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97 lines
2.2 KiB
C++
97 lines
2.2 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef NS_SMILKEYSPLINE_H_
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#define NS_SMILKEYSPLINE_H_
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/**
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* Utility class to provide scaling defined in a keySplines element.
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*/
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class nsSMILKeySpline
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{
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public:
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nsSMILKeySpline() { /* caller must call Init later */ }
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/**
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* Creates a new key spline control point description.
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*
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* aX1, etc. are the x1, y1, x2, y2 cubic Bezier control points as defined by
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* SMILANIM 3.2.3. They must each be in the range 0.0 <= x <= 1.0
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*/
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nsSMILKeySpline(double aX1, double aY1,
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double aX2, double aY2)
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{
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Init(aX1, aY1, aX2, aY2);
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}
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void Init(double aX1, double aY1,
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double aX2, double aY2);
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/**
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* Gets the output (y) value for an input (x).
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*
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* @param aX The input x value. A floating-point number between 0 and
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* 1 (inclusive).
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*/
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double GetSplineValue(double aX) const;
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void GetSplineDerivativeValues(double aX, double& aDX, double& aDY) const;
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private:
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void
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CalcSampleValues();
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/**
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* Returns x(t) given t, x1, and x2, or y(t) given t, y1, and y2.
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*/
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static double
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CalcBezier(double aT, double aA1, double aA2);
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/**
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* Returns dx/dt given t, x1, and x2, or dy/dt given t, y1, and y2.
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*/
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static double
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GetSlope(double aT, double aA1, double aA2);
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double
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GetTForX(double aX) const;
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double
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NewtonRaphsonIterate(double aX, double aGuessT) const;
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double
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BinarySubdivide(double aX, double aA, double aB) const;
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static double
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A(double aA1, double aA2)
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{
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return 1.0 - 3.0 * aA2 + 3.0 * aA1;
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}
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static double
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B(double aA1, double aA2)
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{
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return 3.0 * aA2 - 6.0 * aA1;
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}
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static double
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C(double aA1)
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{
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return 3.0 * aA1;
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}
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double mX1;
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double mY1;
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double mX2;
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double mY2;
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enum { kSplineTableSize = 11 };
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double mSampleValues[kSplineTableSize];
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static const double kSampleStepSize;
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};
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#endif // NS_SMILKEYSPLINE_H_
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