VK_KHR_format_feature_flags2

Other Extension Metadata

Last Modified Date

2021-07-01

IP Status

No known IP claims.

Contributors

• Lionel Landwerlin, Intel
• Faith Ekstrand, Intel
• Tobias Hector, AMD
• Spencer Fricke, Samsung Electronics
• Graeme Leese, Broadcom
• Jan-Harald Fredriksen, ARM

Description

This extension adds a new VkFormatFeatureFlagBits2KHR 64bits format feature flag type to extend the existing VkFormatFeatureFlagBits which is limited to 31 flags. At the time of this writing 29 bits of VkFormatFeatureFlagBits are already used.

Because VkFormatProperties2 is already defined to extend the Vulkan 1.0 vkGetPhysicalDeviceFormatProperties command, this extension defines a new VkFormatProperties3KHR to extend the VkFormatProperties.

On top of replicating all the bits from VkFormatFeatureFlagBits, VkFormatFeatureFlagBits2KHR adds the following bits :

• VK_FORMAT_FEATURE_2_STORAGE_READ_WITHOUT_FORMAT_BIT_KHR and VK_FORMAT_FEATURE_2_STORAGE_WRITE_WITHOUT_FORMAT_BIT_KHR indicate that an implementation supports respectively reading and writing a given VkFormat through storage operations without specifying the format in the shader.
• VK_FORMAT_FEATURE_2_SAMPLED_IMAGE_DEPTH_COMPARISON_BIT_KHR indicates that an implementation supports depth comparison performed by OpImage*Dref* instructions on a given VkFormat. Previously the result of executing a OpImage*Dref* instruction on an image view, where the format was not one of the depth/stencil formats with a depth component, was undefined. This bit clarifies on which formats such instructions can be used.

Prior to version 2 of this extension, implementations exposing the shaderStorageImageReadWithoutFormat and shaderStorageImageWriteWithoutFormat features may not report VK_FORMAT_FEATURE_2_STORAGE_READ_WITHOUT_FORMAT_BIT_KHR and VK_FORMAT_FEATURE_2_STORAGE_WRITE_WITHOUT_FORMAT_BIT_KHR in VkFormatProperties3KHR::bufferFeatures. Despite this, buffer reads/writes are supported as intended by the original features.

New Structures

• Extending VkFormatProperties2:
  • VkFormatProperties3KHR

New Enums

• VkFormatFeatureFlagBits2KHR

New Bitmasks

• VkFormatFeatureFlags2KHR

New Enum Constants

• VK_KHR_FORMAT_FEATURE_FLAGS_2_EXTENSION_NAME
• VK_KHR_FORMAT_FEATURE_FLAGS_2_SPEC_VERSION
• Extending VkStructureType:
  • VK_STRUCTURE_TYPE_FORMAT_PROPERTIES_3_KHR

Promotion to Vulkan 1.3

Functionality in this extension is included in core Vulkan 1.3, with the KHR suffix omitted. The original type, enum, and command names are still available as aliases of the core functionality.

Version History

• Revision 2, 2022-07-20 (Lionel Landwerlin)
  • Clarify that VK_FORMAT_FEATURE_2_STORAGE_(READ|WRITE)_WITHOUT_FORMAT_BIT also apply to buffer views.
• Revision 1, 2020-07-21 (Lionel Landwerlin)
  • Initial draft