Oscillator.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;
import java.util.Arrays;
/**
* This generates variable frequency oscillation curves
*
* @suppress
*/
public class Oscillator {
public static String TAG = "Oscillator";
float[] mPeriod = {};
double[] mPosition = {};
double[] mArea;
public static final int SIN_WAVE = 0; // theses must line up with attributes
public static final int SQUARE_WAVE = 1;
public static final int TRIANGLE_WAVE = 2;
public static final int SAW_WAVE = 3;
public static final int REVERSE_SAW_WAVE = 4;
public static final int COS_WAVE = 5;
public static final int BOUNCE = 6;
public static final int CUSTOM = 7;
String mCustomType;
MonotonicCurveFit mCustomCurve;
int mType;
double PI2 = Math.PI * 2;
private boolean mNormalized = false;
public Oscillator() {
}
@Override
public String toString() {
return "pos =" + Arrays.toString(mPosition) + " period=" + Arrays.toString(mPeriod);
}
public void setType(int type, String customType) {
mType = type;
mCustomType = customType;
if (mCustomType != null) {
mCustomCurve = MonotonicCurveFit.buildWave(customType);
}
}
public void addPoint(double position, float period) {
int len = mPeriod.length + 1;
int j = Arrays.binarySearch(mPosition, position);
if (j < 0) {
j = -j - 1;
}
mPosition = Arrays.copyOf(mPosition, len);
mPeriod = Arrays.copyOf(mPeriod, len);
mArea = new double[len];
System.arraycopy(mPosition, j, mPosition, j + 1, len - j - 1);
mPosition[j] = position;
mPeriod[j] = period;
mNormalized = false;
}
/**
* After adding point every thing must be normalized
*/
public void normalize() {
double totalArea = 0;
double totalCount = 0;
for (int i = 0; i < mPeriod.length; i++) {
totalCount += mPeriod[i];
}
for (int i = 1; i < mPeriod.length; i++) {
float h = (mPeriod[i - 1] + mPeriod[i]) / 2;
double w = mPosition[i] - mPosition[i - 1];
totalArea = totalArea + w * h;
}
// scale periods to normalize it
for (int i = 0; i < mPeriod.length; i++) {
mPeriod[i] *= totalCount / totalArea;
}
mArea[0] = 0;
for (int i = 1; i < mPeriod.length; i++) {
float h = (mPeriod[i - 1] + mPeriod[i]) / 2;
double w = mPosition[i] - mPosition[i - 1];
mArea[i] = mArea[i - 1] + w * h;
}
mNormalized = true;
}
double getP(double time) {
if (time < 0) {
time = 0;
} else if (time > 1) {
time = 1;
}
int index = Arrays.binarySearch(mPosition, time);
double p = 0;
if (index > 0) {
p = 1;
} else if (index != 0) {
index = -index - 1;
double t = time;
double m = (mPeriod[index] - mPeriod[index - 1]) / (mPosition[index] - mPosition[index - 1]);
p = mArea[index - 1]
+ (mPeriod[index - 1] - m * mPosition[index - 1]) * (t - mPosition[index - 1])
+ m * (t * t - mPosition[index - 1] * mPosition[index - 1]) / 2;
}
return p;
}
public double getValue(double time, double phase) {
double angle = phase + getP(time); // angle is / by 360
switch (mType) {
default:
case SIN_WAVE:
return Math.sin(PI2 * (angle));
case SQUARE_WAVE:
return Math.signum(0.5 - angle % 1);
case TRIANGLE_WAVE:
return 1 - Math.abs(((angle) * 4 + 1) % 4 - 2);
case SAW_WAVE:
return ((angle * 2 + 1) % 2) - 1;
case REVERSE_SAW_WAVE:
return (1 - ((angle * 2 + 1) % 2));
case COS_WAVE:
return Math.cos(PI2 * (phase + angle));
case BOUNCE:
double x = 1 - Math.abs(((angle) * 4) % 4 - 2);
return 1 - x * x;
case CUSTOM:
return mCustomCurve.getPos(angle % 1, 0);
}
}
double getDP(double time) {
if (time <= 0) {
time = 0.00001;
} else if (time >= 1) {
time = .999999;
}
int index = Arrays.binarySearch(mPosition, time);
double p = 0;
if (index > 0) {
return 0;
}
if (index != 0) {
index = -index - 1;
double t = time;
double m = (mPeriod[index] - mPeriod[index - 1]) / (mPosition[index] - mPosition[index - 1]);
p = m * t + (mPeriod[index - 1] - m * mPosition[index - 1]);
}
return p;
}
public double getSlope(double time, double phase, double dphase) {
double angle = phase + getP(time);
double dangle_dtime = getDP(time) + dphase;
switch (mType) {
default:
case SIN_WAVE:
return PI2 * dangle_dtime * Math.cos(PI2 * angle);
case SQUARE_WAVE:
return 0;
case TRIANGLE_WAVE:
return 4 * dangle_dtime * Math.signum(((angle) * 4 + 3) % 4 - 2);
case SAW_WAVE:
return dangle_dtime * 2;
case REVERSE_SAW_WAVE:
return -dangle_dtime * 2;
case COS_WAVE:
return -PI2 * dangle_dtime * Math.sin(PI2 * angle);
case BOUNCE:
return 4 * dangle_dtime * (((angle) * 4 + 2) % 4 - 2);
case CUSTOM:
return mCustomCurve.getSlope(angle % 1, 0);
}
}
}