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Existing OCCT path tracing engine used very simple additive material (BSDF) model, so it was possible to reproduce behavior only of very basic materials such as metal, glass, or plastic. However, some important in CAD industry materials like car paint or ceramic could not be modeled well. In this patch, OCCT BSDF was significantly improved by replacing additive model with two-layered scattering model. Therefore, we have base diffuse, glossy, or transmissive layer, covered by one glossy/specular coat. The layers themselves have no thickness; they can simply reflect light or transmits it to the layer under it. Balancing different combinations of layer properties can produce a wide range of different effects. At the same time, disabling the first (coat) layer allows to keep full compatibility with previously supported scattering model. All new parameters are available via 'vbsdf' command. Location of new sample for few material examples: samples\tcl\pathtrace_materials.tcl Fix shader compilation issue. Fix test case sample_ball_alpha. Shaders_PathtraceBase_fs.pxx - regenerate resource from origin
192 lines
6.5 KiB
C++
192 lines
6.5 KiB
C++
// Created on: 2015-01-19
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// Created by: Denis BOGOLEPOV
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// Copyright (c) 2014 OPEN CASCADE SAS
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//
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// This file is part of Open CASCADE Technology software library.
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//
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// This library is free software; you can redistribute it and/or modify it under
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// the terms of the GNU Lesser General Public License version 2.1 as published
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// by the Free Software Foundation, with special exception defined in the file
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// OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included in OCCT
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// distribution for complete text of the license and disclaimer of any warranty.
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//
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// Alternatively, this file may be used under the terms of Open CASCADE
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// commercial license or contractual agreement.
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#include <Graphic3d_BSDF.hxx>
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#include <algorithm>
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// =======================================================================
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// function : Serialize
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// purpose :
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// =======================================================================
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Graphic3d_Vec4 Graphic3d_Fresnel::Serialize() const
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{
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Graphic3d_Vec4 aData = Graphic3d_Vec4 (myFresnelData, 0.f);
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if (myFresnelType != Graphic3d_FM_SCHLICK)
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{
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aData.x() = -static_cast<float> (myFresnelType);
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}
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return aData;
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}
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// =======================================================================
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// function : fresnelNormal
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// purpose :
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// =======================================================================
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inline float fresnelNormal (float theN,
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float theK)
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{
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return ((theN - 1.f) * (theN - 1.f) + theK * theK) /
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((theN + 1.f) * (theN + 1.f) + theK * theK);
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}
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// =======================================================================
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// function : CreateConductor
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// purpose :
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// =======================================================================
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Graphic3d_Fresnel Graphic3d_Fresnel::CreateConductor (const Graphic3d_Vec3& theRefractionIndex,
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const Graphic3d_Vec3& theAbsorptionIndex)
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{
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const Graphic3d_Vec3 aFresnel (fresnelNormal (theRefractionIndex.x(), theAbsorptionIndex.x()),
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fresnelNormal (theRefractionIndex.y(), theAbsorptionIndex.y()),
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fresnelNormal (theRefractionIndex.z(), theAbsorptionIndex.z()));
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return Graphic3d_Fresnel (Graphic3d_FM_SCHLICK, aFresnel);
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}
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// =======================================================================
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// function : Graphic3d_BSDF
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// purpose :
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// =======================================================================
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Graphic3d_BSDF::Graphic3d_BSDF()
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{
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FresnelCoat = Graphic3d_Fresnel::CreateConstant (0.f);
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FresnelBase = Graphic3d_Fresnel::CreateConstant (1.f);
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}
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// =======================================================================
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// function : operator==
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// purpose :
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// =======================================================================
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bool Graphic3d_BSDF::operator== (const Graphic3d_BSDF& theOther) const
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{
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return Kc == theOther.Kc
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&& Kd == theOther.Kd
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&& Kt == theOther.Kt
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&& Ks == theOther.Ks
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&& Le == theOther.Le
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&& Absorption == theOther.Absorption
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&& FresnelCoat == theOther.FresnelCoat
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&& FresnelBase == theOther.FresnelBase;
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}
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// =======================================================================
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// function : Normalize
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// purpose :
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// =======================================================================
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void Graphic3d_BSDF::Normalize()
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{
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float aMax = 0.f;
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for (int aChannelID = 0; aChannelID < 3; ++aChannelID)
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{
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aMax = std::max (aMax, Kd[aChannelID] + Ks[aChannelID] + Kt[aChannelID]);
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}
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if (aMax > 1.f)
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{
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for (int aChannelID = 0; aChannelID < 3; ++aChannelID)
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{
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Kd[aChannelID] /= aMax;
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Ks[aChannelID] /= aMax;
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Kt[aChannelID] /= aMax;
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}
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}
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}
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// =======================================================================
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// function : CreateDiffuse
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// purpose :
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// =======================================================================
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Graphic3d_BSDF Graphic3d_BSDF::CreateDiffuse (const Graphic3d_Vec3& theWeight)
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{
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Graphic3d_BSDF aBSDF;
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aBSDF.Kd = theWeight;
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return aBSDF;
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}
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// =======================================================================
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// function : CreateMetallic
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// purpose :
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// =======================================================================
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Graphic3d_BSDF Graphic3d_BSDF::CreateMetallic (const Graphic3d_Vec3& theWeight, const Graphic3d_Fresnel& theFresnel, const float theRoughness)
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{
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Graphic3d_BSDF aBSDF;
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aBSDF.FresnelBase = theFresnel;
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// Selecting between specular and glossy
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// BRDF depending on the given roughness
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aBSDF.Ks = Graphic3d_Vec4 (theWeight, theRoughness);
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return aBSDF;
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}
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// =======================================================================
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// function : CreateTransparent
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// purpose :
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// =======================================================================
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Graphic3d_BSDF Graphic3d_BSDF::CreateTransparent (const Graphic3d_Vec3& theWeight,
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const Graphic3d_Vec3& theAbsorptionColor,
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const float theAbsorptionCoeff)
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{
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Graphic3d_BSDF aBSDF;
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// Create Fresnel parameters for the coat layer;
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// set it to 0 value to simulate ideal refractor
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aBSDF.FresnelCoat = Graphic3d_Fresnel::CreateConstant (0.f);
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aBSDF.Kt = theWeight;
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// Link reflection and transmission coefficients
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aBSDF.Kc.r() = aBSDF.Kt.r();
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aBSDF.Kc.g() = aBSDF.Kt.g();
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aBSDF.Kc.b() = aBSDF.Kt.b();
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aBSDF.Absorption = Graphic3d_Vec4 (theAbsorptionColor,
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theAbsorptionCoeff);
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return aBSDF;
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}
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// =======================================================================
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// function : CreateGlass
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// purpose :
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// =======================================================================
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Graphic3d_BSDF Graphic3d_BSDF::CreateGlass (const Graphic3d_Vec3& theWeight,
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const Graphic3d_Vec3& theAbsorptionColor,
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const float theAbsorptionCoeff,
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const float theRefractionIndex)
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{
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Graphic3d_BSDF aBSDF;
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// Create Fresnel parameters for the coat layer
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aBSDF.FresnelCoat = Graphic3d_Fresnel::CreateDielectric (theRefractionIndex);
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aBSDF.Kt = theWeight;
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aBSDF.Kc.r() = aBSDF.Kt.r();
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aBSDF.Kc.g() = aBSDF.Kt.g();
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aBSDF.Kc.b() = aBSDF.Kt.b();
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aBSDF.Absorption = Graphic3d_Vec4 (theAbsorptionColor,
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theAbsorptionCoeff);
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return aBSDF;
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} |