math2d.h
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 00023 #define CS_POLY_IN 1 00024 #define CS_POLY_ON 0 00025 #define CS_POLY_OUT -1 00026 00027 #include "csgeom/vector2.h" 00028 #include "csgeom/plane2.h" 00029 #include "csgeom/segment.h" 00030 00031 class csBox2; 00032 class csPoly2D; 00033 00038 class csMath2 00039 { 00040 public: 00047 static int WhichSide2D (const csVector2& v, 00048 const csVector2& s1, const csVector2& s2) 00049 { 00050 float k = (s1.y - v.y)*(s2.x - s1.x); 00051 float k1 = (s1.x - v.x)*(s2.y - s1.y); 00052 if (k < k1) return -1; 00053 else if (k > k1) return 1; 00054 else return 0; 00055 } 00056 00063 static int WhichSide2D (const csVector2& v, 00064 const csSegment2& s) 00065 { 00066 return WhichSide2D (v, s.Start (), s.End ()); 00067 } 00068 00076 static int InPoly2D (const csVector2& v, 00077 csVector2* P, int n, csBox2* bounding_box); 00078 00084 static float Area2 (const csVector2& a, 00085 const csVector2& b, 00086 const csVector2& c) 00087 { 00088 return 00089 a.x * b.y - a.y * b.x + 00090 a.y * c.x - a.x * c.y + 00091 b.x * c.y - c.x * b.y; 00092 } 00093 00099 static float Right (const csVector2& a, 00100 const csVector2& b, 00101 const csVector2& c) 00102 { 00103 return Area2 (a, b, c) <= -SMALL_EPSILON; 00104 } 00105 00111 static float Left (const csVector2& a, 00112 const csVector2& b, 00113 const csVector2& c) 00114 { 00115 return Area2 (a, b, c) >= SMALL_EPSILON; 00116 } 00117 00123 static bool Visible (const csVector2& p, const csPlane2& pl) 00124 { return pl.Classify (p) <= 0; } 00125 00132 static bool PlanesEqual (const csPlane2& p1, const csPlane2& p2) 00133 { 00134 return ( ( p1.norm - p2.norm) < (float).001 ) && 00135 ( ABS (p1.CC-p2.CC) < (float).001 ); 00136 } 00137 00143 static bool PlanesClose (const csPlane2& p1, const csPlane2& p2); 00144 }; 00145 00151 class csIntersect2 00152 { 00153 public: 00160 static bool IntersectPolygon (const csPlane2& plane, csPoly2D* poly, 00161 csSegment2& segment); 00162 00168 static bool Segments ( 00169 const csSegment2& a, const csSegment2& b, // Two segments. 00170 csVector2& isect, float& dist); // intersection point and distance 00171 00177 static bool SegmentLine ( 00178 const csSegment2& a, // First segment. 00179 const csSegment2& b, // A line (end is only direction) 00180 csVector2& isect, float& dist); // intersection point and distance 00181 00186 static bool Lines ( 00187 // Two lines (end is only direction). 00188 const csSegment2& a, const csSegment2& b, 00189 csVector2& isect); // intersection point 00190 00199 static bool Plane ( 00200 const csVector2& u, const csVector2& v, 00201 const csPlane2& p, // plane Ax+By+Cz+D=0 00202 csVector2& isect, // intersection point 00203 float& dist); // distance from u to isect 00204 00213 static bool Plane ( 00214 const csSegment2& uv, // Segment. 00215 const csPlane2& p, // plane Ax+By+Cz+D=0 00216 csVector2& isect, // intersection point 00217 float& dist) // distance from u to isect 00218 { 00219 return Plane (uv.Start (), uv.End (), p, isect, dist); 00220 } 00221 00226 static void PlaneNoTest (const csVector2& u, const csVector2& v, 00227 const csPlane2& p, csVector2& isect, float& dist) 00228 { 00229 float x,y, denom; 00230 x = v.x-u.x; y = v.y-u.y; 00231 denom = p.norm.x*x + p.norm.y*y; 00232 dist = -(p.norm*u + p.CC) / denom; 00233 isect.x = u.x + dist*x; isect.y = u.y + dist*y; 00234 } 00235 00240 static void PlaneNoTest (const csSegment2& uv, 00241 const csPlane2& p, csVector2& isect, float& dist) 00242 { 00243 PlaneNoTest (uv.Start (), uv.End (), p, isect, dist); 00244 } 00245 00251 static bool Planes (const csPlane2& p1, const csPlane2& p2, 00252 csVector2& isect); 00253 00254 }; 00255 00256 #endif // __CS_MATH_H__
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