// Setup the offscreen framebuffer for rendering the blurred scene
// The color attachment of this framebuffer will then be used to sample frame in the fragment shader of the final pass
void prepareOffscreen()
{
offscreenPass.width = FB_DIM;
offscreenPass.height = FB_DIM;
// Find a suitable depth format
VkFormat fbDepthFormat;
VkBool32 validDepthFormat = Tools.getSupportedDepthFormat(physicalDevice, &fbDepthFormat);
Debug.Assert(validDepthFormat);
// Color attachment
VkImageCreateInfo image = Initializers.imageCreateInfo();
image.imageType = VK_IMAGE_TYPE_2D;
image.format = FB_COLOR_FORMAT;
image.extent.width = (uint)offscreenPass.width;
image.extent.height = (uint)offscreenPass.height;
image.extent.depth = 1;
image.mipLevels = 1;
image.arrayLayers = 1;
image.samples = VK_SAMPLE_COUNT_1_BIT;
image.tiling = VK_IMAGE_TILING_OPTIMAL;
// We will sample directly from the color attachment
image.usage = VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT | VK_IMAGE_USAGE_SAMPLED_BIT;
VkMemoryAllocateInfo memAlloc = Initializers.memoryAllocateInfo();
VkMemoryRequirements memReqs;
Util.CheckResult(vkCreateImage(device, &image, null, out offscreenPass.color.image));
vkGetImageMemoryRequirements(device, offscreenPass.color.image, &memReqs);
memAlloc.allocationSize = memReqs.size;
memAlloc.memoryTypeIndex = vulkanDevice.getMemoryType(memReqs.memoryTypeBits, VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT);
Util.CheckResult(vkAllocateMemory(device, &memAlloc, null, out offscreenPass.color.mem));
Util.CheckResult(vkBindImageMemory(device, offscreenPass.color.image, offscreenPass.color.mem, 0));
VkImageViewCreateInfo colorImageView = Initializers.imageViewCreateInfo();
colorImageView.viewType = VK_IMAGE_VIEW_TYPE_2D;
colorImageView.format = FB_COLOR_FORMAT;
colorImageView.subresourceRange = new VkImageSubresourceRange();
colorImageView.subresourceRange.aspectMask = VK_IMAGE_ASPECT_COLOR_BIT;
colorImageView.subresourceRange.baseMipLevel = 0;
colorImageView.subresourceRange.levelCount = 1;
colorImageView.subresourceRange.baseArrayLayer = 0;
colorImageView.subresourceRange.layerCount = 1;
colorImageView.image = offscreenPass.color.image;
Util.CheckResult(vkCreateImageView(device, &colorImageView, null, out offscreenPass.color.view));
// Create sampler to sample from the attachment in the fragment shader
VkSamplerCreateInfo samplerInfo = Initializers.samplerCreateInfo();
samplerInfo.magFilter = VK_FILTER_LINEAR;
samplerInfo.minFilter = VK_FILTER_LINEAR;
samplerInfo.mipmapMode = VK_SAMPLER_MIPMAP_MODE_LINEAR;
samplerInfo.addressModeU = VK_SAMPLER_ADDRESS_MODE_CLAMP_TO_EDGE;
samplerInfo.addressModeV = samplerInfo.addressModeU;
samplerInfo.addressModeW = samplerInfo.addressModeU;
samplerInfo.mipLodBias = 0.0f;
samplerInfo.maxAnisotropy = 0;
samplerInfo.minLod = 0.0f;
samplerInfo.maxLod = 1.0f;
samplerInfo.borderColor = VK_BORDER_COLOR_FLOAT_OPAQUE_WHITE;
Util.CheckResult(vkCreateSampler(device, &samplerInfo, null, out offscreenPass.sampler));
// Depth stencil attachment
image.format = fbDepthFormat;
image.usage = VK_IMAGE_USAGE_DEPTH_STENCIL_ATTACHMENT_BIT;
Util.CheckResult(vkCreateImage(device, &image, null, out offscreenPass.depth.image));
vkGetImageMemoryRequirements(device, offscreenPass.depth.image, &memReqs);
memAlloc.allocationSize = memReqs.size;
memAlloc.memoryTypeIndex = vulkanDevice.getMemoryType(memReqs.memoryTypeBits, VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT);
Util.CheckResult(vkAllocateMemory(device, &memAlloc, null, out offscreenPass.depth.mem));
Util.CheckResult(vkBindImageMemory(device, offscreenPass.depth.image, offscreenPass.depth.mem, 0));
VkImageViewCreateInfo depthStencilView = Initializers.imageViewCreateInfo();
depthStencilView.viewType = VK_IMAGE_VIEW_TYPE_2D;
depthStencilView.format = fbDepthFormat;
depthStencilView.flags = 0;
depthStencilView.subresourceRange = new VkImageSubresourceRange();
depthStencilView.subresourceRange.aspectMask = VK_IMAGE_ASPECT_DEPTH_BIT | VK_IMAGE_ASPECT_STENCIL_BIT;
depthStencilView.subresourceRange.baseMipLevel = 0;
depthStencilView.subresourceRange.levelCount = 1;
depthStencilView.subresourceRange.baseArrayLayer = 0;
depthStencilView.subresourceRange.layerCount = 1;
depthStencilView.image = offscreenPass.depth.image;
Util.CheckResult(vkCreateImageView(device, &depthStencilView, null, out offscreenPass.depth.view));
// Create a separate render pass for the offscreen rendering as it may differ from the one used for scene rendering
FixedArray2 <VkAttachmentDescription> attchmentDescriptions = new FixedArray2 <VkAttachmentDescription>();
// Color attachment
attchmentDescriptions.First.format = FB_COLOR_FORMAT;
attchmentDescriptions.First.samples = VK_SAMPLE_COUNT_1_BIT;
attchmentDescriptions.First.loadOp = VK_ATTACHMENT_LOAD_OP_CLEAR;
attchmentDescriptions.First.storeOp = VK_ATTACHMENT_STORE_OP_STORE;
attchmentDescriptions.First.stencilLoadOp = VK_ATTACHMENT_LOAD_OP_DONT_CARE;
attchmentDescriptions.First.stencilStoreOp = VK_ATTACHMENT_STORE_OP_DONT_CARE;
attchmentDescriptions.First.initialLayout = VK_IMAGE_LAYOUT_UNDEFINED;
attchmentDescriptions.First.finalLayout = VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL;
// Depth attachment
attchmentDescriptions.Second.format = fbDepthFormat;
attchmentDescriptions.Second.samples = VK_SAMPLE_COUNT_1_BIT;
attchmentDescriptions.Second.loadOp = VK_ATTACHMENT_LOAD_OP_CLEAR;
attchmentDescriptions.Second.storeOp = VK_ATTACHMENT_STORE_OP_DONT_CARE;
attchmentDescriptions.Second.stencilLoadOp = VK_ATTACHMENT_LOAD_OP_DONT_CARE;
attchmentDescriptions.Second.stencilStoreOp = VK_ATTACHMENT_STORE_OP_DONT_CARE;
attchmentDescriptions.Second.initialLayout = VK_IMAGE_LAYOUT_UNDEFINED;
attchmentDescriptions.Second.finalLayout = VK_IMAGE_LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL;
VkAttachmentReference colorReference = new VkAttachmentReference {
attachment = 0, layout = VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL
};
VkAttachmentReference depthReference = new VkAttachmentReference {
attachment = 1, layout = VK_IMAGE_LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL
};
VkSubpassDescription subpassDescription = new VkSubpassDescription();
subpassDescription.pipelineBindPoint = VK_PIPELINE_BIND_POINT_GRAPHICS;
subpassDescription.colorAttachmentCount = 1;
subpassDescription.pColorAttachments = &colorReference;
subpassDescription.pDepthStencilAttachment = &depthReference;
// Use subpass dependencies for layout transitions
FixedArray2 <VkSubpassDependency> dependencies = new FixedArray2 <VkSubpassDependency>();
dependencies.First.srcSubpass = VK_SUBPASS_EXTERNAL;
dependencies.First.dstSubpass = 0;
dependencies.First.srcStageMask = VK_PIPELINE_STAGE_BOTTOM_OF_PIPE_BIT;
dependencies.First.dstStageMask = VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT;
dependencies.First.srcAccessMask = VK_ACCESS_MEMORY_READ_BIT;
dependencies.First.dstAccessMask = VK_ACCESS_COLOR_ATTACHMENT_READ_BIT | VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT;
dependencies.First.dependencyFlags = VK_DEPENDENCY_BY_REGION_BIT;
dependencies.Second.srcSubpass = 0;
dependencies.Second.dstSubpass = VK_SUBPASS_EXTERNAL;
dependencies.Second.srcStageMask = VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT;
dependencies.Second.dstStageMask = VK_PIPELINE_STAGE_BOTTOM_OF_PIPE_BIT;
dependencies.Second.srcAccessMask = VK_ACCESS_COLOR_ATTACHMENT_READ_BIT | VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT;
dependencies.Second.dstAccessMask = VK_ACCESS_MEMORY_READ_BIT;
dependencies.Second.dependencyFlags = VK_DEPENDENCY_BY_REGION_BIT;
// Create the actual renderpass
VkRenderPassCreateInfo renderPassInfo = VkRenderPassCreateInfo.New();
renderPassInfo.attachmentCount = attchmentDescriptions.Count;
renderPassInfo.pAttachments = &attchmentDescriptions.First;
renderPassInfo.subpassCount = 1;
renderPassInfo.pSubpasses = &subpassDescription;
renderPassInfo.dependencyCount = dependencies.Count;
renderPassInfo.pDependencies = &dependencies.First;
Util.CheckResult(vkCreateRenderPass(device, &renderPassInfo, null, out offscreenPass.renderPass));
FixedArray2 <VkImageView> attachments = new FixedArray2 <VkImageView>(offscreenPass.color.view, offscreenPass.depth.view);
VkFramebufferCreateInfo fbufCreateInfo = Initializers.framebufferCreateInfo();
fbufCreateInfo.renderPass = offscreenPass.renderPass;
fbufCreateInfo.attachmentCount = 2;
fbufCreateInfo.pAttachments = &attachments.First;
fbufCreateInfo.width = (uint)offscreenPass.width;
fbufCreateInfo.height = (uint)offscreenPass.height;
fbufCreateInfo.layers = 1;
Util.CheckResult(vkCreateFramebuffer(device, &fbufCreateInfo, null, out offscreenPass.frameBuffer));
// Fill a descriptor for later use in a descriptor set
offscreenPass.descriptor.imageLayout = VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL;
offscreenPass.descriptor.imageView = offscreenPass.color.view;
offscreenPass.descriptor.sampler = offscreenPass.sampler;
}