org.joml.sampling.StratifiedSampling Maven / Gradle / Ivy
/*
* The MIT License
*
* Copyright (c) 2016-2020 JOML
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package org.joml.sampling;
import org.joml.Random;
/**
* Creates samples on a unit quad using an NxN strata grid.
*
* @author Kai Burjack
*/
public class StratifiedSampling {
private final Random rnd;
/**
* Create a new instance of {@link StratifiedSampling} and initialize the random number generator with the given
* seed.
*
* @param seed
* the seed to initialize the random number generator with
*/
public StratifiedSampling(long seed) {
this.rnd = new Random(seed);
}
/**
* Generate n * n random sample positions in the unit square of x, y = [-1..+1].
*
* Each sample within its stratum is distributed randomly.
*
* @param n
* the number of strata in each dimension
* @param callback
* will be called for each generated sample position
*/
public void generateRandom(int n, Callback2d callback) {
for (int y = 0; y < n; y++) {
for (int x = 0; x < n; x++) {
float sampleX = (rnd.nextFloat() / n + (float) x / n) * 2.0f - 1.0f;
float sampleY = (rnd.nextFloat() / n + (float) y / n) * 2.0f - 1.0f;
callback.onNewSample(sampleX, sampleY);
}
}
}
/**
* Generate n * n random sample positions in the unit square of x, y = [-1..+1].
*
* Each sample within its stratum is confined to be within [-centering/2..1-centering] of its stratum.
*
* @param n
* the number of strata in each dimension
* @param centering
* determines how much the random samples in each stratum are confined to be near the center of the
* stratum. Possible values are [0..1]
* @param callback
* will be called for each generated sample position
*/
public void generateCentered(int n, float centering, Callback2d callback) {
float start = centering * 0.5f;
float end = 1.0f - centering;
for (int y = 0; y < n; y++) {
for (int x = 0; x < n; x++) {
float sampleX = ((start + rnd.nextFloat() * end) / n + (float) x / n) * 2.0f - 1.0f;
float sampleY = ((start + rnd.nextFloat() * end) / n + (float) y / n) * 2.0f - 1.0f;
callback.onNewSample(sampleX, sampleY);
}
}
}
}