Colour sample(Scene scene, Ray ray, bool emission, int samples, int depth, Random rand)
{
if (depth > MaxBounces)
{
return(Colour.Black);
}
var hit = scene.Intersect(ray);
if (!hit.Ok())
{
return(sampleEnvironment(scene, ray));
}
var info = hit.Info(ray);
var material = info.material;
var result = Colour.Black;
if (material.Emittance > 0)
{
if (DirectLighting && !emission)
{
return(Colour.Black);
}
result = result.Add(material.Color.MulScalar(material.Emittance * samples));
}
var n = (int)Math.Sqrt(samples);
BounceType ma, mb;
if (SpecularMode == SpecularMode.SpecularModeAll || depth == 0 && SpecularMode == SpecularMode.SpecularModeFirst)
{
ma = BounceType.BounceTypeDiffuse;
mb = BounceType.BounceTypeSpecular;
}
else
{
ma = BounceType.BounceTypeAny;
mb = BounceType.BounceTypeAny;
}
for (int u = 0; u < n; u++)
{
for (int v = 0; v < n; v++)
{
for (BounceType mode = ma; mode <= mb; mode++)
{
var fu = (u + ThreadSafeRandom.NextDouble()) / n;
var fv = (v + ThreadSafeRandom.NextDouble()) / n;
(var newRay, var reflected, var p) = ray.Bounce(info, fu, fv, mode, rand);
if (mode == BounceType.BounceTypeAny)
{
p = 1;
}
if (p > 0 && reflected)
{
// specular
var indirect = sample(scene, newRay, reflected, 1, depth + 1, rand);
var tinted = indirect.Mix(material.Color.Mul(indirect), material.Tint);
result = result.Add(tinted.MulScalar(p));
}
if (p > 0 && !reflected)
{
// diffuse
var indirect = sample(scene, newRay, reflected, 1, depth + 1, rand);
var direct = Colour.Black;
if (DirectLighting)
{
direct = sampleLights(scene, info.Ray, rand);
}
result = result.Add(material.Color.Mul(direct.Add(indirect)).MulScalar(p));
}
}
}
}
return(result.DivScalar(n * n));
}
public void RenderParallel()
{
Scene scene = Scene;
Camera camera = Camera;
Sampler sampler = Sampler;
Buffer buf = PBuffer;
(int w, int h) = (buf.W, buf.H);
int spp = SamplesPerPixel;
int sppRoot = (int)(Math.Sqrt(SamplesPerPixel));
scene.Compile();
scene.rays = 0;
// Stop watch timer
Stopwatch sw = new Stopwatch();
sw.Start();
// Random Number Generator from on Math.Numerics
System.Random rand = new SystemRandomSource(sw.Elapsed.Milliseconds, true);
// Frame resolution
int totalPixels = h * w;
// Create a cancellation token for Parallel.For loop control
CancellationTokenSource cts = new CancellationTokenSource();
// ParallelOptions for Parallel.For
ParallelOptions po = new ParallelOptions();
po.CancellationToken = cts.Token;
// Set number of cores/threads
po.MaxDegreeOfParallelism = Environment.ProcessorCount;
Console.WriteLine("{0} x {1} pixels, {2} spp, {3} core(s)", w, h, spp, po.MaxDegreeOfParallelism);
if (StratifiedSampling)
{
_ = Parallel.For(0, w * h, po, (i, loopState) =>
{
int y = i / w, x = i % w;
for (int u = 0; u < sppRoot; u++)
{
for (int v = 0; v < sppRoot; v++)
{
var fu = (u + 0.5) / sppRoot;
var fv = (v + 0.5) / sppRoot;
Ray ray = camera.CastRay(x, y, w, h, fu, fv, rand);
Colour sample = sampler.Sample(scene, ray, rand);
buf.AddSample(x, y, sample);
}
}
});
Console.WriteLine("time elapsed:" + sw.Elapsed);
}
else
{
//Random subsampling
_ = Parallel.ForEach(Partitioner.Create(0, totalPixels), po, (range) =>
{
for (int i = range.Item1; i < range.Item2; i++)
{
for (int s = 0; s < spp; s++)
{
int y = i / w, x = i % w;
var fu = ThreadSafeRandom.NextDouble(rand);
var fv = ThreadSafeRandom.NextDouble(rand);
var ray = camera.CastRay(x, y, w, h, fu, fv, rand);
var sample = sampler.Sample(scene, ray, rand);
buf.AddSample(x, y, sample);
}
}
});
Console.WriteLine("time elapsed:" + sw.Elapsed);
}
if (AdaptiveSamples > 0)
{
_ = Parallel.For(0, w * h, po, (i, loopState) =>
{
int y = i / w, x = i % w;
double v = buf.StandardDeviation(x, y).MaxComponent();
v = Util.Clamp(v / AdaptiveThreshold, 0, 1);
v = Math.Pow(v, AdaptiveExponent);
int samples = (int)(v * AdaptiveSamples);
for (int s = 0; s < samples; s++)
{
var fu = rand.NextDouble();
var fv = rand.NextDouble();
Ray ray = camera.CastRay(x, y, w, h, fu, fv, rand);
Colour sample = sampler.Sample(scene, ray, rand);
buf.AddSample(x, y, sample);
}
});
}
if (FireflySamples > 0)
{
_ = Parallel.For(0, w * h, po, (i, loopState) =>
{
int y = i / w, x = i % w;
if (PBuffer.StandardDeviation(x, y).MaxComponent() > FireflyThreshold)
{
Parallel.For(0, FireflySamples, po, (e, loop) =>
{
var fu = rand.NextDouble();
var fv = rand.NextDouble();
Ray ray = camera.CastRay(x, y, w, h, fu, fv, rand);
Colour sample = sampler.Sample(scene, ray, rand);
buf.AddSample(x, y, sample);
});
}
});
}
sw.Stop();
}
