Hi list,
I’m having some problems doing depth sorting, because I’m stuck on one thing. I
can extract the x,y,z translation from the modelview matrix, but just using
that straight with a 3d pythag to find the distances of my billboards leads to
draw errors. By examining the modelview matrix I realised that I need to rotate
the x,y,z translation coords that I extract from the model view matrix.
Only problem, I’ve never done vector rotation, and also never in combination
with OpenGL.
I know how to extract the rotation matrix. Or even if I don’t know I can work
it out by doing glrotatef and then examing the modelview matrix to see what has
changed.
But the problem is, what do I do with the x,y,z rotations? Does OpenGL suffer
from gimbal lock using Euler angles? Or do I do some full matrix rotation? Like
I said, I’ve never done vector rotation, and I don’t know what type of vector
rotation OpenGL uses (I know there are several: Euler Angles, quaternion,
matrix, and more)