darwin.util.image.AmbientOcclusionOp Maven / Gradle / Ivy

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/*
 * Copyright (C) 2012 daniel
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see .
 */
package darwin.util.image;

import java.awt.*;
import java.awt.image.BufferedImage;

import darwin.util.math.base.tupel.Tupel2;
import darwin.util.math.base.vector.*;

import static java.lang.Math.*;

/**
 *
 * @author daniel
 */
public class AmbientOcclusionOp {

    private final Tupel2[] samplePositions;

    public AmbientOcclusionOp(int sampleCount, int sampleOffset,
                              int sampleRadius) {
        samplePositions = new Tupel2[sampleCount];

        for (int i = 1; i < sampleCount + 1; i++) {
            float s = i / (float) sampleCount;
            double a = sqrt(s * sampleCount * sampleOffset);
            double b = sqrt(s);
            double x = sin(a) * b;
            double y = cos(a) * b;

            samplePositions[i - 1] = new Vector2((float) x, (float) y).mul(sampleRadius);
        }
    }

    public BufferedImage filter(BufferedImage heightMap, BufferedImage normalMap) {
        BufferedImage dest = new BufferedImage(heightMap.getWidth(),
                                               heightMap.getHeight(),
                                               BufferedImage.TYPE_BYTE_GRAY);

        int[] tmp = new int[4];
        for (int x = 0; x < heightMap.getWidth(); ++x) {
            for (int y = 0; y < heightMap.getHeight(); ++y) {
                normalMap.getRaster().getPixel(x, y, tmp);
                ImmutableVector normal = new Vector3(tmp[0] / 255f * 2f - 1f,
                                                              tmp[1] / 255f * 2f - 1f,
                                                              tmp[2] / 255f).normalize();

                heightMap.getRaster().getPixel(x, y, tmp);
                ImmutableVector position = new Vector3(x, y, tmp[0]);

                int count = samplePositions.length;
                double sumOcclusion = 0;
                for (Tupel2 t : samplePositions) {
                    int sx = round(x + t.getX());
                    int sy = round(y + t.getY());

                    if (sx < 0 || sy < 0 || sx >= heightMap.getWidth()
                        || sy >= heightMap.getHeight()) {
                        --count;
                        continue;
                    }

                    heightMap.getRaster().getPixel(sx, sy, tmp);
                    Vector3 dir = new Vector3(sx, sy, tmp[0]).sub(position);
                    double lenSqrt = sqrt(dir.length());
                    double cosa = dir.normalize().dot(normal);
                    if (cosa >= 0.) {
                        sumOcclusion += cosa / lenSqrt;
                    } else {
                        sumOcclusion += (2 - cosa) / lenSqrt;
                    }
                }
                sumOcclusion /= count * 2;

                dest.getRaster().setPixel(x, y, new int[]{(int) (sumOcclusion * 255)});
            }
        }
        return dest;
    }
}