public void CanFailToInsersectWithRayFacingAwayFromSphere()
{
// Arrange
var sphere = new Sphere() { Center = new Vector(0, 0, 0), Radius = 1 };
var ray = new Ray() { Start = new Vector(0, 0, -2), Direction = new Vector(0, 0, -1) };
// Act
var isect = sphere.Intersect(ray);
// Assert
Assert.IsNull(isect);
}
public void CanCalculateNormalToSphere()
{
// Arrange
var sphere = new Sphere() { Center = new Vector(0, 0, 0), Radius = 1 };
var position = new Vector(1,0,0);
// Act
var normal = sphere.Normal(position);
// Assert
Assert.NotNull(normal);
Assert.IsTrue(normal.Equals(new Vector(1,0,0)));
}
public void CanIntersectEdgeOfSphere()
{
// Arrange
var sphere = new Sphere() { Center = new Vector(0, 0, 0), Radius = 1 };
var ray = new Ray() { Start = new Vector(1, 0, -2), Direction = new Vector(0, 0, 1) };
// Act
var isect = sphere.Intersect(ray);
// Assert
Assert.NotNull(isect);
Assert.AreEqual(2, isect.Distance);
Assert.AreEqual(sphere, isect.Element);
}