src/Graphic3d/Graphic3d_BSDF.hxx

   1 // Created on: 2015-01-15
   2 // Created by: Danila ULYANOV
   3 // Copyright (c) 2014 OPEN CASCADE SAS
   4 //
   5 // This file is part of Open CASCADE Technology software library.
   6 //
   7 // This library is free software; you can redistribute it and/or modify it under
   8 // the terms of the GNU Lesser General Public License version 2.1 as published
   9 // by the Free Software Foundation, with special exception defined in the file
  10 // OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included in OCCT
  11 // distribution for complete text of the license and disclaimer of any warranty.
  12 //
  13 // Alternatively, this file may be used under the terms of Open CASCADE
  14 // commercial license or contractual agreement.
  15
  16 #ifndef _Graphic3d_BSDF_HeaderFile
  17 #define _Graphic3d_BSDF_HeaderFile
  18
  19 #include <Graphic3d_Vec3.hxx>
  20 #include <Graphic3d_Vec4.hxx>
  21
  22 //! Type of the Fresnel model.
  23 enum Graphic3d_FresnelModel
  24 {
  25   Graphic3d_FM_SCHLICK    = 0,
  26   Graphic3d_FM_CONSTANT   = 1,
  27   Graphic3d_FM_CONDUCTOR  = 2,
  28   Graphic3d_FM_DIELECTRIC = 3
  29 };
  30
  31 //! Describes Fresnel reflectance parameters.
  32 class Graphic3d_Fresnel
  33 {
  34 public:
  35
  36   //! Creates uninitialized Fresnel factor.
  37   Graphic3d_Fresnel() : myFresnelType (Graphic3d_FM_CONSTANT)
  38   {
  39     // ideal specular reflector
  40     myFresnelData = Graphic3d_Vec3 (0.f, 1.f, 0.f);
  41   }
  42
  43   //! Creates Schlick's approximation of Fresnel factor.
  44   static Graphic3d_Fresnel CreateSchlick (const Graphic3d_Vec3& theSpecularColor)
  45   {
  46     return Graphic3d_Fresnel (Graphic3d_FM_SCHLICK, theSpecularColor);
  47   }
  48
  49   //! Creates Fresnel factor for constant reflection.
  50   static Graphic3d_Fresnel CreateConstant (const Standard_ShortReal theReflection)
  51   {
  52     return Graphic3d_Fresnel (Graphic3d_FM_CONSTANT, Graphic3d_Vec3 (0.f, 1.f, theReflection));
  53   }
  54
  55   //! Creates Fresnel factor for physical-based dielectric model.
  56   static Graphic3d_Fresnel CreateDielectric (Standard_ShortReal theRefractionIndex)
  57   {
  58     return Graphic3d_Fresnel (Graphic3d_FM_DIELECTRIC, Graphic3d_Vec3 (0.f, theRefractionIndex, 0.f));
  59   }
  60
  61   //! Creates Fresnel factor for physical-based conductor model.
  62   static Graphic3d_Fresnel CreateConductor (Standard_ShortReal theRefractionIndex,
  63                                             Standard_ShortReal theAbsorptionIndex)
  64   {
  65     return Graphic3d_Fresnel (Graphic3d_FM_CONDUCTOR, Graphic3d_Vec3 (0.f, theRefractionIndex, theAbsorptionIndex));
  66   }
  67
  68   //! Creates Fresnel factor for physical-based conductor model (spectral version).
  69   Standard_EXPORT static Graphic3d_Fresnel CreateConductor (const Graphic3d_Vec3& theRefractionIndex,
  70                                                             const Graphic3d_Vec3& theAbsorptionIndex);
  71
  72 public:
  73
  74   //! Returns serialized representation of Fresnel factor.
  75   Standard_EXPORT Graphic3d_Vec4 Serialize() const;
  76
  77   //! Performs comparison of two objects describing Fresnel factor.
  78   bool operator== (const Graphic3d_Fresnel& theOther) const
  79   {
  80     return myFresnelType == theOther.myFresnelType
  81         && myFresnelData == theOther.myFresnelData;
  82   }
  83
  84   //! Returns type of Fresnel.
  85   Graphic3d_FresnelModel FresnelType() const
  86   {
  87     return myFresnelType;
  88   }
  89
  90 protected:
  91
  92   //! Creates new Fresnel reflectance factor.
  93   Graphic3d_Fresnel (Graphic3d_FresnelModel theType, const Graphic3d_Vec3& theData)
  94   : myFresnelType (theType),
  95     myFresnelData (theData)
  96   {
  97     //
  98   }
  99
 100 private:
 101
 102   //! Type of Fresnel approximation.
 103   Graphic3d_FresnelModel myFresnelType;
 104
 105   //! Serialized parameters of specific approximation.
 106   Graphic3d_Vec3 myFresnelData;
 107 };
 108
 109 //! Describes material's BSDF (Bidirectional Scattering Distribution Function) used
 110 //! for physically-based rendering (in path tracing engine). BSDF is represented as
 111 //! weighted mixture of basic BRDFs/BTDFs (Bidirectional Reflectance (Transmittance)
 112 //! Distribution Functions).
 113 //!
 114 //! NOTE: OCCT uses two-layer material model. We have base diffuse, glossy, or transmissive
 115 //! layer, covered by one glossy/specular coat. In the current model, the layers themselves
 116 //! have no thickness; they can simply reflect light or transmits it to the layer under it.
 117 //! We use actual BRDF model only for direct reflection by the coat layer. For transmission
 118 //! through this layer, we approximate it as a flat specular surface.
 119 class Graphic3d_BSDF
 120 {
 121 public:
 122
 123   //! Weight of coat specular/glossy BRDF.
 124   Graphic3d_Vec4 Kc;
 125
 126   //! Weight of base diffuse BRDF.
 127   Graphic3d_Vec3 Kd;
 128
 129   //! Weight of base specular/glossy BRDF.
 130   Graphic3d_Vec4 Ks;
 131
 132   //! Weight of base specular/glossy BTDF.
 133   Graphic3d_Vec3 Kt;
 134
 135   //! Radiance emitted by the surface.
 136   Graphic3d_Vec3 Le;
 137
 138   //! Volume scattering color/density.
 139   Graphic3d_Vec4 Absorption;
 140
 141   //! Parameters of Fresnel reflectance of coat layer.
 142   Graphic3d_Fresnel FresnelCoat;
 143
 144   //! Parameters of Fresnel reflectance of base layer.
 145   Graphic3d_Fresnel FresnelBase;
 146
 147 public:
 148
 149   //! Creates BSDF describing diffuse (Lambertian) surface.
 150   static Standard_EXPORT Graphic3d_BSDF CreateDiffuse (const Graphic3d_Vec3& theWeight);
 151
 152   //! Creates BSDF describing polished metallic-like surface.
 153   static Standard_EXPORT Graphic3d_BSDF CreateMetallic (const Graphic3d_Vec3&    theWeight,
 154                                                         const Graphic3d_Fresnel& theFresnel,
 155                                                         const Standard_ShortReal theRoughness);
 156
 157   //! Creates BSDF describing transparent object.
 158   //! Transparent BSDF models simple transparency without
 159   //! refraction (the ray passes straight through the surface).
 160   static Standard_EXPORT Graphic3d_BSDF CreateTransparent (const Graphic3d_Vec3&    theWeight,
 161                                                            const Graphic3d_Vec3&    theAbsorptionColor,
 162                                                            const Standard_ShortReal theAbsorptionCoeff);
 163
 164   //! Creates BSDF describing glass-like object.
 165   //! Glass-like BSDF mixes refraction and reflection effects at
 166   //! grazing angles using physically-based Fresnel dielectric model.
 167   static Standard_EXPORT Graphic3d_BSDF CreateGlass (const Graphic3d_Vec3&    theWeight,
 168                                                      const Graphic3d_Vec3&    theAbsorptionColor,
 169                                                      const Standard_ShortReal theAbsorptionCoeff,
 170                                                      const Standard_ShortReal theRefractionIndex);
 171
 172 public:
 173
 174   //! Creates uninitialized BSDF.
 175   Standard_EXPORT Graphic3d_BSDF();
 176
 177   //! Normalizes BSDF components.
 178   Standard_EXPORT void Normalize();
 179
 180   //! Performs comparison of two BSDFs.
 181   Standard_EXPORT bool operator== (const Graphic3d_BSDF& theOther) const;
 182
 183 };
 184
 185 #endif // _Graphic3d_BSDF_HeaderFile