Vulkan official example interpretation shadows (rasterization)

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Preface

• Render shadows for directional lights . For the first time, store the pov Depth value of , Compare these values a second time to check if the clip is shaded . Use depth deviation to avoid shadow artifacts , And Application PCF Filter to smooth shadow edges .
• Core principles and OpenGL In the same , Just use vulkanAPI.
• Shadow mapping (Shadow Mapping) The idea behind it is very simple ： We use The position of the light is the angle of view Rendering , Everything we can see will be lit up , What cannot be seen must be in the shadow . Suppose there is a floor , There is a big box between the light source and it . Because the light source looks in the direction of light , You can see this box , But I can't see part of the floor , This part should be in the shadow .
• In this example, the depth perspective of the light source is specially added to observe the object .

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One 、CPP file

1. Classes and variables

class VulkanExample : public VulkanExampleBase
{
    
public:
	bool displayShadowMap = false;
	bool filterPCF = true;

	// Keep depth range as small as possible
	// for better shadow map precision
	float zNear = 1.0f;
	float zFar = 96.0f;

	// Depth bias (and slope) are used to avoid shadowing artifacts
	//（ depth offset  （ And the slope ） Used to avoid shadow artifacts ）
	// Constant depth bias factor (always applied)
	// Constant depth offset factor （ Always apply ）
	float depthBiasConstant = 1.25f;
	// Slope depth bias factor, applied depending on polygon's slope
	// Slope depth offset factor , Apply according to the slope of the polygon 
	float depthBiasSlope = 1.75f;

	glm::vec3 lightPos = glm::vec3();// Light source location 
	float lightFOV = 45.0f;

	std::vector<vkglTF::Model> scenes;
	std::vector<std::string> sceneNames;
	int32_t sceneIndex = 0;

	struct {
    
		vks::Buffer scene;
		vks::Buffer offscreen;
	} uniformBuffers;
	// Set up UBO
	struct {
    
		glm::mat4 projection;
		glm::mat4 view;
		glm::mat4 model;
		glm::mat4 depthBiasMVP;
		glm::vec4 lightPos;
		// Used for depth map visualization
		float zNear;
		float zFar;
	} uboVSscene;
	
	// Off screen information for viewing depth of light source 
	struct {
    
		glm::mat4 depthMVP;
	} uboOffscreenVS;
	
	// Multiple render pipelines are used for rendering 
	struct {
    
		VkPipeline offscreen;
		VkPipeline sceneShadow;
		VkPipeline sceneShadowPCF;
		VkPipeline debug;
	} pipelines;
	VkPipelineLayout pipelineLayout;

	struct {
    
		VkDescriptorSet offscreen;
		VkDescriptorSet scene;
		VkDescriptorSet debug;
	} descriptorSets;

	VkDescriptorSetLayout descriptorSetLayout;

	// Framebuffer for offscreen rendering
	//  Frame buffer for off screen rendering 
	struct FrameBufferAttachment {
    
		VkImage image;
		VkDeviceMemory mem;
		VkImageView view;
	};
	struct OffscreenPass {
    
		int32_t width, height;
		VkFramebuffer frameBuffer;
		FrameBufferAttachment depth;
		VkRenderPass renderPass;
		VkSampler depthSampler;
		VkDescriptorImageInfo descriptor;
	} offscreenPass;

2. Important functions

1） by Off screen frame buffer Set up Separate render channels . This is a It's necessary Of , Because the off screen frame buffer attachment uses the same format as in the example The format is different .

	void prepareOffscreenRenderpass()
	{
    
		VkAttachmentDescription attachmentDescription{
    };
		attachmentDescription.format = DEPTH_FORMAT;
		attachmentDescription.samples = VK_SAMPLE_COUNT_1_BIT;
		attachmentDescription.loadOp = VK_ATTACHMENT_LOAD_OP_CLEAR;							// Clear depth at beginning of the render pass
		attachmentDescription.storeOp = VK_ATTACHMENT_STORE_OP_STORE;						// We will read from depth, so it's important to store the depth attachment results
		attachmentDescription.stencilLoadOp = VK_ATTACHMENT_LOAD_OP_DONT_CARE;
		attachmentDescription.stencilStoreOp = VK_ATTACHMENT_STORE_OP_DONT_CARE;
		attachmentDescription.initialLayout = VK_IMAGE_LAYOUT_UNDEFINED;					// We don't care about initial layout of the attachment
		attachmentDescription.finalLayout = VK_IMAGE_LAYOUT_DEPTH_STENCIL_READ_ONLY_OPTIMAL;// Attachment will be transitioned to shader read at render pass end

		VkAttachmentReference depthReference = {
    };
		depthReference.attachment = 0;
		depthReference.layout = VK_IMAGE_LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL;			// Attachment will be used as depth/stencil during render pass

		VkSubpassDescription subpass = {
    };
		subpass.pipelineBindPoint = VK_PIPELINE_BIND_POINT_GRAPHICS;
		subpass.colorAttachmentCount = 0;													// No color attachments
		subpass.pDepthStencilAttachment = &depthReference;									// Reference to our depth attachment

		// Use subpass dependencies for layout transitions
		std::array<VkSubpassDependency, 2> dependencies;

		dependencies[0].srcSubpass = VK_SUBPASS_EXTERNAL;
		dependencies[0].dstSubpass = 0;
		dependencies[0].srcStageMask = VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT;
		dependencies[0].dstStageMask = VK_PIPELINE_STAGE_EARLY_FRAGMENT_TESTS_BIT;
		dependencies[0].srcAccessMask = VK_ACCESS_SHADER_READ_BIT;
		dependencies[0].dstAccessMask = VK_ACCESS_DEPTH_STENCIL_ATTACHMENT_WRITE_BIT;
		dependencies[0].dependencyFlags = VK_DEPENDENCY_BY_REGION_BIT;

		dependencies[1].srcSubpass = 0;
		dependencies[1].dstSubpass = VK_SUBPASS_EXTERNAL;
		dependencies[1].srcStageMask = VK_PIPELINE_STAGE_LATE_FRAGMENT_TESTS_BIT;
		dependencies[1].dstStageMask = VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT;
		dependencies[1].srcAccessMask = VK_ACCESS_DEPTH_STENCIL_ATTACHMENT_WRITE_BIT;
		dependencies[1].dstAccessMask = VK_ACCESS_SHADER_READ_BIT;
		dependencies[1].dependencyFlags = VK_DEPENDENCY_BY_REGION_BIT;

		VkRenderPassCreateInfo renderPassCreateInfo = vks::initializers::renderPassCreateInfo();
		renderPassCreateInfo.attachmentCount = 1;
		renderPassCreateInfo.pAttachments = &attachmentDescription;
		renderPassCreateInfo.subpassCount = 1;
		renderPassCreateInfo.pSubpasses = &subpass;
		renderPassCreateInfo.dependencyCount = static_cast<uint32_t>(dependencies.size());
		renderPassCreateInfo.pDependencies = dependencies.data();

		VK_CHECK_RESULT(vkCreateRenderPass(device, &renderPassCreateInfo, nullptr, &offscreenPass.renderPass));
	}

2） Set up Off screen frame buffer , Used to render a scene from the viewpoint of a light source . then , The depth connection of this frame buffer will be used to sample from the shadow channel's clip shader .

	void prepareOffscreenFramebuffer()
	{
    
		offscreenPass.width = SHADOWMAP_DIM;
		offscreenPass.height = SHADOWMAP_DIM;

		// For shadow mapping we only need a depth attachment
		VkImageCreateInfo image = vks::initializers::imageCreateInfo();
		image.imageType = VK_IMAGE_TYPE_2D;
		image.extent.width = offscreenPass.width;
		image.extent.height = offscreenPass.height;
		image.extent.depth = 1;
		image.mipLevels = 1;
		image.arrayLayers = 1;
		image.samples = VK_SAMPLE_COUNT_1_BIT;
		image.tiling = VK_IMAGE_TILING_OPTIMAL;
		image.format = DEPTH_FORMAT;																// Depth stencil attachment
		image.usage = VK_IMAGE_USAGE_DEPTH_STENCIL_ATTACHMENT_BIT | VK_IMAGE_USAGE_SAMPLED_BIT;		// We will sample directly from the depth attachment for the shadow mapping
		VK_CHECK_RESULT(vkCreateImage(device, &image, nullptr, &offscreenPass.depth.image));

		VkMemoryAllocateInfo memAlloc = vks::initializers::memoryAllocateInfo();
		VkMemoryRequirements memReqs;
		vkGetImageMemoryRequirements(device, offscreenPass.depth.image, &memReqs);
		memAlloc.allocationSize = memReqs.size;
		memAlloc.memoryTypeIndex = vulkanDevice->getMemoryType(memReqs.memoryTypeBits, VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT);
		VK_CHECK_RESULT(vkAllocateMemory(device, &memAlloc, nullptr, &offscreenPass.depth.mem));
		VK_CHECK_RESULT(vkBindImageMemory(device, offscreenPass.depth.image, offscreenPass.depth.mem, 0));

		VkImageViewCreateInfo depthStencilView = vks::initializers::imageViewCreateInfo();
		depthStencilView.viewType = VK_IMAGE_VIEW_TYPE_2D;
		depthStencilView.format = DEPTH_FORMAT;
		depthStencilView.subresourceRange = {
    };
		depthStencilView.subresourceRange.aspectMask = VK_IMAGE_ASPECT_DEPTH_BIT;
		depthStencilView.subresourceRange.baseMipLevel = 0;
		depthStencilView.subresourceRange.levelCount = 1;
		depthStencilView.subresourceRange.baseArrayLayer = 0;
		depthStencilView.subresourceRange.layerCount = 1;
		depthStencilView.image = offscreenPass.depth.image;
		VK_CHECK_RESULT(vkCreateImageView(device, &depthStencilView, nullptr, &offscreenPass.depth.view));

		// Create sampler to sample from to depth attachment
		// Used to sample in the fragment shader for shadowed rendering
		VkFilter shadowmap_filter = vks::tools::formatIsFilterable(physicalDevice, DEPTH_FORMAT, VK_IMAGE_TILING_OPTIMAL) ?
		   DEFAULT_SHADOWMAP_FILTER :
		   VK_FILTER_NEAREST;
		VkSamplerCreateInfo sampler = vks::initializers::samplerCreateInfo();
		sampler.magFilter = shadowmap_filter;
		sampler.minFilter = shadowmap_filter;
		sampler.mipmapMode = VK_SAMPLER_MIPMAP_MODE_LINEAR;
		sampler.addressModeU = VK_SAMPLER_ADDRESS_MODE_CLAMP_TO_EDGE;
		sampler.addressModeV = sampler.addressModeU;
		sampler.addressModeW = sampler.addressModeU;
		sampler.mipLodBias = 0.0f;
		sampler.maxAnisotropy = 1.0f;
		sampler.minLod = 0.0f;
		sampler.maxLod = 1.0f;
		sampler.borderColor = VK_BORDER_COLOR_FLOAT_OPAQUE_WHITE;
		VK_CHECK_RESULT(vkCreateSampler(device, &sampler, nullptr, &offscreenPass.depthSampler));

		prepareOffscreenRenderpass();

		// Create frame buffer
		VkFramebufferCreateInfo fbufCreateInfo = vks::initializers::framebufferCreateInfo();
		fbufCreateInfo.renderPass = offscreenPass.renderPass;
		fbufCreateInfo.attachmentCount = 1;
		fbufCreateInfo.pAttachments = &offscreenPass.depth.view;
		fbufCreateInfo.width = offscreenPass.width;
		fbufCreateInfo.height = offscreenPass.height;
		fbufCreateInfo.layers = 1;

		VK_CHECK_RESULT(vkCreateFramebuffer(device, &fbufCreateInfo, nullptr, &offscreenPass.frameBuffer));
	}

3） The create command buffer in this example ： Notice that two render channels are used , First for Generate shadow maps , And choosing whether to render with the light angle is in the second .

	void buildCommandBuffers()
	{
    
		VkCommandBufferBeginInfo cmdBufInfo = vks::initializers::commandBufferBeginInfo();

		VkClearValue clearValues[2];
		VkViewport viewport;
		VkRect2D scissor;

		for (int32_t i = 0; i < drawCmdBuffers.size(); ++i)
		{
    
			VK_CHECK_RESULT(vkBeginCommandBuffer(drawCmdBuffers[i], &cmdBufInfo));

			/* First render pass: Generate shadow map by rendering the scene from light's POV（ First render channel ： From the light source  POV  Render the scene to generate shadow maps ） */
			{
    
				clearValues[0].depthStencil = {
     1.0f, 0 };

				VkRenderPassBeginInfo renderPassBeginInfo = vks::initializers::renderPassBeginInfo();
				renderPassBeginInfo.renderPass = offscreenPass.renderPass;
				renderPassBeginInfo.framebuffer = offscreenPass.frameBuffer;
				renderPassBeginInfo.renderArea.extent.width = offscreenPass.width;
				renderPassBeginInfo.renderArea.extent.height = offscreenPass.height;
				renderPassBeginInfo.clearValueCount = 1;
				renderPassBeginInfo.pClearValues = clearValues;

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

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

				scissor = vks::initializers::rect2D(offscreenPass.width, offscreenPass.height, 0, 0);
				vkCmdSetScissor(drawCmdBuffers[i], 0, 1, &scissor);

				// Set depth bias (aka "Polygon offset")
				// Required to avoid shadow mapping artifacts
				vkCmdSetDepthBias(
					drawCmdBuffers[i],
					depthBiasConstant,
					0.0f,
					depthBiasSlope);

				vkCmdBindPipeline(drawCmdBuffers[i], VK_PIPELINE_BIND_POINT_GRAPHICS, pipelines.offscreen);
				vkCmdBindDescriptorSets(drawCmdBuffers[i], VK_PIPELINE_BIND_POINT_GRAPHICS, pipelineLayout, 0, 1, &descriptorSets.offscreen, 0, nullptr);
				scenes[sceneIndex].draw(drawCmdBuffers[i]);

				vkCmdEndRenderPass(drawCmdBuffers[i]);
			}


			//Note: Explicit synchronization is not required between the render pass, as this is done implicit via sub pass dependencies
			// There is no need for explicit synchronization between render channels , Because this is done implicitly through child pass dependencies 


			/* //Second pass: Scene rendering with applied shadow map */

			{
    
				// Note that this render channel has both color and depth 
				clearValues[0].color = defaultClearColor;
				clearValues[1].depthStencil = {
     1.0f, 0 };

				VkRenderPassBeginInfo renderPassBeginInfo = vks::initializers::renderPassBeginInfo();
				renderPassBeginInfo.renderPass = renderPass;
				renderPassBeginInfo.framebuffer = frameBuffers[i];
				renderPassBeginInfo.renderArea.extent.width = width;
				renderPassBeginInfo.renderArea.extent.height = height;
				renderPassBeginInfo.clearValueCount = 2;
				renderPassBeginInfo.pClearValues = clearValues;

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

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

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

				// Visualize shadow map
				if (displayShadowMap) {
    
					vkCmdBindDescriptorSets(drawCmdBuffers[i], VK_PIPELINE_BIND_POINT_GRAPHICS, pipelineLayout, 0, 1, &descriptorSets.debug, 0, nullptr);
					vkCmdBindPipeline(drawCmdBuffers[i], VK_PIPELINE_BIND_POINT_GRAPHICS, pipelines.debug);
					vkCmdDraw(drawCmdBuffers[i], 3, 1, 0, 0);
				}

				// 3D scene
				vkCmdBindDescriptorSets(drawCmdBuffers[i], VK_PIPELINE_BIND_POINT_GRAPHICS, pipelineLayout, 0, 1, &descriptorSets.scene, 0, nullptr);
				vkCmdBindPipeline(drawCmdBuffers[i], VK_PIPELINE_BIND_POINT_GRAPHICS, (filterPCF) ? pipelines.sceneShadowPCF : pipelines.sceneShadow);
				scenes[sceneIndex].draw(drawCmdBuffers[i]);

				drawUI(drawCmdBuffers[i]);

				vkCmdEndRenderPass(drawCmdBuffers[i]);
			}

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

4） Descriptor layout

	void setupDescriptorSetLayout()
	{
    
		// Shared pipeline layout for all pipelines used in this sample
		std::vector<VkDescriptorSetLayoutBinding> setLayoutBindings = {
    
			// Binding 0 : Vertex shader uniform buffer
			vks::initializers::descriptorSetLayoutBinding(VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER, VK_SHADER_STAGE_VERTEX_BIT | VK_SHADER_STAGE_FRAGMENT_BIT, 0),
			// Binding 1 : Fragment shader image sampler (shadow map)
			vks::initializers::descriptorSetLayoutBinding(VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER, VK_SHADER_STAGE_FRAGMENT_BIT, 1)
		};
		VkDescriptorSetLayoutCreateInfo descriptorLayout = vks::initializers::descriptorSetLayoutCreateInfo(setLayoutBindings);
		VK_CHECK_RESULT(vkCreateDescriptorSetLayout(device, &descriptorLayout, nullptr, &descriptorSetLayout));
		VkPipelineLayoutCreateInfo pPipelineLayoutCreateInfo = vks::initializers::pipelineLayoutCreateInfo(&descriptorSetLayout, 1);
		VK_CHECK_RESULT(vkCreatePipelineLayout(device, &pPipelineLayoutCreateInfo, nullptr, &pipelineLayout));
	}

5） Descriptor set

	void setupDescriptorSets()
	{
    
		std::vector<VkWriteDescriptorSet> writeDescriptorSets;

		// Image descriptor for the shadow map attachment
		VkDescriptorImageInfo shadowMapDescriptor =
		    vks::initializers::descriptorImageInfo(
		        offscreenPass.depthSampler,
		        offscreenPass.depth.view,
		        VK_IMAGE_LAYOUT_DEPTH_STENCIL_READ_ONLY_OPTIMAL);

		// Debug display
		VkDescriptorSetAllocateInfo allocInfo = vks::initializers::descriptorSetAllocateInfo(descriptorPool, &descriptorSetLayout, 1);
		VK_CHECK_RESULT(vkAllocateDescriptorSets(device, &allocInfo, &descriptorSets.debug));
		writeDescriptorSets = {
    
			// Binding 0 : Parameters uniform buffer
			vks::initializers::writeDescriptorSet(descriptorSets.debug, VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER, 0, &uniformBuffers.scene.descriptor),
			// Binding 1 : Fragment shader texture sampler
		    vks::initializers::writeDescriptorSet(descriptorSets.debug, VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER, 1, &shadowMapDescriptor)
		};
		vkUpdateDescriptorSets(device, writeDescriptorSets.size(), writeDescriptorSets.data(), 0, nullptr);

		// Offscreen shadow map generation
		VK_CHECK_RESULT(vkAllocateDescriptorSets(device, &allocInfo, &descriptorSets.offscreen));
		writeDescriptorSets = {
    
			// Binding 0 : Vertex shader uniform buffer
			vks::initializers::writeDescriptorSet(descriptorSets.offscreen, VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER, 0, &uniformBuffers.offscreen.descriptor),
		};
		vkUpdateDescriptorSets(device, writeDescriptorSets.size(), writeDescriptorSets.data(), 0, nullptr);

		// Scene rendering with shadow map applied
		VK_CHECK_RESULT(vkAllocateDescriptorSets(device, &allocInfo, &descriptorSets.scene));
		writeDescriptorSets = {
    
			// Binding 0 : Vertex shader uniform buffer
			vks::initializers::writeDescriptorSet(descriptorSets.scene, VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER, 0, &uniformBuffers.scene.descriptor),
			// Binding 1 : Fragment shader shadow sampler
		    vks::initializers::writeDescriptorSet(descriptorSets.scene, VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER, 1, &shadowMapDescriptor)
		};
		vkUpdateDescriptorSets(device, writeDescriptorSets.size(), writeDescriptorSets.data(), 0, nullptr);
	}

6） pipeline

	void preparePipelines()
	{
    
		VkPipelineInputAssemblyStateCreateInfo inputAssemblyStateCI = vks::initializers::pipelineInputAssemblyStateCreateInfo(VK_PRIMITIVE_TOPOLOGY_TRIANGLE_LIST, 0, VK_FALSE);
		VkPipelineRasterizationStateCreateInfo rasterizationStateCI = vks::initializers::pipelineRasterizationStateCreateInfo(VK_POLYGON_MODE_FILL, VK_CULL_MODE_BACK_BIT, VK_FRONT_FACE_COUNTER_CLOCKWISE, 0);
		VkPipelineColorBlendAttachmentState blendAttachmentState = vks::initializers::pipelineColorBlendAttachmentState(0xf, VK_FALSE);
		VkPipelineColorBlendStateCreateInfo colorBlendStateCI = vks::initializers::pipelineColorBlendStateCreateInfo(1, &blendAttachmentState);
		VkPipelineDepthStencilStateCreateInfo depthStencilStateCI = vks::initializers::pipelineDepthStencilStateCreateInfo(VK_TRUE, VK_TRUE, VK_COMPARE_OP_LESS_OR_EQUAL);
		VkPipelineViewportStateCreateInfo viewportStateCI = vks::initializers::pipelineViewportStateCreateInfo(1, 1, 0);
		VkPipelineMultisampleStateCreateInfo multisampleStateCI = vks::initializers::pipelineMultisampleStateCreateInfo(VK_SAMPLE_COUNT_1_BIT, 0);
		std::vector<VkDynamicState> dynamicStateEnables = {
     VK_DYNAMIC_STATE_VIEWPORT, VK_DYNAMIC_STATE_SCISSOR };
		VkPipelineDynamicStateCreateInfo dynamicStateCI = vks::initializers::pipelineDynamicStateCreateInfo(dynamicStateEnables.data(), dynamicStateEnables.size(), 0);
		std::array<VkPipelineShaderStageCreateInfo, 2> shaderStages;

		VkGraphicsPipelineCreateInfo pipelineCI = vks::initializers::pipelineCreateInfo(pipelineLayout, renderPass, 0);
		pipelineCI.pInputAssemblyState = &inputAssemblyStateCI;
		pipelineCI.pRasterizationState = &rasterizationStateCI;
		pipelineCI.pColorBlendState = &colorBlendStateCI;
		pipelineCI.pMultisampleState = &multisampleStateCI;
		pipelineCI.pViewportState = &viewportStateCI;
		pipelineCI.pDepthStencilState = &depthStencilStateCI;
		pipelineCI.pDynamicState = &dynamicStateCI;
		pipelineCI.stageCount = shaderStages.size();
		pipelineCI.pStages = shaderStages.data();

		// Shadow mapping debug quad display
		rasterizationStateCI.cullMode = VK_CULL_MODE_NONE;
		shaderStages[0] = loadShader(getShadersPath() + "shadowmapping/quad.vert.spv", VK_SHADER_STAGE_VERTEX_BIT);
		shaderStages[1] = loadShader(getShadersPath() + "shadowmapping/quad.frag.spv", VK_SHADER_STAGE_FRAGMENT_BIT);
		// Empty vertex input state
		VkPipelineVertexInputStateCreateInfo emptyInputState = vks::initializers::pipelineVertexInputStateCreateInfo();
		pipelineCI.pVertexInputState = &emptyInputState;
		VK_CHECK_RESULT(vkCreateGraphicsPipelines(device, pipelineCache, 1, &pipelineCI, nullptr, &pipelines.debug));

		// Scene rendering with shadows applied
		pipelineCI.pVertexInputState  = vkglTF::Vertex::getPipelineVertexInputState({
    vkglTF::VertexComponent::Position, vkglTF::VertexComponent::UV, vkglTF::VertexComponent::Color, vkglTF::VertexComponent::Normal});
		rasterizationStateCI.cullMode = VK_CULL_MODE_BACK_BIT;
		shaderStages[0] = loadShader(getShadersPath() + "shadowmapping/scene.vert.spv", VK_SHADER_STAGE_VERTEX_BIT);
		shaderStages[1] = loadShader(getShadersPath() + "shadowmapping/scene.frag.spv", VK_SHADER_STAGE_FRAGMENT_BIT);
		// Use specialization constants to select between horizontal and vertical blur
		uint32_t enablePCF = 0;
		VkSpecializationMapEntry specializationMapEntry = vks::initializers::specializationMapEntry(0, 0, sizeof(uint32_t));
		VkSpecializationInfo specializationInfo = vks::initializers::specializationInfo(1, &specializationMapEntry, sizeof(uint32_t), &enablePCF);
		shaderStages[1].pSpecializationInfo = &specializationInfo;
		// No filtering
		VK_CHECK_RESULT(vkCreateGraphicsPipelines(device, pipelineCache, 1, &pipelineCI, nullptr, &pipelines.sceneShadow));
		// PCF filtering
		enablePCF = 1;
		VK_CHECK_RESULT(vkCreateGraphicsPipelines(device, pipelineCache, 1, &pipelineCI, nullptr, &pipelines.sceneShadowPCF));

		// Offscreen pipeline (vertex shader only)
		shaderStages[0] = loadShader(getShadersPath() + "shadowmapping/offscreen.vert.spv", VK_SHADER_STAGE_VERTEX_BIT);
		pipelineCI.stageCount = 1;
		// No blend attachment states (no color attachments used)
		colorBlendStateCI.attachmentCount = 0;
		// Cull front faces
		depthStencilStateCI.depthCompareOp = VK_COMPARE_OP_LESS_OR_EQUAL;
		// Enable depth bias
		rasterizationStateCI.depthBiasEnable = VK_TRUE;
		// Add depth bias to dynamic state, so we can change it at runtime
		dynamicStateEnables.push_back(VK_DYNAMIC_STATE_DEPTH_BIAS);
		dynamicStateCI =
			vks::initializers::pipelineDynamicStateCreateInfo(
				dynamicStateEnables.data(),
				dynamicStateEnables.size(),
				0);

		pipelineCI.renderPass = offscreenPass.renderPass;
		VK_CHECK_RESULT(vkCreateGraphicsPipelines(device, pipelineCache, 1, &pipelineCI, nullptr, &pipelines.offscreen));
	}

7）uniform

	// Prepare and initialize uniform buffer containing shader uniforms
	void prepareUniformBuffers()
	{
    
		// Offscreen vertex shader uniform buffer block
		VK_CHECK_RESULT(vulkanDevice->createBuffer(
			VK_BUFFER_USAGE_UNIFORM_BUFFER_BIT,
			VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT | VK_MEMORY_PROPERTY_HOST_COHERENT_BIT,
			&uniformBuffers.offscreen,
			sizeof(uboOffscreenVS)));

		// Scene vertex shader uniform buffer block
		VK_CHECK_RESULT(vulkanDevice->createBuffer(
			VK_BUFFER_USAGE_UNIFORM_BUFFER_BIT,
			VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT | VK_MEMORY_PROPERTY_HOST_COHERENT_BIT,
			&uniformBuffers.scene,
			sizeof(uboVSscene)));

		// Map persistent
		VK_CHECK_RESULT(uniformBuffers.offscreen.map());
		VK_CHECK_RESULT(uniformBuffers.scene.map());

		updateLight();
		updateUniformBufferOffscreen();
		updateUniformBuffers();
	}

Two 、Shader

1.offscreen Shadow map rendering

vert

#version 450

layout (location = 0) in vec3 inPos;

layout (binding = 0) uniform UBO 
{
    
	mat4 depthMVP;
} ubo;

out gl_PerVertex 
{
    
    vec4 gl_Position;   
};
void main()
{
    
	gl_Position =  ubo.depthMVP * vec4(inPos, 1.0);
}

frag

#version 450

layout(location = 0) out vec4 color;

void main() 
{
    	
	color = vec4(1.0, 0.0, 0.0, 1.0);
}

2.scene Model rendering

vert

#version 450

layout (location = 0) in vec3 inPos;
layout (location = 1) in vec2 inUV;
layout (location = 2) in vec3 inColor;
layout (location = 3) in vec3 inNormal;

layout (binding = 0) uniform UBO 
{
    
	mat4 projection;
	mat4 view;
	mat4 model;
	mat4 lightSpace;
	vec4 lightPos;
	float zNear;
	float zFar;
} ubo;

layout (location = 0) out vec3 outNormal;
layout (location = 1) out vec3 outColor;
layout (location = 2) out vec3 outViewVec;
layout (location = 3) out vec3 outLightVec;
layout (location = 4) out vec4 outShadowCoord;

const mat4 biasMat = mat4( 
	0.5, 0.0, 0.0, 0.0,
	0.0, 0.5, 0.0, 0.0,
	0.0, 0.0, 1.0, 0.0,
	0.5, 0.5, 0.0, 1.0 );

void main() 
{
    
	outColor = inColor;
	outNormal = inNormal;

	gl_Position = ubo.projection * ubo.view * ubo.model * vec4(inPos.xyz, 1.0);
	
    vec4 pos = ubo.model * vec4(inPos, 1.0);
    outNormal = mat3(ubo.model) * inNormal;
    outLightVec = normalize(ubo.lightPos.xyz - inPos);
    outViewVec = -pos.xyz;			

	outShadowCoord = ( biasMat * ubo.lightSpace * ubo.model ) * vec4(inPos, 1.0);	
}

frag

#version 450

layout (binding = 1) uniform sampler2D shadowMap;

layout (location = 0) in vec3 inNormal;
layout (location = 1) in vec3 inColor;
layout (location = 2) in vec3 inViewVec;
layout (location = 3) in vec3 inLightVec;
layout (location = 4) in vec4 inShadowCoord;

layout (constant_id = 0) const int enablePCF = 0;

layout (location = 0) out vec4 outFragColor;

#define ambient 0.1

float textureProj(vec4 shadowCoord, vec2 off)
{
    
	float shadow = 1.0;
	if ( shadowCoord.z > -1.0 && shadowCoord.z < 1.0 ) 
	{
    
		float dist = texture( shadowMap, shadowCoord.st + off ).r;
		if ( shadowCoord.w > 0.0 && dist < shadowCoord.z ) 
		{
    
			shadow = ambient;
		}
	}
	return shadow;
}

float filterPCF(vec4 sc)
{
    
	ivec2 texDim = textureSize(shadowMap, 0);
	float scale = 1.5;
	float dx = scale * 1.0 / float(texDim.x);
	float dy = scale * 1.0 / float(texDim.y);

	float shadowFactor = 0.0;
	int count = 0;
	int range = 1;
	
	for (int x = -range; x <= range; x++)
	{
    
		for (int y = -range; y <= range; y++)
		{
    
			shadowFactor += textureProj(sc, vec2(dx*x, dy*y));
			count++;
		}
	
	}
	return shadowFactor / count;
}

void main() 
{
    	
	float shadow = (enablePCF == 1) ? filterPCF(inShadowCoord / inShadowCoord.w) : textureProj(inShadowCoord / inShadowCoord.w, vec2(0.0));

	vec3 N = normalize(inNormal);
	vec3 L = normalize(inLightVec);
	vec3 V = normalize(inViewVec);
	vec3 R = normalize(-reflect(L, N));
	vec3 diffuse = max(dot(N, L), ambient) * inColor;

	outFragColor = vec4(diffuse * shadow, 1.0);

}

3.quad Deep rendering

vert

#version 450

layout (location = 0) out vec2 outUV;

void main() 
{
    
	outUV = vec2((gl_VertexIndex << 1) & 2, gl_VertexIndex & 2);
	gl_Position = vec4(outUV * 2.0f - 1.0f, 0.0f, 1.0f);
}

frag

#version 450

layout (binding = 1) uniform sampler2D samplerColor;

layout (location = 0) in vec2 inUV;

layout (location = 0) out vec4 outFragColor;

layout (binding = 0) uniform UBO 
{
    
	mat4 projection;
	mat4 view;
	mat4 model;
	mat4 lightSpace;
	vec4 lightPos;
	float zNear;
	float zFar;
} ubo;

float LinearizeDepth(float depth)
{
    
  float n = ubo.zNear;
  float f = ubo.zFar;
  float z = depth;
  return (2.0 * n) / (f + n - z * (f - n));	
}

void main() 
{
    
	float depth = texture(samplerColor, inUV).r;
	outFragColor = vec4(vec3(1.0-LinearizeDepth(depth)), 1.0);
}

---

summary

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