001/* ===========================================================
002 * Orson Charts : a 3D chart library for the Java(tm) platform
003 * ===========================================================
004 * 
005 * (C)opyright 2013-2016, by Object Refinery Limited.  All rights reserved.
006 * 
007 * http://www.object-refinery.com/orsoncharts/index.html
008 * 
009 * This program is free software: you can redistribute it and/or modify
010 * it under the terms of the GNU General Public License as published by
011 * the Free Software Foundation, either version 3 of the License, or
012 * (at your option) any later version.
013 *
014 * This program is distributed in the hope that it will be useful,
015 * but WITHOUT ANY WARRANTY; without even the implied warranty of
016 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
017 * GNU General Public License for more details.
018 *
019 * You should have received a copy of the GNU General Public License
020 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
021 * 
022 * [Oracle and Java are registered trademarks of Oracle and/or its affiliates. 
023 * Other names may be trademarks of their respective owners.]
024 * 
025 * If you do not wish to be bound by the terms of the GPL, an alternative
026 * commercial license can be purchased.  For details, please see visit the
027 * Orson Charts home page:
028 * 
029 * http://www.object-refinery.com/orsoncharts/index.html
030 * 
031 */
032
033package com.orsoncharts.graphics3d;
034
035import java.awt.Dimension;
036import java.awt.geom.Line2D;
037import java.awt.geom.Point2D;
038
039/**
040 * A collection of utility methods for 2D geometry.
041 */
042public class Utils2D {
043    
044    private Utils2D() {
045        // no need to instantiate
046    }
047    
048    /**
049     * Returns {@code true} if the specified value is spanned by the
050     * two bounds, and {@code false} otherwise.
051     * 
052     * @param value  the value.
053     * @param bound1  the first boundary.
054     * @param bound2  the second boundary.
055     * 
056     * @return A boolean. 
057     */
058    public static boolean spans(double value, double bound1, double bound2) {
059        return (bound1 < value && bound2 > value)
060                || (bound1 > value && bound2 < value);
061    }
062
063    /**
064     * Calculates twice the area of a triangle for points specified in 
065     * counter-clockwise order (if the points are specified in clockwise order
066     * the result will be negative).
067     * 
068     * @param a  the first point ({@code null} not permitted).
069     * @param b  the second point ({@code null} not permitted).
070     * @param c  the third point ({@code null} not permitted).
071     * 
072     * @return The area x 2.
073     */
074    public static double area2(Point2D a, Point2D b, Point2D c) {
075        double ax = a.getX();
076        double ay = a.getY();
077        double bx = b.getX();
078        double by = b.getY();
079        double cx = c.getX();
080        double cy = c.getY();
081        return (ax - cx) * (by - cy) - (ay - cy) * (bx - cx);
082    }
083    
084    /**
085     * Returns the point in the center of the four supplied points.
086     * 
087     * @param pt0  point 0 ({@code null} not permitted).
088     * @param pt1  point 1 ({@code null} not permitted).
089     * @param pt2  point 2 ({@code null} not permitted).
090     * @param pt3  point 3 ({@code null} not permitted).
091     * 
092     * @return  The center point (never {@code null}).
093     */
094    public static Point2D centerPoint(Point2D pt0, Point2D pt1, Point2D pt2, 
095            Point2D pt3) {
096        float x = (float) ((pt0.getX() + pt1.getX() + pt2.getX() + pt3.getX()) 
097                / 4.0);
098        float y = (float) ((pt0.getY() + pt1.getY() + pt2.getY() + pt3.getY()) 
099                / 4.0);
100        return new Point2D.Float(x, y);
101    }
102
103    /**
104     * Returns the dimensions of the smallest rectangle that could contain
105     * the supplied points.
106     * 
107     * @param pts  an array of points ({@code null} not permitted).
108     * 
109     * @return The dimensions.
110     */
111    public static Dimension findDimension(Point2D[] pts) {
112        double minx = Double.POSITIVE_INFINITY;
113        double maxx = Double.NEGATIVE_INFINITY;
114        double miny = Double.POSITIVE_INFINITY;
115        double maxy = Double.NEGATIVE_INFINITY;
116        for (Point2D pt : pts) {
117            minx = Math.min(minx, pt.getX());
118            maxx = Math.max(maxx, pt.getX());
119            miny = Math.min(miny, pt.getY());
120            maxy = Math.max(maxy, pt.getY());
121        }
122        return new Dimension((int) (maxx - minx), (int) (maxy - miny));
123    }
124  
125    /**
126     * Creates and returns a line that is perpendicular to the specified line.
127     *
128     * @param line  the reference line ({@code null} not permitted).
129     * @param b  the base point, expressed as a percentage along the length of 
130     *     the reference line.
131     * @param size  the size or length of the perpendicular line.
132     * @param opposingPoint  an opposing point, to define which side of the 
133     *     reference line the perpendicular line will extend ({@code null} 
134     *     not permitted).
135     *
136     * @return The perpendicular line.
137     */
138    public static Line2D createPerpendicularLine(Line2D line, double b, 
139            double size, Point2D opposingPoint) {
140        double dx = line.getX2() - line.getX1();
141        double dy = line.getY2() - line.getY1();
142        double length = Math.sqrt(dx * dx + dy * dy);
143        double pdx = dy / length;
144        double pdy = -dx / length;
145        int ccw = line.relativeCCW(opposingPoint);
146        Point2D pt1 = new Point2D.Double(line.getX1() + b * dx, 
147                line.getY1() + b * dy);
148        Point2D pt2 = new Point2D.Double(pt1.getX() - ccw * size * pdx, 
149                pt1.getY() - ccw * size * pdy);
150        return new Line2D.Double(pt1, pt2);
151    }
152    
153    /**
154     * Creates and returns a line that is perpendicular to the specified 
155     * line.
156     * 
157     * @param line  the reference line ({@code null} not permitted).
158     * @param pt1  a point on the reference line ({@code null} not 
159     *     permitted).
160     * @param size  the length of the new line.
161     * @param opposingPoint  an opposing point, to define which side of the 
162     *     reference line the perpendicular line will extend ({@code null} 
163     *     not permitted).
164     * 
165     * @return The perpendicular line. 
166     */
167    public static Line2D createPerpendicularLine(Line2D line, Point2D pt1, 
168            double size, Point2D opposingPoint) {
169        double dx = line.getX2() - line.getX1();
170        double dy = line.getY2() - line.getY1();
171        double length = Math.sqrt(dx * dx + dy * dy);
172        double pdx = dy / length;
173        double pdy = -dx / length;
174        int ccw = line.relativeCCW(opposingPoint);
175        Point2D pt2 = new Point2D.Double(pt1.getX() - ccw * size * pdx, 
176                pt1.getY() - ccw * size * pdy);
177        return new Line2D.Double(pt1, pt2);
178    }
179  
180    /**
181     * Returns the angle of rotation (in radians) for the specified line.
182     * 
183     * @param line  the line ({@code null} not permitted).
184     * 
185     * @return The angle of rotation (in radians). 
186     */
187    public static double calculateTheta(Line2D line) {
188        double dx = line.getX2() - line.getX1();
189        double dy = line.getY2() - line.getY1();
190        return Math.atan2(dy, dx);
191    }
192    
193    /**
194     * Returns the length of the line.
195     * 
196     * @param line  the line ({@code null} not permitted).
197     * 
198     * @return The length of the line.
199     */
200    public static double length(Line2D line) {
201        double dx = line.getX2() - line.getX1();
202        double dy = line.getY2() - line.getY1();
203        return Math.sqrt(dx * dx + dy * dy);
204    }
205
206}