VK_KHR_imageless_framebuffer.adoc

VK_KHR_imageless_framebuffer

Note	Promoted to core in Vulkan 1.2

When creating a VkFramebuffer you normally need to pass the VkImageView`s being used in `VkFramebufferCreateInfo::pAttachments. Needing the VkImageView forces an application to make a framebuffer for each swapchain image. With VK_KHR_imageless_framebuffer the VkImageView information is given at vkCmdBeginRenderPass time instead. This means only one VkFramebuffer for all the swapchain images. It is important to notice that when the size of the swapchain changes, the VkFramebuffer will still need to be recreated to adjust information such as the height and width.

To use an imageless VkFramebuffer

• Make sure the implementation has support for it by querying VkPhysicalDeviceImagelessFramebufferFeatures::imagelessFramebuffer or VkPhysicalDeviceVulkan12Features::imagelessFramebuffer

• Set the VK_FRAMEBUFFER_CREATE_IMAGELESS_BIT in VkFramebufferCreateInfo::flags

• Include a VkFramebufferAttachmentsCreateInfo struct in the VkFramebufferCreateInfo::pNext

• When beginning the render pass, pass in a VkRenderPassAttachmentBeginInfo structure into VkRenderPassBeginInfo::pNext with the compatible attachments

// Fill information about attachment
VkFramebufferAttachmentImageInfo attachments_image_info = {};
// ...

VkFramebufferAttachmentsCreateInfo attachments_create_info = {};
// ...
attachments_create_info.attachmentImageInfoCount = 1;
attachments_create_info.pAttachmentImageInfos = &attachments_image_info;

// Create FrameBuffer as imageless
VkFramebufferCreateInfo framebuffer_info = {};
framebuffer_info.pNext = &attachments_create_info;
framebuffer_info.flags |= VK_FRAMEBUFFER_CREATE_IMAGELESS_BIT;
// ...
framebffer_info.pAttachments = NULL; // pAttachments is ignored here now

vkCreateFramebuffer(device, &framebuffer_info, NULL, &framebuffer_object);

// ...

// Start recording a command buffer
VkRenderPassAttachmentBeginInfo attachment_begin_info = {};
// attachment_begin_info.pAttachments contains VkImageView objects

VkRenderPassBeginInfo begin_info = {};
begin_info.pNext = &attachment_begin_info;
// ...

vkCmdBeginRenderPass(command_buffer, &begin_info, VK_SUBPASS_CONTENTS_INLINE);