Mercurial > projects > dwt-addons

comparison dwtx/draw2d/geometry/Geometry.d @ 98:95307ad235d9

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Added Draw2d code, still work in progress
author Frank Benoit <benoit@tionex.de>
date Sun, 03 Aug 2008 00:52:14 +0200
parents
children
comparison
equal deleted inserted replaced
96:b492ba44e44d 98:95307ad235d9
1 /*******************************************************************************
2 * Copyright (c) 2005, 2008 IBM Corporation and others.
3 * All rights reserved. This program and the accompanying materials
4 * are made available under the terms of the Eclipse Public License v1.0
5 * which accompanies this distribution, and is available at
6 * http://www.eclipse.org/legal/epl-v10.html
7 *
8 * Contributors:
9 * IBM Corporation - initial API and implementation
10 * Port to the D programming language:
11 * Frank Benoit <benoit@tionex.de>
12 *******************************************************************************/
13 module dwtx.draw2d.geometry.Geometry;
14
15 import dwt.dwthelper.utils;
16
17 /**
18 * A Utilities class for geometry operations.
19 * @author Pratik Shah
20 * @since 3.1
21 */
22 public class Geometry
23 {
24
25 /**
26 * Determines whether the two line segments formed by the given coordinates intersect. If
27 * one of the two line segments starts or ends on the other line, then they are considered
28 * to be intersecting.
29 *
30 * @param ux x coordinate of starting point of line 1
31 * @param uy y coordinate of starting point of line 1
32 * @param vx x coordinate of ending point of line 1
33 * @param vy y coordinate of endpoing point of line 1
34 * @param sx x coordinate of the starting point of line 2
35 * @param sy y coordinate of the starting point of line 2
36 * @param tx x coordinate of the ending point of line 2
37 * @param ty y coordinate of the ending point of line 2
38 * @return <code>true</code> if the two line segments formed by the given coordinates
39 * cross
40 * @since 3.1
41 */
42 public static bool linesIntersect(int ux, int uy, int vx, int vy,
43 int sx, int sy, int tx, int ty) {
44 /*
45 * Given the segments: u-------v. s-------t. If s->t is inside the triangle u-v-s,
46 * then check whether the line u->u splits the line s->t.
47 */
48 /* Values are casted to long to avoid integer overflows */
49 long usX = cast(long) ux - sx;
50 long usY = cast(long) uy - sy;
51 long vsX = cast(long) vx - sx;
52 long vsY = cast(long) vy - sy;
53 long stX = cast(long) sx - tx;
54 long stY = cast(long) sy - ty;
55 if (productSign(cross(vsX, vsY, stX, stY), cross(stX, stY, usX, usY)) >= 0) {
56 long vuX = cast(long) vx - ux;
57 long vuY = cast(long) vy - uy;
58 long utX = cast(long) ux - tx;
59 long utY = cast(long) uy - ty;
60 return productSign(cross(-usX, -usY, vuX, vuY), cross(vuX, vuY, utX, utY)) <= 0;
61 }
62 return false;
63 }
64
65 private static int productSign(long x, long y) {
66 if (x is 0 || y is 0) {
67 return 0;
68 } else if (x < 0 ^ y < 0) {
69 return -1;
70 }
71 return 1;
72 }
73
74 private static long cross(long x1, long y1, long x2, long y2) {
75 return x1 * y2 - x2 * y1;
76 }
77
78 }