BRDF.h

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/* $Id: BRDF.h,v 1.1 2002/12/05 15:02:18 cvs Exp $ */

#ifndef __BRDF_H
#define __BRDF_H

#include <esg/Definitions.h>
#include <esg/ESGObject.h>
#include <esg/visitor/MatVisitor.h>
#include <esg/Export>

namespace esg {

class OGSCENE_EXPORT BRDF : public ESGObject {
public:
        enum RetVal {
            NONZERO_CONTRIB   = 1, 
            BAD_PARAMS        = 2, 
            NL_NEGATIVE       = 3, 
            NV_NEGATIVE       = 4, 
            NL_OR_NV_NEGATIVE = 5, 
            ZERO_CONTRIB      = 6  
        };

protected:
        bool _isDiffuse;
        bool _isIsotropic;

protected:
        virtual void _duplicate_attributes (const BRDF& src) {
            _isDiffuse   = src._isDiffuse;
            _isIsotropic = src._isIsotropic;
        }
    
public:
        BRDF (bool diffuse, bool isotropic)
            : _isDiffuse(diffuse), _isIsotropic(isotropic) {}

        virtual ~BRDF() {}

        bool diffuse (void) const { return _isDiffuse; }

        bool specular (void) const { return ! _isDiffuse; }

        bool isotropic (void) const { return _isIsotropic; }

        bool anisotropic (void) const { return ! _isIsotropic; }

        virtual RetVal reflectance(const MatVisitor& visitor,
                                   const Vector3*    L,
                                   const Vector3*    V,
                                   const Vector3*    N,
                                   Vector3&          color) = 0;

        virtual RetVal reflectanceVNL(const MatVisitor& visitor,
                                      const Vector3*    L,
                                      const Vector3*    V,
                                      const Vector3*    N,
                                      double            NV,
                                      double            NL,
                                      Vector3&          color) = 0;

        virtual RetVal reflectanceNL(const MatVisitor& visitor,
                                     const Vector3*    L,
                                     const Vector3*    V,
                                     const Vector3*    N,
                                     double            NL,
                                     Vector3&          color) = 0;

        virtual BRDF* clone () const = 0;

        virtual double albedo (const MatVisitor& visitor,
                               const Vector3&    N,
                               const Vector3*    V) const = 0;

        virtual void importanceSample(const MatVisitor& visitor,
                                      const Vector3&    D,
                                      double            r1,
                                      double            r2,
                                      Vector3&          dir,
                                      double*           pPDFVal) = 0;

        virtual Vector2 dir2uv (const MatVisitor& visitor,
                                const Vector3&    N,
                                const Vector3&    D) const = 0;


        // Vector3* stratifiedSamples(unsigned /* # subdomains */);
};

}; // namespace

#endif // __BRDF_H

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