mgcbeziertriangle2g.h

《3D游戏引擎设计》的源码

// Magic Software, Inc.
// http://www.magic-software.com
// Copyright (c) 2000, All Rights Reserved
//
// Source code from Magic Software is supplied under the terms of a license
// agreement and may not be copied or disclosed except in accordance with the
// terms of that agreement.  The various license agreements may be found at
// the Magic Software web site.  This file is subject to the license
//
// FREE SOURCE CODE
// http://www.magic-software.com/License/free.pdf

#ifndef MGCBEZIERTRIANGLE2G_H
#define MGCBEZIERTRIANGLE2G_H

#include "MgcBezierTriangleG.h"
#include "MgcVector3.h"


class MgcBezierTriangle2G : public MgcBezierTriangleG
{
public:
    // Construction.  MgcBezierTriangle2G accepts responsibility for deleting
    // the input array.
    MgcBezierTriangle2G (MgcVector3* akCtrlPoint);

    // position and derivatives up to second order
    virtual MgcVector3 GetPosition (MgcReal fU, MgcReal fV) const;
    virtual MgcVector3 GetDerivativeU (MgcReal fU, MgcReal fV) const;
    virtual MgcVector3 GetDerivativeV (MgcReal fU, MgcReal fV) const;
    virtual MgcVector3 GetDerivativeUU (MgcReal fU, MgcReal fV) const;
    virtual MgcVector3 GetDerivativeUV (MgcReal fU, MgcReal fV) const;
    virtual MgcVector3 GetDerivativeVV (MgcReal fU, MgcReal fV) const;

    // tessellation by recursive subdivision
    virtual void Tessellate (unsigned int uiLevel, bool bWantNormals);

protected:
    // precomputation (d/dh = d/du - d/dv)
    class BlockParameters
    {
    public:
        MgcVector3 m_kXuu, m_kXvv, m_kXhh;
    };

    // subdivide triangle with right angle at Lower Left corner
    void SubdivideLL (unsigned int uiLevel, MgcReal fDSqr, MgcVector3* akX,
        MgcVector3* akXu, MgcVector3* akXv, unsigned int uiI0,
        unsigned int uiI1, unsigned int uiI2, BlockParameters& rkBP);

    // subdivide triangle with right angle at Upper Right corner
    void SubdivideUR (unsigned int uiLevel, MgcReal fDSqr, MgcVector3* akX,
        MgcVector3* akXu, MgcVector3* akXv, unsigned int uiI0,
        unsigned int uiI1, unsigned int uiI2, BlockParameters& rkBP);
};

#endif