VK_CHECK_RESULT(vkQueueSubmit(compute.queue, 1, &computeSubmitInfo, compute.fence));
	}

	void prepare()
	{
		VulkanExampleBase::prepare();
		prepareUniformBuffers();
		prepareTextureTarget(&textureComputeTarget, TEX_DIM, TEX_DIM, VK_FORMAT_R8G8B8A8_UNORM);
		setupDescriptorSetLayout();
		preparePipelines();
		setupDescriptorPool();
		setupDescriptorSet();
		prepareCompute();
		buildCommandBuffers(); 
		prepared = true;
	}

	virtual void render()
	{
		if (!prepared)
			return;
		draw();
		if (!paused)
		{
			updateUniformBuffers();
		}
	}

	virtual void viewChanged()
	{
		uboCompute.aspectRatio = (float)width / (float)height;
		updateUniformBuffers();
	}
};

VULKAN_EXAMPLE_MAIN()