public override bool Scatter(Ray rIn, HitRecord rec, ref Vec3 attenuation, ref Ray scattered)
{
attenuation = new Vec3(1, 1, 1);
double etaIOverEtaT = rec.FrontFace ? (1.0 / RefIdx) : RefIdx;
Vec3 unitDirection = Vec3.UnitVector(rIn.Direction);
double cosTheta = Math.Min(Vec3.Dot(-unitDirection, rec.Normal), 1.0);
double sinTheta = Math.Sqrt(1.0 - cosTheta * cosTheta);
if (etaIOverEtaT * sinTheta > 1.0)
{
Vec3 reflected = Vec3.Reflect(unitDirection, rec.Normal);
scattered = new Ray(rec.P, reflected);
return(true);
}
double reflectProb = RayTracerUtils.Schlick(cosTheta, etaIOverEtaT);
if (RayTracerUtils.RandomDouble() < reflectProb)
{
Vec3 reflected = Vec3.Reflect(unitDirection, rec.Normal);
scattered = new Ray(rec.P, reflected);
return(true);
}
Vec3 refracted = Vec3.Refract(unitDirection, rec.Normal, etaIOverEtaT);
scattered = new Ray(rec.P, refracted);
return(true);
}
public static Vec3 RandomUnitVector()
{
double a = RayTracerUtils.RandomDouble(0, 2 * Math.PI);
double z = RayTracerUtils.RandomDouble(-1, 1);
double r = Math.Sqrt(1 - z * z);
return(new Vec3(r * Math.Cos(a), r * Math.Sin(a), z));
}
public static Vec3 RandomInUnitDisk()
{
Vec3 p;
do
{
p = new Vec3(RayTracerUtils.RandomDouble(-1, 1), RayTracerUtils.RandomDouble(-1, 1), 0);
} while (p.LengthSquared >= 1);
return(p);
}
public void WriteColor(StreamWriter writer, int samplesPerPixel)
{
double scale = 1.0 / samplesPerPixel;
double r = Math.Sqrt(scale * e[0]);
double g = Math.Sqrt(scale * e[1]);
double b = Math.Sqrt(scale * e[2]);
int ri = (int)(256 * RayTracerUtils.Clamp(r, 0.0, 0.999));
int gi = (int)(256 * RayTracerUtils.Clamp(g, 0.0, 0.999));
int bi = (int)(256 * RayTracerUtils.Clamp(b, 0.0, 0.999));
writer.WriteLine($"{ri} {gi} {bi}");
}
private HittableList RandomScene()
{
HittableList world = new HittableList();
world.Objects.Add(new Sphere(new Vec3(0, -1000, 0), 1000, new Lambertian(new Vec3(0.5, 0.5, 0.5))));
int i = 1;
Vec3 differenceCenter = new Vec3(4, 0.2, 0);
for (int a = -11; a < 11; a++)
{
for (int b = -11; b < 11; b++)
{
double chooseMat = RayTracerUtils.RandomDouble();
Vec3 center = new Vec3(a + 0.9 * RayTracerUtils.RandomDouble(), 0.2, b + 0.9 * RayTracerUtils.RandomDouble());
if ((center - differenceCenter).Length > 0.9)
{
if (chooseMat < 0.8)
{
//diffuse
Vec3 albedo = Vec3.Random() * Vec3.Random();
world.Objects.Add(new Sphere(center, 0.2, new Lambertian(albedo)));
}
else if (chooseMat < 0.95)
{
//metal
Vec3 albedo = Vec3.Random(0.5, 1);
double fuzz = RayTracerUtils.RandomDouble(0, 0.5);
world.Objects.Add(new Sphere(center, 0.2, new Metal(albedo, fuzz)));
}
else
{
//glass
world.Objects.Add(new Sphere(center, 0.2, new Dielectric(1.5)));
}
}
}
}
world.Objects.Add(new Sphere(new Vec3(0, 1, 0), 1.0, new Dielectric(1.5)));
world.Objects.Add(new Sphere(new Vec3(-4, 1, 0), 1.0, new Lambertian(new Vec3(0.4, 0.2, 0.1))));
world.Objects.Add(new Sphere(new Vec3(4, 1, 0), 1.0, new Metal(new Vec3(0.7, 0.6, 0.5), 0.0)));
return(world);
}
/// <param name="vFov">Top to bottom, in degrees</param>
public Camera(Vec3 lookFrom, Vec3 lookAt, Vec3 vUp, double vFov, double aspect, double aperture, double focusDistance)
{
Origin = lookFrom;
LensRadius = aperture / 2;
double theta = RayTracerUtils.DegreesToRadians(vFov);
double halfHeight = Math.Tan(theta / 2);
double halfWidth = aspect * halfHeight;
W = Vec3.UnitVector(lookFrom - lookAt);
U = Vec3.UnitVector(Vec3.Cross(vUp, W));
V = Vec3.Cross(W, U);
LowerLeftCorner = Origin - halfWidth * focusDistance * U - halfHeight * focusDistance * V - focusDistance * W;
Horizontal = 2 * halfWidth * focusDistance * U;
Vertical = 2 * halfHeight * focusDistance * V;
}
public void Output(string path)
{
Stopwatch sw = new Stopwatch();
sw.Start();
using (StreamWriter writer = new StreamWriter(path))
{
writer.WriteLine("P3");
writer.WriteLine(IMAGE_WIDTH + " " + IMAGE_HEIGHT);
writer.WriteLine("255");
double aspectRatio = IMAGE_WIDTH / IMAGE_HEIGHT;
Vec3 lookFrom = new Vec3(13, 2, 3);
Vec3 lookAt = new Vec3(0, 0, 0);
Vec3 vUp = new Vec3(0, 1, 0);
double distanceToFocus = 10.0;
double aperture = 0.1;
Camera cam = new Camera(lookFrom, lookAt, vUp, 20, aspectRatio, aperture, distanceToFocus);
HittableList world = RandomScene();
Vec3[,] colors = new Vec3[IMAGE_HEIGHT, IMAGE_WIDTH];
int linesRemaining = IMAGE_HEIGHT;
Parallel.For(0, IMAGE_HEIGHT, j =>
{
// We handle each pixel of the line on a different thread to speed up the process
Parallel.For(0, IMAGE_WIDTH, i =>
{
Vec3 color = new Vec3();
for (int s = 0; s < SAMPLES_PER_PIXEL; ++s)
{
double u = (i + RayTracerUtils.RandomDouble()) / IMAGE_WIDTH;
double v = (j + RayTracerUtils.RandomDouble()) / IMAGE_HEIGHT;
Ray r = cam.GetRay(u, v);
color += RayColor(r, world, MAX_DEPTH);
}
lock (colors)
{
colors[j, i] = color;
}
});
double percentage = 100.0 - (double)--linesRemaining / IMAGE_HEIGHT * 100.0;
Progress(this, new ProgressArgs(percentage));
});
// Output the colors in the file
for (int j = IMAGE_HEIGHT - 1; j >= 0; --j)
{
for (int i = 0; i < IMAGE_WIDTH; ++i)
{
colors[j, i].WriteColor(writer, SAMPLES_PER_PIXEL);
}
}
}
sw.Stop();
Console.WriteLine();
Console.WriteLine($"Time: {sw.Elapsed.Minutes}:{sw.Elapsed.Seconds:00}");
}
public static Vec3 Random(double min, double max)
{
return(new Vec3(RayTracerUtils.RandomDouble(min, max), RayTracerUtils.RandomDouble(min, max), RayTracerUtils.RandomDouble(min, max)));
}
public static Vec3 Random()
{
return(new Vec3(RayTracerUtils.RandomDouble(), RayTracerUtils.RandomDouble(), RayTracerUtils.RandomDouble()));
}