I have found openGL fragment shader tutorials on the web, some that use use inverse calculations to revert the fragment coordinate back to the world space and others that interpolate the position. With that said...
- Is there a difference between interpolated world-space position and the actual world space position calculated using inverse matrices and the fragment window space coordinates?
- Does anyone know of any resources that would help me understand the mathematical differences between these two things, if they are different?
- If they aren't different, then why would anyone use inverse matrices instead of interpolating, which seems less expensive?
I wrote a shader to test 1, but I cannot tell if rounding errors are to blame for the differences or not.