68 lines
1.7 KiB
C++
68 lines
1.7 KiB
C++
/*
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* This file is part of libgim.
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*
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* libgim is free software: you can redistribute it and/or modify it under the
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* terms of the GNU General Public License as published by the Free Software
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* Foundation, either version 3 of the License, or (at your option) any later
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* version.
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*
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* libgim is distributed in the hope that it will be useful, but WITHOUT ANY
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* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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* FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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* details.
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*
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* You should have received a copy of the GNU General Public License
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* along with libgim. If not, see <http://www.gnu.org/licenses/>.
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*
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* Copyright 2011 Danny Robson <danny@nerdcruft.net>
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*/
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#include "lerp.hpp"
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#include "debug.hpp"
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#include "maths.hpp"
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#include <cmath>
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double
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lerp::sigmoid (double val) {
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return -1.0 + 2.0 / (1.0 + exp (-2.0 * val));
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}
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double lerp::trunc (double a, double, double)
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{ return a; }
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double
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lerp::linear (double a, double b, double weight) {
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CHECK (weight >= 0.0 && weight <= 1.0);
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return a * (1.0 - weight) + b * weight;
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}
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double
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lerp::cosine (double a, double b, double weight) {
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CHECK (weight >= 0.0 && weight <= 1.0);
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double t = (1.0 - cos (weight * PI)) * 0.5;
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return a * (1.0 - t) + b * t;
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}
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double
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lerp::cubic (double a, double b, double weight) {
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CHECK (weight >= 0.0 && weight <= 1.0);
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double t = weight * weight * (3.0 - 2.0 * weight);
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return a * (1.0 - t) + b * t;
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}
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double
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lerp::quintic (double a, double b, double weight) {
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CHECK (weight >= 0.0 && weight <= 1.0);
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double t = weight * weight * weight * (weight * (weight * 6.0 - 15.0) + 10.0);
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return a * (1.0 - t) + b * t;
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}
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