public static bool Dielectric(Ray r, HitRecord rec,
ref float3 attenuation, ref Ray scattered, ref Random rand)
{
var refractionIndex = rec.material.refractionIndex;
float3 outwardNormal;
float3 reflected = RayMath.Reflect(r.direction, rec.normal);
float niOverNt;
attenuation = new float3(1f, 1f, 1f);
float3 refracted;
float cosine;
if (math.dot(r.direction, rec.normal) > 0f)
{
outwardNormal = -rec.normal;
niOverNt = refractionIndex;
cosine = refractionIndex * math.dot(r.direction, rec.normal) / math.length(r.direction);
}
else
{
outwardNormal = rec.normal;
niOverNt = 1f / refractionIndex;
cosine = -math.dot(r.direction, rec.normal) / math.length(r.direction);
}
var reflectProbability = RayMath.Refract(r.direction, outwardNormal, niOverNt, out refracted)
? RayMath.Schlick(cosine, refractionIndex) : 1f;
scattered = rand.NextFloat() < reflectProbability
? new Ray(rec.p, reflected) : new Ray(rec.p, refracted);
return(true);
}
public static bool Metal(Ray r, HitRecord rec, ref float3 attenuation, ref Ray scattered, ref Random random)
{
var m = rec.material;
float3 reflected = RayMath.Reflect(math.normalize(r.direction), rec.normal);
scattered = new Ray(rec.p, reflected + m.fuzziness * Utils.RandomInUnitSphere(random));
attenuation = m.albedo;
return(math.dot(scattered.direction, rec.normal) > 0);
}