/* ** Command & Conquer Generals Zero Hour(tm) ** Copyright 2025 Electronic Arts Inc. ** ** This program 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 3 of the License, or ** (at your option) any later version. ** ** This program 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 this program. If not, see . */ // ============================================================================ // Copyright (C) 2003, 2004 Electronic Arts // // ParabolicEase.h // Ease in and out based on a parabolic function. // Author: Robert Minsk May 12, 2003 // ============================================================================ #pragma once #ifndef _PARABOLICEASE_H #define _PARABOLICEASE_H // ============================================================================ #include "Lib/BaseType.h" // ============================================================================ /// Ease in and out based on a linear velocity. /** * This ends up being a function that is parabolic at both ends and a linear * middle section with respect to position. * * velocity(0.0) = 0.0 * velocity(in) = v0 * velocity(out) = v0 * velocity(1.0) = 0.0 * * From 0.0->in velocity is linearly increasing. * From out->1.0 velocity is linearly decreasing. * * velocity(t) = v0*t/in t = [0, in] Linear increasing segment * = v0 t = (in, out] Constant segment * = (1-t)*v0/(1-out) t = (out, 1.0] Linear decreasing segment * * We need to calculate v0. We want the total distance covered to be 1.0. * * 1 = integral(velocity(t), 0, 1) * 1 = integral(velocity(t), 0, in) + * integral(velocity(t), in, out) + * integral(velocity(t), out, 1.0) * 1 = v0*in/2 + v0*(out - in) + v0*(1 - out)/2 * = v0*(out-in+1)/2 * v0 = 2/(out-in+1) * * Now we can calculate the distance function. * * d(0->in) = integral(velocity(t), 0, s) * = v0*s*s/(2*in) * d(in->out) = d(0->in) + integral(velocity(t), in, s) * = (v0*in/2) + (v0*(s - in)) * d(out->1) = d(0->in) + d(in->out) + integral(velocity(t), out, s) * = (v0*in/2) + (v0*(out - in)) + (s-s*s/2-out+out*out/2)*v0/(1-out) */ class ParabolicEase { public: explicit ParabolicEase(Real easeInTime = 0.0f, Real easeOutTime = 0.0f) { setEaseTimes(easeInTime, easeOutTime); } /// Initialize the ease-in/ease-out function. /** * \param easeInTime/\param easeOutTime is the amount of time to * accomplish the transition. The time is normalized from 0 to 1. */ void setEaseTimes(Real easeInTime, Real easeOutTime); /// Evaluate the ease-in/ease-out function at time \param param. /** * \param param is normalized from 0 to 1. */ Real operator ()(Real param) const; private: Real m_in, m_out; }; // ============================================================================ #endif // _PARABOLICEASE_H