dynamicuniformbuffer.cpp

/*
* Vulkan Example - Dynamic uniform buffers
*
* Copyright (C) 2016-2025 by Sascha Willems - www.saschawillems.de
*
* This code is licensed under the MIT license (MIT) (http://opensource.org/licenses/MIT)
*
* Summary:
* Demonstrates the use of dynamic uniform buffers.
*
* Instead of using one uniform buffer per-object, this example allocates one big uniform buffer
* with respect to the alignment reported by the device via minUniformBufferOffsetAlignment that
* contains all matrices for the objects in the scene.
*
* The used descriptor type VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER_DYNAMIC then allows to set a dynamic
* offset used to pass data from the single uniform buffer to the connected shader binding point.
*/

#include "vulkanexamplebase.h"

constexpr auto OBJECT_INSTANCES = 125;

// Vertex layout for this example
struct Vertex {
	float pos[3];
	float color[3];
};

// Wrapper functions for aligned memory allocation
// There is currently no standard for this in C++ that works across all platforms and vendors, so we abstract this
void* alignedAlloc(size_t size, size_t alignment)
{
	void *data = nullptr;
#if defined(_MSC_VER) || defined(__MINGW32__)
	data = _aligned_malloc(size, alignment);
#else
	int res = posix_memalign(&data, alignment, size);
	if (res != 0)
		data = nullptr;
#endif
	return data;
}

void alignedFree(void* data)
{
#if	defined(_MSC_VER) || defined(__MINGW32__)
	_aligned_free(data);
#else
	free(data);
#endif
}

class VulkanExample : public VulkanExampleBase
{
public:
	vks::Buffer vertexBuffer;
	vks::Buffer indexBuffer;
	uint32_t indexCount{ 0 };

	struct UniformBuffers {
		vks::Buffer view;
		vks::Buffer dynamic;
	};
	std::array<UniformBuffers, maxConcurrentFrames> uniformBuffers;

	struct {
		glm::mat4 projection;
		glm::mat4 view;
	} uboVS;

	// Store random per-object rotations
	glm::vec3 rotations[OBJECT_INSTANCES];
	glm::vec3 rotationSpeeds[OBJECT_INSTANCES];

	// One big uniform buffer that contains all matrices
	// Note that we need to manually allocate the data to cope for GPU-specific uniform buffer offset alignments
	struct UboDataDynamic {
		glm::mat4* model{ nullptr };
	} uboDataDynamic;

	VkPipeline pipeline{ VK_NULL_HANDLE };
	VkPipelineLayout pipelineLayout{ VK_NULL_HANDLE };
	VkDescriptorSet descriptorSet{ VK_NULL_HANDLE };
	VkDescriptorSetLayout descriptorSetLayout{ VK_NULL_HANDLE };

	size_t dynamicAlignment{ 0 };

	VulkanExample() : VulkanExampleBase()
	{
		title = "Dynamic uniform buffers";
		camera.type = Camera::CameraType::lookat;
		camera.setPosition(glm::vec3(0.0f, 0.0f, -30.0f));
		camera.setRotation(glm::vec3(0.0f));
		camera.setPerspective(60.0f, (float)width / (float)height, 0.1f, 256.0f);
	}

	~VulkanExample()
	{
		if (device) {
			if (uboDataDynamic.model) {
				alignedFree(uboDataDynamic.model);
			}
			vkDestroyPipeline(device, pipeline, nullptr);
			vkDestroyPipelineLayout(device, pipelineLayout, nullptr);
			vkDestroyDescriptorSetLayout(device, descriptorSetLayout, nullptr);
			vertexBuffer.destroy();
			indexBuffer.destroy();
			for (auto& buffer : uniformBuffers) {
				buffer.view.destroy();
				buffer.dynamic.destroy();
			}
		}
	}

	void generateCube()
	{
		// Setup vertices indices for a colored cube
		std::vector<Vertex> vertices = {
			{ { -1.0f, -1.0f,  1.0f },{ 1.0f, 0.0f, 0.0f } },
			{ {  1.0f, -1.0f,  1.0f },{ 0.0f, 1.0f, 0.0f } },
			{ {  1.0f,  1.0f,  1.0f },{ 0.0f, 0.0f, 1.0f } },
			{ { -1.0f,  1.0f,  1.0f },{ 0.0f, 0.0f, 0.0f } },
			{ { -1.0f, -1.0f, -1.0f },{ 1.0f, 0.0f, 0.0f } },
			{ {  1.0f, -1.0f, -1.0f },{ 0.0f, 1.0f, 0.0f } },
			{ {  1.0f,  1.0f, -1.0f },{ 0.0f, 0.0f, 1.0f } },
			{ { -1.0f,  1.0f, -1.0f },{ 0.0f, 0.0f, 0.0f } },
		};

		std::vector<uint32_t> indices = {
			0,1,2, 2,3,0, 1,5,6, 6,2,1, 7,6,5, 5,4,7, 4,0,3, 3,7,4, 4,5,1, 1,0,4, 3,2,6, 6,7,3,
		};

		indexCount = static_cast<uint32_t>(indices.size());

		// Create buffers
		// For the sake of simplicity we won't stage the vertex data to the gpu memory
		// Vertex buffer
		VK_CHECK_RESULT(vulkanDevice->createBuffer(
			VK_BUFFER_USAGE_VERTEX_BUFFER_BIT,
			VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT | VK_MEMORY_PROPERTY_HOST_COHERENT_BIT,
			&vertexBuffer,
			vertices.size() * sizeof(Vertex),
			vertices.data()));
		// Index buffer
		VK_CHECK_RESULT(vulkanDevice->createBuffer(
			VK_BUFFER_USAGE_INDEX_BUFFER_BIT,
			VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT | VK_MEMORY_PROPERTY_HOST_COHERENT_BIT,
			&indexBuffer,
			indices.size() * sizeof(uint32_t),
			indices.data()));
	}
	void setupDescriptors()
	{
		// Pool
		std::vector<VkDescriptorPoolSize> poolSizes = {
			vks::initializers::descriptorPoolSize(VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER, maxConcurrentFrames),
			// Dynamic uniform buffers require a different descriptor type
			vks::initializers::descriptorPoolSize(VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER_DYNAMIC, maxConcurrentFrames)
		};

		VkDescriptorPoolCreateInfo descriptorPoolInfo = vks::initializers::descriptorPoolCreateInfo(poolSizes, maxConcurrentFrames);
		VK_CHECK_RESULT(vkCreateDescriptorPool(device, &descriptorPoolInfo, nullptr, &descriptorPool));

		// Layout
		std::vector<VkDescriptorSetLayoutBinding> setLayoutBindings = {
			vks::initializers::descriptorSetLayoutBinding(VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER, VK_SHADER_STAGE_VERTEX_BIT, 0),
			// Dynamic uniform buffer
			vks::initializers::descriptorSetLayoutBinding(VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER_DYNAMIC, VK_SHADER_STAGE_VERTEX_BIT, 1)
		};

		VkDescriptorSetLayoutCreateInfo descriptorLayout = vks::initializers::descriptorSetLayoutCreateInfo(setLayoutBindings);
		VK_CHECK_RESULT(vkCreateDescriptorSetLayout(device, &descriptorLayout, nullptr, &descriptorSetLayout));

		// Sets per frame, just like the buffers themselves
		// Images do not need to be duplicated per frame, we reuse the same one for each frame
		VkDescriptorSetAllocateInfo allocInfo = vks::initializers::descriptorSetAllocateInfo(descriptorPool, &descriptorSetLayout, 1);
		for (auto i = 0; i < uniformBuffers.size(); i++) {
			VkDescriptorSetAllocateInfo allocInfo = vks::initializers::descriptorSetAllocateInfo(descriptorPool, &descriptorSetLayout, 1);
			VK_CHECK_RESULT(vkAllocateDescriptorSets(device, &allocInfo, &descriptorSet));
			std::vector<VkWriteDescriptorSet> writeDescriptorSets = {
				// Binding 0 : Projection/View matrix as uniform buffer
				vks::initializers::writeDescriptorSet(descriptorSet, VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER, 0, &uniformBuffers[currentBuffer].view.descriptor),
				// Binding 1 : Instance matrix as dynamic uniform buffer
				vks::initializers::writeDescriptorSet(descriptorSet, VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER_DYNAMIC, 1, &uniformBuffers[currentBuffer].dynamic.descriptor),
			};
			vkUpdateDescriptorSets(device, static_cast<uint32_t>(writeDescriptorSets.size()), writeDescriptorSets.data(), 0, nullptr);
		}
	}

	void preparePipelines()
	{
		// Layout
		VkPipelineLayoutCreateInfo pipelineLayoutCreateInfo = vks::initializers::pipelineLayoutCreateInfo(&descriptorSetLayout, 1);
		VK_CHECK_RESULT(vkCreatePipelineLayout(device, &pipelineLayoutCreateInfo, nullptr, &pipelineLayout));

		// Pipeline
		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, 0);
		VkPipelineColorBlendAttachmentState blendAttachmentState = vks::initializers::pipelineColorBlendAttachmentState(0xf, VK_FALSE);
		VkPipelineColorBlendStateCreateInfo colorBlendState = vks::initializers::pipelineColorBlendStateCreateInfo(1, &blendAttachmentState);
		VkPipelineDepthStencilStateCreateInfo depthStencilState = vks::initializers::pipelineDepthStencilStateCreateInfo(VK_TRUE, VK_TRUE, VK_COMPARE_OP_LESS_OR_EQUAL);
		VkPipelineViewportStateCreateInfo viewportState = vks::initializers::pipelineViewportStateCreateInfo(1, 1, 0);
		VkPipelineMultisampleStateCreateInfo multisampleState = vks::initializers::pipelineMultisampleStateCreateInfo(VK_SAMPLE_COUNT_1_BIT, 0);
		std::vector<VkDynamicState> dynamicStateEnables = { VK_DYNAMIC_STATE_VIEWPORT, VK_DYNAMIC_STATE_SCISSOR };
		VkPipelineDynamicStateCreateInfo dynamicState = vks::initializers::pipelineDynamicStateCreateInfo(dynamicStateEnables);
		std::array<VkPipelineShaderStageCreateInfo, 2> shaderStages{};

		// Vertex bindings and attributes
		VkVertexInputBindingDescription vertexInputBinding = { 
			vks::initializers::vertexInputBindingDescription(0, sizeof(Vertex), VK_VERTEX_INPUT_RATE_VERTEX)
		};
		std::vector<VkVertexInputAttributeDescription> vertexInputAttributes = {
			vks::initializers::vertexInputAttributeDescription(0, 0, VK_FORMAT_R32G32B32_SFLOAT, offsetof(Vertex, pos)),	// Location 0 : Position
			vks::initializers::vertexInputAttributeDescription(0, 1, VK_FORMAT_R32G32B32_SFLOAT, offsetof(Vertex, color)),	// Location 1 : Color
		};
		VkPipelineVertexInputStateCreateInfo vertexInputStateCI = vks::initializers::pipelineVertexInputStateCreateInfo();
		vertexInputStateCI.vertexBindingDescriptionCount = 1;
		vertexInputStateCI.pVertexBindingDescriptions = &vertexInputBinding;
		vertexInputStateCI.vertexAttributeDescriptionCount = static_cast<uint32_t>(vertexInputAttributes.size());
		vertexInputStateCI.pVertexAttributeDescriptions = vertexInputAttributes.data();

		shaderStages[0] = loadShader(getShadersPath() + "dynamicuniformbuffer/base.vert.spv", VK_SHADER_STAGE_VERTEX_BIT);
		shaderStages[1] = loadShader(getShadersPath() + "dynamicuniformbuffer/base.frag.spv", VK_SHADER_STAGE_FRAGMENT_BIT);

		VkGraphicsPipelineCreateInfo pipelineCreateInfo = vks::initializers::pipelineCreateInfo(pipelineLayout, renderPass, 0);
		pipelineCreateInfo.pVertexInputState = &vertexInputStateCI;
		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();
		VK_CHECK_RESULT(vkCreateGraphicsPipelines(device, pipelineCache, 1, &pipelineCreateInfo, nullptr, &pipeline));
	}

	// Prepare and initialize uniform buffer containing shader uniforms
	void prepareUniformBuffers()
	{
		// Allocate data for the dynamic uniform buffer object
		// We allocate this manually as the alignment of the offset differs between GPUs

		// Calculate required alignment based on minimum device offset alignment
		size_t minUboAlignment = vulkanDevice->properties.limits.minUniformBufferOffsetAlignment;
		dynamicAlignment = sizeof(glm::mat4);
		if (minUboAlignment > 0) {
			dynamicAlignment = (dynamicAlignment + minUboAlignment - 1) & ~(minUboAlignment - 1);
		}

		size_t bufferSize = OBJECT_INSTANCES * dynamicAlignment;

		uboDataDynamic.model = (glm::mat4*)alignedAlloc(bufferSize, dynamicAlignment);
		assert(uboDataDynamic.model);

		std::cout << "minUniformBufferOffsetAlignment = " << minUboAlignment << std::endl;
		std::cout << "dynamicAlignment = " << dynamicAlignment << std::endl;

		for (auto& buffer : uniformBuffers) {
			// Static shared uniform buffer object with projection and view matrix
			VK_CHECK_RESULT(vulkanDevice->createBuffer(
				VK_BUFFER_USAGE_UNIFORM_BUFFER_BIT,
				VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT | VK_MEMORY_PROPERTY_HOST_COHERENT_BIT,
				&buffer.view,
				sizeof(uboVS)));

			// Uniform buffer object with per-object matrices
			VK_CHECK_RESULT(vulkanDevice->createBuffer(
				VK_BUFFER_USAGE_UNIFORM_BUFFER_BIT,
				VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT,
				&buffer.dynamic,
				bufferSize));

			// Override descriptor range to [base, base + dynamicAlignment]
			buffer.dynamic.descriptor.range = dynamicAlignment;

			// Map persistent
			VK_CHECK_RESULT(buffer.view.map());
			VK_CHECK_RESULT(buffer.dynamic.map());
		}

		// Prepare per-object matrices with offsets and random rotations
		std::default_random_engine rndEngine(benchmark.active ? 0 : (unsigned)time(nullptr));
		std::normal_distribution<float> rndDist(-1.0f, 1.0f);
		for (uint32_t i = 0; i < OBJECT_INSTANCES; i++) {
			rotations[i] = glm::vec3(rndDist(rndEngine), rndDist(rndEngine), rndDist(rndEngine)) * 2.0f * (float)M_PI;
			rotationSpeeds[i] = glm::vec3(rndDist(rndEngine), rndDist(rndEngine), rndDist(rndEngine));
		}
	}

	void updateUniformBuffers()
	{
		// Fixed ubo with projection and view matrices
		uboVS.projection = camera.matrices.perspective;
		uboVS.view = camera.matrices.view;
		memcpy(uniformBuffers[currentBuffer].view.mapped, &uboVS, sizeof(uboVS));
	}

	void updateDynamicUniformBuffer()
	{
		// Dynamic ubo with per-object model matrices indexed by offsets in the command buffer
		uint32_t dim = static_cast<uint32_t>(pow(OBJECT_INSTANCES, (1.0f / 3.0f)));
		glm::vec3 offset(5.0f);
		for (uint32_t x = 0; x < dim; x++) {
			for (uint32_t y = 0; y < dim; y++) {
				for (uint32_t z = 0; z < dim; z++) {
					const uint32_t index = x * dim * dim + y * dim + z;

					// Aligned offset
					glm::mat4* modelMat = (glm::mat4*)(((uint64_t)uboDataDynamic.model + (index * dynamicAlignment)));

					// Update rotations
					rotations[index] += frameTimer * rotationSpeeds[index];

					// Update matrices
					glm::vec3 pos = glm::vec3(-((dim * offset.x) / 2.0f) + offset.x / 2.0f + x * offset.x, -((dim * offset.y) / 2.0f) + offset.y / 2.0f + y * offset.y, -((dim * offset.z) / 2.0f) + offset.z / 2.0f + z * offset.z);
					*modelMat = glm::translate(glm::mat4(1.0f), pos);
					*modelMat = glm::rotate(*modelMat, rotations[index].x, glm::vec3(1.0f, 1.0f, 0.0f));
					*modelMat = glm::rotate(*modelMat, rotations[index].y, glm::vec3(0.0f, 1.0f, 0.0f));
					*modelMat = glm::rotate(*modelMat, rotations[index].z, glm::vec3(0.0f, 0.0f, 1.0f));
				}
			}
		}
		memcpy(uniformBuffers[currentBuffer].dynamic.mapped, uboDataDynamic.model, uniformBuffers[currentBuffer].dynamic.size);
		// Flush to make changes visible to the host
		VkMappedMemoryRange memoryRange = vks::initializers::mappedMemoryRange();
		memoryRange.memory = uniformBuffers[currentBuffer].dynamic.memory;
		memoryRange.size = uniformBuffers[currentBuffer].dynamic.size;
		vkFlushMappedMemoryRanges(device, 1, &memoryRange);
	}

	void prepare()
	{
		VulkanExampleBase::prepare();
		generateCube();
		prepareUniformBuffers();
		setupDescriptors();
		preparePipelines();
		prepared = true;
	}

	void buildCommandBuffer()
	{
		VkCommandBuffer cmdBuffer = drawCmdBuffers[currentBuffer];
		
		VkCommandBufferBeginInfo cmdBufInfo = vks::initializers::commandBufferBeginInfo();

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

		VkRenderPassBeginInfo renderPassBeginInfo = vks::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;
		renderPassBeginInfo.framebuffer = frameBuffers[currentImageIndex];

		VK_CHECK_RESULT(vkBeginCommandBuffer(cmdBuffer, &cmdBufInfo));

		vkCmdBeginRenderPass(cmdBuffer, &renderPassBeginInfo, VK_SUBPASS_CONTENTS_INLINE);

		VkViewport viewport = vks::initializers::viewport((float)width, (float)height, 0.0f, 1.0f);
		vkCmdSetViewport(cmdBuffer, 0, 1, &viewport);

		VkRect2D scissor = vks::initializers::rect2D(width, height, 0, 0);
		vkCmdSetScissor(cmdBuffer, 0, 1, &scissor);

		vkCmdBindPipeline(cmdBuffer, VK_PIPELINE_BIND_POINT_GRAPHICS, pipeline);

		VkDeviceSize offsets[1] = { 0 };
		vkCmdBindVertexBuffers(cmdBuffer, 0, 1, &vertexBuffer.buffer, offsets);
		vkCmdBindIndexBuffer(cmdBuffer, indexBuffer.buffer, 0, VK_INDEX_TYPE_UINT32);

		// Render multiple objects using different model matrices by dynamically offsetting into one uniform buffer
		for (uint32_t j = 0; j < OBJECT_INSTANCES; j++) {
			// One dynamic offset per dynamic descriptor to offset into the ubo containing all model matrices
			uint32_t dynamicOffset = j * static_cast<uint32_t>(dynamicAlignment);
			// Bind the descriptor set for rendering a mesh using the dynamic offset
			vkCmdBindDescriptorSets(cmdBuffer, VK_PIPELINE_BIND_POINT_GRAPHICS, pipelineLayout, 0, 1, &descriptorSet, 1, &dynamicOffset);

			vkCmdDrawIndexed(cmdBuffer, indexCount, 1, 0, 0, 0);
		}

		drawUI(cmdBuffer);

		vkCmdEndRenderPass(cmdBuffer);

		VK_CHECK_RESULT(vkEndCommandBuffer(cmdBuffer));
	}

	virtual void render()
	{
		if (!prepared)
			return;
		VulkanExampleBase::prepareFrame();
		updateUniformBuffers();
		updateDynamicUniformBuffer();
		buildCommandBuffer();
		VulkanExampleBase::submitFrame();
	}
};

VULKAN_EXAMPLE_MAIN()