VK_EXT_fragment_density_map(3) Manual Page

// Create fragment density map
VkImageCreateInfo imageCreateInfo =
{
   .sType = VK_STRUCTURE_TYPE_IMAGE_CREATE_INFO,
   .pNext = nullptr,
   .flags = 0,
   .imageType = VK_IMAGE_TYPE_2D,    // Must be 2D
   .format = VK_FORMAT_R8G8_UNORM,   // Must have VK_FORMAT_FEATURE_FRAGMENT_DENSITY_MAP_BIT_EXT
   .extend = {64, 64, 1},
   .mipLevels = 1,
   .arrayLayers = 2,                 // 1 for each multiview view
   .samples = VK_SAMPLE_COUNT_1_BIT, // Must be 1x MSAA
   .tiling = tiling,
   .usage = VK_IMAGE_USAGE_FRAGMENT_DENSITY_MAP_BIT_EXT,
   // ...
};

vkCreateImage(device, &imageCreateInfo, nullptr, &fdmImage);

VkImageViewCreateInfo viewCreateInfo =
{
   .sType = VK_STRUCTURE_TYPE_IMAGE_VIEW_CREATE_INFO,
   .pNext = nullptr,
   .flags = 0,                      // VkImageViewCreateFlags
   .image = fdmImage,
   .viewType = VK_IMAGE_VIEW_TYPE_2D_ARRAY,
   .format = VK_FORMAT_R8G8_UNORM,
   .components = { 0 },             // VK_COMPONENT_SWIZZLE_IDENTITY
   .subresourceRange = {
        .aspectMask = VK_IMAGE_ASPECT_COLOR_BIT,
        .baseMipLevel = 0,
        .levelCount = 1,
        .baseArrayLayer = 0,
        .layerCount = 2,
   }
};

vkCreateImageView(device, &viewCreateInfo, nullptr, &fdmImageView);

// Add fdmImage to render pass

VkAttachmentReference fragmentDensityMapAttachmentReference =
{
   fdmAttachmentIdx,
   VK_IMAGE_LAYOUT_FRAGMENT_DENSITY_MAP_OPTIMAL_EXT,
};

VkRenderPassFragmentDensityMapCreateInfoEXT fdmAttachmentCreateInfo =
{
   VK_STRUCTURE_TYPE_RENDER_PASS_FRAGMENT_DENSITY_MAP_CREATE_INFO_EXT,
   // ...
   fragmentDensityMapAttachmentReference,
};

VkRenderPassCreateInfo2 renderPassCreateInfo =
{
   VK_STRUCTURE_TYPE_RENDER_PASS_CREATE_INFO_2,
   &fdmAttachmentCreateInfo,
   // ...
};

vkCreateRenderPass2(device, &renderPassCreateInfo, nullptr, &renderPass);

// Add fdmImage to framebuffer
// Color attachments can be created with VK_IMAGE_CREATE_SUBSAMPLED_BIT_EXT
// All attachments must be created with VK_IMAGE_CREATE_FRAGMENT_DENSITY_MAP_OFFSETS_BIT_EXT
VkFramebufferCreateInfo framebufferCreateInfo =
{
   .sType = VK_STRUCTURE_TYPE_FRAME_BUFFER_CREATE_INFO,
   // ...
   .renderPass = renderPass,
   // ...
   .pAttachments = pAttachments, // Includes fdmImageView at fdmAttachmentIdx
   .width = 1024,
   .height = 1024,
   .layers = 1
};

vkCreateFramebuffer(device, &framebufferCreateInfo, nullptr, &framebuffer);

// Start recording render pass in command buffer

VkRenderPassBeginInfo renderPassBeginInfo =
{
   .sType = VK_STRUCTURE_TYPE_RENDER_PASS_BEGIN_INFO,
   // ...
   .renderPass = renderPass,
   .framebuffer = framebuffer,
   // ...
};

// Can no longer modify the fdmImage's contents after this call
vkCmdBeginRenderPass2(commandBuffer, &renderPassBeginInfo, pSubpassBeginInfo);