public override void GenerateLiRays(IRayEngineScene scn, Sample sample, ref RayData ray, VolumeComputation comp)
{
comp.Reset();
var scene = (RayEngineScene)(scn);
var sigs = sig_s;
comp.EmittedLight = lightEmission;
float t0, t1;
if (!region.Intersect(ray, out t0, out t1))
return;
if (sigs.IsBlack() || (scene.Lights.Length < 1))
{
float distance = t1 - t0;
comp.EmittedLight = lightEmission * distance;
}
else
{
// Prepare for volume integration stepping
float distance = t1 - t0;
var nSamples = MathLab.Ceil2UInt(distance / stepSize);
float step = distance / nSamples;
RgbSpectrum Tr = new RgbSpectrum(1f);
RgbSpectrum Lv = new RgbSpectrum();
var p = ray.Point(t0);
float offset = sample.GetLazyValue();
t0 += offset * step;
//Vector pPrev;
for (var i = 0; i < nSamples; ++i, t0 += step)
{
//pPrev = p;
p = ray.Point(t0);
Sigma_s(ref p, out sigs);
//sigs = NoiseProvider.Instance.Noise3D(((Vector)p).Normalize());
Lv += lightEmission;
if (!sigs.IsBlack() && (scene.Lights.Length) > 0)
{
// Select the light to sample
float lightStrategyPdf;
var light = scene.Lights[scene.SampleLights(sample.GetLazyValue(), out lightStrategyPdf)];
// Select a point on the light surface
float lightPdf;
Normal fakeNorml = new Normal(0f, 0f, 1f);
LightSample ls = new LightSample();
light.EvaluateShadow(ref p, ref fakeNorml, sample.GetLazyValue(),
sample.GetLazyValue(), sample.GetLazyValue(), ref ls);
var lightColor = (RgbSpectrumInfo)(ls.Spectrum);
lightPdf = ls.Pdf;
comp.Rays[comp.RayCount] = ls.LightRay;
if ((lightPdf > 0f) && !lightColor.IsBlack())
{
comp.ScatteredLight[comp.RayCount] =(RgbSpectrum)(Tr * sigs * lightColor * MathLab.Exp(-distance) *
((Density(ref p) * step) / (4f * MathLab.M_PI * lightPdf * lightStrategyPdf)));
comp.RayCount++;
}
}
comp.EmittedLight = Lv * step;
}
}
}
