[request] jit.euler2quat & jit.quat2euler _ attribute for order of rotation


    Sep 06 2012 | 6:12 pm
    it seems that the order of rotation used in jit.euler2quat is YZX:
    first X rot, second Z rot, third Y rot
    so X is the bank (tilt) axe.
    there is 12 rotation order possibilities.
    A convenient order of rotation for openGL, when object is facing the camera is YXZ:
    first Z rot, second X rot, third Y rot
    It is more logical to use this order, respect to the direction and lookat attributes of jit.anim.node that use the Z axis of the object.
    so Z is the bank (tilt) axe.
    Could you create an attribute for those 2 objects like: rotation_order (default: yzx, yxz etc...)
    or make an object like jit.eulerYXZ2quat and jit.quat2eulerYXZ
    or perhaps send me or make the code public for jit.euler2quat & jit.quat2euler, so i can adapt them.
    thanks
    I created a mxj for this:
    public final void yxz_r(double x, double y, double z) {
    // Y : heading, X : attitude, Z : bank
    // enter: XYZ _ order process: YXZ
    // first Z rot, second X rot, third Y rot, for jitter conveniences
    // Assuming the angles are in radians.
    double sx = Math.sin(x/2);
    double cx = Math.cos(x/2);
    double sy = Math.sin(y/2);
    double cy = Math.cos(y/2);
    double sz = Math.sin(z/2);
    double cz = Math.cos(z/2);
    // R= Qx*Qz _ first Zrot then Xrot
    // double Rx = cz*sx;
    //double Ry = -sz*sx;
    //double Rz = sz*cx;
    //double Rw = cz*cx;
    // R= Qy*Qxz first XZrot then Yrot
    //qx = Rx*cy+Rz*sy;
    //qy = Rw*sy+Ry*cy;
    //qz = -Rx*sy+Rz*cy;
    //qw = Rw*cy-Ry*sy;
    // R= Qy*Qx*Qz first Zrot then Xrot then Yrot
    qx = cz*sx*cy+sz*cx*sy;
    qy = cz*cx*sy-sz*sx*cy;
    qz = -cz*sx*sy+sz*cx*cy;
    qw = cz*cx*cy+sz*sx*sy;
    quat_out();
    }

    • Sep 06 2012 | 8:22 pm
      hello Spa.
      i have logged a feature request for a rotation-order attribute to the quaternion objects.
      our implementation is more or less derived from this website:
    • Sep 06 2012 | 9:58 pm
      Thanks Robert.
      Is it possible to have a code example of these objects, so i could use them as base for developing similar objects.
      thanks
    • Sep 06 2012 | 10:53 pm
      i'm not sure what you are asking.
      the website i linked to has sample code.
      your mxj code you posted should also work fine.
      if you want to develop externals, the sdk is the place to start:
    • Sep 06 2012 | 11:09 pm
      I just wanted the jit.euler2quat and jit.quat2euler source code ...
      mxj seems 4 times slower than native objects, due to bridge from max to java i suppose.
    • Sep 11 2012 | 1:58 pm
      well, i suppose it was a bit short to include it in the 6.0.7 release.
      Hope it will appear in the next one.
      thanxs
    • Jun 19 2013 | 7:37 pm
      with 6.1.3, jit.euler2quat and quat2euler have an attribute called @rotate_order, allowing you to specify the order rotations are applied.