wmlapprpolyfit2.cpp

来自「3D Game Engine Design Source Code非常棒」· C++ 代码 · 共 98 行

// Magic Software, Inc.
// http://www.magic-software.com
// http://www.wild-magic.com
// Copyright (c) 2003.  All Rights Reserved
//
// The Wild Magic Library (WML) source code is supplied under the terms of
// the license agreement http://www.magic-software.com/License/WildMagic.pdf
// and may not be copied or disclosed except in accordance with the terms of
// that agreement.

#include "WmlApprPolyFit2.h"
#include "WmlLinearSystem.h"
using namespace Wml;

//----------------------------------------------------------------------------
template <class Real>
void Wml::PolyFit2 (int iSamples, const Real* afX, const Real* afY,
    const Real* afW, int iXDegree, int iYDegree, int& riQuantity, Real*& rafC)
{
    int i0, j0, i1, j1, iS;

    int iXBound = iXDegree + 1;
    int iYBound = iYDegree + 1;
    riQuantity = iXBound*iYBound;
    rafC = new Real[riQuantity];

    // powers of x, y
    Real** aafXP;
    Real** aafYP;
    Allocate2D(2*iXBound,iSamples,aafXP);
    Allocate2D(2*iYBound,iSamples,aafYP);
    for (iS = 0; iS < iSamples; iS++)
    {
        aafXP[iS][0] = (Real)1.0;
        for (i0 = 1; i0 <= 2*iXDegree; i0++)
            aafXP[iS][i0] = afX[iS]*aafXP[iS][i0-1];

        aafYP[iS][0] = (Real)1.0;
        for (j0 = 1; j0 <= 2*iYDegree; j0++)
            aafYP[iS][j0] = afY[iS]*aafYP[iS][j0-1];
    }

    // Vandermonde matrix and right-hand side of linear system
    GMatrix<Real> kA(riQuantity,riQuantity);
    Real* afB = new Real[riQuantity];

    for (j0 = 0; j0 <= iYDegree; j0++)
    {
        for (i0 = 0; i0 <= iXDegree; i0++)
        {
            int iIndex0 = i0+iXBound*j0;

            Real fSum = (Real)0.0;
            for (iS = 0; iS < iSamples; iS++)
            {
                fSum += afW[iS]*aafXP[iS][i0]*aafYP[iS][j0];
            }
            afB[iIndex0] = fSum;

            for (j1 = 0; j1 <= iYDegree; j1++)
            {
                for (i1 = 0; i1 <= iXDegree; i1++)
                {
                    int iIndex1 = i1+iXBound*j1;

                    fSum = (Real)0.0;
                    for (iS = 0; iS < iSamples; iS++)
                    {
                        fSum += aafXP[iS][i0+i1]*aafYP[iS][j0+j1];
                    }
                    kA(iIndex0,iIndex1) = fSum;
                }
            }
        }
    }

    // solve for the polynomial coefficients
    bool bHasSolution = LinearSystem<Real>::Solve(kA,afB,rafC);
    assert( bHasSolution );

    Deallocate2D(aafXP);
    Deallocate2D(aafYP);
}
//----------------------------------------------------------------------------

//----------------------------------------------------------------------------
// explicit instantiation
//----------------------------------------------------------------------------
namespace Wml
{
template WML_ITEM void PolyFit2<float> (int, const float*, const float*,
    const float*, int, int, int&, float*&);

template WML_ITEM void PolyFit2<double> (int, const double*, const double*,
    const double*, int, int, int&, double*&);
}
//----------------------------------------------------------------------------