I have some problem about mentalray shader.
I am using the fisheye source code from below mentalray document.
In the upper page, there is no explanation about code,
so I couldn't understand about below area.
dir.x = camdir.x * r;
dir.y = camdir.y * r;
Because of upper code, the fisheye shader receive side effect when I change focal length.
Is there anybody who can explain to me about this two line of code?
Any advise or feedback about this problem will be very helpful for me.