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VK_QCOM_rotated_copy_commands

Other Extension Metadata

Last Modified Date

2023-12-13

Interactions and External Dependencies
Contributors
  • Jeff Leger, Qualcomm Technologies, Inc.
  • Matthew Netsch, Qualcomm Technologies, Inc.

Description

This extension extends adds an optional rotation transform to copy commands vkCmdBlitImage2KHR, vkCmdCopyImageToBuffer2KHR and vkCmdCopyBufferToImage2KHR. When copying between two resources, where one resource contains rotated content and the other does not, a rotated copy may be desired. This extension may be used in combination with VK_QCOM_render_pass_transform which adds rotated render passes.

This extension adds an extension structure to the following commands: vkCmdBlitImage2KHR, vkCmdCopyImageToBuffer2KHR and vkCmdCopyBufferToImage2KHR

Issues

1) What is an appropriate name for the added extension structure? The style guide says Structures which extend other structures through the pNext chain should reflect the name of the base structure they extend., but in this case a single extension structure is used to extend three base structures (vkCmdBlitImage2KHR, vkCmdCopyImageToBuffer2KHR and vkCmdCopyBufferToImage2KHR). Creating three identical structures with unique names seemed undesirable.

RESOLVED: Deviate from the style guide for extension structure naming.

2) Should this extension add a rotation capability to vkCmdCopyImage2KHR?

RESOLVED: No. Use of rotated vkCmdBlitImage2KHR can fully address this use case.

3) Should this extension add a rotation capability to vkCmdResolveImage2KHR?

RESOLVED No. Use of vkCmdResolveImage2KHR is very slow and extremely bandwidth intensive on Qualcomm’s GPU architecture and use of pResolveAttachments in vkRenderPass is the strongly preferred approach. Therefore, we choose not to introduce a rotation capability to vkCmdResolveImage2KHR.

New Structures

New Enum Constants

  • VK_QCOM_ROTATED_COPY_COMMANDS_EXTENSION_NAME
  • VK_QCOM_ROTATED_COPY_COMMANDS_SPEC_VERSION
  • Extending VkStructureType:
    • VK_STRUCTURE_TYPE_COPY_COMMAND_TRANSFORM_INFO_QCOM

Version History

  • Revision 1, 2020-09-19 (Jeff Leger)
  • Revision 2, 2023-12-13 (Matthew Netsch)
    • Relax dependency on VK_KHR_swapchain