nel/src/pacs/vector_2s.cpp

   1 // NeL - MMORPG Framework <http://dev.ryzom.com/projects/nel/>
   2 // Copyright (C) 2010  Winch Gate Property Limited
   3 //
   4 // This program is free software: you can redistribute it and/or modify
   5 // it under the terms of the GNU Affero General Public License as
   6 // published by the Free Software Foundation, either version 3 of the
   7 // License, or (at your option) any later version.
   8 //
   9 // This program is distributed in the hope that it will be useful,
  10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 // GNU Affero General Public License for more details.
  13 //
  14 // You should have received a copy of the GNU Affero General Public License
  15 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16
  17 #include "stdpacs.h"
  18
  19 #include "nel/pacs/vector_2s.h"
  20
  21 namespace NLPACS {
  22
  23
  24 // Test if 2 segments intersects
  25 bool    CVector2s::intersect(const CVector2s& a0, const CVector2s& a1, const CVector2s& b0, const CVector2s& b1, double* pa, double* pb)
  26 {
  27
  28         double          a0x = CVector2s::unpack(a0.x);
  29         double          a0y = CVector2s::unpack(a0.y);
  30         double          a1x = CVector2s::unpack(a1.x);
  31         double          a1y = CVector2s::unpack(a1.y);
  32         double          b0x = CVector2s::unpack(b0.x);
  33         double          b0y = CVector2s::unpack(b0.y);
  34         double          b1x = CVector2s::unpack(b1.x);
  35         double          b1y = CVector2s::unpack(b1.y);
  36
  37         double          ax = +(a1x-a0x);
  38         double          ay = +(a1y-a0y);
  39         double          bx = +(b1x-b0x);
  40         double          by = +(b1y-b0y);
  41         double          cx = +(b0x-a0x);
  42         double          cy = +(b0y-a0y);
  43
  44         double          d = -ax*by + ay*bx;
  45
  46         if (d == 0.0)
  47                 return false;
  48
  49         double          a = (bx*cy - by*cx) / d;
  50         double          b = (ax*cy - ay*cx) / d;
  51
  52         if (pa != NULL)
  53                 *pa = a;
  54         if (pb != NULL)
  55                 *pb = b;
  56
  57         return d != 0.0 && a >= 0.0 && a <= 1.0 && b >= 0.0 && b <= 1.0;
  58 }
  59
  60
  61 } // NLPACS