| 1 | //
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| 2 | // ********************************************************************
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| 3 | // * License and Disclaimer *
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| 4 | // * *
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| 5 | // * The Geant4 software is copyright of the Copyright Holders of *
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| 6 | // * the Geant4 Collaboration. It is provided under the terms and *
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| 7 | // * conditions of the Geant4 Software License, included in the file *
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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 | // * subject to DEFCON 705 IPR conditions. *
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| 21 | // * By using, copying, modifying or distributing the software (or *
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| 22 | // * any work based on the software) you agree to acknowledge its *
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| 23 | // * use in resulting scientific publications, and indicate your *
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| 24 | // * acceptance of all terms of the Geant4 Software license. *
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| 25 | // ********************************************************************
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| 26 | //
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| 27 | //
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| 28 | // $Id: G4TessellatedGeometryAlgorithms.cc,v 1.6 2008/12/18 12:57:36 gunter Exp $
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| 29 | // GEANT4 tag $Name: geant4-09-04-beta-01 $
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| 30 | //
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| 31 | // %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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| 32 | //
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| 33 | // MODULE: G4TessellatedGeometryAlgorithms.cc
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| 34 | //
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| 35 | // Date: 07/08/2005
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| 36 | // Author: Rickard Holmberg & Pete Truscott
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| 37 | // Organisation: QinetiQ Ltd, UK (PT)
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| 38 | // Customer: ESA-ESTEC / TEC-EES
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| 39 | // Contract:
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| 40 | //
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| 41 | // %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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| 42 | //
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| 43 | // CHANGE HISTORY
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| 44 | // --------------
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| 45 | //
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| 46 | // 07 August 2007, P R Truscott, QinetiQ Ltd, UK - Created, with member
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| 47 | // functions based on the work of Rickard Holmberg.
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| 48 | //
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| 49 | // 26 September 2007
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| 50 | // P R Truscott, qinetiQ Ltd, UK
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| 51 | // Updated to assign values of location array, not update
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| 52 | // just the pointer.
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| 53 | //
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| 54 | ///////////////////////////////////////////////////////////////////////////////
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| 55 |
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| 56 | #include "G4TessellatedGeometryAlgorithms.hh"
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| 57 | ///////////////////////////////////////////////////////////////////////////////
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| 58 | //
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| 59 | // Pointer to single instance of class.
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| 60 | //
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| 61 | G4TessellatedGeometryAlgorithms* G4TessellatedGeometryAlgorithms::fInstance = 0;
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| 62 |
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| 63 | ///////////////////////////////////////////////////////////////////////////////
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| 64 | //
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| 65 | // G4TessellatedGeometryAlgorithms
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| 66 | //
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| 67 | // Constructor doesn't need to do anything since this class just allows access
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| 68 | // to the geometric algorithms contained in member functions.
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| 69 | //
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| 70 | G4TessellatedGeometryAlgorithms::G4TessellatedGeometryAlgorithms ()
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| 71 | {
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| 72 | }
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| 73 |
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| 74 | ///////////////////////////////////////////////////////////////////////////////
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| 75 | //
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| 76 | // GetInstance
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| 77 | //
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| 78 | // This is the access point for this singleton.
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| 79 | //
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| 80 | G4TessellatedGeometryAlgorithms* G4TessellatedGeometryAlgorithms::GetInstance()
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| 81 | {
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| 82 | static G4TessellatedGeometryAlgorithms worldStdGeom;
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| 83 | if (!fInstance)
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| 84 | {
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| 85 | fInstance = &worldStdGeom;
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| 86 | }
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| 87 | return fInstance;
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| 88 | }
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| 89 |
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| 90 | ///////////////////////////////////////////////////////////////////////////////
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| 91 | //
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| 92 | // IntersectLineAndTriangle2D
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| 93 | //
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| 94 | // Determines whether there is an intersection between a line defined
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| 95 | // by r = p + s.v and a triangle defined by verticies P0, P0+E0 and P0+E1.
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| 96 | //
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| 97 | // Here:
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| 98 | // p = 2D vector
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| 99 | // s = scaler on [0,infinity)
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| 100 | // v = 2D vector
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| 101 | // P0, E0 and E1 are 2D vectors
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| 102 | // Information about where the intersection occurs is returned in the
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| 103 | // variable location.
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| 104 | //
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| 105 | // This is based on the work of Rickard Holmberg.
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| 106 | //
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| 107 | G4bool G4TessellatedGeometryAlgorithms::IntersectLineAndTriangle2D (
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| 108 | const G4TwoVector p, const G4TwoVector v,
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| 109 | const G4TwoVector P0, const G4TwoVector E0, const G4TwoVector E1,
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| 110 | G4TwoVector location[2])
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| 111 | {
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| 112 | G4TwoVector loc0[2];
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| 113 | G4int e0i = IntersectLineAndLineSegment2D (p,v,P0,E0,loc0);
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| 114 | if (e0i == 2)
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| 115 | {
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| 116 | location[0] = loc0[0];
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| 117 | location[1] = loc0[1];
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| 118 | return true;
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| 119 | }
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| 120 |
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| 121 | G4TwoVector loc1[2];
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| 122 | G4int e1i = IntersectLineAndLineSegment2D (p,v,P0,E1,loc1);
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| 123 | if (e1i == 2)
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| 124 | {
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| 125 | location[0] = loc1[0];
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| 126 | location[1] = loc1[1];
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| 127 | return true;
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| 128 | }
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| 129 |
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| 130 | if ((e0i == 1) && (e1i == 1))
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| 131 | {
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| 132 | if ((loc0[0]-p).mag2() < (loc1[0]-p).mag2())
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| 133 | {
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| 134 | location[0] = loc0[0];
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| 135 | location[1] = loc1[0];
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| 136 | }
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| 137 | else
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| 138 | {
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| 139 | location[0] = loc1[0];
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| 140 | location[1] = loc0[0];
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| 141 | }
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| 142 | return true;
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| 143 | }
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| 144 |
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| 145 | G4TwoVector P1 = P0 + E0;
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| 146 | G4TwoVector DE = E1 - E0;
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| 147 | G4TwoVector loc2[2];
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| 148 | G4int e2i = IntersectLineAndLineSegment2D (p,v,P1,DE,loc2);
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| 149 | if (e2i == 2)
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| 150 | {
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| 151 | location[0] = loc2[0];
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| 152 | location[1] = loc2[1];
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| 153 | return true;
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| 154 | }
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| 155 |
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| 156 | if ((e0i == 0) && (e1i == 0) && (e2i == 0)) { return false; }
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| 157 |
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| 158 | if ((e0i == 1) && (e2i == 1))
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| 159 | {
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| 160 | if ((loc0[0]-p).mag2() < (loc2[0]-p).mag2())
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| 161 | {
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| 162 | location[0] = loc0[0];
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| 163 | location[1] = loc2[0];
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| 164 | }
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| 165 | else
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| 166 | {
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| 167 | location[0] = loc2[0];
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| 168 | location[1] = loc0[0];
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| 169 | }
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| 170 | return true;
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| 171 | }
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| 172 |
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| 173 | if ((e1i == 1) && (e2i == 1))
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| 174 | {
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| 175 | if ((loc1[0]-p).mag2() < (loc2[0]-p).mag2())
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| 176 | {
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| 177 | location[0] = loc1[0];
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| 178 | location[1] = loc2[0];
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| 179 | }
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| 180 | else
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| 181 | {
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| 182 | location[0] = loc2[0];
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| 183 | location[1] = loc1[0];
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| 184 | }
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| 185 | return true;
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| 186 | }
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| 187 |
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| 188 | return false;
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| 189 | }
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| 190 |
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| 191 | ///////////////////////////////////////////////////////////////////////////////
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| 192 | //
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| 193 | // IntersectLineAndLineSegment2D
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| 194 | //
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| 195 | // Determines whether there is an intersection between a line defined
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| 196 | // by r = P0 + s.D0 and a line-segment with endpoints P1 and P1+D1.
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| 197 | // Here:
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| 198 | // P0 = 2D vector
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| 199 | // s = scaler on [0,infinity)
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| 200 | // D0 = 2D vector
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| 201 | // P1 and D1 are 2D vectors
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| 202 | //
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| 203 | // This function returns:
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| 204 | // 0 - if there is no intersection;
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| 205 | // 1 - if there is a unique intersection;
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| 206 | // 2 - if the line and line-segments overlap, and the intersection is a
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| 207 | // segment itself.
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| 208 | // Information about where the intersection occurs is returned in the
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| 209 | // as ??.
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| 210 | //
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| 211 | // This is based on the work of Rickard Holmberg as well as material published
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| 212 | // by Philip J Schneider and David H Eberly, "Geometric Tools for Computer
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| 213 | // Graphics," ISBN 1-55860-694-0, pp 244-245, 2003.
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| 214 | //
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| 215 | G4int G4TessellatedGeometryAlgorithms::IntersectLineAndLineSegment2D (
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| 216 | const G4TwoVector P0, const G4TwoVector D0,
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| 217 | const G4TwoVector P1, const G4TwoVector D1,
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| 218 | G4TwoVector location[2])
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| 219 | {
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| 220 | G4TwoVector E = P1 - P0;
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| 221 | G4double kross = cross(D0,D1);
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| 222 | G4double sqrKross = kross * kross;
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| 223 | G4double sqrLen0 = D0.mag2();
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| 224 | G4double sqrLen1 = D1.mag2();
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| 225 | location[0] = G4TwoVector(0.0,0.0);
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| 226 | location[1] = G4TwoVector(0.0,0.0);
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| 227 |
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| 228 | if (sqrKross > DBL_EPSILON * DBL_EPSILON * sqrLen0 * sqrLen1)
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| 229 | {
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| 230 | //
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| 231 | //
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| 232 | // The line and line segment are not parallel. Determine if the intersection
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| 233 | // is in positive s where r = P0 + s*D0, and for 0<=t<=1 where r = p1 + t*D1.
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| 234 | //
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| 235 | G4double s = cross(E,D1)/kross;
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| 236 | if (s < 0) return 0; // Intersection does not occur for positive s.
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| 237 | G4double t = cross(E,D0)/kross;
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| 238 | if (t < 0 || t > 1) return 0; // Intersection does not occur on line-segment.
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| 239 | //
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| 240 | //
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| 241 | // Intersection of lines is a single point on the forward-propagating line
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| 242 | // defined by r = P0 + s*D0, and the line segment defined by r = p1 + t*D1.
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| 243 | //
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| 244 | location[0] = P0 + s*D0;
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| 245 | return 1;
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| 246 | }
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| 247 | //
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| 248 | //
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| 249 | // Line and line segment are parallel. Determine whether they overlap or not.
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| 250 | //
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| 251 | G4double sqrLenE = E.mag2();
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| 252 | kross = cross(E,D0);
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| 253 | sqrKross = kross * kross;
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| 254 | if (sqrKross > DBL_EPSILON * DBL_EPSILON * sqrLen0 * sqrLenE)
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| 255 | {
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| 256 | return 0; //Lines are different.
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| 257 | }
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| 258 | //
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| 259 | //
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| 260 | // Lines are the same. Test for overlap.
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| 261 | //
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| 262 | G4double s0 = D0.dot(E)/sqrLen0;
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| 263 | G4double s1 = s0 + D0.dot(D1)/sqrLen0;
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| 264 | G4double smin = 0.0;
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| 265 | G4double smax = 0.0;
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| 266 |
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| 267 | if (s0 < s1) {smin = s0; smax = s1;}
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| 268 | else {smin = s1; smax = s0;}
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| 269 |
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| 270 | if (smax < 0.0) return 0;
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| 271 | else if (smin < 0.0)
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| 272 | {
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| 273 | location[0] = P0;
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| 274 | location[1] = P0 + smax*D0;
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| 275 | return 2;
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| 276 | }
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| 277 | else
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| 278 | {
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| 279 | location[0] = P0 + smin*D0;
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| 280 | location[1] = P0 + smax*D0;
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| 281 | return 2;
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| 282 | }
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| 283 | }
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