I'm having some problems getting the ARB_texture_gather extension (spec here) to behave in my OpenGL application. According to glGetString(GL_EXTENSIONS), the extension should be available. However, when I try to enable it in my shader using an #extension directive, the compiler gives me this:
WARNING: 1:1: warning(#62) enable/warn/disable extension isn't found, extension 'GL_ARB_texture_gather' is not supported
Nor is GL_ARB_texture_gather defined by the GLSL preprocessor. My GL_EXTENSIONS string and the GLSL compiler can't seem to agree about whether or not the extension is present. Is this a driver issue, or is something else amiss?
I'm running Windows 7 (64-bit), ATI Mobility Radeon HD 4650 (driver version 220.127.116.11)