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 Vector3?Sample(Vector3 outDir, bool isOnLightSubpath, Vector2 primarySample)
{
if (outDir.Z == 0)
{
return(null);
}
Vector3 wh = distribution.Sample(outDir, primarySample);
if (Vector3.Dot(outDir, wh) < 0)
{
return(null);
}
float eta = ShadingSpace.CosTheta(outDir) > 0 ? (outsideIOR / insideIOR) : (insideIOR / outsideIOR);
var inDir = ShadingSpace.Refract(outDir, wh, eta);
return(inDir);
}
public Vector3?Sample(Vector3 outDir, bool isOnLightSubpath, Vector2 primarySample)
{
if (outDir.Z == 0)
{
return(null);
}
var halfVector = distribution.Sample(outDir, primarySample);
if (Vector3.Dot(halfVector, outDir) < 0)
{
return(null);
}
var inDir = ShadingSpace.Reflect(outDir, halfVector);
if (!ShadingSpace.SameHemisphere(outDir, inDir))
{
return(null);
}
return(inDir);
}