Hi Igor, What Bin Chen wrote is probably the most painless way of achieving what you want. If you are however interested in the math, here goes my stab: If I understand you correctly, you know the leaf normal, and the branch direction vector, then you're searching for the matrix that transforms the former to the latter. Basically you need to find the matrix that satisfies: b = A * n (b is the branch direction, n is the leaf normal). This equation however is underdetemined, meaning you can have several rotations done in sequence that give you the same result, so you'd need to do some "trickery". One of the usual ways to solve such a problem is to use Euler angles[1], where the idea is to make elemental rotations with respect to the principle axes of the (global) coordinate systems. To that end you'd need to calculate the projections (i.e. dot products) of b and n to the principal axes and extract the angles of rotation from there, then construct each rotation matrix around a principal axis of the coordinate system and finally multiply them to obtain the final transformation.
[1]: https://en.wikipedia.org/wiki/Euler_angles I hope that helps. Konstantin.
_______________________________________________ Interest mailing list Interest@qt-project.org http://lists.qt-project.org/mailman/listinfo/interest
