Mercurial > projects > doodle
annotate doodle/tk/geometry.d @ 79:535bae7a7305
Checkpoint
author | "David Bryant <bagnose@gmail.com>" |
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date | Sun, 15 Aug 2010 23:18:05 +0930 |
parents | 024a5608087f |
children | a274d16ab6ce |
rev | line source |
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1 module doodle.tk.geometry; |
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2 |
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3 private { |
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4 import std.stdio; |
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5 import std.math; |
67 | 6 import doodle.core.misc; |
41 | 7 import doodle.core.logging; |
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8 } |
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9 |
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10 // In doodle x and y increase right/east and up/north respectively. |
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11 |
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12 // TODO explain the strategy for ensuring numerical stability |
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13 // and the division of responsibility between users of these |
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14 // types and the types themselves. |
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15 // |
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16 // Explain how numerical instability is handled. The current policy |
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17 // is to correct bad user input (eg a gradient with miniscule length) and |
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18 // print warnings rather than have assertions that cause crashes. |
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19 // |
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20 // There are no mutating operations other than opAssign |
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21 |
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22 // |
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23 // A location in 2D space |
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24 // |
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25 |
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26 struct Point { |
51 | 27 static immutable Point DEFAULT = Point(0.0, 0.0); |
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28 |
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29 this(in double x, in double y) { |
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30 _x = x; |
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31 _y = y; |
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32 } |
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33 |
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34 Point opAdd(in Vector v) const { |
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35 return Point(_x + v._x, _y + v._y); |
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36 } |
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37 |
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38 Point opSub(in Vector v) const { |
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39 return Point(_x - v._x, _y - v._y); |
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40 } |
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41 |
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42 Vector opSub(in Point p) const { |
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43 return Vector(_x - p._x, _y - p._y); |
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44 } |
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45 |
62 | 46 string toString() { |
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47 return std.string.format("(%f, %f)", _x, _y); |
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48 } |
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49 |
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50 double x() const { return _x; } |
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51 double y() const { return _y; } |
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52 |
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53 private { |
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54 double _x, _y; |
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55 } |
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56 } |
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57 |
48 | 58 Point minExtents(in Point a, in Point b) { |
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59 return Point(min(a.x, b.x), min(a.y, b.y)); |
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60 } |
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61 |
48 | 62 Point maxExtents(in Point a, in Point b) { |
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63 return Point(max(a.x, b.x), max(a.y, b.y)); |
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64 } |
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65 |
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66 // |
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67 // The displacement between two locations in 2D space |
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68 // |
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69 |
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70 struct Vector { |
51 | 71 static Vector DEFAULT = Vector(0.0, 0.0); |
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72 |
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73 this(in double x, in double y) { |
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74 _x = x; |
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75 _y = y; |
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76 } |
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77 |
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78 Vector opAdd(in Vector v) const { |
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79 return Vector(_x + v._x, _y + v._y); |
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80 } |
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81 |
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82 Vector opSub(in Vector v) const { |
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83 return Vector(_x - v._x, _y - v._y); |
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84 } |
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85 |
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86 Vector opNeg() const { |
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87 return Vector(-_x, -_y); |
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88 } |
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89 |
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90 Vector opMul_r(in double d) const { |
41 | 91 assert(!isnan(d)); |
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92 return Vector(d * _x, d * _y); |
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93 } |
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94 |
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95 Vector opDiv(in double d) const { |
41 | 96 assert(!isnan(d)); |
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97 return Vector(_x / d, _y / d); |
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98 } |
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99 |
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100 double length() const { |
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101 return sqrt(_x * _x + _y * _y); |
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102 } |
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103 |
62 | 104 string toString() { |
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105 return std.string.format("[%f, %f]", _x, _y); |
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106 } |
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107 |
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108 double x() const { return _x; } |
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109 double y() const { return _y; } |
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110 |
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111 private { |
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112 double _x, _y; |
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113 } |
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114 } |
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115 |
79 | 116 /* |
117 Vector normal(in Vector v) { | |
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118 double l = v.length; |
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119 |
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120 if (l < 1e-9) { // TODO consolidate numerical stability constants |
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121 writefln("Warning: normalising tiny vector. Length: %f", l); |
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122 return Vector(1.0, 0.0); |
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123 } |
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124 else { |
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125 return v / l; |
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126 } |
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127 } |
79 | 128 */ |
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129 |
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130 // |
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131 // A rectangle in 2D space. |
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132 // Internally represented by: |
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133 // a point defining the bottom left corner |
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134 // a vector defining the displacement to the upper right corner |
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135 // |
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136 |
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137 struct Rectangle { |
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138 static Rectangle DEFAULT; |
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139 |
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140 static this() { |
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141 DEFAULT = Rectangle(Point.DEFAULT, Vector.DEFAULT); |
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142 } |
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143 |
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144 /* |
66 | 145 static Rectangle from_arbitrary_corners(in Point corner1, in Point corner) { |
146 } | |
147 */ | |
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148 |
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149 this(in Point position, in Vector size) { |
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150 this(position.x, position.y, size.x, size.y); |
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151 } |
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152 |
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153 this(in Point corner1, in Point corner) { |
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154 this(corner1.x, corner1.y, corner.x - corner1.x, corner.y - corner1.y); |
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155 } |
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156 |
79 | 157 double x0() const { return _position.x; } |
158 double y0() const { return _position.y; } | |
159 double w() const { return _size.x; } | |
160 double h() const { return _size.y; } | |
161 double x1() const { return x0 + w; } | |
162 double y1() const { return y0 + h; } | |
70 | 163 |
164 alias position corner0; | |
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165 Point position() const { return _position; } |
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166 |
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167 Vector size() const { return _size; } |
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168 |
70 | 169 Point corner1() const { return _position + _size; } |
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170 |
41 | 171 bool valid() const { return _size.x > 0.0 && _size.y > 0.0; } |
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172 |
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173 bool invalid() const { return !valid(); } |
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174 |
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175 double area() const { return _size.x * _size.y; } |
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176 |
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177 // Intersection |
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178 Rectangle opAnd(in Rectangle r) const { |
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179 if (invalid() || r.invalid()) { |
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180 return DEFAULT; |
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181 } |
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182 else { |
70 | 183 Point max = minExtents(corner1(), r.corner1()); |
184 Point min = maxExtents(corner0(), r.corner0()); | |
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185 |
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186 if (max.x < min.x || max.y < min.y) { |
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187 return DEFAULT; |
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188 } |
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189 else { |
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190 return Rectangle(min, max); |
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191 } |
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192 } |
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193 } |
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194 |
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195 // Union |
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196 Rectangle opOr(in Rectangle r) const { |
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197 if (invalid()) { |
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198 return r; |
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199 } |
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200 else if (r.invalid()) { |
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201 return this; |
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202 } |
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203 else { |
70 | 204 return Rectangle(minExtents(corner0(), r.corner0()), |
205 maxExtents(corner1(), r.corner1())); | |
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206 } |
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207 } |
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208 |
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209 // |
15 | 210 |
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211 // FIXME this method is all about pixels. Not sure it belongs in |
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212 // this file, let alone this class. |
48 | 213 void getQuantised(out int x, out int y, out int w, out int h) const { |
17 | 214 x = cast(int)floor(_position.x); |
215 y = cast(int)floor(_position.y); | |
216 w = cast(int)ceil(_position.x + _size.x) - x; | |
217 h = cast(int)ceil(_position.y + _size.y) - y; | |
218 } | |
219 | |
220 // | |
221 | |
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222 Point centre() const { return _position + _size / 2.0; } |
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223 |
62 | 224 string toString() { |
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225 return std.string.format("{%s, %s}", _position, _size); |
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226 } |
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227 |
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228 private { |
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229 this(double x, double y, double w, double h) { |
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230 if (w < 0.0) { x += w; w = -w; } |
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231 if (h < 0.0) { y += h; h = -h; } |
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232 _position = Point(x, y); |
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233 _size = Vector(w, h); |
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234 } |
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235 |
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236 Point _position; |
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237 Vector _size; |
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238 } |
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239 } |
25 | 240 |
79 | 241 Rectangle growCentre(in Rectangle r, in Vector amount) { |
242 return Rectangle(r.x0 - amount.x / 2, r.y0 - amount.y / 2, r.w + amount.x, r.h + amount.y); | |
243 } | |
244 | |
245 Rectangle growCentre(in Rectangle r, in double amount) { | |
246 return Rectangle(r.x0 - amount / 2, r.y0 - amount / 2, r.w + amount, r.h + amount); | |
247 } | |
248 | |
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249 // TODO review these functions. |
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250 // Want a clear and simple set. |
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251 |
79 | 252 /+ |
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253 Rectangle move(in Rectangle r, in Vector displacement) { |
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254 return Rectangle(r.position + displacement, r.size); |
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255 } |
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256 |
66 | 257 Rectangle reposition(in Rectangle r, in Point newPosition) { |
258 return Rectangle(newPosition, r.size); | |
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259 } |
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260 |
41 | 261 Rectangle resize(in Rectangle r, in Vector new_size) { |
262 return Rectangle(r.position, new_size); | |
263 } | |
264 | |
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265 // Operations about the bottom left corner |
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266 |
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267 Rectangle expand(in Rectangle r, in Vector expand_amount) { |
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268 return Rectangle(r.position, r.size + expand_amount); |
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269 } |
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270 |
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271 Rectangle shrink(in Rectangle r, in Vector shrink_amount) { |
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272 return Rectangle(r.position, r.size - shrink_amount); |
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273 } |
79 | 274 +/ |
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275 |
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276 // Operations about the centre |
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277 |
79 | 278 /+ |
78 | 279 Rectangle feather(in Rectangle r, double amount) { // feather isn't the right name |
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280 assert(amount >= 0.0); |
41 | 281 assert(!isnan(amount)); |
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282 return Rectangle(Point(r.position.x - amount, r.position.y - amount), |
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283 Vector(r.size.x + 2.0 * amount, r.size.y + 2.0 * amount)); |
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284 } |
79 | 285 +/ |
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286 |
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287 private { |
41 | 288 // This function computes the intersection of two lines. |
289 // The lines are defined by a start point and an end point, however they | |
290 // notionally extend infinitely in each direction. | |
291 // The out parameters specify the fraction along the line-segment at which | |
292 // intersection occurred. | |
293 // | |
294 // This is a commmon building block for computing intersection between lines, segments, | |
295 // rectangles, etc. | |
296 // | |
297 // The function returns false if the lines are parallel or nearly so. | |
298 // | |
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299 // Influenced by http://ozviz.wasp.uwa.edu.au/~pbourke/geometry/lineline2d/ |
48 | 300 bool computeIntersection(in Point pa1, in Point pa2, out double ua, |
66 | 301 in Point pb1, in Point pb2, out double ub) { |
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302 double den = (pb2.y - pb1.y) * (pa2.x - pa1.x) - (pb2.x - pb1.x) * (pa2.y - pa1.y); |
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303 |
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304 if (abs(den) < 1e-9) { // TODO consolidate constants used for numerical stability |
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305 // Lines are parallel or nearly so |
41 | 306 warning("Warning, parallel lines!"); |
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307 return false; |
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308 } |
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309 else { |
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310 // It will be safe to divide by den |
66 | 311 double numA = (pb2.x - pb1.x) * (pa1.y - pb1.y) - (pb2.y - pb1.y) * (pa1.x - pb1.x); |
312 double numB = (pa2.x - pa1.x) * (pa1.y - pb1.y) - (pa2.y - pa1.y) * (pa1.x - pb1.x); | |
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313 |
66 | 314 ua = numA / den; |
315 ub = numB / den; | |
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316 |
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317 return true; |
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318 } |
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319 } |
41 | 320 |
321 /+ | |
66 | 322 double compute_angle(in Point p1, in Point p2) { |
323 } | |
41 | 324 +/ |
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325 } |
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326 |
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327 // |
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328 // A line (notionally infinitely extending in both directions) in 2D space. |
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329 // Internally represented by: |
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330 // a point at an arbitrary location along the line |
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331 // a vector defining the gradient of the line |
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332 // |
33
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333 |
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334 struct Line { |
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335 this(in Point p, in Vector g) { |
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336 _point = p; |
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337 _gradient = g; |
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338 // FIXME should we normalise (make unit length) the gradient? |
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339 assert(_gradient.length > 1e-6); // FIXME how to best deal with this |
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340 } |
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341 |
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342 this(in Point a, in Point b) { |
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343 _point = a; |
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344 _gradient = b - a; |
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345 assert(_gradient.length > 1e-6); // FIXME as above |
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346 } |
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347 |
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348 Point point() const { return _point; } |
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349 Vector gradient() const { return _gradient; } |
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350 |
62 | 351 string toString() { |
34
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352 return std.string.format("{%s %s}", _point, _gradient); |
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353 } |
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354 |
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355 private { |
51 | 356 Point _point; // Arbitrary point along line |
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357 Vector _gradient; |
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358 } |
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359 } |
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360 |
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361 // Calculate the point "p" where lines "a" and "b" intersect. |
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362 // Returns false if lines are parallel or too close for numerical stability |
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363 bool intersection(in Line a, in Line b, out Point p) { |
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364 Point pa = a.point; |
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365 Vector va = a.gradient; |
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366 double ua; |
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367 |
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368 Point pb = b.point; |
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369 Vector vb = b.gradient; |
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370 double ub; |
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371 |
48 | 372 if (computeIntersection(pa, pa + va, ua, pb, pb + vb, ub)) { |
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373 // We could just have easily evaluated for line b... |
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374 p = pa + ua * va; |
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375 // p = pb + ub * vb; |
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376 return true; |
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377 } |
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378 else { |
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379 return false; |
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380 } |
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381 } |
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382 |
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383 // |
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384 // A line segment (has a beginning and an end) in 2D space. |
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385 // |
33
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386 |
25 | 387 struct Segment { |
33
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388 this(in Point a, in Point b) { |
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389 _begin = a; |
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390 _end = b; |
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391 } |
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392 |
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393 Point begin() const { return _begin; } |
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394 Point end() const { return _end; } |
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395 |
62 | 396 string toString() { |
34
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397 return std.string.format("{%s %s}", _begin, _end); |
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398 } |
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399 |
25 | 400 private { |
401 Point _begin, _end; | |
402 } | |
403 } | |
404 | |
79 | 405 /* |
34
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406 Segment reverse(in Segment s) { |
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407 return Segment(s.end, s.begin); |
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408 } |
79 | 409 */ |
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410 |
33
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411 bool intersection(in Segment a, in Segment b, out Point p) { |
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412 Point pa1 = a.begin; |
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413 Point pa2 = a.end; |
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414 double ua; |
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415 |
33
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416 Point pb1 = b.begin; |
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417 Point pb2 = b.end; |
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418 double ub; |
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419 |
48 | 420 if (computeIntersection(pa1, pa2, ua, pb1, pb2, ub)) { |
33
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421 if (ua >= 0.0 && ua <= 1.0 && // inside of segment a |
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422 ub >= 0.0 && ub <= 1.0) { // inside of segment b |
67 | 423 // We could just as easily evaluated for line b... |
33
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424 p = pa1 + ua * (pa2 - pa1); |
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425 // p = pa2 + ub * (pb2 - pb1); |
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426 return true; |
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427 } |
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428 else { |
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429 return false; |
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|
430 } |
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|
431 } |
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432 else { |
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433 return false; |
25 | 434 } |
435 } | |
34
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436 |
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437 bool intersection(in Segment a, in Line b, out Point p) { |
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438 Point pa1 = a.begin; |
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439 Point pa2 = a.end; |
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440 double ua; |
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|
441 |
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442 Point pb = b.point; |
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443 Vector vb = b.gradient; |
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444 double ub; |
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445 |
48 | 446 if (computeIntersection(pa1, pa2, ua, pb, pb + vb, ub)) { |
34
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447 if (ua >= 0.0 && ua <= 1.0) { // inside of segment |
67 | 448 // We could just as easily evaluated for line b... |
34
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449 p = pa1 + ua * (pa2 - pa1); |
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450 // p = pb + ub * vb; |
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451 return true; |
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452 } |
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453 else { |
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454 return false; |
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Geometry cleanup and checkpoint.
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455 } |
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456 } |
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457 else { |
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458 return false; |
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|
459 } |
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|
460 } |
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|
461 |
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|
462 bool intersection(in Line a, in Segment b, out Point p) { |
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463 // Equivalent to intersection of segment and line. Just reverse the args. |
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464 return intersection(b, a, p); |
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|
465 } |
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|
466 |
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|
467 /+ |
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468 bool intersection(in Line l, in Rectangle r, out Point p1, out Point p2) { |
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469 // TODO |
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470 return false; |
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|
471 } |
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|
472 |
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473 bool intersection(in Segment s, in Rectangle r, out Point p1, out Point p2) { |
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|
474 // TODO |
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475 return false; |
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|
476 } |
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|
477 +/ |