Schlick.java
/*
* Copyright (C) 2020 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package androidx.constraintlayout.core.motion.utils;
/**
* Schlick’s bias and gain functions
* curve for use in an easing function including quantize functions
*
*/
public class Schlick extends Easing {
private final static boolean DEBUG = false;
double mS, mT;
double eps;
Schlick(String configString) {
// done this way for efficiency
str = configString;
int start = configString.indexOf('(');
int off1 = configString.indexOf(',', start);
mS = Double.parseDouble(configString.substring(start + 1, off1).trim());
int off2 = configString.indexOf(',', off1 + 1);
mT = Double.parseDouble(configString.substring(off1 + 1, off2).trim());
}
private double func(double x) {
if (x < mT) {
return mT * x / (x + mS * (mT - x));
}
return ((1 - mT) * (x - 1)) / (1 - x - mS * (mT - x));
}
private double dfunc(double x) {
if (x < mT) {
return (mS * mT * mT) / ((mS * (mT - x) + x) * (mS * (mT - x) + x));
}
return (mS * (mT - 1) * (mT - 1)) / ((-mS * (mT - x) - x + 1) * (-mS * (mT - x) - x + 1));
}
public double getDiff(double x) {
return dfunc(x);
}
public double get(double x) {
return func(x);
}
}