Initial commit that renders two triangles

.gitignore

@@ -0,0 +1,4 @@
+subpass
+subpass.png
+subpass.vert.spv
+subpass.frag.spv

Makefile

@@ -0,0 +1,63 @@
+ifeq ($(target), cheza)
+	CXX = /usr/bin/armv7a-cros-linux-gnueabihf-clang++
+	CC = /usr/bin/armv7a-cros-linux-gnueabihf-clang
+	SYSROOT = /build/cheza
+	SSH_DUT = cheza
+else ifeq ($(target), atlas)
+	CXX = /usr/bin/x86_64-cros-linux-gnu-clang++
+	CC = /usr/bin/x86_64-cros-linux-gnu-clang
+	SYSROOT = /build/atlas
+	SSH_DUT = atlas
+else ifeq ($(target), local)
+	CXX = clang++
+	CC = clang
+else
+	CXX = INVALID
+	CC = INVALID
+endif
+
+SUBDIR = "subpass/"
+NAME = subpass
+CFLAGS = -std=c++17 --sysroot="$(SYSROOT)" -Wall
+LDFLAGS = -lvulkan -lpng
+
+all: build deploy run
+
+build: check
+	@echo Building...
+	@$(CXX) $(CFLAGS) -o ${NAME} ${NAME}.cc $(LDFLAGS)
+
+deploy: check
+ifneq ($(target), local)
+	@echo Deploying to $(SSH_DUT)...
+	@scp ${NAME}.vert.spv $(SSH_DUT):~/${SUBDIR}${NAME}.vert.spv
+	@scp ${NAME}.frag.spv $(SSH_DUT):~/${SUBDIR}${NAME}.frag.spv
+	@scp ${NAME} $(SSH_DUT):~/${SUBDIR}
+endif
+
+run: check
+ifneq ($(target), local)
+	@echo Running on $(SSH_DUT)...
+	@ssh $(SSH_DUT) 'cd ~/${SUBDIR} && ./${NAME}'
+	@echo Copying artifacts back to local device...
+	@scp $(SSH_DUT):~/${SUBDIR}${NAME}.png .
+else
+	@echo Running locally...
+	@./$(NAME)
+endif
+
+shaders:
+	@glslc -c ${NAME}.vert
+	@glslc -c ${NAME}.frag
+
+clean: check
+	@rm -f ${NAME} ${NAME}.png ${NAME}.vert.spv ${NAME}.frag.spv
+ifneq ($(target), local)
+	@ssh $(SSH_DUT) 'rm -f ~/${SUBDIR}${NAME} ~/${SUBDIR}${NAME}.png \
+		 ~/${SUBDIR}${NAME}.vert.spv ~/${SUBDIR}${NAME}.frag.spv'
+endif
+
+check:
+ifeq ($(CXX), INVALID)
+	$(error $$target must be one of [atlas, cheza, local] )
+endif

README.md

@@ -0,0 +1,10 @@
+# Vulkan subpass demo
+
+## Overview
+This repo contains the source for a Vulkan applicaiton that renders a triangle in one subpass, and in the next, darkens it. The application then saves the output as a PNG.
+
+## Instructions
+- Enter the CrOS chroot and set up the boards you want to test against (`setup_board --board=${BOARD}`).
+- Emerge Vulkan, mesa, and libpng to the device under test (`emerge vulkan-loader media-libs/mesa libpng && cros deploy ${IP_ADDR} ${PACKAGES}`).
+- `make shaders`
+- `target={local, atlas (i915), cheza (adreno)} make`

subpass.cc

@@ -0,0 +1,704 @@
+#include <png.h>
+#include <vulkan/vulkan.h>
+
+#include <array>
+#include <fstream>
+#include <iostream>
+#include <sstream>
+#include <string>
+#include <vector>
+
+const uint32_t kWidth = 256;
+const uint32_t kHeight = 256;
+const VkFormat kVulkanFormat = VK_FORMAT_A8B8G8R8_UNORM_PACK32;
+const VkFormat kVulkanDepthFormat = VK_FORMAT_D32_SFLOAT;
+const std::string kVertexShaderPath = "subpass.vert.spv";
+const std::string kFragmentShaderPath = "subpass.frag.spv";
+
+#define ERROR(message) \
+    std::cerr << message << std::endl; \
+    std::exit(EXIT_FAILURE)
+
+VkInstance CreateVkInstance() {
+  VkApplicationInfo app_info = {};
+  app_info.sType = VK_STRUCTURE_TYPE_APPLICATION_INFO;
+  app_info.apiVersion = VK_API_VERSION_1_1;
+
+  VkInstanceCreateInfo create_info = {};
+  create_info.sType = VK_STRUCTURE_TYPE_INSTANCE_CREATE_INFO;
+  create_info.pApplicationInfo = &app_info;
+  create_info.enabledExtensionCount = 0;
+  create_info.ppEnabledExtensionNames = nullptr;
+  create_info.enabledLayerCount = 0;
+  create_info.ppEnabledLayerNames = nullptr;
+
+  VkInstance instance;
+  VkResult result = vkCreateInstance(&create_info, nullptr, &instance);
+  if (result != VK_SUCCESS) {
+    ERROR("Error creating VkInstance: " << result);
+  }
+  return instance;
+}
+
+VkPhysicalDevice ChooseVkPhysicalDevice(VkInstance instance) {
+  uint32_t device_count = 0;
+  VkResult result = vkEnumeratePhysicalDevices(instance, &device_count, nullptr);
+  if (result != VK_SUCCESS) {
+    ERROR("Error enumerating VkPhysicalDevices: " << result);
+  }
+  if (device_count == 0) {
+    ERROR("No available VkPhysicalDevices");
+  }
+
+  std::vector<VkPhysicalDevice> devices(device_count);
+  result = vkEnumeratePhysicalDevices(instance, &device_count, devices.data());
+  if (result != VK_SUCCESS) {
+    ERROR("Error fetching VkPhysicalDevices: " << result);
+  }
+
+  std::cout << "Found " << device_count << " device(s):" << std::endl;
+  VkPhysicalDevice chosen_device = VK_NULL_HANDLE;
+  for (VkPhysicalDevice device : devices) {
+    VkPhysicalDeviceProperties device_props;
+    vkGetPhysicalDeviceProperties(device, &device_props);
+    std::cout << "\t- " << device_props.deviceName << " [V: " <<
+        VK_VERSION_MAJOR(device_props.apiVersion) << "." <<
+        VK_VERSION_MINOR(device_props.apiVersion) << "." <<
+        VK_VERSION_PATCH(device_props.apiVersion) << "]" << std::endl;
+    // Currently, any device with Vulkan API version 1.1 is fine.
+    if (chosen_device == VK_NULL_HANDLE && device_props.apiVersion >= VK_API_VERSION_1_1) {
+      chosen_device = device;
+    }
+  }
+
+  if (chosen_device == VK_NULL_HANDLE) {
+    ERROR("Unable to find suitable VkPhysicalDevice");
+  }
+  return chosen_device;
+}
+
+uint32_t ChooseDeviceQueueFamilyIndex(VkPhysicalDevice physical_device) {
+  uint32_t props_count;
+  vkGetPhysicalDeviceQueueFamilyProperties(physical_device, &props_count, nullptr);
+  std::vector<VkQueueFamilyProperties> props(props_count);
+  vkGetPhysicalDeviceQueueFamilyProperties(physical_device, &props_count, props.data());
+
+  // Simply choose the first graphics queue.
+  for (size_t i = 0; i < props_count; i++) {
+    const VkQueueFamilyProperties& prop = props[i];
+    if ((prop.queueFlags & VK_QUEUE_GRAPHICS_BIT) && prop.queueCount > 0) {
+      return i;
+    }
+  }
+
+  ERROR("Unable to find suitable queue family");
+}
+
+VkDevice CreateVkDevice(VkPhysicalDevice physical_device, uint32_t device_queue_family_index) {
+  VkDeviceQueueCreateInfo queue_create_info = {};
+  queue_create_info.sType = VK_STRUCTURE_TYPE_DEVICE_QUEUE_CREATE_INFO;
+  queue_create_info.queueFamilyIndex = device_queue_family_index;
+  queue_create_info.queueCount = 1;
+  float queue_priority = 1.0f;
+  queue_create_info.pQueuePriorities = &queue_priority;
+
+  VkDeviceCreateInfo device_create_info = {};
+  device_create_info.sType = VK_STRUCTURE_TYPE_DEVICE_CREATE_INFO;
+  device_create_info.queueCreateInfoCount = 1;
+  device_create_info.pQueueCreateInfos = &queue_create_info;
+  // Let's not use any device extensions for now.
+  device_create_info.enabledExtensionCount = 0;
+  device_create_info.ppEnabledExtensionNames = nullptr;
+
+  VkDevice device;
+  VkResult result = vkCreateDevice(physical_device, &device_create_info, nullptr, &device);
+  if (result != VK_SUCCESS) {
+    ERROR("Unable to create logical device: " << result);
+  }
+  return device;
+}
+
+VkQueue GetVkQueue(VkDevice device, uint32_t device_queue_family_index) {
+  VkQueue queue;
+  vkGetDeviceQueue(device, device_queue_family_index, /*queueIndex*/ 0, &queue);
+  return queue;
+}
+
+VkCommandPool CreateVkCommandPool(VkDevice device, uint32_t device_queue_family_index) {
+  VkCommandPool command_pool;
+  VkCommandPoolCreateInfo create_info = {};
+  create_info.sType = VK_STRUCTURE_TYPE_COMMAND_POOL_CREATE_INFO;
+  create_info.flags = 0;
+  create_info.queueFamilyIndex = device_queue_family_index;
+  VkResult result = vkCreateCommandPool(device, &create_info, nullptr, &command_pool);
+  if (result != VK_SUCCESS) {
+    ERROR("Unable to create command pool: " << result);
+  }
+  return command_pool;
+}
+
+VkCommandBuffer CreateVkCommandBuffer(VkDevice device, VkCommandPool command_pool) {
+  VkCommandBufferAllocateInfo allocate_info = {};
+  allocate_info.sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_ALLOCATE_INFO;
+  allocate_info.commandPool = command_pool;
+  allocate_info.level = VK_COMMAND_BUFFER_LEVEL_PRIMARY;
+  allocate_info.commandBufferCount = 1;
+
+  VkCommandBuffer command_buffer;
+  VkResult result = vkAllocateCommandBuffers( device, &allocate_info, &command_buffer);
+  if (result != VK_SUCCESS) {
+    ERROR("Unable to create VkCommandBuffer: " << result);
+  }
+  return command_buffer;
+}
+
+VkRenderPass CreateVkRenderPass(VkDevice device) {
+  std::array<VkAttachmentDescription, 2> attachment_descriptions = {};
+
+  VkAttachmentDescription* color_attachment_description = &attachment_descriptions[0];
+  color_attachment_description->format = kVulkanFormat;
+  color_attachment_description->samples = VK_SAMPLE_COUNT_1_BIT;
+  color_attachment_description->loadOp = VK_ATTACHMENT_LOAD_OP_CLEAR;
+  color_attachment_description->storeOp = VK_ATTACHMENT_STORE_OP_STORE;
+  color_attachment_description->stencilLoadOp = VK_ATTACHMENT_LOAD_OP_DONT_CARE;
+  color_attachment_description->stencilStoreOp = VK_ATTACHMENT_STORE_OP_DONT_CARE;
+  color_attachment_description->initialLayout = VK_IMAGE_LAYOUT_UNDEFINED;
+  color_attachment_description->finalLayout = VK_IMAGE_LAYOUT_TRANSFER_SRC_OPTIMAL;
+
+  VkAttachmentReference color_attachment_reference = {};
+  color_attachment_reference.attachment = 0;
+  color_attachment_reference.layout = VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL;
+
+  VkAttachmentDescription* depth_attachment_description = &attachment_descriptions[1];
+  depth_attachment_description->format = kVulkanDepthFormat;
+  depth_attachment_description->samples = VK_SAMPLE_COUNT_1_BIT;
+  depth_attachment_description->loadOp = VK_ATTACHMENT_LOAD_OP_CLEAR;
+  depth_attachment_description->storeOp = VK_ATTACHMENT_STORE_OP_DONT_CARE;
+  depth_attachment_description->stencilLoadOp = VK_ATTACHMENT_LOAD_OP_DONT_CARE;
+  depth_attachment_description->stencilStoreOp = VK_ATTACHMENT_STORE_OP_DONT_CARE;
+  depth_attachment_description->initialLayout = VK_IMAGE_LAYOUT_UNDEFINED;
+  depth_attachment_description->finalLayout = VK_IMAGE_LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL;
+
+  VkAttachmentReference depth_attachment_reference = {};
+  depth_attachment_reference.attachment = 1;
+  depth_attachment_reference.layout = VK_IMAGE_LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL;
+
+  VkSubpassDescription subpass_description = {};
+  subpass_description.pipelineBindPoint = VK_PIPELINE_BIND_POINT_GRAPHICS;
+  subpass_description.colorAttachmentCount = 1;
+  subpass_description.pColorAttachments = &color_attachment_reference;
+  subpass_description.pDepthStencilAttachment = &depth_attachment_reference;
+
+  VkSubpassDependency subpass_dependency = {};
+  subpass_dependency.srcSubpass = VK_SUBPASS_EXTERNAL;
+  subpass_dependency.dstSubpass = 0;
+  subpass_dependency.srcStageMask = VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT;
+  subpass_dependency.srcAccessMask = 0;
+  subpass_dependency.dstStageMask = VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT;
+  subpass_dependency.dstAccessMask = VK_ACCESS_COLOR_ATTACHMENT_READ_BIT |
+      VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT;
+
+  VkRenderPassCreateInfo render_pass_info = {};
+  render_pass_info.sType = VK_STRUCTURE_TYPE_RENDER_PASS_CREATE_INFO;
+  render_pass_info.attachmentCount = attachment_descriptions.size();
+  render_pass_info.pAttachments = attachment_descriptions.data();
+  render_pass_info.subpassCount = 1;
+  render_pass_info.pSubpasses = &subpass_description;
+  render_pass_info.dependencyCount = 1;
+  render_pass_info.pDependencies = &subpass_dependency;
+
+  VkRenderPass render_pass;
+  VkResult result = vkCreateRenderPass(device, &render_pass_info, nullptr, &render_pass);
+  if (result != VK_SUCCESS) {
+    ERROR("Unable to create render pass: " << result);
+  }
+  return render_pass;
+}
+
+VkShaderModule CreateVkShaderModule(VkDevice device, std::string path) {
+  std::ifstream fstream(path);
+  if (!fstream) {
+    ERROR("Unable to open: " << path);
+  }
+  std::stringstream buffer;
+  buffer << fstream.rdbuf();
+  std::string spirv_source = buffer.str();
+
+  VkShaderModuleCreateInfo create_info = {};
+  create_info.sType = VK_STRUCTURE_TYPE_SHADER_MODULE_CREATE_INFO;
+  create_info.codeSize = spirv_source.length();
+  create_info.pCode = (const uint32_t*)spirv_source.c_str();
+
+  VkShaderModule shader_module;
+  VkResult result = vkCreateShaderModule(device, &create_info, nullptr, &shader_module);
+  if (result != VK_SUCCESS) {
+    ERROR("Unable to create shader module for " << path << ": ");
+  }
+  return shader_module;
+}
+
+VkPipeline CreateVkPipeline(VkDevice device, VkRenderPass render_pass) {
+  VkShaderModule vertex_shader_module = CreateVkShaderModule(device, kVertexShaderPath);
+  VkShaderModule fragment_shader_module = CreateVkShaderModule(device, kFragmentShaderPath);
+
+  VkPipelineShaderStageCreateInfo vertex_shader_stage_info = {};
+  vertex_shader_stage_info.sType = VK_STRUCTURE_TYPE_PIPELINE_SHADER_STAGE_CREATE_INFO;
+  vertex_shader_stage_info.stage = VK_SHADER_STAGE_VERTEX_BIT;
+  vertex_shader_stage_info.module = vertex_shader_module;
+  vertex_shader_stage_info.pName = "main";
+
+  VkPipelineShaderStageCreateInfo fragment_shader_stage_info = {};
+  fragment_shader_stage_info.sType = VK_STRUCTURE_TYPE_PIPELINE_SHADER_STAGE_CREATE_INFO;
+  fragment_shader_stage_info.stage = VK_SHADER_STAGE_FRAGMENT_BIT;
+  fragment_shader_stage_info.module = fragment_shader_module;
+  fragment_shader_stage_info.pName = "main";
+
+  std::vector<VkPipelineShaderStageCreateInfo> shader_stages =
+      {vertex_shader_stage_info, fragment_shader_stage_info};
+
+  VkPipelineVertexInputStateCreateInfo vertex_input_info = {};
+  vertex_input_info.sType = VK_STRUCTURE_TYPE_PIPELINE_VERTEX_INPUT_STATE_CREATE_INFO;
+  vertex_input_info.vertexBindingDescriptionCount = 0;
+  vertex_input_info.pVertexBindingDescriptions = nullptr;
+  vertex_input_info.vertexAttributeDescriptionCount = 0;
+  vertex_input_info.pVertexAttributeDescriptions = nullptr;
+
+  VkPipelineInputAssemblyStateCreateInfo input_assembly_info = {};
+  input_assembly_info.sType = VK_STRUCTURE_TYPE_PIPELINE_INPUT_ASSEMBLY_STATE_CREATE_INFO;
+  input_assembly_info.topology = VK_PRIMITIVE_TOPOLOGY_TRIANGLE_LIST;
+  input_assembly_info.primitiveRestartEnable = VK_FALSE;
+
+  VkViewport viewport = {};
+  viewport.x = 0.0f;
+  viewport.y = 0.0f;
+  viewport.width = (float)kWidth;
+  viewport.height = (float)kHeight;
+  viewport.minDepth = 0.0f;
+  viewport.maxDepth = 1.0f;
+
+  VkExtent2D extent = {};
+  extent.width = kWidth;
+  extent.height = kHeight;
+  VkRect2D scissor = {};
+  scissor.offset = {0, 0};
+  scissor.extent = extent;
+
+  VkPipelineViewportStateCreateInfo viewport_state_info = {};
+  viewport_state_info.sType = VK_STRUCTURE_TYPE_PIPELINE_VIEWPORT_STATE_CREATE_INFO;
+  viewport_state_info.viewportCount = 1;
+  viewport_state_info.pViewports = &viewport;
+  viewport_state_info.scissorCount = 1;
+  viewport_state_info.pScissors = &scissor;
+
+  VkPipelineRasterizationStateCreateInfo rasterization_state_info = {};
+  rasterization_state_info.sType = VK_STRUCTURE_TYPE_PIPELINE_RASTERIZATION_STATE_CREATE_INFO;
+  rasterization_state_info.depthClampEnable = VK_FALSE;
+  rasterization_state_info.rasterizerDiscardEnable = VK_FALSE;
+  rasterization_state_info.polygonMode = VK_POLYGON_MODE_FILL;
+  rasterization_state_info.lineWidth = 1.0f;
+  rasterization_state_info.cullMode = VK_CULL_MODE_BACK_BIT;
+  rasterization_state_info.frontFace = VK_FRONT_FACE_CLOCKWISE;
+  rasterization_state_info.depthBiasEnable = VK_FALSE;
+
+  VkPipelineMultisampleStateCreateInfo multisampling_state_info = {};
+  multisampling_state_info.sType = VK_STRUCTURE_TYPE_PIPELINE_MULTISAMPLE_STATE_CREATE_INFO;
+  multisampling_state_info.sampleShadingEnable = VK_FALSE;
+  multisampling_state_info.rasterizationSamples = VK_SAMPLE_COUNT_1_BIT;
+
+  VkPipelineDepthStencilStateCreateInfo depth_stencil_create_info = {};
+  depth_stencil_create_info.sType = VK_STRUCTURE_TYPE_PIPELINE_DEPTH_STENCIL_STATE_CREATE_INFO;
+  depth_stencil_create_info.depthTestEnable = VK_TRUE;
+  depth_stencil_create_info.depthWriteEnable = VK_TRUE;
+  depth_stencil_create_info.depthCompareOp = VK_COMPARE_OP_LESS;
+  // TODO(brkho): Test depth bounds functionality.
+  depth_stencil_create_info.depthBoundsTestEnable = VK_FALSE;
+  depth_stencil_create_info.minDepthBounds = 0.0f;
+  depth_stencil_create_info.maxDepthBounds = 1.0f;
+  depth_stencil_create_info.stencilTestEnable = VK_FALSE;
+
+  VkPipelineColorBlendAttachmentState color_blend_attachment_state = {};
+  color_blend_attachment_state.colorWriteMask = VK_COLOR_COMPONENT_R_BIT |
+      VK_COLOR_COMPONENT_G_BIT | VK_COLOR_COMPONENT_B_BIT | VK_COLOR_COMPONENT_A_BIT;
+  color_blend_attachment_state.blendEnable = VK_FALSE;
+
+  VkPipelineColorBlendStateCreateInfo color_blend_state = {};
+  color_blend_state.sType = VK_STRUCTURE_TYPE_PIPELINE_COLOR_BLEND_STATE_CREATE_INFO;
+  color_blend_state.logicOpEnable = VK_FALSE;
+  color_blend_state.attachmentCount = 1;
+  color_blend_state.pAttachments = &color_blend_attachment_state;
+
+  VkPipelineLayoutCreateInfo pipeline_layout_create_info = {};
+  pipeline_layout_create_info.sType = VK_STRUCTURE_TYPE_PIPELINE_LAYOUT_CREATE_INFO;
+
+  VkPipelineLayout pipeline_layout;
+  VkResult result = vkCreatePipelineLayout(device, &pipeline_layout_create_info, nullptr,
+      &pipeline_layout);
+  if (result != VK_SUCCESS) {
+    ERROR("Unable to create VkPipelineLayout: " << result);
+  }
+
+  VkGraphicsPipelineCreateInfo pipeline_create_info = {};
+  pipeline_create_info.sType = VK_STRUCTURE_TYPE_GRAPHICS_PIPELINE_CREATE_INFO;
+  pipeline_create_info.stageCount = 2;
+  pipeline_create_info.pStages = shader_stages.data();
+  pipeline_create_info.pVertexInputState = &vertex_input_info;
+  pipeline_create_info.pInputAssemblyState = &input_assembly_info;
+  pipeline_create_info.pViewportState = &viewport_state_info;
+  pipeline_create_info.pRasterizationState = &rasterization_state_info;
+  pipeline_create_info.pMultisampleState = &multisampling_state_info;
+  pipeline_create_info.pDepthStencilState = &depth_stencil_create_info;
+  pipeline_create_info.pColorBlendState = &color_blend_state;
+  pipeline_create_info.pDynamicState = nullptr;
+  pipeline_create_info.layout = pipeline_layout;
+  pipeline_create_info.renderPass = render_pass;
+  pipeline_create_info.subpass = 0;
+  pipeline_create_info.basePipelineHandle = VK_NULL_HANDLE;
+  pipeline_create_info.basePipelineIndex = -1;
+
+  VkPipeline pipeline;
+  result = vkCreateGraphicsPipelines(device, VK_NULL_HANDLE, 1, &pipeline_create_info, nullptr,
+      &pipeline);
+  if (result != VK_SUCCESS) {
+    ERROR("Unable to create VkPipeline: " << result);
+  }
+  return pipeline;
+}
+
+VkImage CreateVkImage(VkDevice device, VkFormat format, VkImageTiling image_tiling,
+    VkImageUsageFlags usage) {
+  VkImageCreateInfo create_info = {};
+  create_info.sType = VK_STRUCTURE_TYPE_IMAGE_CREATE_INFO;
+  create_info.pNext = nullptr;
+  create_info.imageType = VK_IMAGE_TYPE_2D;
+  create_info.format = format;
+  VkExtent3D extent  = {};
+  extent.width = kWidth;
+  extent.height = kHeight;
+  extent.depth = 1;
+  create_info.extent = extent;
+  create_info.mipLevels = 1;
+  create_info.arrayLayers = 1;
+  create_info.samples = VK_SAMPLE_COUNT_1_BIT;
+  create_info.sharingMode = VK_SHARING_MODE_EXCLUSIVE;
+  create_info.tiling = image_tiling;
+  create_info.usage = usage;
+  create_info.initialLayout = VK_IMAGE_LAYOUT_UNDEFINED;
+
+  VkImage image;
+  VkResult result = vkCreateImage(device, &create_info, nullptr, &image);
+  if (result != VK_SUCCESS) {
+    ERROR("Unable to create VkImage: " << result);
+  }
+  return image;
+}
+
+inline VkImage CreateRenderVkImage(VkDevice device) {
+  return CreateVkImage(device, kVulkanFormat, VK_IMAGE_TILING_OPTIMAL,
+      VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT | VK_IMAGE_USAGE_TRANSFER_SRC_BIT);
+}
+
+inline VkImage CreateDepthVkImage(VkDevice device) {
+  return CreateVkImage(device, kVulkanDepthFormat, VK_IMAGE_TILING_OPTIMAL,
+      VK_IMAGE_USAGE_DEPTH_STENCIL_ATTACHMENT_BIT);
+}
+
+inline VkImage CreateScanoutVkImage(VkDevice device) {
+  return CreateVkImage(device, kVulkanFormat, VK_IMAGE_TILING_LINEAR,
+      VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT | VK_IMAGE_USAGE_TRANSFER_DST_BIT);
+}
+
+uint32_t FindMemoryType(uint32_t valid_image_memory_types,
+    VkPhysicalDeviceMemoryProperties device_memory_properties,
+    VkMemoryPropertyFlags memory_property_flags) {
+  for (uint32_t i = 0; i < device_memory_properties.memoryTypeCount; i++) {
+    // We don't care about performance, so just choose the first mappable memory type.
+    if ((valid_image_memory_types & (1 << i)) &&
+        ((device_memory_properties.memoryTypes[i].propertyFlags & memory_property_flags) ==
+        memory_property_flags)) {
+      return i;
+    }
+  }
+  ERROR("Unable to find suitable memory type index");
+}
+
+VkDeviceMemory AllocateAndBindMemory(VkPhysicalDevice physical_device, VkDevice device,
+    VkImage image, VkMemoryPropertyFlags memory_property_flags) {
+  VkMemoryRequirements image_memory_requirements;
+  vkGetImageMemoryRequirements(device, image, &image_memory_requirements);
+
+  VkPhysicalDeviceMemoryProperties device_memory_properties;
+  vkGetPhysicalDeviceMemoryProperties(physical_device, &device_memory_properties);
+
+  VkMemoryAllocateInfo memory_allocate_info = {};
+  memory_allocate_info.sType = VK_STRUCTURE_TYPE_MEMORY_ALLOCATE_INFO;
+  memory_allocate_info.allocationSize = image_memory_requirements.size;
+  memory_allocate_info.memoryTypeIndex = FindMemoryType(
+      image_memory_requirements.memoryTypeBits, device_memory_properties,
+      memory_property_flags);
+
+  VkDeviceMemory image_memory;
+  VkResult result = vkAllocateMemory(device, &memory_allocate_info, nullptr, &image_memory);
+  if (result != VK_SUCCESS) {
+    ERROR("Unable to allocate image memory: " << result);
+  }
+
+  result = vkBindImageMemory(device, image, image_memory, 0);
+  if (result != VK_SUCCESS) {
+    ERROR("Unable to bind image memory: " << result);
+  }
+  return image_memory;
+}
+
+inline VkDeviceMemory AllocateAndBindRenderMemory(VkPhysicalDevice physical_device,
+    VkDevice device, VkImage image) {
+  return AllocateAndBindMemory(physical_device, device, image, VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT);
+}
+
+inline VkDeviceMemory AllocateAndBindDepthMemory(VkPhysicalDevice physical_device,
+    VkDevice device, VkImage image) {
+  return AllocateAndBindMemory(physical_device, device, image, VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT);
+}
+
+inline VkDeviceMemory AllocateAndBindScanoutMemory(VkPhysicalDevice physical_device,
+    VkDevice device, VkImage image) {
+  return AllocateAndBindMemory(physical_device, device, image, VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT);
+}
+
+VkImageView CreateVkImageView(VkDevice device, VkImage image, VkFormat format,
+    VkImageAspectFlags aspect) {
+  VkImageViewCreateInfo create_info = {};
+  create_info.sType = VK_STRUCTURE_TYPE_IMAGE_VIEW_CREATE_INFO;
+  create_info.image = image;
+  create_info.viewType = VK_IMAGE_VIEW_TYPE_2D;
+  create_info.format = format;
+
+  VkComponentMapping component_mapping = {};
+  component_mapping.r = VK_COMPONENT_SWIZZLE_IDENTITY;
+  component_mapping.b = VK_COMPONENT_SWIZZLE_IDENTITY;
+  component_mapping.g = VK_COMPONENT_SWIZZLE_IDENTITY;
+  component_mapping.a = VK_COMPONENT_SWIZZLE_IDENTITY;
+  create_info.components = component_mapping;
+
+  VkImageSubresourceRange subresource_range = {};
+  subresource_range.aspectMask = aspect;
+  subresource_range.baseMipLevel = 0;
+  subresource_range.levelCount = 1;
+  subresource_range.baseArrayLayer = 0;
+  subresource_range.layerCount = 1;
+  create_info.subresourceRange = subresource_range;
+
+  VkImageView image_view;
+  VkResult result = vkCreateImageView(device, &create_info, nullptr, &image_view);
+  if (result != VK_SUCCESS) {
+    ERROR("Unable to create VkImageView: " << result);
+  }
+  return image_view;
+}
+
+VkImageView CreateRenderVkImageView(VkDevice device, VkImage image) {
+  return CreateVkImageView(device, image, kVulkanFormat, VK_IMAGE_ASPECT_COLOR_BIT);
+}
+
+VkImageView CreateDepthVkImageView(VkDevice device, VkImage image) {
+  return CreateVkImageView(device, image, kVulkanDepthFormat, VK_IMAGE_ASPECT_DEPTH_BIT);
+}
+
+VkFramebuffer CreateVkFramebuffer(VkDevice device, VkRenderPass render_pass,
+    VkImageView render_image_view, VkImageView depth_image_view) {
+  std::array<VkImageView, 2> attachments = { render_image_view, depth_image_view };
+
+  VkFramebufferCreateInfo create_info = {};
+  create_info.sType = VK_STRUCTURE_TYPE_FRAMEBUFFER_CREATE_INFO;
+  create_info.renderPass = render_pass;
+  create_info.attachmentCount = attachments.size();
+  create_info.pAttachments = attachments.data();
+  create_info.width = kWidth;
+  create_info.height = kHeight;
+  create_info.layers = 1;
+
+  VkFramebuffer framebuffer;
+  VkResult result = vkCreateFramebuffer(device, &create_info, nullptr, &framebuffer);
+  if (result != VK_SUCCESS) {
+    ERROR("Unable to create VkFramebuffer: " << result);
+  }
+  return framebuffer;
+}
+
+void BeginCommandBuffer(VkCommandBuffer command_buffer) {
+  VkCommandBufferBeginInfo command_buffer_begin_info = {};
+  command_buffer_begin_info.sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_BEGIN_INFO;
+  command_buffer_begin_info.flags = VK_COMMAND_BUFFER_USAGE_ONE_TIME_SUBMIT_BIT;
+  VkResult result = vkBeginCommandBuffer(command_buffer, &command_buffer_begin_info);
+  if (result != VK_SUCCESS) {
+    ERROR("Unable to begin command buffer recording: " << result);
+  }
+}
+
+void EndCommandBufferAndSubmit(VkCommandBuffer command_buffer, VkQueue queue) {
+  VkResult result = vkEndCommandBuffer(command_buffer);
+  if (result != VK_SUCCESS) {
+    ERROR("Unable to end command buffer recording: " << result);
+  }
+
+  VkSubmitInfo submit_info = {};
+  submit_info.sType = VK_STRUCTURE_TYPE_SUBMIT_INFO;
+  submit_info.commandBufferCount = 1;
+  submit_info.pCommandBuffers = &command_buffer;
+  result = vkQueueSubmit(queue, 1, &submit_info, VK_NULL_HANDLE);
+  if (result != VK_SUCCESS) {
+    ERROR("Error in submitting command buffer to queue: " << result);
+  }
+}
+
+void WaitForIdle(VkQueue queue) {
+  // In a real application, we should use real synchronization primitives to figure out when the
+  // command buffers have been executed. Waiting on an idle queue is simple, but it can cause
+  // deadlock if we continue to submit to the queue while we wait for idle.
+  VkResult result = vkQueueWaitIdle(queue);
+  if (result != VK_SUCCESS) {
+    ERROR("Error in waiting for graphics queue to reach idle state: " << result);
+  }
+}
+
+void Draw(VkDevice device, VkQueue queue, VkRenderPass render_pass, VkPipeline pipeline,
+    VkFramebuffer framebuffer, VkCommandBuffer command_buffer) {
+  BeginCommandBuffer(command_buffer);
+  VkRenderPassBeginInfo render_pass_begin_info = {};
+  render_pass_begin_info.sType = VK_STRUCTURE_TYPE_RENDER_PASS_BEGIN_INFO;
+  render_pass_begin_info.renderPass = render_pass;
+  render_pass_begin_info.framebuffer = framebuffer;
+  VkRect2D render_area = {};
+  render_area.offset = { 0, 0 };
+  render_area.extent = { kWidth, kHeight };
+  render_pass_begin_info.renderArea = render_area;
+
+  std::array<VkClearValue, 2> clear_values = {};
+  clear_values[0].color.float32[0] = 1.0f;
+  clear_values[0].color.float32[1] = 1.0f;
+  clear_values[0].color.float32[2] = 1.0f;
+  clear_values[0].color.float32[3] = 1.0f;
+  clear_values[1].depthStencil.depth = 1.0f;
+  clear_values[1].depthStencil.stencil = 0.0f;
+
+  render_pass_begin_info.clearValueCount = clear_values.size();
+  render_pass_begin_info.pClearValues = clear_values.data();
+  vkCmdBeginRenderPass(command_buffer, &render_pass_begin_info, VK_SUBPASS_CONTENTS_INLINE);
+
+  vkCmdBindPipeline(command_buffer, VK_PIPELINE_BIND_POINT_GRAPHICS, pipeline);
+  vkCmdDraw(command_buffer, 3, 1, 0, 0);
+  vkCmdDraw(command_buffer, 3, 1, 3, 0);
+  vkCmdEndRenderPass(command_buffer);
+}
+
+void BlitToScanoutImage(VkQueue queue, VkCommandBuffer command_buffer, VkImage source_image,
+    VkImage dest_image) {
+  // We need to make sure the writes of the render pass have executed before actually scanning out
+  // the rendered image. Also, we need to transition the layout of the scanout image to
+  // VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL.
+  VkImageMemoryBarrier image_memory_barrier = {};
+  image_memory_barrier.sType = VK_STRUCTURE_TYPE_IMAGE_MEMORY_BARRIER,
+  image_memory_barrier.pNext = nullptr;
+  image_memory_barrier.srcAccessMask = 0;
+  image_memory_barrier.dstAccessMask = 0;
+  image_memory_barrier.oldLayout = VK_IMAGE_LAYOUT_UNDEFINED;
+  image_memory_barrier.newLayout = VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL;
+  image_memory_barrier.srcQueueFamilyIndex = VK_QUEUE_FAMILY_IGNORED;
+  image_memory_barrier.dstQueueFamilyIndex = VK_QUEUE_FAMILY_IGNORED;
+  image_memory_barrier.image = dest_image;
+  VkImageSubresourceRange subresource_range = {};
+  subresource_range.aspectMask = VK_IMAGE_ASPECT_COLOR_BIT;
+  subresource_range.baseMipLevel = 0;
+  subresource_range.levelCount = 1;
+  subresource_range.baseArrayLayer = 0;
+  subresource_range.layerCount = 1;
+  image_memory_barrier.subresourceRange = subresource_range;
+  vkCmdPipelineBarrier(command_buffer, VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT,
+      VK_PIPELINE_STAGE_TRANSFER_BIT, 0, 0, nullptr, 0, nullptr, 1, &image_memory_barrier);
+
+  VkOffset3D blit_start = {};
+  blit_start.x = 0;
+  blit_start.y = 0;
+  blit_start.z = 0;
+  VkOffset3D blit_end = {};
+  blit_end.x = kWidth;
+  blit_end.y = kHeight;
+  blit_end.z = 1;
+  VkImageSubresourceLayers subresource_layers = {};
+  subresource_layers.aspectMask = VK_IMAGE_ASPECT_COLOR_BIT;
+  subresource_layers.mipLevel = 0;
+  subresource_layers.baseArrayLayer = 0;
+  subresource_layers.layerCount = 1;
+  VkImageBlit image_blit = {};
+  image_blit.srcSubresource = subresource_layers;
+  image_blit.srcOffsets[0] = blit_start;
+  image_blit.srcOffsets[1] = blit_end;
+  image_blit.dstSubresource = subresource_layers;
+  image_blit.dstOffsets[0] = blit_start;
+  image_blit.dstOffsets[1] = blit_end;
+  // TODO(brkho): Support multi-planar formats.
+  vkCmdBlitImage(command_buffer, source_image, VK_IMAGE_LAYOUT_TRANSFER_SRC_OPTIMAL, dest_image,
+      VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL, 1, &image_blit, VK_FILTER_NEAREST);
+
+  EndCommandBufferAndSubmit(command_buffer, queue);
+}
+
+uint8_t* MapVkDeviceMemory(VkDevice device, VkDeviceMemory image_memory) {
+  void* mapped_memory = nullptr;
+  VkResult result = vkMapMemory(device, image_memory, 0, kWidth * kHeight * 4, 0, &mapped_memory);
+  if (result != VK_SUCCESS) {
+    ERROR("Unable to map device memory: " << result);
+  }
+  return static_cast<uint8_t*>(mapped_memory);
+}
+
+void WriteImage(uint8_t* pixels) {
+  FILE *f = fopen("subpass.png", "wb");
+
+  png_image image_info = {};
+  image_info.version = PNG_IMAGE_VERSION;
+  image_info.width = kWidth;
+  image_info.height = kHeight;
+  image_info.format = PNG_FORMAT_RGBA;
+  if (png_image_write_to_stdio(&image_info, f, 0, pixels, kWidth * 4, nullptr) == 0) {
+    ERROR("Error writing PNG: " << image_info.message);
+  }
+
+  fclose(f);
+}
+
+int main() {
+  VkInstance instance = CreateVkInstance();
+  VkPhysicalDevice physical_device = ChooseVkPhysicalDevice(instance);
+  uint32_t device_queue_family_index = ChooseDeviceQueueFamilyIndex(physical_device);
+  VkDevice device = CreateVkDevice(physical_device, device_queue_family_index);
+  VkQueue queue = GetVkQueue(device, device_queue_family_index);
+  VkCommandPool command_pool = CreateVkCommandPool(device, device_queue_family_index);
+  VkCommandBuffer command_buffer = CreateVkCommandBuffer(device, command_pool);
+
+  VkRenderPass render_pass = CreateVkRenderPass(device);
+  VkPipeline pipeline = CreateVkPipeline(device, render_pass);
+
+  VkImage render_image = CreateRenderVkImage(device);
+  AllocateAndBindRenderMemory(physical_device, device, render_image);
+  VkImageView render_image_view = CreateRenderVkImageView(device, render_image);
+  VkImage depth_image = CreateDepthVkImage(device);
+  AllocateAndBindDepthMemory(physical_device, device, depth_image);
+  VkImageView depth_image_view = CreateDepthVkImageView(device, depth_image);
+  VkFramebuffer framebuffer = CreateVkFramebuffer(device, render_pass, render_image_view,
+      depth_image_view);
+
+  VkImage scanout_image = CreateScanoutVkImage(device);
+  VkDeviceMemory scanout_image_memory =
+      AllocateAndBindScanoutMemory(physical_device, device, scanout_image);
+
+  Draw(device, queue, render_pass, pipeline, framebuffer, command_buffer);
+  // Since the render target is created with VK_IMAGE_TILING_OPTIMAL, we need to copy it to a linear
+  // format before scanning out.
+  BlitToScanoutImage(queue, command_buffer, render_image, scanout_image);
+  WaitForIdle(queue);
+
+  uint8_t* pixels = MapVkDeviceMemory(device, scanout_image_memory);
+  WriteImage(pixels);
+
+  return EXIT_SUCCESS;
+}

subpass.frag

@@ -0,0 +1,9 @@
+#version 450
+
+layout(location = 0) in vec3 fragColor;
+
+layout(location = 0) out vec4 outColor;
+
+void main() {
+    outColor = vec4(fragColor / 2, 1.0);
+}

subpass.vert

@@ -0,0 +1,26 @@
+#version 450
+
+layout(location = 0) out vec3 fragColor;
+
+vec3 positions[6] = vec3[](
+    vec3(0.5, -0.5, 0.7),
+    vec3(0.5, 0.5, 0.7),
+    vec3(-0.5, 0.5, 0.7),
+    vec3(-0.5, -0.5, 0.6),
+    vec3(0.5, 0.5, 0.6),
+    vec3(-0.5, 0.5, 0.6)
+);
+
+vec3 colors[6] = vec3[](
+    vec3(1.0, 0.0, 0.0),
+    vec3(0.0, 1.0, 0.0),
+    vec3(0.0, 0.0, 1.0),
+    vec3(1.0, 1.0, 0.0),
+    vec3(0.0, 1.0, 1.0),
+    vec3(1.0, 0.0, 1.0)
+);
+
+void main() {
+    gl_Position = vec4(positions[gl_VertexIndex], 1.0);
+    fragColor = colors[gl_VertexIndex];
+}