Create common.hlsl

but don't implement the caches yet

Author: devshgraphicsprogramming

include/nbl/builtin/hlsl/bxdf/common.hlsl

@@ -0,0 +1,224 @@
+// Copyright (C) 2018-2022 - 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_COMMON_INCLUDED_
+#define _NBL_BUILTIN_HLSL_BXDF_COMMON_INCLUDED_
+
+namespace nbl
+{
+namespace hlsl
+{
+namespace bxdf
+{
+
+
+namespace ray_dir_info
+{
+
+// no ray-differentials, nothing
+struct Basic
+{
+  float3 getDirection() {return direction;}
+
+  float3 direction;
+};
+// more to come!
+
+}
+
+
+namespace surface_interactions
+{
+
+template<class RayDirInfo>
+struct Isotropic
+{
+  // WARNING: Changed since GLSL, now arguments need to be normalized!
+  static Isotropic<RayDirInfo> create(const RayDirInfo normalizedV, const float3 normalizedN)
+  {
+    Isotropic<RayDirInfo> retval;
+    retval.V = normalizedV;
+    retval.N = normalizedN;
+
+    retval.NdotV = dot(retval.N,retval.V.getDirection());
+    retval.NdotV_squared = retval.NdotV*retval.NdotV;
+
+    return retval;
+  }
+
+  RayDirInfo V;
+  float3 N;
+  float NdotV;
+  float NdotV2; // old NdotV_squared
+};
+
+template<class RayDirInfo>
+struct Anisotropic : Isotropic<RayDirInfo>
+{
+  // WARNING: Changed since GLSL, now arguments need to be normalized!
+  static Anisotropic<RayDirInfo> create(
+    const Isotropic<RayDirInfo> isotropic,
+    const float3 normalizedT,
+    const float normalizedB
+  )
+  {
+    Anisotropic<RayDirInfo> retval;
+    retval::Isotropic<RayDirInfo> = isotropic;
+    retval.T = normalizedT;
+    retval.B = normalizedB;
+    
+    const float3 V = retval.getDirection();
+    retval.TdotV = dot(V,retval.T);
+    retval.BdotV = dot(V,retval.B);
+
+    return retval;
+  }
+  static Anisotropic<RayDirInfo> create(const Isotropic<RayDirInfo> isotropic, const float3 normalizedT)
+  {
+    return create(isotropic,normalizedT,cross(isotropic.N,normalizedT));
+  }
+  static Anisotropic<RayDirInfo> create(const Isotropic<RayDirInfo> isotropic)
+  {
+    float2x3 TB = nbl::hlsl::frisvad(isotropic.N);
+    return create(isotropic,TB[0],TB[1]);
+  }
+
+  float3 getTangentSpaceV() {return float3(Tdot,BdotV,Isotropic<RayDirInfo>::NdotV);}
+  // WARNING: its the transpose of the old GLSL function return value!
+  float3x3 getTangentFrame() {return float3x3(T,B,Isotropic<RayDirInfo>::N);}
+
+  float3 T;
+  float3 B;
+  float3 TdotV;
+  float3 BdotV;
+};
+
+}
+
+
+template<class RayDirInfo>
+struct LightSample
+{
+  static LightSample<RayDirInfo> createTangentSpace(
+    const float3 tangentSpaceV,
+    const RayDirInfo tangentSpaceL,
+    const float3x3 tangentFrame // WARNING: its the transpose of the old GLSL function return value!
+  )
+  {
+    LightSample<RayDirInfo> retval;
+    
+    retval.L = RayDirInfo::transform(tangentSpaceL,tangentFrame);
+    retval.VdotL = dot(tangentSpaceV,tangentSpaceL);
+
+    retval.TdotL = tangentSpaceL.x;
+    retval.BdotL = tangentSpaceL.y;
+    retval.NdotL = tangentSpaceL.z;
+    retval.NdotL2 = retval.NdotL*retval.NdotL;
+    
+    return retval;
+  }
+  static LightSample<RayDirInfo> create(const RayDirInfo L, const float VdotL, const float3 N)
+  {
+    LightSample<RayDirInfo> retval;
+    
+    retval.L = L;
+    retval.VdotL = VdotL;
+
+    retval.TdotL = nbl::hlsl::numeric_limits<float>::nan();
+    retval.BdotL = nbl::hlsl::numeric_limits<float>::nan();
+    retval.NdotL = dot(N,L);
+    retval.NdotL2 = retval.NdotL*retval.NdotL;
+    
+    return retval;
+  }
+  static LightSample<RayDirInfo> create(const RayDirInfo L, const float VdotL, const float3 T, const float3 B, const float3 N)
+  {
+    LightSample<RayDirInfo> retval = create(L,VdotL,N);
+    
+    retval.TdotL = dot(T,L);
+    retval.BdotL = dot(B,L);
+    
+    return retval;
+  }
+  // overloads for surface_interactions
+  template<class ObserverRayDirInfo>
+  static LightSample<RayDirInfo> create(const float3 L, const surface_interactions::Isotropic<ObserverRayDirInfo> interaction)
+  {
+    const float3 V = interaction.V.getDirection();
+    const float VdotL = dot(V,L);
+    return create(L,VdotL,interaction.N);
+  }
+  template<class ObserverRayDirInfo>
+  static LightSample<RayDirInfo> create(const float3 L, const surface_interactions::Anisotropic<ObserverRayDirInfo> interaction)
+  {
+    const float3 V = interaction.V.getDirection();
+    const float VdotL = dot(V,L);
+    return create(L,VdotL,interaction.T,interaction.B,interaction.N);
+  }
+  //
+  float3 getTangentSpaceL()
+  {
+    return float3(TdotL,BdotL,NdotL);
+  }
+
+  RayDirInfo L;
+  float VdotL;
+
+  float TdotL; 
+  float BdotL;
+  float NdotL;
+  float NdotL2;
+};
+
+//
+struct IsotropicMicrofacetCache
+{
+  // always valid because its specialized for the reflective case
+  static IsotropicMicrofacetCache create(const float NdotV, const float NdotL, const float VdotL, out float LplusV_rcpLen)
+  {
+    LplusV_rcpLen = inversesqrt(2.0+2.0*VdotL);
+
+    IsotropicMicrofacetCache retval;
+    
+    retval.VdotH = LplusV_rcpLen*VdotL+LplusV_rcpLen;
+    retval.LdotH = retval.VdotH;
+    retval.NdotH = (NdotL+NdotV)*LplusV_rcpLen;
+    retval.NdotH2 = retval.NdotH*retval.NdotH;
+    
+    return retval;
+  }
+  static IsotropicMicrofacetCache create(const float NdotV, const float NdotL, const float VdotL)
+  {
+    float dummy;
+    return create(NdotV,NdotL,VdotL,dummy);
+  }
+
+  bool isValidVNDFMicrofacet(const bool is_bsdf, const bool transmission, const float VdotL, const float eta, const float rcp_eta)
+  {
+    return NdotH >= 0.0 && !(is_bsdf && transmission && (VdotL > -min(eta,rcp_eta)));
+  }
+
+  float VdotH;
+  float LdotH;
+  float NdotH;
+  float NdotH2;
+};
+struct AnisotropicMicrofacetCache : IsotropicMicrofacetCache
+{
+    float TdotH;
+    float BdotH;
+};
+
+
+// finally fixed the semantic F-up, value/pdf = quotient not remainder
+template<typename SpectralBuckets>
+SpectralBuckets quotient_to_value(const SpectralBuckets quotient, const float pdf)
+{
+  return quotient*pdf;
+}
+
+}
+}
+}
+
+#endif