protected static double heightAngleToRelativeHeight(float heightAngle) {
        double radians = heightAngle / 180d * Math.PI;

        return Math.tan(radians) * Math.sqrt(2d);
    }
@Test
    public void heightAngleToRelativeHeight() {
//        assertThat("nan", DiffuseShadingAlgorithm.heightAngleToRelativeHeight(90), is(Double.NaN));
        assertThat("flat", DiffuseLightShadingAlgorithm.heightAngleToRelativeHeight(0), is(0d));
//        assertThat("half", DiffuseShadingAlgorithm.heightAngleToRelativeHeight(45), is(Math.sqrt(2d)));

    }