private Color Shade(ISect isect, Scene scene, int depth)
{
var d = isect.Ray.Dir;
var pos = Vector.Plus(Vector.Times(isect.Dist, isect.Ray.Dir), isect.Ray.Start);
var normal = isect.Thing.Normal(pos);
var reflectDir = Vector.Minus(d, Vector.Times(2*Vector.Dot(normal, d), normal));
Color ret = Color.DefaultColor;
ret = Color.Plus(ret, GetNaturalColor(isect.Thing, pos, normal, reflectDir, scene));
if (depth >= MaxDepth)
{
return Color.Plus(ret, Color.Make(.5, .5, .5));
}
return Color.Plus(ret, this.GetReflectionColor(isect.Thing, Vector.Plus(pos, Vector.Times(.001, reflectDir)), normal, reflectDir, scene, depth));
}
private Color TraceRay(Ray ray, Scene scene, int depth)
{
var isects = Intersections(ray, scene);
ISect isect = isects.FirstOrDefault();
if (isect == null)
{
return Color.Background;
}
return this.Shade(isect, scene, depth);
}
private Color GetReflectionColor(SceneObject thing, Vector pos, Vector norm, Vector rd, Scene scene, int depth)
{
return Color.Times(thing.Surface.Reflect(pos), this.TraceRay(new Ray {Start = pos, Dir = rd}, scene, depth + 1));
}
private static double TestRay(Ray ray, Scene scene)
{
var isects = Intersections(ray, scene);
ISect isect = isects.FirstOrDefault();
if (isect == null)
{
return 0;
}
return isect.Dist;
}
private static IEnumerable<ISect> Intersections(Ray ray, Scene scene)
{
return scene.Things
.Select(obj => obj.Intersect(ray))
.Where(inter => inter != null)
.OrderBy(inter => inter.Dist);
}
private static Color GetNaturalColor(SceneObject thing, Vector pos, Vector norm, Vector rd, Scene scene)
{
Color ret = Color.Make(0, 0, 0);
foreach (Light light in scene.Lights)
{
Vector ldis = Vector.Minus(light.Pos, pos);
Vector livec = Vector.Norm(ldis);
double neatIsect = TestRay(new Ray {Start = pos, Dir = livec}, scene);
bool isInShadow = !((neatIsect > Vector.Mag(ldis)) || (neatIsect == 0));
if (!isInShadow)
{
double illum = Vector.Dot(livec, norm);
Color lcolor = illum > 0 ? Color.Times(illum, light.Color) : Color.Make(0, 0, 0);
double specular = Vector.Dot(livec, Vector.Norm(rd));
Color scolor = specular > 0 ? Color.Times(Math.Pow(specular, thing.Surface.Roughness), light.Color) : Color.Make(0, 0, 0);
ret = Color.Plus(ret, Color.Plus(Color.Times(thing.Surface.Diffuse(pos), lcolor),
Color.Times(thing.Surface.Specular(pos), scolor)));
}
}
return ret;
}
internal void Render(Scene scene)
{
for (int y = 0; y < this.screenHeight; y++)
{
for (int x = 0; x < this.screenWidth; x++)
{
Color color = this.TraceRay(new Ray {Start = scene.Camera.Pos, Dir = this.GetPoint(x, y, scene.Camera)}, scene, 0);
this.setPixel(x, y, color.ToDrawingColor());
}
}
}