KhronosGroup / KhronosGroup/glslang

Feature Request: support mapping xfb layout qualifier in TIoMapResolver

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C++
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Description

Currently one can provide a custom TIoMapResolver to TProgram::mapIO() to assign newBinding, newSet, newLocation etc to any IO variable as needed after linking the program. What is missing is to assign transform feedback related layout qualifier to variable such as newXfbBuffer, newXfbOffset and newXfbStride.

Because there is an OpenGL API "glTransformFeedbackVaryings" that supports assigning transform feedback layout outside of shader source code, there should be a way to assign them in glslang after linking and I think the mapIO is the place to implement it the same way as newLocation etc.

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Research direction

Start at TProgram::mapIO and TIoMapResolver's existing newBinding, newSet, and newLocation handling. Trace how transform-feedback qualifiers are represented after linking, then determine how newXfbBuffer, newXfbOffset, and newXfbStride should be assigned consistently with glTransformFeedbackVaryings; done means custom resolvers can set those qualifiers through mapIO.

Written by the indexing model from the issue text.

Assessment

Tech stack
cpp
Domain
compilers
Issue type
Feature
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
45/100

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