one.empty3.feature20220726.HoughLine Maven / Gradle / Ivy

Show more of this group Show more artifacts with this name
Show all versions of empty3-library-3d Show documentation
3D rendering engine. Plus modeling. Expected glsl textures 3d and 2d rendering
There is a newer version: 2024.5.10
/*
 * Copyright (c) 2023. Manuel Daniel Dahmen
 *
 *
 *    Copyright 2012-2023 Manuel Daniel Dahmen
 *
 *    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 one.empty3.feature20220726;

import java.awt.image.BufferedImage;

/*
 * Represents a linear line as detected by the hough transform.
 * This line is represented by an angle theta and a radius from the centre.
 *
 * @author Olly Oechsle, University of Essex, Date: 13-Mar-2008
 * @version 1.0
 */
public class HoughLine implements Comparable {

    protected double theta;
    protected double r;
    private int votes = 0;

    /*
     * Initialises the hough line
     */
    public HoughLine(double theta, double r) {
        this.theta = theta;
        this.r = r;
    }

    public HoughLine(double theta, int r, int votes) {
        this.theta = theta;
        this.r = r;
        this.votes = votes;
    }

    /*
     * Draws the line on the image of your choice with the RGB colour of your choice.
     */
    public void draw(BufferedImage image, int color) {

        int height = image.getHeight();
        int width = image.getWidth();

        // During processing h_h is doubled so that -ve r values 
        int houghHeight = (int) (Math.sqrt(2) * Math.max(height, width)) / 2;

        // Find edge points and vote in array 
        float centerX = width / 2;
        float centerY = height / 2;

        // Draw edges in output array 
        double tsin = Math.sin(theta);
        double tcos = Math.cos(theta);

        if (theta < Math.PI * 0.25 || theta > Math.PI * 0.75) {
            // Draw vertical-ish lines 
            for (int y = 0; y < height; y++) {
                int x = (int) ((((r - houghHeight) - ((y - centerY) * tsin)) / tcos) + centerX);
                if (x < width && x >= 0) {
                    image.setRGB(x, y, color);
                }
            }
        } else {
            // Draw horizontal-sh lines 
            for (int x = 0; x < width; x++) {
                int y = (int) ((((r - houghHeight) - ((x - centerX) * tcos)) / tsin) + centerY);
                if (y < height && y >= 0) {
                    image.setRGB(x, y, color);
                }
            }
        }
    }


    @Override
    public int compareTo(Object o) {
        if (o instanceof HoughLine) {
            return votes - ((HoughLine) o).votes;
        } else {
            return 0;
        }
    }
}