When and how does openGL calculate F_depth(depth value)

[nirla123]

@GClements

That is the formula used for transforming NDC to window coordinates (x,y) and depth (z). Note that farVal and nearVal are the glDepthRange parameters, not the near/far distances used to generate the projection matrix.

Note that the calculation for zNDC->zw is equivalent to this one:

@GClements

depth = n + (f-n)*(zNDC+1)/2

just factored differently.

I just got everything how the F_depth and how [-1,1] to [0,1] mapping occurs. I very much thank you and Alfonse for that.

But, one thing, during window transformation z value seems to map to [0,1], meaning (x’,y’,z’), where x’,y’,z’ are the window transformed coordinates. meaning (x’,y’,z’) don’t span a plane, they span a space, so while drawing, the z’ coords are ignored?