// Fatory Methods
public static Matrix3 rotation(Vector3 axis, final float angle) {
if (angle == 0) return Identity;
axis = axis.unit();
if (!axis.isFinite()) throw new RuntimeException();
final float c = GMath.cos(angle), s = GMath.sin(angle);
return axis.mul(1 - c).mul(axis).add(Identity, c).add(axis.mul(s).tilda());
}
public static Quaternion makeRotation(Quaternion result, float theta, Vector axis) {
float halfTheta = theta / 2;
float sinHalfTheta = GMath.sin(halfTheta);
result.w = GMath.cos(halfTheta);
result.x = axis.getX() * sinHalfTheta;
result.y = axis.getY() * sinHalfTheta;
result.z = axis.getZ() * sinHalfTheta;
return result;
}
