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

You may need to change the depth texture parameters to display it as greyscale levels :

glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_COMPARE_MODE, GL_NONE )
glTexParameteri( GL_TEXTURE_2D, GL_DEPTH_TEXTURE_MODE, GL_LUMINANCE )

You can then normally use the texture as a 'normal' greyscale 2d texture, either via fixed function, or a 'sampler2d' shader uniform.