I just wanted to try out some shaders on a flat image. Turns out that writing a C program, which just takes a picture as a texture and applies, let\'s say a gaussian blur, a
This tutorial might be useful (note that it does contain GLSL material besides the old Cg stuff).
Note that I'd consider writing shaders to implement non-graphical, GPGPU-type things to be an obsolete approach these days. OpenCL or CUDA are clearly they way to go in future.