C Specification

The VkSubpassDependency structure is defined as:

Warning
 This functionality is superseded by Vulkan Version 1.2. See Legacy Functionality for more information. 
// Provided by VK_VERSION_1_0
typedef struct VkSubpassDependency {
    uint32_t                srcSubpass;
    uint32_t                dstSubpass;
    VkPipelineStageFlags    srcStageMask;
    VkPipelineStageFlags    dstStageMask;
    VkAccessFlags           srcAccessMask;
    VkAccessFlags           dstAccessMask;
    VkDependencyFlags       dependencyFlags;
} VkSubpassDependency;

Members

Description

If srcSubpass is equal to dstSubpass then the VkSubpassDependency does not directly define a dependency. Instead, it enables pipeline barriers to be used in a render pass instance within the identified subpass, where the scopes of one pipeline barrier must be a subset of those described by one subpass dependency. Subpass dependencies specified in this way that include framebuffer-space stages in the srcStageMask must only include framebuffer-space stages in dstStageMask, and must include VK_DEPENDENCY_BY_REGION_BIT. When a subpass dependency is specified in this way for a subpass that has more than one view in its view mask, its dependencyFlags must include VK_DEPENDENCY_VIEW_LOCAL_BIT.

If srcSubpass and dstSubpass are not equal, when a render pass instance which includes a subpass dependency is submitted to a queue, it defines a dependency between the subpasses identified by srcSubpass and dstSubpass.

If srcSubpass is equal to VK_SUBPASS_EXTERNAL, the first synchronization scope includes commands that occur earlier in submission order than the vkCmdBeginRenderPass used to begin the render pass instance. Otherwise, the first set of commands includes all commands submitted as part of the subpass instance identified by srcSubpass and any load, store, or multisample resolve operations on attachments used in srcSubpass. In either case, the first synchronization scope is limited to operations on the pipeline stages determined by the source stage mask specified by srcStageMask.

If dstSubpass is equal to VK_SUBPASS_EXTERNAL, the second synchronization scope includes commands that occur later in submission order than the vkCmdEndRenderPass used to end the render pass instance. Otherwise, the second set of commands includes all commands submitted as part of the subpass instance identified by dstSubpass and any load, store, and multisample resolve operations on attachments used in dstSubpass. In either case, the second synchronization scope is limited to operations on the pipeline stages determined by the destination stage mask specified by dstStageMask.

The first access scope is limited to accesses in the pipeline stages determined by the source stage mask specified by srcStageMask. It is also limited to access types in the source access mask specified by srcAccessMask.

The second access scope is limited to accesses in the pipeline stages determined by the destination stage mask specified by dstStageMask. It is also limited to access types in the destination access mask specified by dstAccessMask.

The availability and visibility operations defined by a subpass dependency affect the execution of image layout transitions within the render pass.

Note

For non-attachment resources, the memory dependency expressed by subpass dependency is nearly identical to that of a VkMemoryBarrier (with matching srcAccessMask and dstAccessMask parameters) submitted as a part of a vkCmdPipelineBarrier (with matching srcStageMask and dstStageMask parameters). The only difference being that its scopes are limited to the identified subpasses rather than potentially affecting everything before and after.

For attachments however, subpass dependencies work more like a VkImageMemoryBarrier defined similarly to the VkMemoryBarrier above, the queue family indices set to VK_QUEUE_FAMILY_IGNORED, and layouts as follows:

  • The equivalent to oldLayout is the attachment’s layout according to the subpass description for srcSubpass.

  • The equivalent to newLayout is the attachment’s layout according to the subpass description for dstSubpass.
Valid Usage
Valid Usage (Implicit)

  • VUID-VkSubpassDependency-srcStageMask-parameter
    srcStageMask must be a valid combination of VkPipelineStageFlagBits values

  • VUID-VkSubpassDependency-dstStageMask-parameter
    dstStageMask must be a valid combination of VkPipelineStageFlagBits values

  • VUID-VkSubpassDependency-srcAccessMask-parameter
    srcAccessMask must be a valid combination of VkAccessFlagBits values

  • VUID-VkSubpassDependency-dstAccessMask-parameter
    dstAccessMask must be a valid combination of VkAccessFlagBits values

  • VUID-VkSubpassDependency-dependencyFlags-parameter
    dependencyFlags must be a valid combination of VkDependencyFlagBits values

See Also

VK_VERSION_1_0, VkAccessFlags, VkDependencyFlags, VkPipelineStageFlags, VkRenderPassCreateInfo

Document Notes

For more information, see the Vulkan Specification.

This page is extracted from the Vulkan Specification. Fixes and changes should be made to the Specification, not directly.

Copyright

Copyright 2014-2026 The Khronos Group Inc.

SPDX-License-Identifier: CC-BY-4.0