public static Computations Prepare(Intersection hit, Ray ray, List <Intersection> xs)
{
float n1 = 0;
float n2 = 0;
var containers = new List <IShape>();
foreach (var i in xs)
{
if (i == hit)
{
n1 = !containers.Any() ? 1 : containers.Last().Material.RefractiveIndex;
}
if (containers.Contains(i.Shape))
{
containers.Remove(i.Shape);
}
else
{
containers.Add(i.Shape);
}
if (i == hit)
{
n2 = !containers.Any() ? 1 : containers.Last().Material.RefractiveIndex;
break;
}
}
var point = ray.ComputePosition(hit.T);
return(new Computations(hit.T, hit.Shape, point, -ray.Direction, hit.Shape.GetNormalAt(point), n1, n2));
}
