How to visualize a depth texture in OpenGL?

Question

I'm working on a shadow mapping algorithm, and I'd like to debug the depth map that it's generating on its first pass. However, depth textures don't seem to render properly to the viewport. Is there any easy way to display a depth texture as a greyscale image, preferably without using a shader?

Answer 1

Depth textures (2D) can be used just like any regular grayscale texture. The only problem might be that the values inside it are all too high and you only see a white texture. If that's the case play around with the z-near and -far planes that are used when creating the depth texture (or scale the values with a shader or maybe glTexEnv).