OpenGL code runnable on x86 CPU?

Question

I understand that AMD created an alternative implementation of OpenCL that runs on x86 CPUs. This is very useful from the standpoint of simplified debugging. Unfortunately, OpenCL isn't an option for me.

Are there any Open GL x86 implementations in existence? This would greatly ease my development process, at the cost of some CPU time, of course. I would then run the same code on a GPU, later, with no changes necessary.

Answer 1

Mesa might be an option for you.

From their website:

Mesa is the OpenGL implementation for several types of hardware made by Intel, AMD and NVIDIA, plus the VMware virtual GPU. There's also several software-based renderers: swrast (the legacy Mesa rasterizer), softpipe (a gallium reference driver) and llvmpipe (LLVM/JIT-based high-speed rasterizer).

When using Mesa you can set the LIBGL_ALWAYS_SOFTWARE environment variable, which will cause Mesa to "always use software rendering".

Answer 2

OpenGL is not an instruction set, neither is it a library. It's a drawing API for interfacing with GPUs (yes there are software based rasterizers like Mesa softpipe). Most computers you can find these days support OpenGL.

When you use the OpenGL API it's not like your OpenGL calls get "translated" into a special instruction set for the GPU that's then part of your program. OpenGL operations will just create calls that eventually end up in a device driver, just like reading or writing to a file.