> On Fri, 3 Mar 2000, pine wrote:
>
> > t = new Transform3D();
> > t.setRotation(new Quat4f(0.78f, 0.78f, 0.78f,0.0f));
> >
> > What's the four parameters in Quat4f( ) mean?
>
> Dunno exactly (it's a complex number of some sort), but if you're
> interested in rotation about a particular axis by a particular angle (e.g.
> for a RotPosPathInterpolator), try this FriendlyQuat class. Use it like:
>
> Quat4f myquat = new FriendlyQuat(1, 0, 0, Math.PI * 60/180);
>
> The comments in the class will give more clues about how to do it without
> the class.
>
> class FriendlyQuat extends Quat4f {
> // A quat (x,y,z,w) for a rotation about (x,y,z) by angle t is:
> // (x*sin(t/2),y*sin(t/2),z*sin(t/2),cos(t/2))
> // (a,b,c) must be a unit vector. This class normalizes the vector for you.
> public FriendlyQuat(float x, float y, float z, float theta) {
> this(new Vector3f(x,y,z), theta);
> }
>
> public FriendlyQuat(double x, double y, double z, double theta) {
> this(new Vector3f((float)x,(float)y,(float)z), (float)theta);
> }
>
> public FriendlyQuat(Vector3f u, float theta) {
> super();
> Vector3f nu = new Vector3f();
> nu.normalize(u);
> float[] t = new float[3];
> nu.get(t);
> float mst2 = (float) Math.sin(theta/2);
> set(t[0] * mst2, t[1] * mst2, t[2] * mst2, (float) Math.cos(theta/2));
> }
>
> public FriendlyQuat(AxisAngle4f aa) {
> super();
> set(aa);
> }
> }
>
> Gareth
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