Add a depth buffer

This causes the green triangle to fail some depth tests which in
turn affects the occlusion query

occlusion.cc

@@ -1,6 +1,7 @@
 #include <png.h>
 #include <vulkan/vulkan.h>
 
+#include <array>
 #include <fstream>
 #include <iostream>
 #include <sstream>
@@ -10,6 +11,7 @@
 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 = "occlusion.vert.spv";
 const std::string kFragmentShaderPath = "occlusion.frag.spv";
 
@@ -168,24 +170,41 @@ VkQueryPool CreateVkQueryPool(VkDevice device) {
 }
 
 VkRenderPass CreateVkRenderPass(VkDevice device) {
-  VkAttachmentDescription attachment_description = {};
-  attachment_description.format = kVulkanFormat;
-  attachment_description.samples = VK_SAMPLE_COUNT_1_BIT;
-  attachment_description.loadOp = VK_ATTACHMENT_LOAD_OP_CLEAR;
-  attachment_description.storeOp = VK_ATTACHMENT_STORE_OP_STORE;
-  attachment_description.stencilLoadOp = VK_ATTACHMENT_LOAD_OP_DONT_CARE;
-  attachment_description.stencilStoreOp = VK_ATTACHMENT_STORE_OP_DONT_CARE;
-  attachment_description.initialLayout = VK_IMAGE_LAYOUT_UNDEFINED;
-  attachment_description.finalLayout = VK_IMAGE_LAYOUT_TRANSFER_SRC_OPTIMAL;
-
-  VkAttachmentReference attachment_reference = {};
-  attachment_reference.attachment = 0;
-  attachment_reference.layout = VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL;
+  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 = &attachment_reference;
+  subpass_description.pColorAttachments = &color_attachment_reference;
+  subpass_description.pDepthStencilAttachment = &depth_attachment_reference;
 
   VkSubpassDependency subpass_dependency = {};
   subpass_dependency.srcSubpass = VK_SUBPASS_EXTERNAL;
@@ -198,8 +217,8 @@ VkRenderPass CreateVkRenderPass(VkDevice device) {
 
   VkRenderPassCreateInfo render_pass_info = {};
   render_pass_info.sType = VK_STRUCTURE_TYPE_RENDER_PASS_CREATE_INFO;
-  render_pass_info.attachmentCount = 1;
-  render_pass_info.pAttachments = &attachment_description;
+  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;
@@ -303,6 +322,17 @@ VkPipeline CreateVkPipeline(VkDevice device, VkRenderPass render_pass) {
   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;
@@ -333,7 +363,7 @@ VkPipeline CreateVkPipeline(VkDevice device, VkRenderPass render_pass) {
   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 = nullptr;
+  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;
@@ -351,12 +381,13 @@ VkPipeline CreateVkPipeline(VkDevice device, VkRenderPass render_pass) {
   return pipeline;
 }
 
-VkImage CreateVkImage(VkDevice device, VkImageTiling image_tiling, VkImageUsageFlags usage) {
+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 = kVulkanFormat;
+  create_info.format = format;
   VkExtent3D extent  = {};
   extent.width = kWidth;
   extent.height = kHeight;
@@ -379,12 +410,17 @@ VkImage CreateVkImage(VkDevice device, VkImageTiling image_tiling, VkImageUsageF
 }
 
 inline VkImage CreateRenderVkImage(VkDevice device) {
-  return CreateVkImage(device, VK_IMAGE_TILING_OPTIMAL,
+  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, VK_IMAGE_TILING_LINEAR,
+  return CreateVkImage(device, kVulkanFormat, VK_IMAGE_TILING_LINEAR,
       VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT | VK_IMAGE_USAGE_TRANSFER_DST_BIT);
 }
 
@@ -435,17 +471,23 @@ inline VkDeviceMemory AllocateAndBindRenderMemory(VkPhysicalDevice physical_devi
   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) {
+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 = kVulkanFormat;
+  create_info.format = format;
 
   VkComponentMapping component_mapping = {};
   component_mapping.r = VK_COMPONENT_SWIZZLE_IDENTITY;
@@ -455,7 +497,7 @@ VkImageView CreateVkImageView(VkDevice device, VkImage image) {
   create_info.components = component_mapping;
 
   VkImageSubresourceRange subresource_range = {};
-  subresource_range.aspectMask = VK_IMAGE_ASPECT_COLOR_BIT;
+  subresource_range.aspectMask = aspect;
   subresource_range.baseMipLevel = 0;
   subresource_range.levelCount = 1;
   subresource_range.baseArrayLayer = 0;
@@ -470,13 +512,23 @@ VkImageView CreateVkImageView(VkDevice device, VkImage image) {
   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 image_view) {
+    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 = 1;
-  create_info.pAttachments = &image_view;
+  create_info.attachmentCount = attachments.size();
+  create_info.pAttachments = attachments.data();
   create_info.width = kWidth;
   create_info.height = kHeight;
   create_info.layers = 1;
@@ -546,13 +598,17 @@ void Draw(VkDevice device, VkQueue queue, VkRenderPass render_pass, VkPipeline p
   render_area.offset = { 0, 0 };
   render_area.extent = { kWidth, kHeight };
   render_pass_begin_info.renderArea = render_area;
-  render_pass_begin_info.clearValueCount = 1;
-  VkClearValue clear_value = {};
-  clear_value.color.float32[0] = 0.0f;
-  clear_value.color.float32[1] = 0.0f;
-  clear_value.color.float32[2] = 1.0f;
-  clear_value.color.float32[3] = 1.0f;
-  render_pass_begin_info.pClearValues = &clear_value;
+
+  std::array<VkClearValue, 2> clear_values = {};
+  clear_values[0].color.float32[0] = 0.0f;
+  clear_values[0].color.float32[1] = 0.0f;
+  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);
@@ -679,8 +735,12 @@ int main() {
 
   VkImage render_image = CreateRenderVkImage(device);
   AllocateAndBindRenderMemory(physical_device, device, render_image);
-  VkImageView render_image_view = CreateVkImageView(device, render_image);
-  VkFramebuffer framebuffer = CreateVkFramebuffer(device, render_pass, render_image_view);
+  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 =

occlusion.vert

@@ -3,12 +3,12 @@
 layout(location = 0) out vec3 fragColor;
 
 vec3 positions[6] = vec3[](
-    vec3(0.5, -0.5, 1.0),
-    vec3(0.5, 0.5, 1.0),
-    vec3(-0.5, 0.5, 1.0),
-    vec3(-0.5, -0.5, 0.0),
+    vec3(0.5, -0.5, 0.0),
     vec3(0.5, 0.5, 0.0),
-    vec3(-0.5, 0.5, 0.0)
+    vec3(-0.5, 0.5, 0.0),
+    vec3(-0.5, -0.5, 0.1),
+    vec3(0.5, 0.5, 0.1),
+    vec3(-0.5, 0.5, 0.1)
 );
 
 vec3 colors[6] = vec3[](