Today I discovered this code in linker.cpp: if (sh->num_samplers > ctx->Const.Program[i].MaxTextureImageUnits) { linker_error(prog, "Too many %s shader texture samplers", _mesa_shader_stage_to_string(i)); } This prevents you from using more sampler uniforms than you have texture units. However, I'm failing to find any justification for doing that. Why can't I create 40 sampler uniforms and bind them all to the same texture unit? Note: I haven't seen this in a real application, just a Piglit test I was developing to try and provoke a different bug I found. Ian, feel free to reject this bug if I'm missing something in the specs.
From OpenGL 4.5 Core (same text can be found from ES spec), last clause in 'Samplers' section 7.10 discussing about when LinkProgram fails: "If it determines that the count of active samplers exceeds the allowable limits, then the link fails (these limits can be different for different types of shaders). Each active sampler variable counts against the limit, even if multiple samplers refer to the same texture image unit."
Thanks Tapani, that does make sense!
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