65 lines
1.6 KiB
C++
65 lines
1.6 KiB
C++
/*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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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_d)) * 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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