Alex Harker
94 lines
2.1 KiB
C++
94 lines
2.1 KiB
C++
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#ifndef INTERPOLATION_HPP
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#define INTERPOLATION_HPP
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// Enumeration of interpolation types
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enum InterpType
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{
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kInterpNone, kInterpLinear, kInterpCubicHermite, kInterpCubicLagrange, kInterpCubicBSpline
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};
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// Linear
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template <class T>
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struct linear_interp
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{
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T operator()(const T& x, const T& y0, const T& y1) { return (y0 + x * ((y1 - y0))); }
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};
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// Cubic Hermite
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template <class T>
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struct cubic_hermite_interp
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{
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cubic_hermite_interp() : _5div2(2.5), _3div2(1.5), _1div2(0.5) {}
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T operator()(const T& x, const T& y0, const T& y1, const T& y2, const T& y3)
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{
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const T c0 = y1;
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const T c1 = _1div2 * (y2 - y0);
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const T c2 = y0 - _5div2 * y1 + y2 + y2 - _1div2 * y3;
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const T c3 = _1div2 * (y3 - y0) + _3div2 * (y1 - y2);
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return (((c3 * x + c2) * x + c1) * x + c0);
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}
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private:
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const T _5div2;
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const T _3div2;
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const T _1div2;
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};
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// Cubic Lagrange
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template <class T>
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struct cubic_lagrange_interp
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{
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cubic_lagrange_interp() : _1div3(T(1)/T(3)), _1div6(T(1)/T(6)), _1div2(0.5) {}
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T operator()(const T& x, const T& y0, const T& y1, const T& y2, const T& y3)
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{
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const T c0 = y1;
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const T c1 = y2 - _1div3 * y0 - _1div2 * y1 - _1div6 * y3;
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const T c2 = _1div2 * (y0 + y2) - y1;
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const T c3 = _1div6 * (y3 - y0) + _1div2 * (y1 - y2);
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return (((c3 * x + c2) * x + c1) * x + c0);
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}
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private:
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const T _1div3;
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const T _1div6;
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const T _1div2;
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};
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// Cubic B-spline
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template <class T>
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struct cubic_bspline_interp
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{
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cubic_bspline_interp() : _2div3(T(2)/T(3)), _1div6(T(1)/T(6)), _1div2(0.5) {}
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T operator()(const T& x, const T& y0, const T& y1, const T& y2, const T& y3)
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{
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const T y0py2 = y0 + y2;
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const T c0 = _1div6 * y0py2 + _2div3 * y1;
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const T c1 = _1div2 * (y2 - y0);
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const T c2 = _1div2 * y0py2 - y1;
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const T c3 = _1div2 * (y1 - y2) + _1div6 * (y3 - y0);
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return (((c3 * x + c2) * x + c1) * x + c0);
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}
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private:
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const T _2div3;
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const T _1div6;
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const T _1div2;
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};
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#endif /* Interpolation_h */
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