public void ComputeScatteringFunctions(SurfaceInteraction si,
IObjectArena arena,
TransportMode mode,
bool allowMultipleLobes)
{
BumpMap?.Bump(si);
var bsdf = si.BSDF.Initialize(in si);
var kd = Kd.Evaluate(in si).Clamp();
if (!kd.IsBlack())
{
bsdf.Add(arena.Create <LambertianReflection>().Initialize(in kd));
}
var ks = Ks.Evaluate(in si).Clamp();
if (ks.IsBlack())
{
return;
}
var fresnel = arena.Create <FresnelDielectric>().Initialize(1.5f, 1f);
var rough = Roughness.Evaluate(in si);
if (RemapRoughness)
{
rough = TrowbridgeReitzDistribution.RoughnessToAlpha(rough);
}
var distribution = arena.Create <TrowbridgeReitzDistribution>().Initialize(rough, rough);
bsdf.Add(arena.Create <MicrofacetReflection>().Initialize(ks, distribution, fresnel));
}
public void SampleCornerCases_ShouldBeFinite()
{
float ax = 0.5f;
float ay = 0.3f;
var dist = new TrowbridgeReitzDistribution()
{
AlphaX = ax, AlphaY = ay
};
var dir1 = dist.Sample(Vector3.UnitZ, new(0, 1));
var dir2 = dist.Sample(new(MathF.Sqrt(2), 0, MathF.Sqrt(2)), new(1, 0));
var dir3 = dist.Sample(Vector3.UnitZ, new(1, 0));
Assert.True(float.IsFinite(dir1.X));
Assert.True(float.IsFinite(dir1.Y));
Assert.True(float.IsFinite(dir1.Z));
Assert.True(float.IsFinite(dir2.X));
Assert.True(float.IsFinite(dir2.Y));
Assert.True(float.IsFinite(dir2.Z));
Assert.True(float.IsFinite(dir3.X));
Assert.True(float.IsFinite(dir3.Y));
Assert.True(float.IsFinite(dir3.Z));
}
public MicrofacetTransmission(RgbColor transmittance, TrowbridgeReitzDistribution distribution,
float outsideIOR, float insideIOR)
{
this.transmittance = transmittance;
this.distribution = distribution;
this.outsideIOR = outsideIOR;
this.insideIOR = insideIOR;
Debug.Assert(outsideIOR != insideIOR);
}
public void NDF_Orthogonal()
{
float ax = 0.5f;
float ay = 0.3f;
var dist = new TrowbridgeReitzDistribution()
{
AlphaX = ax, AlphaY = ay
};
var ndf = dist.NormalDistribution(new System.Numerics.Vector3(0, 0, 1));
float expectedNdf = 1 / (MathF.PI * ax * ay);
Assert.Equal(expectedNdf, ndf, 4);
}
public void NDF_GrazingAngle()
{
float ax = 0.5f;
float ay = 0.3f;
var dist = new TrowbridgeReitzDistribution()
{
AlphaX = ax, AlphaY = ay
};
var ndf = dist.NormalDistribution(new System.Numerics.Vector3(1, 0, 0));
float expectedNdf = 0;
Assert.Equal(expectedNdf, ndf, 4);
}
public void ComputeScatteringFunctions(SurfaceInteraction inter, bool allowMultipleLobes)
{
inter.Bsdf = new BSDF(inter);
if (!diffuse.IsBlack())
{
inter.Bsdf.Add(new LambertianReflection(diffuse));
}
if (!specular.IsBlack())
{
var fresnel = new FresnelDielectric(1.5f, 1.0f);
var distribution = new TrowbridgeReitzDistribution(roughness);
inter.Bsdf.Add(new MicrofacetReflection(specular, distribution, fresnel));
}
}
public void ComputeScatteringFunctions(SurfaceInteraction si,
IObjectArena arena,
TransportMode mode,
bool allowMultipleLobes)
{
_bumpMap?.Bump(si);
si.BSDF.Initialize(si);
var uRough = _uRoughness?.Evaluate(si) ?? _roughness.Evaluate(si);
var vRough = _vRoughness?.Evaluate(si) ?? _roughness.Evaluate(si);
if (_remapRoughness)
{
uRough = TrowbridgeReitzDistribution.RoughnessToAlpha(uRough);
vRough = TrowbridgeReitzDistribution.RoughnessToAlpha(vRough);
}
var fr = arena.Create <FresnelConductor>().Initialize(Spectrum.One, _eta.Evaluate(si), _k.Evaluate(si));
var dist = arena.Create <TrowbridgeReitzDistribution>().Initialize(uRough, vRough);
si.BSDF.Add(arena.Create <MicrofacetReflection>().Initialize(Spectrum.One, dist, fr));
}
public MicrofacetReflection(TrowbridgeReitzDistribution distribution, Fresnel fresnel, RgbColor tint)
{
this.distribution = distribution;
this.fresnel = fresnel;
this.tint = tint;
}
