debugging - How can I debug shader programs?

I'm in the process of debugging GLSL vertex shaders and I can't shake the feeling that I'm doing it wrong.

In general I have two strategies to make up for the lack of tracing

• I stuff values into a debug color varying that I pass to the fragment shader and then try to interpret the colors.


• I change the vertex shader code and see what happens.

I'm thinking that ideally I could make up for the lack of tracing by writing values to a texture somehow, reading the texture from the GPU and printed the values stuffed in the texture.

My guess is that there might be way better ways. Any suggestions?