Hello,
I am trying to get billboarding to work. I needed a little clarification. This is the way i tried:
From the modelview, i obtain the following:
 
 x1 y1 z1 
 x2 y2 z2 
 x3 y3 z3 
    
 
[(x1, x2, x3) is the vector that provides the X orientation]
[ ** ‘’ implies i’m not using that part of the matrix]
Using the x vector, find the angle between that and
[0, 0, 1] So, this would be the angle i need to rotate the billboard on the y axis.
Let this angle be “Ang”
So, what i’m trying is:

Rotate scene by “rot” angle on the Y axis.

Using the modelview, obtain “Ang” Now, rot will be equal to Ang. So, i just do a negative rotation of Ang on the Y axis.
ie.
. Rotate scene by rot
. Obtain Ang
. Rotate object by Ang
This seems to work. I am trying for billboarding on only one axis. Is there a better way? Or is this method fine?
Thanks!