How to use

subtractLocal

method

in

com.ardor3d.math.Vector4

/**
 * Decrements the values of this vector by the x, y, z and w values from the given source vector.
 * 
 * @param source
 * @return this vector for chaining
 * @throws NullPointerException
 *             if source is null.
 */
public Vector4 subtractLocal(final ReadOnlyVector4 source) {
  return subtractLocal(source.getX(), source.getY(), source.getZ(), source.getW());
}

/**
 * Decrements the values of this vector by the x, y, z and w values from the given source vector.
 * 
 * @param source
 * @return this vector for chaining
 * @throws NullPointerException
 *             if source is null.
 */
public Vector4 subtractLocal(final ReadOnlyVector4 source) {
  return subtractLocal(source.getX(), source.getY(), source.getZ(), source.getW());
}

private void calculateIntersection(final double planeHeight, final ReadOnlyVector2 screenPosition,
    final ReadOnlyMatrix4 modelViewProjectionInverseMatrix) {
  origin.set(screenPosition.getX() * 2 - 1, screenPosition.getY() * 2 - 1, -1, 1);
  direction.set(screenPosition.getX() * 2 - 1, screenPosition.getY() * 2 - 1, 1, 1);
  modelViewProjectionInverseMatrix.applyPre(origin, origin);
  modelViewProjectionInverseMatrix.applyPre(direction, direction);
  direction.subtractLocal(origin);
  // final double t = (planeHeight * origin.getW() - origin.getY())
  // / (direction.getY() - planeHeight * direction.getW());
  if (Math.abs(direction.getY()) > MathUtils.EPSILON) {
    final double t = (planeHeight - origin.getY()) / direction.getY();
    direction.multiplyLocal(t);
  } else {
    direction.normalizeLocal();
    direction.multiplyLocal(mainCamera.getFrustumFar());
  }
  origin.addLocal(direction);
}

private void calculateIntersection(final double planeHeight, final ReadOnlyVector2 screenPosition,
    final ReadOnlyMatrix4 modelViewProjectionInverseMatrix) {
  origin.set(screenPosition.getX() * 2 - 1, screenPosition.getY() * 2 - 1, -1, 1);
  direction.set(screenPosition.getX() * 2 - 1, screenPosition.getY() * 2 - 1, 1, 1);
  modelViewProjectionInverseMatrix.applyPre(origin, origin);
  modelViewProjectionInverseMatrix.applyPre(direction, direction);
  direction.subtractLocal(origin);
  // final double t = (planeHeight * origin.getW() - origin.getY())
  // / (direction.getY() - planeHeight * direction.getW());
  if (Math.abs(direction.getY()) > MathUtils.EPSILON) {
    final double t = (planeHeight - origin.getY()) / direction.getY();
    direction.multiplyLocal(t);
  } else {
    direction.normalizeLocal();
    direction.multiplyLocal(mainCamera.getFrustumFar());
  }
  origin.addLocal(direction);
}

@Test
public void testSubtract() {
  final Vector4 vec1 = new Vector4();
  final Vector4 vec2 = new Vector4(Vector4.ONE);
  vec1.subtractLocal(1, 2, 3, 4);
  assertEquals(new Vector4(-1, -2, -3, -4), vec1);
  vec1.subtractLocal(-1, -2, -3, -4);
  assertEquals(Vector4.ZERO, vec1);
  vec1.zero();
  vec1.subtractLocal(vec2);
  assertEquals(Vector4.NEG_ONE, vec1);
  vec1.zero();
  final Vector4 vec3 = vec1.subtract(vec2, new Vector4());
  assertEquals(Vector4.ZERO, vec1);
  assertEquals(Vector4.NEG_ONE, vec3);
  final Vector4 vec4 = vec1.subtract(0, 0, 0, 1, null);
  assertEquals(Vector4.ZERO, vec1);
  assertEquals(Vector4.NEG_UNIT_W, vec4);
}