private Vector TraceRay(Vector O, Vector D, double tMin, double tMax, int depth)
{
var(closestPrimitive, closest_t) = ClosestIntersection(O, D, tMin, tMax);
if (closestPrimitive == null)
{
return(Vector.FromColor(_options.BgColor));
}
var view = D.Multiply(-1);
var P = O.Add(D.Multiply(closest_t));
Vector normal = new Vector();
if (closestPrimitive is Plane plane)
{
normal = plane.Normal;
}
if (closestPrimitive is Sphere sphere)
{
if (sphere.LightTransparent)
{
return(Vector.FromColor(sphere.Color));
}
normal = P.Subtract(sphere.Center);
}
if (closestPrimitive is Box box)
{
normal = box.GetNormal(O, D, tMin);
}
if (closestPrimitive is Surface surface)
{
normal = surface.GetNormal(O, D, closest_t);
}
if (closestPrimitive is Torus torus)
{
normal = torus.GetNormal(O, D, closest_t);
}
if (closestPrimitive is Disk disk)
{
normal = disk.GetNormal();
}
normal = normal.Multiply(1 / normal.Lenght()); //unit vector
if (normal.DotProduct(D) > 0)
{
normal = normal.Multiply(-1);
}
var color = closestPrimitive.Color;
if (closestPrimitive is Plane)
{
var x = (int)Math.Round(O.D1 + D.D1 * closest_t) % 2;
var z = (int)Math.Round(O.D3 + D.D3 * closest_t) % 2;
if (x == z)
{
color = Color.FromRgb(0, 0, 0);
}
}
var local_color = Vector.FromColor(color)
.Multiply(ComputeLighting(P, normal, view, closestPrimitive.Specular));
var r = closestPrimitive.Reflect;
if (depth <= 0 || r <= 0)
{
return(local_color);
}
var R = ReflectRay(view, normal);
var reflectedColor = TraceRay(P, R, 0.001d, double.PositiveInfinity, depth - 1);
return(local_color.Multiply(1 - r).Add(reflectedColor.Multiply(r)));
}
private Vector ReflectRay(Vector r, Vector normal)
{
return(normal.Multiply(2 * r.DotProduct(normal)).Subtract(r));
}