LambertianBRDF.h

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

#ifndef __LAMBERTIAN_BRDF_H
#define __LAMBERTIAN_BRDF_H

#include <esg/Definitions.h>
#include <esg/visitor/MatVisitor.h>
#include <esg/brdf/DiffuseBRDF.h>
#include <esg/geometry/Hemisphere.h>

namespace esg {

class OGSCENE_EXPORT LambertianBRDF : public DiffuseBRDF {
protected:
        virtual void _duplicate_attributes (const BRDF& src) {
            DiffuseBRDF::_duplicate_attributes(src);
        }
        
public:
        LambertianBRDF (void) : DiffuseBRDF(true) {}

        virtual RetVal reflectance(const MatVisitor& visitor,
                                   const Vector3*    L,
                                   const Vector3*    V,  
                                   const Vector3*    N,
                                   Vector3&          color) {
            color.set(visitor.diffuse());
            return NONZERO_CONTRIB;
        }

        virtual RetVal reflectanceVNL(const MatVisitor& visitor,
                                      const Vector3*    L,
                                      const Vector3*    V,  
                                      const Vector3*    N,
                                      double            NV,
                                      double            NL,
                                      Vector3&          color) {
            color.set(visitor.diffuse());
            return NONZERO_CONTRIB;
        }

        virtual RetVal reflectanceNL(const MatVisitor& visitor,
                                     const Vector3*    L,
                                     const Vector3*    V,  
                                     const Vector3*    N,
                                     double            NL,
                                     Vector3&          color) {
            color.set(visitor.diffuse());
            return NONZERO_CONTRIB;
        }

        virtual BRDF* clone (void) const { return new LambertianBRDF(); }

        virtual double albedo (const MatVisitor& visitor,
                               const Vector3&    N,
                               const Vector3*    V) const {
            return visitor.avgDiffuse() / PI;
        }

        virtual void importanceSample(const MatVisitor& visitor,
                                      const Vector3&    D,
                                      double            r1,
                                      double            r2,
                                      Vector3&          dir,
                                      double*           pPDFVal) {
            Hemisphere hemisphere(D);
            dir.set(hemisphere.sampleUniformly(r1, r2, pPDFVal));
        }

        virtual Vector2 dir2uv (const MatVisitor& visitor,
                                const Vector3&    N,
                                const Vector3&    D) const {
            Hemisphere h(N);
            return h.dir2uvUniformly(D);
        }
};

}; // namespace

#endif // ___LAMBERTIAN_BRDF_H

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