public void ValuesAtRadiusShouldBeZero()
{
var f = new MitchellFilter(new Vector2(2f), 0.5f, 0.25f);
f.Evaluate(new Point2D(2f, 0f)).Should().BeApproximately(0f, 0.001f);
f.Evaluate(new Point2D(0f, 2f)).Should().BeApproximately(0f, 0.001f);
f.Evaluate(new Point2D(0f, -2f)).Should().BeApproximately(0f, 0.001f);
f.Evaluate(new Point2D(System.MathF.Sqrt(2f), System.MathF.Sqrt(2f))).Should().BeApproximately(0f, 0.001f);
}
public void ValueAtOrigin()
{
var b = 0.5f;
var zero1D = (6f - 2 * b) * (1f / 6f);
var f = new MitchellFilter(new Vector2(2f), b, 0.25f);
f.Evaluate(new Point2D(0f, 0f)).Should().BeApproximately(zero1D * zero1D, 0.0001f);
}
public void NegativeLobesNearRadiusExtent()
{
var f = new MitchellFilter(new Vector2(2f), 0.5f, 0.25f);
f.Evaluate(new Point2D(1.8f, 0f)).Should().BeLessThan(0f);
}