public Spectrum Transmittance(Scene scene, Renderer renderer,
Sample sample, Random rng)
{
return renderer.Transmittance(
scene, RayDifferential.FromRay(Ray),
sample, rng);
}
public override void Render(Scene scene, CancellationToken cancellationToken)
{
// Allow integrators to do preprocessing for the scene
_surfaceIntegrator.PreProcess(scene, _camera, this);
_volumeIntegrator.PreProcess(scene, _camera, this);
// Allocate and initialize _sample_
var sample = new Sample(_sampler, _surfaceIntegrator, _volumeIntegrator, scene);
// Create and launch _SamplerRendererTask_s for rendering image
// Compute number of _SamplerRendererTask_s to create for rendering
var numPixels = _camera.Film.XResolution * _camera.Film.YResolution;
var numTasks = Math.Max(32 * Environment.ProcessorCount, numPixels / (16 * 16));
numTasks = (int) MathUtility.RoundUpPow2((uint) numTasks);
var renderTasks = Enumerable.Range(0, numTasks)
.Select(i => CreateRenderTask(scene, sample, cancellationToken,
numTasks - 1 - i, numTasks))
.ToArray();
// Organise tasks such that we do several passes over the whole image,
// of increasing quality.
var groupedRenderTasks = renderTasks.Select((t, i) => new { t, i })
.GroupBy(a => a.i % 6, a => a.t)
.ToArray();
foreach (var groupedTasks in groupedRenderTasks)
foreach (var task in groupedTasks)
task.Start();
Task.WaitAll(renderTasks, cancellationToken);
// Clean up after rendering and store final image
_camera.Film.WriteImage();
}
private Task CreateRenderTask(
Scene scene, Sample origSample, CancellationToken cancellationToken,
int taskNumber, int taskCount)
{
return new Task(() =>
{
var sampler = _sampler.GetSubSampler(taskNumber, taskCount);
if (sampler == null)
return;
var rng = new Random(taskNumber);
// Allocate space for samples and intersections
int maxSamples = _sampler.MaximumSampleCount;
var samples = origSample.Duplicate(maxSamples);
var rays = new RayDifferential[maxSamples];
var Ls = new Spectrum[maxSamples];
var Ts = new Spectrum[maxSamples];
var isects = new Intersection[maxSamples];
// Get samples from _Sampler_ and update image
int sampleCount;
while ((sampleCount = sampler.GetMoreSamples(samples, rng)) > 0)
{
cancellationToken.ThrowIfCancellationRequested();
// Generate camera rays and compute radiance along rays
for (int i = 0; i < sampleCount; ++i)
{
// Find camera ray for _sample[i]_
float rayWeight = _camera.GenerateRayDifferential(samples[i], out rays[i]);
rays[i].ScaleDifferentials(1.0f / MathUtility.Sqrt(sampler.SamplesPerPixel));
// Evaluate radiance along camera ray
if (rayWeight > 0.0f)
{
Ls[i] = rayWeight * Li(scene, rays[i], samples[i], rng, ref isects[i], out Ts[i]);
}
else
{
Ls[i] = new Spectrum(0.0f);
Ts[i] = new Spectrum(1.0f);
}
}
// Report sample results to _Sampler_, add contributions to image
if (sampler.ReportResults(samples, rays, Ls, isects, sampleCount))
for (int i = 0; i < sampleCount; ++i)
_camera.Film.AddSample(samples[i], Ls[i]);
}
_camera.Film.UpdateDisplay(
sampler.XStart, sampler.YStart,
sampler.XEnd + 1, sampler.YEnd + 1);
}, cancellationToken);
}
public BsdfSample(Sample sample, BsdfSampleOffsets offsets, int n)
{
Debug.Assert(n < sample.Num2D[offsets.PosOffset]);
Debug.Assert(n < sample.Num1D[offsets.ComponentOffset]);
UDir0 = sample.TwoD[offsets.PosOffset][2 * n];
UDir1 = sample.TwoD[offsets.PosOffset][2 * n + 1];
UComponent = sample.OneD[offsets.ComponentOffset][n];
Debug.Assert(UDir0 >= 0.0f && UDir0 < 1.0f);
Debug.Assert(UDir1 >= 0.0f && UDir1 < 1.0f);
Debug.Assert(UComponent >= 0.0f && UComponent < 1.0f);
}
public LightSample(Sample sample, LightSampleOffsets offsets, int n)
{
Debug.Assert(n < sample.Num2D[offsets.PosOffset]);
Debug.Assert(n < sample.Num1D[offsets.ComponentOffset]);
UPos0 = sample.TwoD[offsets.PosOffset][2 * n];
UPos1 = sample.TwoD[offsets.PosOffset][2 * n + 1];
UComponent = sample.OneD[offsets.ComponentOffset][n];
Debug.Assert(UPos0 >= 0.0f && UPos0 < 1.0f);
Debug.Assert(UPos1 >= 0.0f && UPos1 < 1.0f);
Debug.Assert(UComponent >= 0.0f && UComponent < 1.0f);
}
public Sample[] Duplicate(int count)
{
var ret = new Sample[count];
for (var i = 0; i < count; ++i)
{
ret[i] = new Sample
{
Num1D = Num1D.Select(x => x).ToList(),
Num2D = Num2D.Select(x => x).ToList()
};
ret[i].AllocateSampleMemory();
}
return ret;
}
public override int GetMoreSamples(Sample[] samples, Random rng)
{
if (_yPos == YEnd) return 0;
int nSamples = _xPixelSamples * _yPixelSamples;
// Generate stratified camera samples for _(xPos, yPos)_
// Generate initial stratified samples into _sampleBuf_ memory
IList<float> imageSamples = new ArraySegment<float>(_sampleBuffer, 0, 2 * nSamples);
IList<float> lensSamples = new ArraySegment<float>(_sampleBuffer, 2 * nSamples, 2 * nSamples);
IList<float> timeSamples = new ArraySegment<float>(_sampleBuffer, 4 * nSamples, nSamples);
SamplingUtilities.StratifiedSample2D(imageSamples, _xPixelSamples, _yPixelSamples, rng, _jitter);
SamplingUtilities.StratifiedSample2D(lensSamples, _xPixelSamples, _yPixelSamples, rng, _jitter);
SamplingUtilities.StratifiedSample1D(timeSamples, _xPixelSamples * _yPixelSamples, rng, _jitter);
// Shift stratified image samples to pixel coordinates
for (int o = 0; o < 2 * _xPixelSamples * _yPixelSamples; o += 2)
{
imageSamples[o] += _xPos;
imageSamples[o + 1] += _yPos;
}
// Decorrelate sample dimensions
SamplingUtilities.Shuffle(lensSamples, _xPixelSamples * _yPixelSamples, 2, rng);
SamplingUtilities.Shuffle(timeSamples, _xPixelSamples * _yPixelSamples, 1, rng);
// Initialize stratified _samples_ with sample values
for (int i = 0; i < nSamples; ++i)
{
samples[i].ImageX = imageSamples[2 * i];
samples[i].ImageY = imageSamples[2 * i + 1];
samples[i].LensU = lensSamples[2 * i];
samples[i].LensV = lensSamples[2 * i + 1];
samples[i].Time = MathUtility.Lerp(timeSamples[i], ShutterOpen, ShutterClose);
// Generate stratified samples for integrators
for (var j = 0; j < samples[i].Num1D.Count; ++j)
MonteCarloUtilities.LatinHypercube(samples[i].OneD[j], samples[i].Num1D[j], 1, rng);
for (var j = 0; j < samples[i].Num2D.Count; ++j)
MonteCarloUtilities.LatinHypercube(samples[i].TwoD[j], samples[i].Num2D[j], 2, rng);
}
// Advance to next pixel for stratified sampling
if (++_xPos == XEnd)
{
_xPos = XStart;
++_yPos;
}
return nSamples;
}
public static Spectrum SpecularTransmit(RayDifferential ray, Bsdf bsdf,
Random rng, Intersection isect, Renderer renderer,
Scene scene, Sample sample)
{
Vector wo = -ray.Direction, wi;
float pdf;
Point p = bsdf.DgShading.Point;
Normal n = bsdf.DgShading.Normal;
Spectrum f = bsdf.SampleF(wo, out wi, new BsdfSample(rng), out pdf,
BxdfType.Transmission | BxdfType.Specular);
Spectrum L = Spectrum.CreateBlack();
if (pdf > 0.0f && !f.IsBlack && Vector.AbsDot(wi, n) != 0.0f)
{
// Compute ray differential _rd_ for specular transmission
var rd = new RayDifferential(p, wi, ray, isect.RayEpsilon);
if (ray.HasDifferentials)
{
rd.HasDifferentials = true;
rd.RxOrigin = p + isect.DifferentialGeometry.DpDx;
rd.RyOrigin = p + isect.DifferentialGeometry.DpDy;
float eta = bsdf.Eta;
Vector w = -wo;
if (Vector.Dot(wo, n) < 0)
eta = 1.0f / eta;
Normal dndx = bsdf.DgShading.DnDu * bsdf.DgShading.DuDx +
bsdf.DgShading.DnDv * bsdf.DgShading.DvDx;
Normal dndy = bsdf.DgShading.DnDu * bsdf.DgShading.DuDy +
bsdf.DgShading.DnDv * bsdf.DgShading.DvDy;
Vector dwodx = -ray.RxDirection - wo, dwody = -ray.RyDirection - wo;
float dDNdx = Vector.Dot(dwodx, n) + Vector.Dot(wo, dndx);
float dDNdy = Vector.Dot(dwody, n) + Vector.Dot(wo, dndy);
float mu = eta * Vector.Dot(w, n) - Vector.Dot(wi, n);
float dmudx = (eta - (eta * eta * Vector.Dot(w, n)) / Vector.Dot(wi, n)) * dDNdx;
float dmudy = (eta - (eta * eta * Vector.Dot(w, n)) / Vector.Dot(wi, n)) * dDNdy;
rd.RxDirection = wi + eta * dwodx - (Vector) (mu * dndx + dmudx * n);
rd.RyDirection = wi + eta * dwody - (Vector) (mu * dndy + dmudy * n);
}
Spectrum Li = renderer.Li(scene, rd, sample, rng);
L = f * Li * Vector.AbsDot(wi, n) / pdf;
}
return L;
}
public override Spectrum Li(Scene scene, Renderer renderer, RayDifferential ray, Intersection intersection,
Sample sample, Random rng)
{
Spectrum L = Spectrum.CreateBlack();
// Compute emitted and reflected light at ray intersection point
// Evaluate BSDF at hit point
var bsdf = intersection.GetBsdf(ray);
// Initialize common variables for Whitted integrator
Point p = bsdf.DgShading.Point;
Normal n = bsdf.DgShading.Normal;
Vector wo = -ray.Direction;
// Compute emitted light if ray hit an area light source
L += intersection.Le(wo);
// Add contribution of each light source
foreach (var light in scene.Lights)
{
Vector wi;
float pdf;
VisibilityTester visibility;
Spectrum Li = light.SampleL(p, intersection.RayEpsilon,
new LightSample(rng), ray.Time, out wi, out pdf, out visibility);
if (Li.IsBlack || pdf == 0.0f)
continue;
Spectrum f = bsdf.F(wo, wi);
if (!f.IsBlack && visibility.Unoccluded(scene))
L += f * Li * Vector.AbsDot(wi, n)
* visibility.Transmittance(scene, renderer, sample, rng)
/ pdf;
}
if (ray.Depth + 1 < _maxDepth)
{
// Trace rays for specular reflection and refraction
L += IntegratorUtilities.SpecularReflect(ray, bsdf, rng, intersection, renderer, scene, sample);
L += IntegratorUtilities.SpecularTransmit(ray, bsdf, rng, intersection, renderer, scene, sample);
}
return L;
}
public abstract Spectrum Li(Scene scene, Renderer renderer, RayDifferential ray,
Sample sample, Random rng, out Spectrum transmittance);
public virtual bool ReportResults(Sample[] samples, RayDifferential[] rays,
Spectrum[] ls, Intersection[] intersections, int count)
{
return true;
}
public abstract int GetMoreSamples(Sample[] samples, Random rng);
public LightSampleOffsets(int numSamples, Sample sample)
{
NumSamples = numSamples;
ComponentOffset = sample.Add1D(numSamples);
PosOffset = sample.Add2D(numSamples);
}
public Spectrum Li(Scene scene, RayDifferential ray, Sample sample, Random rng)
{
Intersection intersection = null;
Spectrum t;
return Li(scene, ray, sample, rng, ref intersection, out t);
}
public abstract Spectrum Transmittance(Scene scene, RayDifferential ray, Sample sample,
Random rng);
public override Spectrum Li(Scene scene, RayDifferential ray, Sample sample, Random rng, ref Intersection intersection, out Spectrum t)
{
Debug.Assert(ray.Time == sample.Time);
Spectrum Li = Spectrum.CreateBlack();
if (scene.TryIntersect(ray, ref intersection))
Li = _surfaceIntegrator.Li(scene, this, ray, intersection, sample, rng);
else
{
// Handle ray that doesn't intersect any geometry
foreach (var light in scene.Lights)
Li += light.Le(ray);
}
Spectrum Lvi = _volumeIntegrator.Li(scene, this, ray, sample, rng, out t);
return t * Li + Lvi;
}
public abstract Spectrum Li(Scene scene, RayDifferential ray, Sample sample, Random rng,
ref Intersection intersection, out Spectrum t);
public virtual void RequestSamples(Sampler sampler, Sample sample, Scene scene)
{
}
public abstract Spectrum Li(Scene scene, Renderer renderer, RayDifferential ray,
Intersection intersection, Sample sample, Random rng);
public override Spectrum Transmittance(Scene scene, Renderer renderer, RayDifferential ray, Sample sample, Random rng)
{
// TODO
return new Spectrum(1.0f);
}
public override Spectrum Li(Scene scene, Renderer renderer, RayDifferential ray, Sample sample, Random rng, out Spectrum transmittance)
{
// TODO
transmittance = new Spectrum(1.0f);
return Spectrum.CreateBlack();
}
public override Spectrum Transmittance(Scene scene, RayDifferential ray, Sample sample, Random rng)
{
return _volumeIntegrator.Transmittance(scene, this, ray, sample, rng);
}
