7919089dd971c50641ea8d1360efd4b235a42019
[occt.git] / 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