public static bool Disk(Disk d, Ray3f r, float tMin, float tMax, out HitRecord hit)
{
hit = new HitRecord();
if (Plane(d.Plane, r, tMin, tMax, out hit))
{
var offset = (hit.point - d.Plane.Center);
if (math.dot(offset, offset) <= d.Radius * d.Radius)
{
return(true);
}
}
return(false);
}
public static bool Plane(Plane p, Ray3f r, float tMin, float tMax, out HitRecord hit)
{
hit = new HitRecord();
const float eps = 0.0001f;
if (math.abs(math.dot(r.direction, p.Normal)) > eps)
{
float t = math.dot((p.Center - r.origin), p.Normal) / math.dot(r.direction, p.Normal);
if (t > eps)
{
hit.t = t;
hit.point = PointOnRay(r, t);
hit.normal = p.Normal;
return(true);
}
}
return(false);
}
public static bool Scatter(Ray3f ray, HitRecord hit, ref Random rng, NativeArray <float3> fibs, out Ray3f scattered)
{
const float epsEscape = 0.002f;
const float refIdx = 1.5f;
switch (hit.material.Type)
{
case MaterialType.Dielectric: {
float3 outwardNormal;
float nint;
float3 reflected = math.reflect(ray.direction, hit.normal);
float cosine;
if (math.dot(ray.direction, hit.normal) > 0f)
{
outwardNormal = -hit.normal;
nint = refIdx;
cosine = refIdx * math.dot(ray.direction, hit.normal);
}
else
{
outwardNormal = hit.normal;
nint = 1f / refIdx;
cosine = -math.dot(ray.direction, hit.normal);
}
float reflectProb = 1f;
float3 refracted;
if (Trace.Refract(ray.direction, outwardNormal, nint, out refracted))
{
reflectProb = Trace.Schlick(cosine, refIdx);
}
bool reflect = rng.NextFloat() < reflectProb;
scattered = new Ray3f(
reflect ? hit.point + outwardNormal * epsEscape : hit.point - outwardNormal * epsEscape,
reflect ? reflected : refracted
);
return(true);
}
case MaterialType.Metal: {
float3 transmitted = math.reflect(ray.direction, hit.normal);
transmitted += fibs[rng.NextInt(0, fibs.Length - 1)] * hit.material.Fuzz;
transmitted = math.normalize(transmitted);
scattered = new Ray3f(hit.point + hit.normal * epsEscape, transmitted);
if (math.dot(scattered.direction, hit.normal) > 0)
{
return(true);
}
return(false);
}
case MaterialType.Lambertian:
default: {
float3 target = hit.normal + fibs[rng.NextInt(0, fibs.Length - 1)];
float3 transmitted = math.normalize(target - hit.point);
scattered = new Ray3f(hit.point + hit.normal * epsEscape, transmitted);
return(true);
}
}
}
public static float3 PointOnRay(Ray3f r, float t)
{
return(r.origin + r.direction * t);
}