Shaders and shading languages

Hello !

I'm not really new to opengl, but I'm a complete newbie with regards to vertex/pixel shaders.
There is something that I don't understand:
What is the relationship of the OpenGL shading language to the type of programs I saw when playing with the examples for OpenGL Shader Builder ?
Is there a compiler on the mac for this (OSL) ?
What about Cg ?

There is also something that troubles me. Some of the examples I played with don't render the same way *at all* on my ATI 9800Pro and 9700 (the bump shader, for example is flat and dark on the 9700). And Shader Builder crashes quite often.
Can someone who writes a shader assume it will work on most recent cards ?

Do you know if Apple actually supports Shader Builder ?

Up until now, I've had the feeling that pixel/vertex shading was for the "initiated", on the mac. No docs/commented samples etc ;-(

thanks in advance for any help on those topics ^_^

[OneSadCookie]

GLSL is not yet supported on the Mac

ARB_fragment_program and ARB_vertex_program are supported, reasonably well (though certainly not bug-freely).

Shader Builder is very crashy. If you're going to use it, save early and often.

Cg works fine on the Mac. You can download the Mac SDK from NVIDIA's website.

Vertex & Pixel shading on the Mac is exactly the same as on Windows or Linux. Examples you find for these platforms should work identically on the Mac.