How to debug a GLSL shader?

opengl debugging glsl
Franck Freiburger picture Franck Freiburger · Mar 24, 2010 · Viewed 136.5k times · Source

I need to debug a GLSL program but I don't know how to output intermediate result. Is it possible to make some debug traces (like with printf) with GLSL ?

Answer

Mr. Berna picture Mr. Berna · Mar 24, 2010

You can't easily communicate back to the CPU from within GLSL. Using glslDevil or other tools is your best bet.

A printf would require trying to get back to the CPU from the GPU running the GLSL code. Instead, you can try pushing ahead to the display. Instead of trying to output text, output something visually distinctive to the screen. For example you can paint something a specific color only if you reach the point of your code where you want add a printf. If you need to printf a value you can set the color according to that value.

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