morient in python

[Alexey Vanzhula]

Hi. I`m looking for a python equivalent to morient expression function

Edited August 13, 2015 by Alexey Vanzhula

[MrScienceOfficer]

You would most likely have to build the matrix yourself, fortunately if you already have two axes, as I assume you do to use the morient expression, although I've never used so it I'm not hundred percent on use cases, it shouldn't be too tough.

 

All you need to do is take the cross product of the two axis vectors which will then give you the third axis and you can build the matrix per component hou.matrix3(X[0], X[1], X[2], Y[0].....,Z[2]).. Houdini uses Row major notation so that should be the proper way to build it.

 

This page seemed to be good as well http://renderdan.blogspot.com/2006/05/rotation-matrix-from-axis-vectors.html

[Alexey Vanzhula]

Thanx !

I have 3 perpendicular vectors and I want to get rotation to that "axis system".
The most simple form to get it is using hou.hscriptVectorExpression to get 3 angles from morient expr.
So I just want to see most elegant (python) way )

EDIT:

x, y, z = hou.hscriptVectorExpression('''
{
matrix mat=morient(vector3(%f, %f, %f), vector3(%f, %f, %f));
return vector3(explodematrix( mat, "SRT", "XYZ", "RX" ), explodematrix( mat, "SRT", "XYZ", "RY" ), explodematrix( mat, "SRT", "XYZ", "RZ" ));
}''' % (dir_y[0], dir_y[1], dir_y[2], dir_z[0],dir_z[1],dir_z[2]) )

Edited August 13, 2015 by Alexey Vanzhula

[MrScienceOfficer]

You could do

 

euler = matrix3(vector1, vector2, vector3).extractRotates()

 

That should give you world space to your vectors' space, in Euler angles.

[Alexey Vanzhula]

Thanx