Create transmission.hlsl

Author: devshgraphicsprogramming

include/nbl/builtin/hlsl/bxdf/transmission.hlsl

@@ -0,0 +1,47 @@
+// Copyright (C) 2018-2020 - DevSH Graphics Programming Sp. z O.O.
+// This file is part of the "Nabla Engine".
+// For conditions of distribution and use, see copyright notice in nabla.h
+#ifndef _NBL_BUILTIN_HLSL_BXDF_TRANSMISSION_INCLUDED_
+#define _NBL_BUILTIN_HLSL_BXDF_TRANSMISSION_INCLUDED_
+
+#include <nbl/builtin/glsl/math/functions.glsl>
+#include <nbl/builtin/hlsl/bxdf/common.hlsl>
+
+namespace nbl
+{
+namespace hlsl
+{
+namespace bxdf
+{
+namespace transmission
+{
+
+template<class RayDirInfo>
+LightSample<RayDirInfo> cos_generate(const surface_interactions::Isotropic<RayDirInfo> interaction)
+{
+  return LightSample<RayDirInfo>(interaction.V.transmit(),-1.f,interaction.N);
+}
+template<class RayDirInfo>
+LightSample<RayDirInfo> cos_generate(const surface_interactions::Anisotropic<RayDirInfo> interaction)
+{
+  return LightSample<RayDirInfo>(interaction.V.transmit(),-1.f,interaction.T,interaction.B,interaction.N);
+}
+
+// Why don't we check that the incoming and outgoing directions equal each other
+// (or similar for other delta distributions such as reflect, or smooth [thin] dielectrics):
+// - The `quotient_and_pdf` functions are meant to be used with MIS and RIS
+// - Our own generator can never pick an improbable path, so no checking necessary
+// - For other generators the estimator will be `f_BSDF*f_Light*f_Visibility*clampedCos(theta)/(1+(p_BSDF^alpha+p_otherNonChosenGenerator^alpha+...)/p_ChosenGenerator^alpha)`
+//	 therefore when `p_BSDF` equals `nbl_glsl_FLT_INF` it will drive the overall MIS estimator for the other generators to 0 so no checking necessary
+template<typename SpectralBins>
+quotient_and_pdf<SpectralBins> cos_quotient_and_pdf()
+{
+  return quotient_and_pdf<SpectralBins>::create(SpectralBins(1.f),nbl::hlsl::numeric_limits<float>::inf());
+}
+
+}
+}
+}
+}
+
+#endif