What are the values passed in _ZBufferParams? My understanding of how to linearize and then expand the OpenGL z-buffer seems to sub-par. I'm not able to use the helper DECODE_EYEDEPTH because my rendered depth buffer has different clipping planes from the actual scene camera, so I'm rebuilding the functionality. This was simple enough in DirectX. All I needed to pass to the shader was the camera's far clip plane and multiply that by the pixel's depth. However, OpenGL seems to be a bit trickier.