OpenGL Shading Language

A good start to learn OpenGL Shading language. This simple program was built under Ubuntu OS.

The process that OpenGL using shading language is the much similar as D3D. Some difference exists like, pixel shader or fragment shader, the vertex element that pass to the shader program and those registers that could be used by application level. Something could go deeper are how to off-line compile the OpenGL shaders into binary files, how to profile GLSL shader performance on PC(windows or ubuntu), and how to debug them? It seems D3D provide some useful tools to help us do the shader profile & debug work, like the PIX. And OpenGL?