I'm using the extension for a vulkan project where I'm compiling all my shaders with a custom build tool using the glslc.exe that is provided by the Vulkan SDK. This compiler doesn't know of 'gl_VertexID', so I'd like to use 'gl_VertexIndex'.
For some reason the extension marks 'gl_VertexIndex' as an undeclared identifier. How could I change this behaviour?