This extension is based on the VK_NV_fragment_shader_barycentric extension, and adds support for the following SPIR-V extension in Vulkan:

• SPV_KHR_fragment_shader_barycentric

The extension provides access to three additional fragment shader variable decorations in SPIR-V:

• PerVertexKHR, which indicates that a fragment shader input will not have interpolated values, but instead must be accessed with an extra array index that identifies one of the vertices of the primitive producing the fragment
• BaryCoordKHR, which indicates that the variable is a three-component floating-point vector holding barycentric weights for the fragment produced using perspective interpolation
• BaryCoordNoPerspKHR, which indicates that the variable is a three-component floating-point vector holding barycentric weights for the fragment produced using linear interpolation

When using GLSL source-based shader languages, the following variables from GL_EXT_fragment_shader_barycentric map to these SPIR-V built-in decorations:

• in vec3 gl_BaryCoordEXT; → BaryCoordKHR
• in vec3 gl_BaryCoordNoPerspEXT; → BaryCoordNoPerspKHR

GLSL variables declared using the pervertexEXT GLSL qualifier are expected to be decorated with PerVertexKHR in SPIR-V.

VK_KHR_fragment_shader_barycentric

Name String

VK_KHR_fragment_shader_barycentric

Extension Type

Device extension

Registered Extension Number

323

Revision

1

Extension and Version Dependencies

VK_KHR_get_physical_device_properties2

Contact

• Stu Smith

Extension Proposal

VK_KHR_fragment_shader_barycentric

Other Extension Metadata

Last Modified Date

2022-03-10

IP Status

No known IP claims.

Interactions and External Dependencies

• This extension requires SPV_KHR_fragment_shader_barycentric
• This extension provides API support for GL_EXT_fragment_shader_barycentric

Contributors

• Stu Smith, AMD
• Tobias Hector, AMD
• Graeme Leese, Broadcom
• Jan-Harald Fredriksen, Arm
• Slawek Grajewski, Intel
• Pat Brown, NVIDIA
• Hans-Kristian Arntzen, Valve
• Contributors to the VK_NV_fragment_shader_barycentric specification