Android游戏市场越来越大，游戏性能的优化也变得愈发重要。Android平台上的游戏开发通常采用OpenGL ES，但是随着硬件和驱动的升级，Vulkan成为了Android游戏开发的更好选择。本文将详细介绍如何使用Vulkan提高Android游戏的性能。
一、Vulkan简介
Vulkan是一种新的图形API，被设计用于提供高性能的图形和计算处理。Vulkan能够更好地利用多核CPU和GPU，显著提高游戏性能。Vulkan还具有更大的灵活性，使开发人员可以更好地控制硬件资源。
Vulkan与OpenGL ES最大的不同是其更为底层的编程接口。OpenGL ES可以被描述为一个状态机，应用程序通过设置一些状态以控制OpenGL ES的行为。但在Vulkan中，应用程序必须以更为严谨的方式来描述渲染和计算操作。
二、使用Vulkan提高Android游戏性能的方法
1、利用多线程的实现
由于Vulkan使用多个线程来执行渲染和计算操作，因此开发人员可以利用多线程来优化Android游戏的性能。例如，可以使用Vulkan中的异步渲染技术，在渲染线程中渲染新的帧，在另一个线程中提交命令缓冲区。
2、使用Vulkan的扩展
Vulkan具有许多扩展，可用于优化Android游戏性能。例如，VK_KHR_maintenance1扩展可以增加绘图管线的性能，VK_KHR_get_memory_requirements2扩展可以增加内存分配的效率等等。开发人员可以针对自己的需求选择不同的扩展。
3、使用Vulkan的低层次优化
Vulkan提供了多种低层次优化技术，如显式同步、细粒度控制、优化图形管线等，开发人员可以根据自己的需求选择合适的优化方式。
三、Vulkan代码实例
// 1. 创建 Vulkan 实例
VkInstance instance;
VkApplicationInfo appInfo = {};
appInfo.sType = VK_STRUCTURE_TYPE_APPLICATION_INFO;
appInfo.pApplicationName = "My Application";
appInfo.applicationVersion = VK_MAKE_VERSION(1, 0, 0);
appInfo.pEngineName = "No Engine";
appInfo.engineVersion = VK_MAKE_VERSION(1, 0, 0);
appInfo.apiVersion = VK_API_VERSION_1_0;
VkInstanceCreateInfo createInfo = {};
createInfo.sType = VK_STRUCTURE_TYPE_INSTANCE_CREATE_INFO;
createInfo.pApplicationInfo = &appInfo;
vkCreateInstance(&createInfo, nullptr, &instance);
// 2. 获取 Vulkan 物理设备
VkPhysicalDevice physicalDevice;
uint32_t deviceCount = 0;
vkEnumeratePhysicalDevices(instance, &deviceCount, nullptr);
if (deviceCount == 0) {
throw std::runtime_error("failed to find GPUs with Vulkan support!");
}
std::vector devices(deviceCount);
vkEnumeratePhysicalDevices(instance, &deviceCount, devices.data());
for (const auto& device : devices) {
if (isDeviceSuitable(device)) {
physicalDevice = device;
break;
}
}
if (physicalDevice == VK_NULL_HANDLE) {
throw std::runtime_error("failed to find a suitable GPU!");
}
// 3. 创建 Vulkan 设备
VkDevice device;
QueueFamilyIndices indices = findQueueFamilies(physicalDevice);
std::vector
queueCreateInfos;
std::set
uniqueQueueFamilies = {indices.graphicsFamily.value(), indices.presentFamily.value()};
float queuePriority = 1.0f;
for (int queueFamily : uniqueQueueFamilies) {
VkDeviceQueueCreateInfo queueCreateInfo = {};
queueCreateInfo.sType = VK_STRUCTURE_TYPE_DEVICE_QUEUE_CREATE_INFO;
queueCreateInfo.queueFamilyIndex = queueFamily;
queueCreateInfo.queueCount = 1;
queueCreateInfo.pQueuePriorities = &queuePriority;
queueCreateInfos.push_back(queueCreateInfo);
}
VkPhysicalDeviceFeatures deviceFeatures = {};
VkDeviceCreateInfo createInfo = {};
createInfo.sType = VK_STRUCTURE_TYPE_DEVICE_CREATE_INFO;
createInfo.pQueueCreateInfos = queueCreateInfos.data();
createInfo.queueCreateInfoCount = static_cast
(queueCreateInfos.size());
createInfo.pEnabledFeatures = &deviceFeatures;
createInfo.enabledExtensionCount = static_cast
(deviceExtensions.size());
createInfo.ppEnabledExtensionNames = deviceExtensions.data();
if (enableValidationLayers) {
createInfo.enabledLayerCount = static_cast
(validationLayers.size()); createInfo.ppEnabledLayerNames = validationLayers.data(); } else { createInfo.enabledLayerCount = 0; } if (vkCreateDevice(physicalDevice, &createInfo, nullptr, &device) != VK_SUCCESS) { throw std::runtime_error("failed to create logical device!"); } // 4. 创建 Vulkan 渲染流程 VkRenderPass renderPass; VkAttachmentDescription colorAttachment = {}; colorAttachment.format = swapChainImageFormat; colorAttachment.samples = VK_SAMPLE_COUNT_1_BIT; colorAttachment.loadOp = VK_ATTACHMENT_LOAD_OP_CLEAR; colorAttachment.storeOp = VK_ATTACHMENT_STORE_OP_STORE; colorAttachment.stencilLoadOp = VK_ATTACHMENT_LOAD_OP_DONT_CARE; colorAttachment.stencilStoreOp = VK_ATTACHMENT_STORE_OP_DONT_CARE; colorAttachment.initialLayout = VK_IMAGE_LAYOUT_UNDEFINED; colorAttachment.finalLayout = VK_IMAGE_LAYOUT_PRESENT_SRC_KHR; VkAttachmentReference colorAttachmentRef = {}; colorAttachmentRef.attachment = 0; colorAttachmentRef.layout = VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL; VkSubpassDescription subpass = {}; subpass.pipelineBindPoint = VK_PIPELINE_BIND_POINT_GRAPHICS; subpass.colorAttachmentCount = 1; subpass.pColorAttachments = &colorAttachmentRef; VkRenderPassCreateInfo renderPassInfo = {}; renderPassInfo.sType = VK_STRUCTURE_TYPE_RENDER_PASS_CREATE_INFO; renderPassInfo.attachmentCount = 1; renderPassInfo.pAttachments = &colorAttachment; renderPassInfo.subpassCount = 1; renderPassInfo.pSubpasses = &subpass; if (vkCreateRenderPass(device, &renderPassInfo, nullptr, &renderPass) != VK_SUCCESS) { throw std::runtime_error("failed to create render pass!"); } // 5. 创建 Vulkan 图形管线 VkPipeline pipeline; auto vertShaderCode = readFile("shaders/vert.spv"); auto fragShaderCode = readFile("shaders/frag.spv"); VkShaderModule vertShaderModule = createShaderModule(vertShaderCode); VkShaderModule fragShaderModule = createShaderModule(fragShaderCode); VkPipelineShaderStageCreateInfo vertShaderStageInfo = {}; vertShaderStageInfo.sType = VK_STRUCTURE_TYPE_PIPELINE_SHADER_STAGE_CREATE_INFO; vertShaderStageInfo.stage = VK_SHADER_STAGE_VERTEX_BIT; vertShaderStageInfo.module = vertShaderModule; vertShaderStageInfo.pName = "main"; VkPipelineShaderStageCreateInfo fragShaderStageInfo = {}; fragShaderStageInfo.sType = VK_STRUCTURE_TYPE_PIPELINE_SHADER_STAGE_CREATE_INFO; fragShaderStageInfo.stage = VK_SHADER_STAGE_FRAGMENT_BIT; fragShaderStageInfo.module = fragShaderModule; fragShaderStageInfo.pName = "main"; VkPipelineShaderStageCreateInfo shaderStages[] = {vertShaderStageInfo, fragShaderStageInfo}; auto bindingDescription = Vertex::getBindingDescription(); auto attributeDescriptions = Vertex::getAttributeDescriptions(); VkPipelineVertexInputStateCreateInfo vertexInputInfo = {}; vertexInputInfo.sType = VK_STRUCTURE_TYPE_PIPELINE_VERTEX_INPUT_STATE_CREATE_INFO; vertexInputInfo.vertexBindingDescriptionCount = 1; vertexInputInfo.vertexAttributeDescriptionCount = static_cast
(attributeDescriptions.size()); vertexInputInfo.pVertexBindingDescriptions = &bindingDescription; vertexInputInfo.pVertexAttributeDescriptions = attributeDescriptions.data(); VkPipelineInputAssemblyStateCreateInfo inputAssembly = {}; inputAssembly.sType = VK_STRUCTURE_TYPE_PIPELINE_INPUT_ASSEMBLY_STATE_CREATE_INFO; inputAssembly.topology = VK_PRIMITIVE_TOPOLOGY_TRIANGLE_LIST; inputAssembly.primitiveRestartEnable = VK_FALSE; VkViewport viewport = {}; viewport.x = 0.0f; viewport.y = 0.0f; viewport.width = (float)swapChainExtent.width; viewport.height = (float)swapChainExtent.height; viewport.minDepth = 0.0f; viewport.maxDepth = 1.0f; VkRect2D scissor = {}; scissor.offset = {0, 0}; scissor.extent = swapChainExtent; VkPipelineViewportStateCreateInfo viewportState = {}; viewportState.sType = VK_STRUCTURE_TYPE_PIPELINE_VIEWPORT_STATE_CREATE_INFO; viewportState.viewportCount = 1; viewportState.pViewports = &viewport; viewportState.scissorCount = 1; viewportState.pScissors = &scissor; VkPipelineRasterizationStateCreateInfo rasterizer = {}; rasterizer.sType = VK_STRUCTURE_TYPE_PIPELINE_RASTERIZATION_STATE_CREATE_INFO; rasterizer.depthClampEnable = VK_FALSE; rasterizer.rasterizerDiscardEnable = VK_FALSE; rasterizer.polygonMode = VK_POLYGON_MODE_FILL; rasterizer.lineWidth = 1.0f; rasterizer.cullMode = VK_CULL_MODE_BACK_BIT; rasterizer.frontFace = VK_FRONT_FACE_CLOCKWISE; rasterizer.depthBiasEnable = VK_FALSE; rasterizer.depthBiasConstantFactor = 0.0f; rasterizer.depthBiasClamp = 0.0f; rasterizer.depthBiasSlopeFactor = 0.0f; VkPipelineMultisampleStateCreateInfo multisampling = {}; multisampling.sType = VK_STRUCTURE_TYPE_PIPELINE_MULTISAMPLE_STATE_CREATE_INFO; multisampling.sampleShadingEnable = VK_FALSE; multisampling.rasterizationSamples = VK_SAMPLE_COUNT_1_BIT; multisampling.minSampleShading = 1.0f; multisampling.pSampleMask = nullptr; multisampling.alphaToCoverageEnable = VK_FALSE; multisampling.alphaToOneEnable = VK_FALSE; VkPipelineColorBlendAttachmentState colorBlendAttachment = {}; colorBlendAttachment.colorWriteMask = VK_COLOR_COMPONENT_R_BIT | VK_COLOR_COMPONENT_G_BIT | VK_COLOR_COMPONENT_B_BIT | VK_COLOR_COMPONENT_A_BIT; colorBlendAttachment.blendEnable = VK_FALSE; VkPipelineColorBlendStateCreateInfo colorBlending = {}; colorBlending.sType = VK_STRUCTURE_TYPE_PIPELINE_COLOR_BLEND_STATE_CREATE_INFO; colorBlending.logicOpEnable = VK_FALSE; colorBlending.logicOp = VK_LOGIC_OP_COPY; colorBlending.attachmentCount = 1; colorBlending.pAttachments = &colorBlendAttachment; VkPipelineLayoutCreateInfo pipelineLayoutInfo = {}; pipelineLayoutInfo.sType = VK_STRUCTURE_TYPE_PIPELINE_LAYOUT_CREATE_INFO; pipelineLayoutInfo.setLayoutCount = 0; pipelineLayoutInfo.pSetLayouts = nullptr; pipelineLayoutInfo.pushConstantRangeCount = 0; pipelineLayoutInfo.pPushConstantRanges = nullptr; if (vkCreatePipelineLayout(device, &pipelineLayoutInfo, nullptr, &pipelineLayout) != VK_SUCCESS) { throw std::runtime_error("failed to create pipeline layout!"); } VkGraphicsPipelineCreateInfo pipelineInfo = {}; pipelineInfo.sType = VK_STRUCTURE_TYPE_GRAPHICS_PIPELINE_CREATE_INFO; pipelineInfo.stageCount = 2; pipelineInfo.pStages = shaderStages; pipelineInfo.pVertexInputState = &vertexInputInfo; pipelineInfo.pInputAssemblyState = &inputAssembly; pipelineInfo.pViewportState = &viewportState; pipelineInfo.pRasterizationState = &rasterizer; pipelineInfo.pMultisampleState = &multisampling; pipelineInfo.pDepthStencilState = nullptr; pipelineInfo.pColorBlendState = &colorBlending; pipelineInfo.pDynamicState = nullptr; pipelineInfo.layout = pipelineLayout; pipelineInfo.renderPass = renderPass; pipelineInfo.subpass = 0; if (vkCreateGraphicsPipelines(device, VK_NULL_HANDLE, 1, &pipelineInfo, nullptr, &pipeline) != VK_SUCCESS) { throw std::runtime_error("failed to create graphics pipeline!"); } vkDestroyShaderModule(device, fragShaderModule, nullptr); vkDestroyShaderModule(device, vertShaderModule, nullptr);
结论
Vulkan可以显著提高Android游戏的性能。通过多线程实现、使用Vulkan扩展和低层次优化等方式，开发人员可以很容易地将性能提升到一个新的水平。使用Vulkan的代码示例也展示了Vulkan的简单易用性，使开发人员可以更加高效地开发Android游戏。
