Reconstructing world coordinates from depth buffer and arbitrary view-projection matrix

Question

I\'m trying to reconstruct 3D world coordinates from depth values in my deferred renderer, but I\'m having a heck of a time. Most of the examples I find online assume a standard

Answer 1

Your general approach is correct, you just did not invert the window space transform correctly. Window space z (which you probably wtrot into your depth texture) is [0,1] (by default, more general would be glDepthRange()), but NDC space z is [-1,1]. So you could change that line analogous to your x and y mappings to

clipSpaceLocation.z = texture(depthSampler, texcoord).r * 2.0 - 1.0;

Answer 2

I only needed to make a tiny fix. The line:

clipSpaceLocation.z = texture(depthSampler, texcoord).r;

should read:

clipSpaceLocation.z = texture(depthSampler, texcoord).r * 2.0f - 1.0f;

The way I understand it, projection matrices are designed so they map the near and far planes to [-1,1], not [0,1] like I had always assumed. OpenGL then normalizes them to the range [0,1] (a.k.a. "Window Space"), so I needed to perform the inverse of that normalization.

This is all assuming glDepthRange(0, 1), which it is by default, and there's little reason to change it.

Answer 3

See my answer on gamedev.stackexchange for a more efficient way to reconstruct world and view space positions:

https://gamedev.stackexchange.com/a/111885/24009