/**
* * Initialize this quaternion with given normalized axis vector and rotation angle
*
* <p>Implementation Details:
*
* <ul>
* <li>{@link #setIdentity()} if axis is {@link FloatUtil#isZero(float, float) is zero} using
* {@link FloatUtil#EPSILON epsilon}
* </ul>
*
* @param angle rotation angle (rads)
* @param vector axis vector normalized
* @return this quaternion for chaining.
* @see <a
* href="http://web.archive.org/web/20041029003853/http://www.j3d.org/matrix_faq/matrfaq_latest.html#Q56">Matrix-FAQ
* Q56</a>
* @see #toAngleAxis(float[])
*/
public final Quaternion setFromAngleNormalAxis(final float angle, final float[] vector) {
if (VectorUtil.isVec3Zero(vector, 0, FloatUtil.EPSILON)) {
setIdentity();
} else {
final float halfangle = angle * 0.5f;
final float sin = FloatUtil.sin(halfangle);
x = vector[0] * sin;
y = vector[1] * sin;
z = vector[2] * sin;
w = FloatUtil.cos(halfangle);
}
return this;
}
/**
* Normalize a quaternion required if to be used as a rotational quaternion.
*
* <p>Implementation Details:
*
* <ul>
* <li>{@link #setIdentity()} if {@link #magnitude()} is {@link FloatUtil#isZero(float, float)
* is zero} using {@link FloatUtil#EPSILON epsilon}
* </ul>
*
* @return this quaternion for chaining.
*/
public final Quaternion normalize() {
final float norm = magnitude();
if (FloatUtil.isZero(norm, FloatUtil.EPSILON)) {
setIdentity();
} else {
final float invNorm = 1f / norm;
w *= invNorm;
x *= invNorm;
y *= invNorm;
z *= invNorm;
}
return this;
}