VK_MESA_image_alignment_control

Other Extension Metadata

Last Modified Date

2024-05-03

IP Status

No known IP claims.

Contributors

Hans-Kristian Arntzen, Valve

This extension allows applications to request a narrower alignment for images than an implementation would otherwise require. Some implementations internally support multiple image layouts in VK_IMAGE_TILING_OPTIMAL, each with different alignment requirements and performance trade-offs. In some API layering use cases such as D3D12, it is beneficial to be able to control the alignment, since certain alignments for placed resources are guaranteed to be supported, and emulating that expectation requires unnecessary padding of allocations.

VkImageAlignmentControlCreateInfoMESA can be chained to VkImageCreateInfo, requesting that the alignment is no more than the provided alignment. If the requested alignment is not supported for a given VkImageCreateInfo, a larger alignment may be returned.

While something similar could be achieved with VK_EXT_image_drm_format_modifier in theory, this is not the intended way to use that extension. Format modifiers are generally used for externally shareable images, and would not be platform portable. It is also a cumbersome API to use just to lower the alignment.

New Structures

Extending VkImageCreateInfo:
- VkImageAlignmentControlCreateInfoMESA
Extending VkPhysicalDeviceFeatures2, VkDeviceCreateInfo:
- VkPhysicalDeviceImageAlignmentControlFeaturesMESA
Extending VkPhysicalDeviceProperties2:
- VkPhysicalDeviceImageAlignmentControlPropertiesMESA

New Enum Constants

VK_MESA_IMAGE_ALIGNMENT_CONTROL_EXTENSION_NAME
VK_MESA_IMAGE_ALIGNMENT_CONTROL_SPEC_VERSION
Extending VkStructureType:
- VK_STRUCTURE_TYPE_IMAGE_ALIGNMENT_CONTROL_CREATE_INFO_MESA
- VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_IMAGE_ALIGNMENT_CONTROL_FEATURES_MESA
- VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_IMAGE_ALIGNMENT_CONTROL_PROPERTIES_MESA

Version History

Revision 1, 2024-04-05 (Hans-Kristian Arntzen)
- Initial specification