csgeom/math2d.h
Go to the documentation of this file.00001 /* 00002 Copyright (C) 1998-2000 by Jorrit Tyberghein 00003 Largely rewritten by Ivan Avramovic <ivan@avramovic.com> 00004 00005 This library is free software; you can redistribute it and/or 00006 modify it under the terms of the GNU Library General Public 00007 License as published by the Free Software Foundation; either 00008 version 2 of the License, or (at your option) any later version. 00009 00010 This library is distributed in the hope that it will be useful, 00011 but WITHOUT ANY WARRANTY; without even the implied warranty of 00012 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 00013 Library General Public License for more details. 00014 00015 You should have received a copy of the GNU Library General Public 00016 License along with this library; if not, write to the Free 00017 Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 00018 */ 00019 00020 #ifndef __CS_MATH2D_H__ 00021 #define __CS_MATH2D_H__ 00022 00029 // These are also defined in plane2.h 00030 #ifndef __CS_POLY_MACROS__ 00031 #define __CS_POLY_MACROS__ 00032 #define CS_POLY_IN 1 00033 #define CS_POLY_ON 0 00034 #define CS_POLY_OUT -1 00035 #endif 00036 00037 #include "csgeom/vector2.h" 00038 #include "csgeom/plane2.h" 00039 #include "csgeom/segment.h" 00040 00041 class csBox2; 00042 class csPoly2D; 00043 00048 class csMath2 00049 { 00050 public: 00057 static int WhichSide2D (const csVector2& v, 00058 const csVector2& s1, const csVector2& s2) 00059 { 00060 float k = (s1.y - v.y)*(s2.x - s1.x); 00061 float k1 = (s1.x - v.x)*(s2.y - s1.y); 00062 if (k < k1) return -1; 00063 else if (k > k1) return 1; 00064 else return 0; 00065 } 00066 00073 static int WhichSide2D (const csVector2& v, 00074 const csSegment2& s) 00075 { 00076 return WhichSide2D (v, s.Start (), s.End ()); 00077 } 00078 00086 static int InPoly2D (const csVector2& v, 00087 csVector2* P, int n, csBox2* bounding_box); 00088 00094 static float Area2 (const csVector2& a, 00095 const csVector2& b, 00096 const csVector2& c) 00097 { 00098 return 00099 a.x * b.y - a.y * b.x + 00100 a.y * c.x - a.x * c.y + 00101 b.x * c.y - c.x * b.y; 00102 } 00103 00109 static float Right (const csVector2& a, 00110 const csVector2& b, 00111 const csVector2& c) 00112 { 00113 return Area2 (a, b, c) <= -SMALL_EPSILON; 00114 } 00115 00121 static float Left (const csVector2& a, 00122 const csVector2& b, 00123 const csVector2& c) 00124 { 00125 return Area2 (a, b, c) >= SMALL_EPSILON; 00126 } 00127 00133 static bool Visible (const csVector2& p, const csPlane2& pl) 00134 { return pl.Classify (p) <= 0; } 00135 00142 static bool PlanesEqual (const csPlane2& p1, const csPlane2& p2) 00143 { 00144 return ( ( p1.norm - p2.norm) < (float).001 ) && 00145 ( ABS (p1.CC-p2.CC) < (float).001 ); 00146 } 00147 00153 static bool PlanesClose (const csPlane2& p1, const csPlane2& p2); 00154 }; 00155 00161 class csIntersect2 00162 { 00163 public: 00170 static bool IntersectPolygon (const csPlane2& plane, csPoly2D* poly, 00171 csSegment2& segment); 00172 00178 static bool Segments ( 00179 const csSegment2& a, const csSegment2& b, // Two segments. 00180 csVector2& isect, float& dist); // intersection point and distance 00181 00187 static bool SegmentLine ( 00188 const csSegment2& a, // First segment. 00189 const csSegment2& b, // A line (end is only direction) 00190 csVector2& isect, float& dist); // intersection point and distance 00191 00196 static bool Lines ( 00197 // Two lines (end is only direction). 00198 const csSegment2& a, const csSegment2& b, 00199 csVector2& isect); // intersection point 00200 00209 static bool Plane ( 00210 const csVector2& u, const csVector2& v, 00211 const csPlane2& p, // plane Ax+By+Cz+D=0 00212 csVector2& isect, // intersection point 00213 float& dist); // distance from u to isect 00214 00223 static bool Plane ( 00224 const csSegment2& uv, // Segment. 00225 const csPlane2& p, // plane Ax+By+Cz+D=0 00226 csVector2& isect, // intersection point 00227 float& dist) // distance from u to isect 00228 { 00229 return Plane (uv.Start (), uv.End (), p, isect, dist); 00230 } 00231 00236 static void PlaneNoTest (const csVector2& u, const csVector2& v, 00237 const csPlane2& p, csVector2& isect, float& dist) 00238 { 00239 float x,y, denom; 00240 x = v.x-u.x; y = v.y-u.y; 00241 denom = p.norm.x*x + p.norm.y*y; 00242 dist = -(p.norm*u + p.CC) / denom; 00243 isect.x = u.x + dist*x; isect.y = u.y + dist*y; 00244 } 00245 00250 static void PlaneNoTest (const csSegment2& uv, 00251 const csPlane2& p, csVector2& isect, float& dist) 00252 { 00253 PlaneNoTest (uv.Start (), uv.End (), p, isect, dist); 00254 } 00255 00261 static bool Planes (const csPlane2& p1, const csPlane2& p2, 00262 csVector2& isect); 00263 00264 }; 00265 00268 #endif // __CS_MATH2D_H__
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