## How to rotate a vertex position matrix with angle-axis input

Jun 13 2012 | 2:02 pm
Hi, I haven't been able to work this one out. How do I rotate a matrix with XYZ position data with an angle-axis vector (a,x,y,z) as input? Is there an external that does this?
Tanx, D.

• Jun 13 2012 | 2:14 pm
Ok I found one solution in Graham Wakefield's quat externals: [axis2quat] and [quatpov]. This forces me to to iterate through the matrix cells though. Is there a solution that transforms the matrix data directly? With the right math code I could make a jit.gen operation as well.
• Jun 13 2012 | 3:04 pm
• Jun 13 2012 | 4:00 pm
I should be able to max-ify that. Tanx!
• Jun 13 2012 | 6:12 pm
couple things to mention. there are max 6 native versions of the quaternion objects. jit.quat jit.quat2euler jit.euler2quat jit.quat2axis jit.axis2quat
if your matrix of vertices came from an jit.gl object in matrixoutput mode, you can apply a rotation to the object itself and use @matrixoutput 2, to output the transformed vertices.
but otherwise, you should be able to construct a gen patch that takes a quaternion as a parameter, and transforms the vertices appropriately.
• Jun 13 2012 | 7:02 pm
tanx!
> if your matrix of vertices came from an jit.gl object in matrixoutput mode, you can apply a rotation to the object itself and use @matrixoutput 2, to output the transformed vertices.
I know but this is exactly to work around the lack of matrixoutput in jit.gl.mesh...
• Jun 21 2012 | 12:33 pm
dtr, I'm interested, by your final solution. jit.gen ?
• Jun 21 2012 | 12:51 pm
Hey, I didn't implement it yet. It's on my list for optimization steps but got more pressing issues right now...
• Jun 21 2012 | 12:54 pm
argh :) all forces with you!
on my side, playing with quaternions.. I'll post my stuff soon
• Jun 21 2012 | 1:00 pm
Thanks! 4 days till graduation exam performance, gotta weave all those loose threads together in a solid fabric...