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/* Copyright (C) 2012 Wildfire Games.
* This file is part of 0 A.D.
*
* 0 A.D. is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 2 of the License, or
* (at your option) any later version.
*
* 0 A.D. is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with 0 A.D. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef INCLUDED_EASE
#define INCLUDED_EASE
/*
* Straightforward C++ port of Robert Penner's easing equations
* http://www.robertpenner.com/easing/
*
* Copyright (c) 2001 Robert Penner
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification, are permitted
* provided that the following conditions are met:
* - Redistributions of source code must retain the above copyright notice, this list of
* conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright notice, this list of
* conditions and the following disclaimer in the documentation and/or other materials provided
* with the distribution.
* - Neither the name of the author nor the names of contributors may be used to endorse or
* promote products derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
* FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
* IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <math.h>
/**
* Generic easing functions. In each function, the parameters are:
*
* @param t Current time in seconds, as a float between 0 and d (inclusive).
* @param d Total duration of the ease, in seconds. Must be strictly positive.
* @param b Baseline value (at t = 0).
* @param c Delta from baseline value to reach the target value (at t = d). I.e., target = b + c.
*
* Each function outputs the eased value between 'b' and 'b+c' at time 't'.
*/
class Ease
{
public:
static float QuadIn(float t, const float b, const float c, const float d)
{
t /= d;
return c*t*t + b;
}
static float QuadOut(float t, const float b, const float c, const float d)
{
t /= d;
return -c * t*(t-2) + b;
}
static float QuadInOut(float t, const float b, const float c, const float d)
{
t /= d/2;
if (t < 1)
return c/2*t*t + b;
--t;
return -c/2 * (t*(t-2) - 1) + b;
}
static float CubicIn(float t, const float b, const float c, const float d)
{
t /= d;
return c*t*t*t + b;
}
static float CubicOut(float t, const float b, const float c, const float d)
{
t = t/d - 1;
return c*(t*t*t + 1) + b;
}
static float CubicInOut(float t, const float b, const float c, const float d)
{
t /= d/2;
if (t < 1)
return c/2*t*t*t + b;
t -= 2;
return c/2*(t*t*t + 2) + b;
}
static float QuartIn(float t, const float b, const float c, const float d)
{
t /= d;
return c*t*t*t*t + b;
}
static float QuartOut(float t, const float b, const float c, const float d)
{
t = t/d - 1;
return -c*(t*t*t*t - 1) + b;
}
static float QuartInOut(float t, const float b, const float c, const float d)
{
t /= d/2;
if (t < 1)
return c/2*t*t*t*t + b;
t -= 2;
return -c/2 * (t*t*t*t - 2) + b;
}
static float QuintIn(float t, const float b, const float c, const float d)
{
t /= d;
return c*t*t*t*t*t + b;
}
static float QuintOut(float t, const float b, const float c, const float d)
{
t = t/d - 1;
return c*(t*t*t*t*t + 1) + b;
}
static float QuintInOut(float t, const float b, const float c, const float d)
{
t /= d/2;
if (t < 1)
return c/2*t*t*t*t*t + b;
t -= 2;
return c/2*(t*t*t*t*t + 2) + b;
}
};
#endif // INCLUDED_EASE
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