1 | // |
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2 | // ******************************************************************** |
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3 | // * License and Disclaimer * |
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8 | // * LICENSE and available at http://cern.ch/geant4/license . These * |
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9 | // * include a list of copyright holders. * |
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10 | // * * |
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11 | // * Neither the authors of this software system, nor their employing * |
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12 | // * institutes,nor the agencies providing financial support for this * |
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13 | // * work make any representation or warranty, express or implied, * |
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14 | // * regarding this software system or assume any liability for its * |
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15 | // * use. Please see the license in the file LICENSE and URL above * |
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16 | // * for the full disclaimer and the limitation of liability. * |
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17 | // * * |
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18 | // * This code implementation is the result of the scientific and * |
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19 | // * technical work of the GEANT4 collaboration and of QinetiQ Ltd, * |
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20 | // * By using, copying, modifying or distributing the software (or * |
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21 | // * any work based on the software) you agree to acknowledge its * |
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22 | // * use in resulting scientific publications, and indicate your * |
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23 | // * acceptance of all terms of the Geant4 Software license. * |
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24 | // ******************************************************************** |
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25 | // |
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26 | // $Id: G4TessellatedGeometryAlgorithms.cc,v 1.5 2007/12/12 16:51:12 gcosmo Exp $ |
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27 | // GEANT4 tag $Name: HEAD $ |
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28 | // |
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29 | // %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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30 | // |
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31 | // MODULE: G4TessellatedGeometryAlgorithms.cc |
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32 | // |
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33 | // Date: 07/08/2005 |
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34 | // Author: Rickard Holmberg & Pete Truscott |
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35 | // Organisation: QinetiQ Ltd, UK (PT) |
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36 | // Customer: ESA-ESTEC / TEC-EES |
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37 | // Contract: |
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38 | // |
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39 | // %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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40 | // |
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41 | // CHANGE HISTORY |
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42 | // -------------- |
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43 | // |
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44 | // 07 August 2007, P R Truscott, QinetiQ Ltd, UK - Created, with member |
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45 | // functions based on the work of Rickard Holmberg. |
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46 | // |
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47 | // 26 September 2007 |
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48 | // P R Truscott, qinetiQ Ltd, UK |
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49 | // Updated to assign values of location array, not update |
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50 | // just the pointer. |
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51 | // |
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52 | /////////////////////////////////////////////////////////////////////////////// |
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53 | |
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54 | #include "G4TessellatedGeometryAlgorithms.hh" |
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55 | /////////////////////////////////////////////////////////////////////////////// |
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56 | // |
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57 | // Pointer to single instance of class. |
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58 | // |
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59 | G4TessellatedGeometryAlgorithms* G4TessellatedGeometryAlgorithms::fInstance = 0; |
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60 | |
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61 | /////////////////////////////////////////////////////////////////////////////// |
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62 | // |
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63 | // G4TessellatedGeometryAlgorithms |
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64 | // |
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65 | // Constructor doesn't need to do anything since this class just allows access |
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66 | // to the geometric algorithms contained in member functions. |
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67 | // |
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68 | G4TessellatedGeometryAlgorithms::G4TessellatedGeometryAlgorithms () |
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69 | { |
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70 | } |
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71 | |
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72 | /////////////////////////////////////////////////////////////////////////////// |
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73 | // |
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74 | // GetInstance |
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75 | // |
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76 | // This is the access point for this singleton. |
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77 | // |
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78 | G4TessellatedGeometryAlgorithms* G4TessellatedGeometryAlgorithms::GetInstance() |
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79 | { |
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80 | static G4TessellatedGeometryAlgorithms worldStdGeom; |
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81 | if (!fInstance) |
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82 | { |
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83 | fInstance = &worldStdGeom; |
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84 | } |
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85 | return fInstance; |
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86 | } |
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87 | |
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88 | /////////////////////////////////////////////////////////////////////////////// |
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89 | // |
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90 | // IntersectLineAndTriangle2D |
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91 | // |
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92 | // Determines whether there is an intersection between a line defined |
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93 | // by r = p + s.v and a triangle defined by verticies P0, P0+E0 and P0+E1. |
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94 | // |
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95 | // Here: |
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96 | // p = 2D vector |
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97 | // s = scaler on [0,infinity) |
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98 | // v = 2D vector |
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99 | // P0, E0 and E1 are 2D vectors |
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100 | // Information about where the intersection occurs is returned in the |
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101 | // variable location. |
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102 | // |
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103 | // This is based on the work of Rickard Holmberg. |
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104 | // |
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105 | G4bool G4TessellatedGeometryAlgorithms::IntersectLineAndTriangle2D ( |
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106 | const G4TwoVector p, const G4TwoVector v, |
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107 | const G4TwoVector P0, const G4TwoVector E0, const G4TwoVector E1, |
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108 | G4TwoVector location[2]) |
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109 | { |
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110 | G4TwoVector loc0[2]; |
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111 | G4int e0i = IntersectLineAndLineSegment2D (p,v,P0,E0,loc0); |
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112 | if (e0i == 2) |
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113 | { |
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114 | location[0] = loc0[0]; |
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115 | location[1] = loc0[1]; |
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116 | return true; |
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117 | } |
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118 | |
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119 | G4TwoVector loc1[2]; |
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120 | G4int e1i = IntersectLineAndLineSegment2D (p,v,P0,E1,loc1); |
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121 | if (e1i == 2) |
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122 | { |
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123 | location[0] = loc1[0]; |
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124 | location[1] = loc1[1]; |
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125 | return true; |
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126 | } |
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127 | |
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128 | if ((e0i == 1) && (e1i == 1)) |
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129 | { |
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130 | if ((loc0[0]-p).mag2() < (loc1[0]-p).mag2()) |
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131 | { |
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132 | location[0] = loc0[0]; |
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133 | location[1] = loc1[0]; |
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134 | } |
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135 | else |
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136 | { |
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137 | location[0] = loc1[0]; |
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138 | location[1] = loc0[0]; |
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139 | } |
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140 | return true; |
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141 | } |
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142 | |
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143 | G4TwoVector P1 = P0 + E0; |
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144 | G4TwoVector DE = E1 - E0; |
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145 | G4TwoVector loc2[2]; |
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146 | G4int e2i = IntersectLineAndLineSegment2D (p,v,P1,DE,loc2); |
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147 | if (e2i == 2) |
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148 | { |
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149 | location[0] = loc2[0]; |
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150 | location[1] = loc2[1]; |
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151 | return true; |
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152 | } |
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153 | |
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154 | if ((e0i == 0) && (e1i == 0) && (e2i == 0)) { return false; } |
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155 | |
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156 | if ((e0i == 1) && (e2i == 1)) |
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157 | { |
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158 | if ((loc0[0]-p).mag2() < (loc2[0]-p).mag2()) |
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159 | { |
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160 | location[0] = loc0[0]; |
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161 | location[1] = loc2[0]; |
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162 | } |
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163 | else |
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164 | { |
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165 | location[0] = loc2[0]; |
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166 | location[1] = loc0[0]; |
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167 | } |
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168 | return true; |
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169 | } |
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170 | |
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171 | if ((e1i == 1) && (e2i == 1)) |
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172 | { |
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173 | if ((loc1[0]-p).mag2() < (loc2[0]-p).mag2()) |
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174 | { |
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175 | location[0] = loc1[0]; |
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176 | location[1] = loc2[0]; |
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177 | } |
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178 | else |
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179 | { |
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180 | location[0] = loc2[0]; |
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181 | location[1] = loc1[0]; |
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182 | } |
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183 | return true; |
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184 | } |
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185 | |
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186 | return false; |
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187 | } |
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188 | |
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189 | /////////////////////////////////////////////////////////////////////////////// |
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190 | // |
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191 | // IntersectLineAndLineSegment2D |
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192 | // |
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193 | // Determines whether there is an intersection between a line defined |
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194 | // by r = P0 + s.D0 and a line-segment with endpoints P1 and P1+D1. |
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195 | // Here: |
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196 | // P0 = 2D vector |
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197 | // s = scaler on [0,infinity) |
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198 | // D0 = 2D vector |
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199 | // P1 and D1 are 2D vectors |
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200 | // |
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201 | // This function returns: |
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202 | // 0 - if there is no intersection; |
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203 | // 1 - if there is a unique intersection; |
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204 | // 2 - if the line and line-segments overlap, and the intersection is a |
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205 | // segment itself. |
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206 | // Information about where the intersection occurs is returned in the |
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207 | // as ??. |
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208 | // |
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209 | // This is based on the work of Rickard Holmberg as well as material published |
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210 | // by Philip J Schneider and David H Eberly, "Geometric Tools for Computer |
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211 | // Graphics," ISBN 1-55860-694-0, pp 244-245, 2003. |
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212 | // |
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213 | G4int G4TessellatedGeometryAlgorithms::IntersectLineAndLineSegment2D ( |
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214 | const G4TwoVector P0, const G4TwoVector D0, |
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215 | const G4TwoVector P1, const G4TwoVector D1, |
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216 | G4TwoVector location[2]) |
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217 | { |
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218 | G4TwoVector E = P1 - P0; |
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219 | G4double kross = cross(D0,D1); |
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220 | G4double sqrKross = kross * kross; |
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221 | G4double sqrLen0 = D0.mag2(); |
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222 | G4double sqrLen1 = D1.mag2(); |
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223 | location[0] = G4TwoVector(0.0,0.0); |
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224 | location[1] = G4TwoVector(0.0,0.0); |
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225 | |
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226 | if (sqrKross > DBL_EPSILON * DBL_EPSILON * sqrLen0 * sqrLen1) |
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227 | { |
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228 | // |
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229 | // |
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230 | // The line and line segment are not parallel. Determine if the intersection |
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231 | // is in positive s where r = P0 + s*D0, and for 0<=t<=1 where r = p1 + t*D1. |
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232 | // |
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233 | G4double s = cross(E,D1)/kross; |
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234 | if (s < 0) return 0; // Intersection does not occur for positive s. |
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235 | G4double t = cross(E,D0)/kross; |
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236 | if (t < 0 || t > 1) return 0; // Intersection does not occur on line-segment. |
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237 | // |
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238 | // |
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239 | // Intersection of lines is a single point on the forward-propagating line |
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240 | // defined by r = P0 + s*D0, and the line segment defined by r = p1 + t*D1. |
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241 | // |
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242 | location[0] = P0 + s*D0; |
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243 | return 1; |
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244 | } |
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245 | // |
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246 | // |
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247 | // Line and line segment are parallel. Determine whether they overlap or not. |
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248 | // |
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249 | G4double sqrLenE = E.mag2(); |
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250 | kross = cross(E,D0); |
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251 | sqrKross = kross * kross; |
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252 | if (sqrKross > DBL_EPSILON * DBL_EPSILON * sqrLen0 * sqrLenE) |
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253 | { |
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254 | return 0; //Lines are different. |
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255 | } |
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256 | // |
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257 | // |
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258 | // Lines are the same. Test for overlap. |
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259 | // |
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260 | G4double s0 = D0.dot(E)/sqrLen0; |
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261 | G4double s1 = s0 + D0.dot(D1)/sqrLen0; |
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262 | G4double smin = 0.0; |
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263 | G4double smax = 0.0; |
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264 | |
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265 | if (s0 < s1) {smin = s0; smax = s1;} |
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266 | else {smin = s1; smax = s0;} |
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267 | |
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268 | if (smax < 0.0) return 0; |
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269 | else if (smin < 0.0) |
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270 | { |
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271 | location[0] = P0; |
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272 | location[1] = P0 + smax*D0; |
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273 | return 2; |
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274 | } |
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275 | else |
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276 | { |
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277 | location[0] = P0 + smin*D0; |
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278 | location[1] = P0 + smax*D0; |
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279 | return 2; |
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280 | } |
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281 | } |
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