generalizedbsdf.h

/*
    Lightmetrica : A research-oriented renderer

    Copyright (c) 2014 Hisanari Otsu

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#pragma once
#ifndef LIB_LIGHTMETRICA_GENERALIZED_BSDF_H
#define LIB_LIGHTMETRICA_GENERALIZED_BSDF_H

#include "asset.h"
#include "math.types.h"
#include "transportdirection.h"

LM_NAMESPACE_BEGIN

enum GeneralizedBSDFType
{

    // Uninitialized value
    None                    = 0,

    // Primitive BSDF types
    DiffuseReflection       = 1<<0,
    DiffuseTransmission     = 1<<1,
    SpecularReflection      = 1<<2,
    SpecularTransmission    = 1<<3,
    GlossyReflection        = 1<<4,
    GlossyTransmission      = 1<<5,

    // Emitter primitive types
    DeltaLightDirection     = 1<<6,
    NonDeltaLightDirection  = 1<<7,
    DeltaEyeDirection       = 1<<8,
    NonDeltaEyeDirection    = 1<<9,

    // Material type flags for BSDF types
    Diffuse                 = DiffuseReflection | DiffuseTransmission,
    Specular                = SpecularReflection | SpecularTransmission,
    Glossy                  = GlossyReflection | GlossyTransmission,
    Reflection              = DiffuseReflection | SpecularReflection | GlossyReflection,
    Transmission            = DiffuseTransmission | SpecularTransmission | GlossyTransmission,

    // Emitter type flags
    LightDirection          = DeltaLightDirection | NonDeltaLightDirection,
    EyeDirection            = DeltaEyeDirection | NonDeltaEyeDirection,

    // Useful type flags
    AllEmitter              = LightDirection | EyeDirection,
    AllBSDF                 = Diffuse | Specular | Glossy,
    All                     = AllEmitter | AllBSDF,

    // Delta or non-delta
    Delta                   = Specular | DeltaLightDirection | DeltaEyeDirection,
    NonDelta                = All & ~Delta

};

struct GeneralizedBSDFSampleQuery
{

    int type;                           
    Math::Vec2 sample;                  
    Math::Float uComp;                  
    TransportDirection transportDir;    
    Math::Vec3 wi;                      

};

struct GeneralizedBSDFSampleResult
{

    int sampledType;                    
    Math::Vec3 wo;                      
    Math::PDFEval pdf;                  

};

struct GeneralizedBSDFSampleBidirResult
{

    int sampledType;                    
    Math::Vec3 wo;                      
    Math::Vec3 weight[2];               
    Math::PDFEval pdf[2];               

};

struct GeneralizedBSDFEvaluateQuery
{

    int type;                           
    TransportDirection transportDir;    
    Math::Vec3 wi;                      
    Math::Vec3 wo;                      
    bool forced;                        

public:

    GeneralizedBSDFEvaluateQuery()
    {

    }

    GeneralizedBSDFEvaluateQuery(const GeneralizedBSDFSampleQuery& query, const GeneralizedBSDFSampleResult& result)
        : type(result.sampledType)
        , transportDir(query.transportDir)
        , wi(query.wi)
        , wo(result.wo)
        , forced(false)
    {

    }

    GeneralizedBSDFEvaluateQuery(int type, TransportDirection transportDir, const Math::Vec3& wi, const Math::Vec3& wo)
        : type(type)
        , transportDir(transportDir)
        , wi(wi)
        , wo(wo)
        , forced(false)
    {

    }

};

struct SurfaceGeometry;

class GeneralizedBSDF : public Asset
{
public:

    GeneralizedBSDF() {}
    virtual ~GeneralizedBSDF() {}

public:

    virtual bool SampleDirection(const GeneralizedBSDFSampleQuery& query, const SurfaceGeometry& geom, GeneralizedBSDFSampleResult& result) const = 0;
    
    virtual Math::Vec3 SampleAndEstimateDirection(const GeneralizedBSDFSampleQuery& query, const SurfaceGeometry& geom, GeneralizedBSDFSampleResult& result) const = 0;

    virtual bool SampleAndEstimateDirectionBidir(const GeneralizedBSDFSampleQuery& query, const SurfaceGeometry& geom, GeneralizedBSDFSampleBidirResult& result) const = 0;

    virtual Math::Vec3 EvaluateDirection(const GeneralizedBSDFEvaluateQuery& query, const SurfaceGeometry& geom) const = 0;
    
    virtual Math::PDFEval EvaluateDirectionPDF(const GeneralizedBSDFEvaluateQuery& query, const SurfaceGeometry& geom) const = 0;

    //virtual bool Degenerated() const = 0;

    //virtual bool Connectable() const = 0;

    virtual int BSDFTypes() const = 0;

};

LM_NAMESPACE_END

#endif // LIB_LIGHTMETRICA_GENERALIZED_BSDF_H