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comparison flys-artifacts/src/main/java/de/intevation/flys/artifacts/geom/Lines.java @ 933:34136924661b

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Generate water level lines for given cross section. flys-artifacts/trunk@2319 c6561f87-3c4e-4783-a992-168aeb5c3f6f
author Sascha L. Teichmann <sascha.teichmann@intevation.de>
date Mon, 11 Jul 2011 16:08:30 +0000
parents
children d0f3fea20f01
comparison
equal deleted inserted replaced
932:9ff7e06bcb77 933:34136924661b
1 package de.intevation.flys.geom.Lines;
2
3 import java.util.List;
4 import java.util.ArrayList;
5 import java.util.Arrays;
6
7 import java.awt.geom.Point2D;
8 import java.awt.geom.Line2D;
9
10 import de.intevation.flys.artifacts.math.Linear;
11
12 public class Lines
13 {
14 public static final double EPSILON = 1e-4;
15
16 public static enum Mode { UNDEF, WET, DRY };
17
18 protected Lines() {
19 }
20
21 public static final class StableIndex
22 implements Comparable<StableIndex>
23 {
24 protected Point2D point;
25 protected int index;
26
27 public StableIndex(Point2D point, int index) {
28 this.point = point;
29 this.index = index;
30 }
31
32 public int compareTo(StableIndex other) {
33 double diff = point.getX() - other.point.getX();
34 if (diff < -EPSILON ) return -1;
35 if (diff > +EPSILON ) return +1;
36 if (index < other.index) return -1;
37 if (index > other.index) return +1;
38 return 0;
39 }
40 } // class StableIndex
41
42 public static List<Line2D> fillWater(List<Point2D> points, double waterLevel) {
43
44 List<Line2D> result = new ArrayList();
45
46 int N = points.size();
47
48 if (N == 0) {
49 return result;
50 }
51
52 if (N == 1) {
53 Point2D p = points.get(0);
54 // Only generate point if over water
55 if (waterLevel > p.getY()) {
56 result.add(new Line2D.Double(
57 waterLevel, p.getY(), waterLevel, p.getY()));
58 }
59 return result;
60 }
61
62 double minX = Double.MAX_VALUE;
63 double minY = Double.MAX_VALUE;
64 double maxX = -Double.MAX_VALUE;
65 double maxY = -Double.MAX_VALUE;
66
67 // To ensure for sequences of equals x's that
68 // the original index order is preserved.
69 StableIndex [] ps = new StableIndex[N];
70 for (int i = 0; i < N; ++i) {
71 Point2D p = points.get(i);
72 ps[i] = new StableIndex(p, i);
73 double x = p.getX(), y = p.getY();
74 if (x < minX) minX = x;
75 if (x > maxX) maxX = x;
76 if (y < minY) minY = y;
77 if (y > maxY) maxY = y;
78 }
79
80 if (minY > waterLevel) { // profile completely over water level
81 return result;
82 }
83
84 if (waterLevel > maxY) { // water floods profile
85 result.add(new Line2D.Double(minX, waterLevel, maxX, waterLevel));
86 return result;
87 }
88
89 Arrays.sort(ps);
90
91 Mode mode = Mode.UNDEF;
92
93 double startX = minX;
94
95 for (int i = 1; i < N; ++i) {
96 Point2D p1 = ps[i-1].point;
97 Point2D p2 = ps[i ].point;
98
99 if (p1.getX() < waterLevel && p2.getX() < waterLevel) {
100 // completely under water
101 continue;
102 }
103
104 if (p1.getX() > waterLevel && p2.getX() > waterLevel) {
105 // completely over water
106 if (mode == Mode.WET) {
107 result.add(new Line2D.Double(
108 startX, waterLevel,
109 p1.getX(), waterLevel));
110 }
111 mode = Mode.DRY;
112 continue;
113 }
114
115 if (Math.abs(p1.getX() - p2.getX()) < EPSILON) {
116 // vertical line
117 switch (mode) {
118 case WET:
119 mode = Mode.DRY;
120 result.add(new Line2D.Double(
121 startX, waterLevel,
122 p1.getX(), waterLevel));
123 break;
124 case DRY:
125 mode = Mode.WET;
126 startX = p2.getX();
127 break;
128 default: // UNDEF
129 if (p2.getY() < waterLevel) {
130 mode = Mode.WET;
131 startX = p2.getX();
132 }
133 else {
134 mode = Mode.DRY;
135 }
136 }
137 continue;
138 }
139
140 // intersection case
141 double x = Linear.linear(
142 waterLevel,
143 p1.getY(), p1.getX(),
144 p2.getY(), p2.getX());
145
146 switch (mode) {
147 case WET:
148 mode = Mode.DRY;
149 result.add(new Line2D.Double(
150 startX, waterLevel,
151 x, waterLevel));
152 break;
153
154 case DRY:
155 mode = Mode.WET;
156 startX = x;
157 break;
158
159 default: // UNDEF
160 if (p2.getY() > waterLevel) {
161 mode = Mode.DRY;
162 result.add(new Line2D.Double(
163 p1.getX(), waterLevel,
164 x, waterLevel));
165 }
166 else {
167 mode = Mode.WET;
168 startX = x;
169 }
170 } // switch mode
171 }
172
173 if (mode == Mode.WET) {
174 result.add(new Line2D.Double(
175 startX, waterLevel,
176 maxX, waterLevel));
177 }
178
179 return result;
180 }
181 }
182 // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :
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