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0028218: Visualization, Path Tracing - Redesign path tracing materials to support two-layered model

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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
This commit is contained in:
dbp
2016-11-18 17:53:10 +03:00
committed by bugmaster
parent dc858f4c5a
commit 05aa616d6d
15 changed files with 1045 additions and 656 deletions
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115
src/Graphic3d/Graphic3d_BSDF.cxx
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@@ -27,7 +27,7 @@ Graphic3d_Vec4 Graphic3d_Fresnel::Serialize() const
if (myFresnelType != Graphic3d_FM_SCHLICK)
{
aData.x() = -static_cast<Standard_ShortReal> (myFresnelType);
aData.x() = -static_cast<float> (myFresnelType);
}
return aData;
@@ -37,8 +37,8 @@ Graphic3d_Vec4 Graphic3d_Fresnel::Serialize() const
// function : fresnelNormal
// purpose :
// =======================================================================
inline Standard_ShortReal fresnelNormal (Standard_ShortReal theN,
Standard_ShortReal theK)
inline float fresnelNormal (float theN,
float theK)
{
return ((theN - 1.f) * (theN - 1.f) + theK * theK) /
((theN + 1.f) * (theN + 1.f) + theK * theK);
@@ -51,10 +51,37 @@ inline Standard_ShortReal fresnelNormal (Standard_ShortReal theN,
Graphic3d_Fresnel Graphic3d_Fresnel::CreateConductor (const Graphic3d_Vec3& theRefractionIndex,
const Graphic3d_Vec3& theAbsorptionIndex)
{
return Graphic3d_Fresnel (Graphic3d_FM_SCHLICK,
Graphic3d_Vec3 (fresnelNormal (theRefractionIndex.x(), theAbsorptionIndex.x()),
fresnelNormal (theRefractionIndex.y(), theAbsorptionIndex.y()),
fresnelNormal (theRefractionIndex.z(), theAbsorptionIndex.z())));
const Graphic3d_Vec3 aFresnel (fresnelNormal (theRefractionIndex.x(), theAbsorptionIndex.x()),
fresnelNormal (theRefractionIndex.y(), theAbsorptionIndex.y()),
fresnelNormal (theRefractionIndex.z(), theAbsorptionIndex.z()));
return Graphic3d_Fresnel (Graphic3d_FM_SCHLICK, aFresnel);
}
// =======================================================================
// function : Graphic3d_BSDF
// purpose :
// =======================================================================
Graphic3d_BSDF::Graphic3d_BSDF()
{
FresnelCoat = Graphic3d_Fresnel::CreateConstant (0.f);
FresnelBase = Graphic3d_Fresnel::CreateConstant (1.f);
}
// =======================================================================
// function : operator==
// purpose :
// =======================================================================
bool Graphic3d_BSDF::operator== (const Graphic3d_BSDF& theOther) const
{
return Kc == theOther.Kc
&& Kd == theOther.Kd
&& Kt == theOther.Kt
&& Ks == theOther.Ks
&& Le == theOther.Le
&& Absorption == theOther.Absorption
&& FresnelCoat == theOther.FresnelCoat
&& FresnelBase == theOther.FresnelBase;
}
// =======================================================================
@@ -63,16 +90,21 @@ Graphic3d_Fresnel Graphic3d_Fresnel::CreateConductor (const Graphic3d_Vec3& theR
// =======================================================================
void Graphic3d_BSDF::Normalize()
{
Standard_ShortReal aMax = std::max (Kd.x() + Ks.x() + Kr.x() + Kt.x(),
std::max (Kd.y() + Ks.y() + Kr.y() + Kt.y(),
Kd.z() + Ks.z() + Kr.z() + Kt.z()));
float aMax = 0.f;
for (int aChannelID = 0; aChannelID < 3; ++aChannelID)
{
aMax = std::max (aMax, Kd[aChannelID] + Ks[aChannelID] + Kt[aChannelID]);
}
if (aMax > 1.f)
{
Kd /= aMax;
Ks /= aMax;
Kr /= aMax;
Ks /= aMax;
for (int aChannelID = 0; aChannelID < 3; ++aChannelID)
{
Kd[aChannelID] /= aMax;
Ks[aChannelID] /= aMax;
Kt[aChannelID] /= aMax;
}
}
}
@@ -93,26 +125,15 @@ Graphic3d_BSDF Graphic3d_BSDF::CreateDiffuse (const Graphic3d_Vec3& theWeight)
// function : CreateMetallic
// purpose :
// =======================================================================
Graphic3d_BSDF Graphic3d_BSDF::CreateMetallic (const Graphic3d_Vec3& theWeight,
const Graphic3d_Fresnel& theFresnel,
const Standard_ShortReal theRoughness)
Graphic3d_BSDF Graphic3d_BSDF::CreateMetallic (const Graphic3d_Vec3& theWeight, const Graphic3d_Fresnel& theFresnel, const float theRoughness)
{
Graphic3d_BSDF aBSDF;
aBSDF.Roughness = theRoughness;
aBSDF.FresnelBase = theFresnel;
// Selecting between specular and glossy
// BRDF depending on the given roughness
if (aBSDF.Roughness > 0.f)
{
aBSDF.Ks = theWeight;
}
else
{
aBSDF.Kr = theWeight;
}
aBSDF.Fresnel = theFresnel;
aBSDF.Ks = Graphic3d_Vec4 (theWeight, theRoughness);
return aBSDF;
}
@@ -121,18 +142,25 @@ Graphic3d_BSDF Graphic3d_BSDF::CreateMetallic (const Graphic3d_Vec3& theWeigh
// function : CreateTransparent
// purpose :
// =======================================================================
Graphic3d_BSDF Graphic3d_BSDF::CreateTransparent (const Graphic3d_Vec3& theWeight,
const Graphic3d_Vec3& theAbsorptionColor,
const Standard_ShortReal theAbsorptionCoeff)
Graphic3d_BSDF Graphic3d_BSDF::CreateTransparent (const Graphic3d_Vec3& theWeight,
const Graphic3d_Vec3& theAbsorptionColor,
const float theAbsorptionCoeff)
{
Graphic3d_BSDF aBSDF;
// Create Fresnel parameters for the coat layer;
// set it to 0 value to simulate ideal refractor
aBSDF.FresnelCoat = Graphic3d_Fresnel::CreateConstant (0.f);
aBSDF.Kt = theWeight;
aBSDF.AbsorptionColor = theAbsorptionColor;
aBSDF.AbsorptionCoeff = theAbsorptionCoeff;
// Link reflection and transmission coefficients
aBSDF.Kc.r() = aBSDF.Kt.r();
aBSDF.Kc.g() = aBSDF.Kt.g();
aBSDF.Kc.b() = aBSDF.Kt.b();
aBSDF.Fresnel = Graphic3d_Fresnel::CreateConstant (0.f);
aBSDF.Absorption = Graphic3d_Vec4 (theAbsorptionColor,
theAbsorptionCoeff);
return aBSDF;
}
@@ -141,19 +169,24 @@ Graphic3d_BSDF Graphic3d_BSDF::CreateTransparent (const Graphic3d_Vec3& theWe
// function : CreateGlass
// purpose :
// =======================================================================
Graphic3d_BSDF Graphic3d_BSDF::CreateGlass (const Graphic3d_Vec3& theWeight,
const Graphic3d_Vec3& theAbsorptionColor,
const Standard_ShortReal theAbsorptionCoeff,
const Standard_ShortReal theRefractionIndex)
Graphic3d_BSDF Graphic3d_BSDF::CreateGlass (const Graphic3d_Vec3& theWeight,
const Graphic3d_Vec3& theAbsorptionColor,
const float theAbsorptionCoeff,
const float theRefractionIndex)
{
Graphic3d_BSDF aBSDF;
// Create Fresnel parameters for the coat layer
aBSDF.FresnelCoat = Graphic3d_Fresnel::CreateDielectric (theRefractionIndex);
aBSDF.Kt = theWeight;
aBSDF.AbsorptionColor = theAbsorptionColor;
aBSDF.AbsorptionCoeff = theAbsorptionCoeff;
aBSDF.Kc.r() = aBSDF.Kt.r();
aBSDF.Kc.g() = aBSDF.Kt.g();
aBSDF.Kc.b() = aBSDF.Kt.b();
aBSDF.Fresnel = Graphic3d_Fresnel::CreateDielectric (theRefractionIndex);
aBSDF.Absorption = Graphic3d_Vec4 (theAbsorptionColor,
theAbsorptionCoeff);
return aBSDF;
}