procedural-3d-engine/base/VulkanUIOverlay.cpp

#include "VulkanUIOverlay.h"
/*
* UI overlay class using ImGui
*
* Copyright (C) 2017 by Sascha Willems - www.saschawillems.de
*
* This code is licensed under the MIT license (MIT) (http://opensource.org/licenses/MIT)
*/

#include "VulkanUIOverlay.h"

namespace vks 
{
	UIOverlay::UIOverlay(vks::VulkanDevice *vulkanDevice, VkQueue copyQueue, std::vector<VkFramebuffer> &framebuffers, VkFormat colorformat, VkFormat depthformat, uint32_t *framebufferwidth, uint32_t *framebufferheight, std::vector<VkPipelineShaderStageCreateInfo> shaderstages) 
	{
		this->device = vulkanDevice;
		this->copyQueue = copyQueue;
		this->colorFormat = colorformat;
		this->depthFormat = depthformat;

		this->frameBuffers.resize(framebuffers.size());
		for (uint32_t i = 0; i < framebuffers.size(); i++) {
			this->frameBuffers[i] = &framebuffers[i];
		}

		this->shaderStages = shaderstages;

		this->frameBufferWidth = framebufferwidth;
		this->frameBufferHeight = framebufferheight;

	#if defined(__ANDROID__)		
		if (vks::android::screenDensity >= ACONFIGURATION_DENSITY_XXHIGH) {
			scale = 3.0f;
		}
		else if (vks::android::screenDensity >= ACONFIGURATION_DENSITY_XHIGH) {
			scale = 2.25f;
		}
		else if (vks::android::screenDensity >= ACONFIGURATION_DENSITY_HIGH) {
			scale = 1.875f;
		};
	#endif

		// Init ImGui
		// Color scheme
		ImGuiStyle& style = ImGui::GetStyle();
		style.Colors[ImGuiCol_TitleBg] = ImVec4(1.0f, 0.0f, 0.0f, 1.0f);
		style.Colors[ImGuiCol_TitleBgActive] = ImVec4(1.0f, 0.0f, 0.0f, 1.0f);
		style.Colors[ImGuiCol_TitleBgCollapsed] = ImVec4(1.0f, 0.0f, 0.0f, 0.1f);
		style.Colors[ImGuiCol_MenuBarBg] = ImVec4(1.0f, 0.0f, 0.0f, 0.4f);
		style.Colors[ImGuiCol_Header] = ImVec4(0.8f, 0.0f, 0.0f, 0.4f);
		style.Colors[ImGuiCol_HeaderActive] = ImVec4(1.0f, 0.0f, 0.0f, 0.4f);
		style.Colors[ImGuiCol_HeaderHovered] = ImVec4(1.0f, 0.0f, 0.0f, 0.4f);
		style.Colors[ImGuiCol_CheckMark] = ImVec4(1.0f, 0.0f, 0.0f, 0.8f);
		// Dimensions
		ImGuiIO& io = ImGui::GetIO();
		io.DisplaySize = ImVec2((float)(*framebufferwidth), (float)(*framebufferheight));
		io.FontGlobalScale = scale;

		cmdBuffers.resize(framebuffers.size());
		prepareResources();
		prepareRenderPass();
		preparePipeline();
	}

	/** Free up all Vulkan resources acquired by the UI overlay */
	UIOverlay::~UIOverlay()
	{
		vertexBuffer.destroy();
		indexBuffer.destroy();
		vkDestroyImageView(device->logicalDevice, fontView, nullptr);
		vkDestroyImage(device->logicalDevice, fontImage, nullptr);
		vkFreeMemory(device->logicalDevice, fontMemory, nullptr);
		vkDestroySampler(device->logicalDevice, sampler, nullptr);
		vkDestroyDescriptorSetLayout(device->logicalDevice, descriptorSetLayout, nullptr);
		vkDestroyDescriptorPool(device->logicalDevice, descriptorPool, nullptr);
		vkDestroyPipelineLayout(device->logicalDevice, pipelineLayout, nullptr);
		vkDestroyPipelineCache(device->logicalDevice, pipelineCache, nullptr);
		vkDestroyPipeline(device->logicalDevice, pipeline, nullptr);
		vkDestroyRenderPass(device->logicalDevice, renderPass, nullptr);
		vkFreeCommandBuffers(device->logicalDevice, commandPool, static_cast<uint32_t>(cmdBuffers.size()), cmdBuffers.data());
		vkDestroyCommandPool(device->logicalDevice, commandPool, nullptr);
		vkDestroyFence(device->logicalDevice, fence, nullptr);
	}

	/** Prepare all vulkan resources required to render the UI overlay */
	void UIOverlay::prepareResources()
	{
		ImGuiIO& io = ImGui::GetIO();

		// Create font texture
		unsigned char* fontData;
		int texWidth, texHeight;
		io.Fonts->GetTexDataAsRGBA32(&fontData, &texWidth, &texHeight);
		VkDeviceSize uploadSize = texWidth*texHeight * 4 * sizeof(char);

		// Create target image for copy
		VkImageCreateInfo imageInfo = vks::initializers::imageCreateInfo();
		imageInfo.imageType = VK_IMAGE_TYPE_2D;
		imageInfo.format = VK_FORMAT_R8G8B8A8_UNORM;
		imageInfo.extent.width = texWidth;
		imageInfo.extent.height = texHeight;
		imageInfo.extent.depth = 1;
		imageInfo.mipLevels = 1;
		imageInfo.arrayLayers = 1;
		imageInfo.samples = VK_SAMPLE_COUNT_1_BIT;
		imageInfo.tiling = VK_IMAGE_TILING_OPTIMAL;
		imageInfo.usage = VK_IMAGE_USAGE_SAMPLED_BIT | VK_IMAGE_USAGE_TRANSFER_DST_BIT;
		imageInfo.sharingMode = VK_SHARING_MODE_EXCLUSIVE;
		imageInfo.initialLayout = VK_IMAGE_LAYOUT_UNDEFINED;
		VK_CHECK_RESULT(vkCreateImage(device->logicalDevice, &imageInfo, nullptr, &fontImage));
		VkMemoryRequirements memReqs;
		vkGetImageMemoryRequirements(device->logicalDevice, fontImage, &memReqs);
		VkMemoryAllocateInfo memAllocInfo = vks::initializers::memoryAllocateInfo();
		memAllocInfo.allocationSize = memReqs.size;
		memAllocInfo.memoryTypeIndex = device->getMemoryType(memReqs.memoryTypeBits, VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT);
		VK_CHECK_RESULT(vkAllocateMemory(device->logicalDevice, &memAllocInfo, nullptr, &fontMemory));
		VK_CHECK_RESULT(vkBindImageMemory(device->logicalDevice, fontImage, fontMemory, 0));

		// Image view
		VkImageViewCreateInfo viewInfo = vks::initializers::imageViewCreateInfo();
		viewInfo.image = fontImage;
		viewInfo.viewType = VK_IMAGE_VIEW_TYPE_2D;
		viewInfo.format = VK_FORMAT_R8G8B8A8_UNORM;
		viewInfo.subresourceRange.aspectMask = VK_IMAGE_ASPECT_COLOR_BIT;
		viewInfo.subresourceRange.levelCount = 1;
		viewInfo.subresourceRange.layerCount = 1;
		VK_CHECK_RESULT(vkCreateImageView(device->logicalDevice, &viewInfo, nullptr, &fontView));

		// Staging buffers for font data upload
		vks::Buffer stagingBuffer;

		VK_CHECK_RESULT(device->createBuffer(
			VK_BUFFER_USAGE_TRANSFER_SRC_BIT,
			VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT | VK_MEMORY_PROPERTY_HOST_COHERENT_BIT,
			&stagingBuffer,
			uploadSize));

		stagingBuffer.map();
		memcpy(stagingBuffer.mapped, fontData, uploadSize);
		stagingBuffer.unmap();

		// Copy buffer data to font image
		VkCommandBuffer copyCmd = device->createCommandBuffer(VK_COMMAND_BUFFER_LEVEL_PRIMARY, true);

		// Prepare for transfer
		vks::tools::setImageLayout(
			copyCmd,
			fontImage,
			VK_IMAGE_ASPECT_COLOR_BIT,
			VK_IMAGE_LAYOUT_UNDEFINED,
			VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL,
			VK_PIPELINE_STAGE_HOST_BIT,
			VK_PIPELINE_STAGE_TRANSFER_BIT);

		// Copy
		VkBufferImageCopy bufferCopyRegion = {};
		bufferCopyRegion.imageSubresource.aspectMask = VK_IMAGE_ASPECT_COLOR_BIT;
		bufferCopyRegion.imageSubresource.layerCount = 1;
		bufferCopyRegion.imageExtent.width = texWidth;
		bufferCopyRegion.imageExtent.height = texHeight;
		bufferCopyRegion.imageExtent.depth = 1;

		vkCmdCopyBufferToImage(
			copyCmd,
			stagingBuffer.buffer,
			fontImage,
			VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL,
			1,
			&bufferCopyRegion
		);

		// Prepare for shader read
		vks::tools::setImageLayout(
			copyCmd,
			fontImage,
			VK_IMAGE_ASPECT_COLOR_BIT,
			VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL,
			VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL,
			VK_PIPELINE_STAGE_TRANSFER_BIT,
			VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT);

		device->flushCommandBuffer(copyCmd, copyQueue, true);

		stagingBuffer.destroy();

		// Font texture Sampler
		VkSamplerCreateInfo samplerInfo = vks::initializers::samplerCreateInfo();
		samplerInfo.magFilter = VK_FILTER_LINEAR;
		samplerInfo.minFilter = VK_FILTER_LINEAR;
		samplerInfo.mipmapMode = VK_SAMPLER_MIPMAP_MODE_LINEAR;
		samplerInfo.addressModeU = VK_SAMPLER_ADDRESS_MODE_CLAMP_TO_EDGE;
		samplerInfo.addressModeV = VK_SAMPLER_ADDRESS_MODE_CLAMP_TO_EDGE;
		samplerInfo.addressModeW = VK_SAMPLER_ADDRESS_MODE_CLAMP_TO_EDGE;
		samplerInfo.borderColor = VK_BORDER_COLOR_FLOAT_OPAQUE_WHITE;
		VK_CHECK_RESULT(vkCreateSampler(device->logicalDevice, &samplerInfo, nullptr, &sampler));

		// Command buffer
		VkCommandPoolCreateInfo cmdPoolInfo = {};
		cmdPoolInfo.sType = VK_STRUCTURE_TYPE_COMMAND_POOL_CREATE_INFO;
		cmdPoolInfo.queueFamilyIndex = device->queueFamilyIndices.graphics;
		cmdPoolInfo.flags = VK_COMMAND_POOL_CREATE_RESET_COMMAND_BUFFER_BIT;
		VK_CHECK_RESULT(vkCreateCommandPool(device->logicalDevice, &cmdPoolInfo, nullptr, &commandPool));

		VkCommandBufferAllocateInfo cmdBufAllocateInfo =
			vks::initializers::commandBufferAllocateInfo(commandPool, VK_COMMAND_BUFFER_LEVEL_PRIMARY, static_cast<uint32_t>(cmdBuffers.size()));
		VK_CHECK_RESULT(vkAllocateCommandBuffers(device->logicalDevice, &cmdBufAllocateInfo, cmdBuffers.data()));

		// Descriptor pool
		std::vector<VkDescriptorPoolSize> poolSizes = {
			vks::initializers::descriptorPoolSize(VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER, 1)
		};
		VkDescriptorPoolCreateInfo descriptorPoolInfo = vks::initializers::descriptorPoolCreateInfo(poolSizes, 2);
		VK_CHECK_RESULT(vkCreateDescriptorPool(device->logicalDevice, &descriptorPoolInfo, nullptr, &descriptorPool));

		// Descriptor set layout
		std::vector<VkDescriptorSetLayoutBinding> setLayoutBindings = {
			vks::initializers::descriptorSetLayoutBinding(VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER, VK_SHADER_STAGE_FRAGMENT_BIT, 0),
		};
		VkDescriptorSetLayoutCreateInfo descriptorLayout = vks::initializers::descriptorSetLayoutCreateInfo(setLayoutBindings);
		VK_CHECK_RESULT(vkCreateDescriptorSetLayout(device->logicalDevice, &descriptorLayout, nullptr, &descriptorSetLayout));

		// Descriptor set
		VkDescriptorSetAllocateInfo allocInfo = vks::initializers::descriptorSetAllocateInfo(descriptorPool, &descriptorSetLayout, 1);
		VK_CHECK_RESULT(vkAllocateDescriptorSets(device->logicalDevice, &allocInfo, &descriptorSet));
		VkDescriptorImageInfo fontDescriptor = vks::initializers::descriptorImageInfo(
			sampler,
			fontView,
			VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL
		);
		std::vector<VkWriteDescriptorSet> writeDescriptorSets = {
			vks::initializers::writeDescriptorSet(descriptorSet, VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER, 0, &fontDescriptor)
		};
		vkUpdateDescriptorSets(device->logicalDevice, static_cast<uint32_t>(writeDescriptorSets.size()), writeDescriptorSets.data(), 0, nullptr);

		// Pipeline cache
		VkPipelineCacheCreateInfo pipelineCacheCreateInfo = {};
		pipelineCacheCreateInfo.sType = VK_STRUCTURE_TYPE_PIPELINE_CACHE_CREATE_INFO;
		VK_CHECK_RESULT(vkCreatePipelineCache(device->logicalDevice, &pipelineCacheCreateInfo, nullptr, &pipelineCache));

		// Pipeline layout
		// Push constants for UI rendering parameters
		VkPushConstantRange pushConstantRange = vks::initializers::pushConstantRange(VK_SHADER_STAGE_VERTEX_BIT, sizeof(PushConstBlock), 0);
		VkPipelineLayoutCreateInfo pipelineLayoutCreateInfo = vks::initializers::pipelineLayoutCreateInfo(&descriptorSetLayout, 1);
		pipelineLayoutCreateInfo.pushConstantRangeCount = 1;
		pipelineLayoutCreateInfo.pPushConstantRanges = &pushConstantRange;
		VK_CHECK_RESULT(vkCreatePipelineLayout(device->logicalDevice, &pipelineLayoutCreateInfo, nullptr, &pipelineLayout));

		// Command buffer execution fence
		VkFenceCreateInfo fenceCreateInfo = vks::initializers::fenceCreateInfo();
		VK_CHECK_RESULT(vkCreateFence(device->logicalDevice, &fenceCreateInfo, nullptr, &fence));
	}

	/** Prepare a separate pipeline for the UI overlay rendering decoupled from the main application */
	void UIOverlay::preparePipeline()
	{
		// Setup graphics pipeline for UI rendering
		VkPipelineInputAssemblyStateCreateInfo inputAssemblyState =
			vks::initializers::pipelineInputAssemblyStateCreateInfo(VK_PRIMITIVE_TOPOLOGY_TRIANGLE_LIST, 0, VK_FALSE);

		VkPipelineRasterizationStateCreateInfo rasterizationState =
			vks::initializers::pipelineRasterizationStateCreateInfo(VK_POLYGON_MODE_FILL, VK_CULL_MODE_NONE, VK_FRONT_FACE_COUNTER_CLOCKWISE);

		// Enable blending
		VkPipelineColorBlendAttachmentState blendAttachmentState{};
		blendAttachmentState.blendEnable = VK_TRUE;
		blendAttachmentState.colorWriteMask = VK_COLOR_COMPONENT_R_BIT | VK_COLOR_COMPONENT_G_BIT | VK_COLOR_COMPONENT_B_BIT | VK_COLOR_COMPONENT_A_BIT;
		blendAttachmentState.srcColorBlendFactor = VK_BLEND_FACTOR_SRC_ALPHA;
		blendAttachmentState.dstColorBlendFactor = VK_BLEND_FACTOR_ONE_MINUS_SRC_ALPHA;
		blendAttachmentState.colorBlendOp = VK_BLEND_OP_ADD;
		blendAttachmentState.srcAlphaBlendFactor = VK_BLEND_FACTOR_ONE_MINUS_SRC_ALPHA;
		blendAttachmentState.dstAlphaBlendFactor = VK_BLEND_FACTOR_ZERO;
		blendAttachmentState.alphaBlendOp = VK_BLEND_OP_ADD;

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

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

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

		VkPipelineMultisampleStateCreateInfo multisampleState =
			vks::initializers::pipelineMultisampleStateCreateInfo(VK_SAMPLE_COUNT_1_BIT);

		std::vector<VkDynamicState> dynamicStateEnables = {
			VK_DYNAMIC_STATE_VIEWPORT,
			VK_DYNAMIC_STATE_SCISSOR
		};
		VkPipelineDynamicStateCreateInfo dynamicState =
			vks::initializers::pipelineDynamicStateCreateInfo(dynamicStateEnables);

		VkGraphicsPipelineCreateInfo pipelineCreateInfo = vks::initializers::pipelineCreateInfo(pipelineLayout, renderPass);

		pipelineCreateInfo.pInputAssemblyState = &inputAssemblyState;
		pipelineCreateInfo.pRasterizationState = &rasterizationState;
		pipelineCreateInfo.pColorBlendState = &colorBlendState;
		pipelineCreateInfo.pMultisampleState = &multisampleState;
		pipelineCreateInfo.pViewportState = &viewportState;
		pipelineCreateInfo.pDepthStencilState = &depthStencilState;
		pipelineCreateInfo.pDynamicState = &dynamicState;
		pipelineCreateInfo.stageCount = static_cast<uint32_t>(shaderStages.size());
		pipelineCreateInfo.pStages = shaderStages.data();

		// Vertex bindings an attributes based on ImGui vertex definition
		std::vector<VkVertexInputBindingDescription> vertexInputBindings = {
			vks::initializers::vertexInputBindingDescription(0, sizeof(ImDrawVert), VK_VERTEX_INPUT_RATE_VERTEX),
		};
		std::vector<VkVertexInputAttributeDescription> vertexInputAttributes = {
			vks::initializers::vertexInputAttributeDescription(0, 0, VK_FORMAT_R32G32_SFLOAT, offsetof(ImDrawVert, pos)),	// Location 0: Position
			vks::initializers::vertexInputAttributeDescription(0, 1, VK_FORMAT_R32G32_SFLOAT, offsetof(ImDrawVert, uv)),	// Location 1: UV
			vks::initializers::vertexInputAttributeDescription(0, 2, VK_FORMAT_R8G8B8A8_UNORM, offsetof(ImDrawVert, col)),	// Location 0: Color
		};
		VkPipelineVertexInputStateCreateInfo vertexInputState = vks::initializers::pipelineVertexInputStateCreateInfo();
		vertexInputState.vertexBindingDescriptionCount = static_cast<uint32_t>(vertexInputBindings.size());
		vertexInputState.pVertexBindingDescriptions = vertexInputBindings.data();
		vertexInputState.vertexAttributeDescriptionCount = static_cast<uint32_t>(vertexInputAttributes.size());
		vertexInputState.pVertexAttributeDescriptions = vertexInputAttributes.data();

		pipelineCreateInfo.pVertexInputState = &vertexInputState;

		VK_CHECK_RESULT(vkCreateGraphicsPipelines(device->logicalDevice, pipelineCache, 1, &pipelineCreateInfo, nullptr, &pipeline));
	}

	/** Prepare a separate render pass for rendering the text as an overlay */
	void UIOverlay::prepareRenderPass()
	{
		VkAttachmentDescription attachments[2] = {};

		// Color attachment
		attachments[0].format = colorFormat;
		attachments[0].samples = VK_SAMPLE_COUNT_1_BIT;
		// Don't clear the framebuffer (like the renderpass from the example does)
		attachments[0].loadOp = VK_ATTACHMENT_LOAD_OP_LOAD;
		attachments[0].storeOp = VK_ATTACHMENT_STORE_OP_STORE;
		attachments[0].stencilLoadOp = VK_ATTACHMENT_LOAD_OP_DONT_CARE;
		attachments[0].stencilStoreOp = VK_ATTACHMENT_STORE_OP_DONT_CARE;
		attachments[0].initialLayout = VK_IMAGE_LAYOUT_UNDEFINED;
		attachments[0].finalLayout = VK_IMAGE_LAYOUT_PRESENT_SRC_KHR;

		// Depth attachment
		attachments[1].format = depthFormat;
		attachments[1].samples = VK_SAMPLE_COUNT_1_BIT;
		attachments[1].loadOp = VK_ATTACHMENT_LOAD_OP_DONT_CARE;
		attachments[1].storeOp = VK_ATTACHMENT_STORE_OP_DONT_CARE;
		attachments[1].stencilLoadOp = VK_ATTACHMENT_LOAD_OP_DONT_CARE;
		attachments[1].stencilStoreOp = VK_ATTACHMENT_STORE_OP_DONT_CARE;
		attachments[1].initialLayout = VK_IMAGE_LAYOUT_UNDEFINED;
		attachments[1].finalLayout = VK_IMAGE_LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL;

		VkAttachmentReference colorReference = {};
		colorReference.attachment = 0;
		colorReference.layout = VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL;

		VkAttachmentReference depthReference = {};
		depthReference.attachment = 1;
		depthReference.layout = VK_IMAGE_LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL;

		VkSubpassDependency subpassDependencies[2] = {};

		// Transition from final to initial (VK_SUBPASS_EXTERNAL refers to all commmands executed outside of the actual renderpass)
		subpassDependencies[0].srcSubpass = VK_SUBPASS_EXTERNAL;
		subpassDependencies[0].dstSubpass = 0;
		subpassDependencies[0].srcStageMask = VK_PIPELINE_STAGE_BOTTOM_OF_PIPE_BIT;
		subpassDependencies[0].dstStageMask = VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT;
		subpassDependencies[0].srcAccessMask = VK_ACCESS_MEMORY_READ_BIT;
		subpassDependencies[0].dstAccessMask = VK_ACCESS_COLOR_ATTACHMENT_READ_BIT | VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT;
		subpassDependencies[0].dependencyFlags = VK_DEPENDENCY_BY_REGION_BIT;

		// Transition from initial to final
		subpassDependencies[1].srcSubpass = 0;
		subpassDependencies[1].dstSubpass = VK_SUBPASS_EXTERNAL;
		subpassDependencies[1].srcStageMask = VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT;
		subpassDependencies[1].dstStageMask = VK_PIPELINE_STAGE_BOTTOM_OF_PIPE_BIT;
		subpassDependencies[1].srcAccessMask = VK_ACCESS_COLOR_ATTACHMENT_READ_BIT | VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT;
		subpassDependencies[1].dstAccessMask = VK_ACCESS_MEMORY_READ_BIT;
		subpassDependencies[1].dependencyFlags = VK_DEPENDENCY_BY_REGION_BIT;

		VkSubpassDescription subpassDescription = {};
		subpassDescription.pipelineBindPoint = VK_PIPELINE_BIND_POINT_GRAPHICS;
		subpassDescription.flags = 0;
		subpassDescription.inputAttachmentCount = 0;
		subpassDescription.pInputAttachments = NULL;
		subpassDescription.colorAttachmentCount = 1;
		subpassDescription.pColorAttachments = &colorReference;
		subpassDescription.pResolveAttachments = NULL;
		subpassDescription.pDepthStencilAttachment = &depthReference;
		subpassDescription.preserveAttachmentCount = 0;
		subpassDescription.pPreserveAttachments = NULL;

		VkRenderPassCreateInfo renderPassInfo = {};
		renderPassInfo.sType = VK_STRUCTURE_TYPE_RENDER_PASS_CREATE_INFO;
		renderPassInfo.pNext = NULL;
		renderPassInfo.attachmentCount = 2;
		renderPassInfo.pAttachments = attachments;
		renderPassInfo.subpassCount = 1;
		renderPassInfo.pSubpasses = &subpassDescription;
		renderPassInfo.dependencyCount = 2;
		renderPassInfo.pDependencies = subpassDependencies;

		VK_CHECK_RESULT(vkCreateRenderPass(device->logicalDevice, &renderPassInfo, nullptr, &renderPass));
	}

	/** Update the command buffers to reflect text changes */
	void UIOverlay::updateCommandBuffers()
	{
		VkCommandBufferBeginInfo cmdBufInfo = vks::initializers::commandBufferBeginInfo();

		VkRenderPassBeginInfo renderPassBeginInfo = vks::initializers::renderPassBeginInfo();
		renderPassBeginInfo.renderPass = renderPass;
		renderPassBeginInfo.renderArea.extent.width = *frameBufferWidth;
		renderPassBeginInfo.renderArea.extent.height = *frameBufferHeight;
		// None of the attachments will be cleared
		renderPassBeginInfo.clearValueCount = 0;
		renderPassBeginInfo.pClearValues = nullptr;

		ImGuiIO& io = ImGui::GetIO();

		for (size_t i = 0; i < cmdBuffers.size(); ++i) {
			renderPassBeginInfo.framebuffer = *frameBuffers[i];

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

			if (vks::debugmarker::active) {
				vks::debugmarker::beginRegion(cmdBuffers[i], "UI overlay", glm::vec4(1.0f, 0.94f, 0.3f, 1.0f));
			}

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

			vkCmdBindPipeline(cmdBuffers[i], VK_PIPELINE_BIND_POINT_GRAPHICS, pipeline);
			vkCmdBindDescriptorSets(cmdBuffers[i], VK_PIPELINE_BIND_POINT_GRAPHICS, pipelineLayout, 0, 1, &descriptorSet, 0, NULL);

			VkDeviceSize offsets[1] = { 0 };
			vkCmdBindVertexBuffers(cmdBuffers[i], 0, 1, &vertexBuffer.buffer, offsets);
			vkCmdBindIndexBuffer(cmdBuffers[i], indexBuffer.buffer, 0, VK_INDEX_TYPE_UINT16);

			VkViewport viewport = vks::initializers::viewport(ImGui::GetIO().DisplaySize.x, ImGui::GetIO().DisplaySize.y, 0.0f, 1.0f);
			vkCmdSetViewport(cmdBuffers[i], 0, 1, &viewport);

			VkRect2D scissor = vks::initializers::rect2D((int32_t)ImGui::GetIO().DisplaySize.x, (int32_t)ImGui::GetIO().DisplaySize.y, 0, 0);
			vkCmdSetScissor(cmdBuffers[i], 0, 1, &scissor);

			// UI scale and translate via push constants
			pushConstBlock.scale = glm::vec2(2.0f / io.DisplaySize.x, 2.0f / io.DisplaySize.y);
			pushConstBlock.translate = glm::vec2(-1.0f);
			vkCmdPushConstants(cmdBuffers[i], pipelineLayout, VK_SHADER_STAGE_VERTEX_BIT, 0, sizeof(PushConstBlock), &pushConstBlock);

			// Render commands
			ImDrawData* imDrawData = ImGui::GetDrawData();
			int32_t vertexOffset = 0;
			int32_t indexOffset = 0;
			for (int32_t j = 0; j < imDrawData->CmdListsCount; j++) {
				const ImDrawList* cmd_list = imDrawData->CmdLists[j];
				for (int32_t k = 0; k < cmd_list->CmdBuffer.Size; k++) {
					const ImDrawCmd* pcmd = &cmd_list->CmdBuffer[k];
					VkRect2D scissorRect;
					scissorRect.offset.x = std::max((int32_t)(pcmd->ClipRect.x), 0);
					scissorRect.offset.y = std::max((int32_t)(pcmd->ClipRect.y), 0);
					scissorRect.extent.width = (uint32_t)(pcmd->ClipRect.z - pcmd->ClipRect.x);
					scissorRect.extent.height = (uint32_t)(pcmd->ClipRect.w - pcmd->ClipRect.y);
					vkCmdSetScissor(cmdBuffers[i], 0, 1, &scissorRect);
					vkCmdDrawIndexed(cmdBuffers[i], pcmd->ElemCount, 1, indexOffset, vertexOffset, 0);
					indexOffset += pcmd->ElemCount;
				}
				vertexOffset += cmd_list->VtxBuffer.Size;
			}

			vkCmdEndRenderPass(cmdBuffers[i]);

			if (vks::debugmarker::active) {
				vks::debugmarker::endRegion(cmdBuffers[i]);
			}

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

	/** Update vertex and index buffer containing the imGui elements when required */
	void UIOverlay::update()
	{
		ImDrawData* imDrawData = ImGui::GetDrawData();
		bool updateCmdBuffers = false;

		if (!imDrawData) { return; };

		// Note: Alignment is done inside buffer creation
		VkDeviceSize vertexBufferSize = imDrawData->TotalVtxCount * sizeof(ImDrawVert);
		VkDeviceSize indexBufferSize = imDrawData->TotalIdxCount * sizeof(ImDrawIdx);

		// Update buffers only if vertex or index count has been changed compared to current buffer size

		// Vertex buffer
		if ((vertexBuffer.buffer == VK_NULL_HANDLE) || (vertexCount != imDrawData->TotalVtxCount)) {
			vertexBuffer.unmap();
			vertexBuffer.destroy();
			VK_CHECK_RESULT(device->createBuffer(VK_BUFFER_USAGE_VERTEX_BUFFER_BIT, VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT, &vertexBuffer, vertexBufferSize));
			vertexCount = imDrawData->TotalVtxCount;
			vertexBuffer.unmap();
			vertexBuffer.map();
			updateCmdBuffers = true;
		}

		// Index buffer
		VkDeviceSize indexSize = imDrawData->TotalIdxCount * sizeof(ImDrawIdx);
		if ((indexBuffer.buffer == VK_NULL_HANDLE) || (indexCount < imDrawData->TotalIdxCount)) {
			indexBuffer.unmap();
			indexBuffer.destroy();
			VK_CHECK_RESULT(device->createBuffer(VK_BUFFER_USAGE_INDEX_BUFFER_BIT, VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT, &indexBuffer, indexBufferSize));
			indexCount = imDrawData->TotalIdxCount;
			indexBuffer.map();
			updateCmdBuffers = true;
		}

		// Upload data
		ImDrawVert* vtxDst = (ImDrawVert*)vertexBuffer.mapped;
		ImDrawIdx* idxDst = (ImDrawIdx*)indexBuffer.mapped;

		for (int n = 0; n < imDrawData->CmdListsCount; n++) {
			const ImDrawList* cmd_list = imDrawData->CmdLists[n];
			memcpy(vtxDst, cmd_list->VtxBuffer.Data, cmd_list->VtxBuffer.Size * sizeof(ImDrawVert));
			memcpy(idxDst, cmd_list->IdxBuffer.Data, cmd_list->IdxBuffer.Size * sizeof(ImDrawIdx));
			vtxDst += cmd_list->VtxBuffer.Size;
			idxDst += cmd_list->IdxBuffer.Size;
		}

		// Flush to make writes visible to GPU
		vertexBuffer.flush();
		indexBuffer.flush();

		if (updateCmdBuffers) {
			updateCommandBuffers();
		}
	}

	/** Submit the overlay command buffers to a queue */
	void UIOverlay::submit(VkQueue queue, uint32_t bufferindex, VkSubmitInfo submitInfo)
	{
		if (!visible) {
			return;
		}

		submitInfo.pCommandBuffers = &cmdBuffers[bufferindex];
		submitInfo.commandBufferCount = 1;

		VK_CHECK_RESULT(vkQueueSubmit(queue, 1, &submitInfo, fence));

		VK_CHECK_RESULT(vkWaitForFences(device->logicalDevice, 1, &fence, VK_TRUE, UINT64_MAX));
		VK_CHECK_RESULT(vkResetFences(device->logicalDevice, 1, &fence));
	}

	/** Reallocate command buffers for the text overlay */
	void UIOverlay::reallocateCommandBuffers()
	{
		vkFreeCommandBuffers(device->logicalDevice, commandPool, static_cast<uint32_t>(cmdBuffers.size()), cmdBuffers.data());
		VkCommandBufferAllocateInfo cmdBufAllocateInfo =
			vks::initializers::commandBufferAllocateInfo(commandPool, VK_COMMAND_BUFFER_LEVEL_PRIMARY, static_cast<uint32_t>(cmdBuffers.size()));
		VK_CHECK_RESULT(vkAllocateCommandBuffers(device->logicalDevice, &cmdBufAllocateInfo, cmdBuffers.data()));
	}

	bool UIOverlay::header(const char *caption)
	{
		return ImGui::CollapsingHeader(caption, ImGuiTreeNodeFlags_DefaultOpen);
	}

	bool UIOverlay::checkBox(const char *caption, bool *value)
	{
		return ImGui::Checkbox(caption, value);
	}

	bool UIOverlay::checkBox(const char *caption, int32_t *value)
	{
		bool val = (*value == 1);
		bool res = ImGui::Checkbox(caption, &val);
		*value = val;
		return res;
	}

	bool UIOverlay::inputFloat(const char *caption, float *value, float step, uint32_t precision)
	{
		return ImGui::InputFloat(caption, value, step, step * 10.0f, precision);
	}

	bool UIOverlay::sliderFloat(const char* caption, float* value, float min, float max)
	{
		return ImGui::SliderFloat(caption, value, min, max);
	}

	bool UIOverlay::sliderInt(const char* caption, int32_t* value, int32_t min, int32_t max)
	{
		return ImGui::SliderInt(caption, value, min, max);
	}

	bool UIOverlay::comboBox(const char *caption, int32_t *itemindex, std::vector<std::string> items)
	{
		if (items.empty()) {
			return false;
		}
		std::vector<const char*> charitems;
		charitems.reserve(items.size());
		for (size_t i = 0; i < items.size(); i++) {
			charitems.push_back(items[i].c_str());
		}
		uint32_t itemCount = static_cast<uint32_t>(charitems.size());
		return ImGui::Combo(caption, itemindex, &charitems[0], itemCount, itemCount);
	}

	bool UIOverlay::button(const char *caption)
	{
		return ImGui::Button(caption);
	}

	void UIOverlay::text(const char *formatstr, ...)
	{
		va_list args;
		va_start(args, formatstr);
		ImGui::TextV(formatstr, args);
		va_end(args);
	}
}