Dynamic Rendering

The source for this sample can be found in the Khronos Vulkan samples github repository.


This sample demonstrates how to use the VK_KHR_dynamic_rendering extension, which eliminates the need to create render passes and improves flexibility while developing render pipelines.

This extension changes how rendering resources are managed. Rather than using render pass objects, this extension allows the developer to directly reference rendering attachments prior to the start of rendering.

Below is a comparison of the common Vulkan render pass construction and dynamic rendering.

Vulkan 1.0 Dynamic Rendering

Rendering begins with vkCmdBeginRenderPass

Rendering begins with vkCmdBeginRenderingKHR

Rendering struct is VkRenderPassBeginInfo

Rendering struct is VkRenderingInfoKHR

Attachments are referenced by VkFramebuffer

Attachments are referenced by VkRenderingAttachmentInfoKHR

VkFramebuffer objects are heap-allocated and opaque

VkRenderingAttachmentInfoKHR objects are stack-allocated

Graphics pipeline creation references a VkRenderPass

Graphics pipeline creation references a VkPipelineRenderingCreateInfoKHR

More detail is provided in the sections that follow.

Rendering Attachments

Previously, developers had to create render passes and framebuffers, which would be referenced in VkRenderPassBeginInfo. This is illustrated in the non-dynamic version of the command buffer construction sample code:

VkRenderPassBeginInfo render_pass_begin_info    = vkb::initializers::render_pass_begin_info();
render_pass_begin_info.renderPass               = render_pass;
render_pass_begin_info.framebuffer              = framebuffers[i];
render_pass_begin_info.renderArea.extent.width  = width;
render_pass_begin_info.renderArea.extent.height = height;
render_pass_begin_info.clearValueCount          = 3;
render_pass_begin_info.pClearValues             = clear_values.data();

vkCmdBeginRenderPass(draw_cmd_buffer, &render_pass_begin_info, VK_SUBPASS_CONTENTS_INLINE);



However, with dynamic rendering, the render pass and framebuffer structs are replaced by VkRenderingAttachmentInfoKHR, which contains information about color, depth, and stencil attachments, and VkRenderingInfoKHR, which references the attachments. These structs are used at the start of rendering with the new command vkCmdBeginRenderingKHR, as shown in the dynamic version of the command buffer construction sample code:

VkRenderingAttachmentInfoKHR color_attachment_info = vkb::initializers::rendering_attachment_info();
color_attachment_info.imageView                    = swapchain_buffers[i].view;        // color_attachment.image_view;

VkRenderingAttachmentInfoKHR depth_attachment_info = vkb::initializers::rendering_attachment_info();
depth_attachment_info.imageView                    = depth_stencil.view;

auto render_area               = VkRect2D{VkOffset2D{}, VkExtent2D{width, height}};
auto render_info               = vkb::initializers::rendering_info(render_area, 1, &color_attachment_info);
render_info.layerCount         = 1;
render_info.pDepthAttachment   = &depth_attachment_info;
render_info.pStencilAttachment = &depth_attachment_info;

vkCmdBeginRenderingKHR(draw_cmd_buffer, &render_info);


Dynamic rendering changes how graphics pipelines are created. Whereas before, the VkGraphicsPipelineCreateInfo struct was required to reference a non-null pointer to a VkRenderPass object, the dynamic rendering information is instead contained in a VkPipelineRenderingCreateInfoKHR struct referenced by pNext of the graphics pipeline create info:

// Provide information for dynamic rendering
pipeline_create.pNext                   = VK_NULL_HANDLE;
pipeline_create.colorAttachmentCount    = 1;
pipeline_create.pColorAttachmentFormats = &color_rendering_format;
pipeline_create.depthAttachmentFormat   = depth_format;
pipeline_create.stencilAttachmentFormat = depth_format;

// Use the pNext to point to the rendering create struct
VkGraphicsPipelineCreateInfo graphics_create{VK_STRUCTURE_TYPE_GRAPHICS_PIPELINE_CREATE_INFO};
graphics_create.pNext               = &pipeline_create; // reference the new dynamic structure
graphics_create.renderPass          = VK_NULL_HANDLE; // previously required non-null

During graphics pipeline construction, the VkPipelineRenderingCreateInfoKHR structure does not contain pointers to the actual attachment images (as the pointers aren’t required until VkRenderingAttachmentInfoKHR); instead, only the number and format of the attachments are required.

Enabling the Extension

The dynamic rendering api is provided in Vulkan 1.2.197 and the appropriate headers / SDK is required.

In addition, since dynamic rendering is provided as an extension and may have varying levels of support, the developer must query availability for each device used.

The device extension is provided by VK_KHR_DYNAMIC_RENDERING_EXTENSION_NAME, and additional features are provided by the VkPhysicalDeviceDynamicRenderingFeaturesKHR struct:

typedef struct VkPhysicalDeviceDynamicRenderingFeaturesKHR {
    VkStructureType    sType;
    void*              pNext;
    VkBool32           dynamicRendering;
} VkPhysicalDeviceDynamicRenderingFeaturesKHR;

In addition to enabling the extension, developers may need to dynamically query the function pointers for vkCmdBeginRenderingKHR and vkCmdEndRenderingKHR if the preprocessor macro VK_NO_PROTOTYPES is enabled. This can be achieved through vkGetInstanceProcAddr:

VkInstance instance = get_device().get_gpu().get_instance().get_handle();
vkCmdBeginRenderingKHR = (PFN_vkCmdBeginRenderingKHR) vkGetInstanceProcAddr(instance, "vkCmdBeginRenderingKHR");
vkCmdEndRenderingKHR   = (PFN_vkCmdEndRenderingKHR) vkGetInstanceProcAddr(instance, "vkCmdEndRenderingKHR");
if (!vkCmdBeginRenderingKHR || !vkCmdEndRenderingKHR)
    throw std::runtime_error("Unable to dynamically load vkCmdBeginRenderingKHR and vkCmdEndRenderingKHR");