public RayScattered Scatter(Dielectric dielectric, Ray ray, RayHitpoint hitpoint, Color rayColor)
{
Vector3 outwardNormal;
var reflected = Maths.Reflect(ray.Direction, hitpoint.Normal);
float niOverNt;
float cosine;
if (Vector3.Dot(ray.Direction, hitpoint.Normal) > 0)
{
outwardNormal = -hitpoint.Normal;
niOverNt = dielectric.Index;
cosine = Vector3.Dot(ray.Direction, hitpoint.Normal) / ray.Direction.Length();
cosine = (float)Math.Sqrt(1 - dielectric.Index * dielectric.Index * (1 - cosine * cosine));
}
else
{
outwardNormal = hitpoint.Normal;
niOverNt = 1.0f / dielectric.Index;
cosine = -Vector3.Dot(ray.Direction, hitpoint.Normal) / ray.Direction.Length();
}
var refracted = Maths.Refract(ray.Direction, outwardNormal, niOverNt);
var reflectProb = refracted.HasValue ? Schlick(cosine, dielectric.Index) : 1.0f;
var newRay = Maths.RandomGenerator.NextDouble() < reflectProb
? new Ray(hitpoint.Point, reflected)
: new Ray(hitpoint.Point, refracted);
return(new RayScattered(newRay, rayColor));
}
public RayScattered Scatter(Diffuse diffuse, Ray ray, RayHitpoint hitpoint, Color rayColor)
{
var target = hitpoint.Point + hitpoint.Normal + Maths.GetRandomInSphere();
var newRay = new Ray(hitpoint.Point, target - hitpoint.Point);
var newColor = new Color(rayColor.Value * diffuse.Albedo);
return(new RayScattered(newRay, newColor));
}
public RayScattered Scatter(Metal metal, Ray ray, RayHitpoint hitpoint, Color rayColor)
{
var reflected = Maths.Reflect(Vector3.Normalize(ray.Direction), hitpoint.Normal);
var newRay = new Ray(hitpoint.Point, reflected + Maths.GetRandomInSphere() * metal.Fuzz);
Color newColor;
newColor = Vector3.Dot(newRay.Direction, hitpoint.Normal) > 0
? new Color(rayColor.Value * metal.Albedo)
: new Color(Vector3.Zero);
return(new RayScattered(newRay, newColor));
}
public EntityRayHitpoint(EntityId id, RayHitpoint hitpoint)
{
Id = id;
Hitpoint = hitpoint;
}
public void Deconstruct(out EntityId id, out RayHitpoint hitpoint)
{
id = Id;
hitpoint = Hitpoint;
}
public RayScattered Scatter(Ray ray, RayHitpoint hitpoint, Color rayColor)
{
return(_computer.Scatter(_diffuse, ray, hitpoint, rayColor));
}
