Bug 636

I am using JOGL 2.0 rc 10.

I tried using Quaternion class that was implemented in jogamp.graph.math.MathFloat.Quaternion and I noticed an error in mult(Quaternion).

I am not a Quaternion expert but according to all math site online quaternion multiplication is done as follows:

Let Q1 and Q2 be two quaternions, which are defined, respectively, as (w1, x1, y1, z1) and (w2, x2, y2, z2).
(Q1 * Q2).w = (w1w2 - x1x2 - y1y2 - z1z2)
(Q1 * Q2).x = (w1x2 + x1w2 + y1z2 - z1y2)
(Q1 * Q2).y = (w1y2 - x1z2 + y1w2 + z1x2)
(Q1 * Q2).z = (w1z2 + x1y2 - y1x2 + z1w2

http://en.wikipedia.org/wiki/Quaternion
http://www.cprogramming.com/tutorial/3d/quaternions.html
http://mathworld.wolfram.com/Quaternion.html

In Quaternion class, mult(Quaternion) is currently defined as:

    public void mult(Quaternion q)
    {
        float w1 = w*q.w - (x*q.x + y*q.y + z*q.z);

        float x1 = w*q.z + q.w*z + y*q.z - z*q.y;
        float y1 = w*q.x + q.w*x + z*q.x - x*q.z;
        float z1 = w*q.y + q.w*y + x*q.y - y*q.x;

        w = w1;
        x = x1;
        y = y1;
        z = z1; 
    }
I believe this multiplication is incorrect and it rotated my jogl model unpredictively.  Also, according to quaternion definition, quaternion multiplication are not commutative!!! (ie: q.w*z is different from z*q.w)

I override the mult(Quaternion) with the definition of quaternion multiplication and it behaves as expected:

    public void mult(Quaternion q)
    {
        float w1 = w*q.w - x*q.x - y*q.y - z*q.z;

        float x1 = w*q.x + x*q.w + y*q.z - z*q.y;
        float y1 = w*q.y - x*q.z + y*q.w + x*q.x;
        float z1 = w*q.z + x*q.y - y*q.x + y*q.w;

        w = w1;
        x = x1;
        y = y1;
        z = z1; 
    }

Thank you in advance