public Color RefractedColor(Computation comps, int remaining = 5)
{
if (remaining <= 0)
{
return(Color.Black);
}
if (comps.Object.Material.Transparency == 0)
{
return(Color.Black);
}
var nRatio = comps.N1 / comps.N2;
var cosI = PointType.DotProduct(comps.EyeV, comps.NormalV);
var sin2t = nRatio * nRatio * (1 - cosI * cosI);
if (sin2t > 1)
{
return(Color.Black);
}
var cosT = Math.Sqrt(1 - sin2t);
var direction = comps.NormalV * (nRatio * cosI - cosT)
- comps.EyeV * nRatio;
var refractRay = new Ray(comps.UnderPoint, direction);
var color = ColorAt(refractRay, remaining - 1) *
comps.Object.Material.Transparency;
return(color);
}
public static Computation PrepareComputations(Intersection i, Ray r, Intersection[] xs = null)
{
var c = new Computation
{
T = i.T,
Object = i.Object
};
c.Point = transform.Position(r, c.T);
c.EyeV = -r.Direction;
c.NormalV = (c.Object as Shape).NormalAt(c.Point, i);
if (PointType.DotProduct(c.NormalV, c.EyeV) < 0)
{
c.Inside = true;
c.NormalV = -c.NormalV;
}
else
{
c.Inside = false;
}
c.OverPoint = c.Point + c.NormalV * EPSILON;
c.UnderPoint = c.Point - c.NormalV * EPSILON;
c.RelflectV = Light.Reflect(r.Direction, c.NormalV);
if (xs == null)
{
xs = new Intersection[] { i }
}
;
GetRefractions(i, xs, out var n1, out var n2);
c.N1 = n1;
c.N2 = n2;
return(c);
}
public static PointType Reflect(PointType vector, PointType normal) => vector - normal * 2 * PointType.DotProduct(vector, normal);
