16#ifndef GDALRESAMPLINGKERNELS_H_INCLUDED
17#define GDALRESAMPLINGKERNELS_H_INCLUDED
23static inline double CubicKernel(
double dfX)
30 double dfAbsX = fabs(dfX);
33 double dfX2 = dfX * dfX;
34 return dfX2 * (1.5 * dfAbsX - 2.5) + 1;
36 else if (dfAbsX <= 2.0)
38 double dfX2 = dfX * dfX;
39 return dfX2 * (-0.5 * dfAbsX + 2.5) - 4 * dfAbsX + 2;
45static inline double CubicSplineKernel(
double dfVal)
50 const double xm1 = dfVal - 1.0;
51 const double xp1 = dfVal + 1.0;
52 const double xp2 = dfVal + 2.0;
54 const double a = xp2 <= 0.0 ? 0.0 : xp2 * xp2 * xp2;
55 const double b = xp1 <= 0.0 ? 0.0 : xp1 * xp1 * xp1;
56 const double c = dfVal <= 0.0 ? 0.0 : dfVal * dfVal * dfVal;
57 const double d = xm1 <= 0.0 ? 0.0 : xm1 * xm1 * xm1;
59 return 0.16666666666666666667 * (a - (4.0 * b) + (6.0 * c) - (4.0 * d));