source/maths/Plane.h

   1 /* Copyright (C) 2009 Wildfire Games.
   2  * This file is part of 0 A.D.
   3  *
   4  * 0 A.D. is free software: you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation, either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * 0 A.D. 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 General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with 0 A.D.  If not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 /*
  19  * A Plane in R3 and several utility methods.
  20  */
  21
  22 // Note that the format used for the plane equation is
  23 // Ax + By + Cz + D = 0, where <A,B,C> is the normal vector.
  24
  25 #ifndef INCLUDED_PLANE
  26 #define INCLUDED_PLANE
  27
  28 #include "Vector3D.h"
  29 #include "Vector4D.h"
  30
  31 enum PLANESIDE
  32 {
  33         PS_FRONT,
  34         PS_BACK,
  35         PS_ON
  36 };
  37
  38 class CPlane
  39 {
  40         public:
  41                 CPlane();
  42                 CPlane(const CVector4D& coeffs) : m_Norm(coeffs.X, coeffs.Y, coeffs.Z), m_Dist(coeffs.W) { }
  43
  44                 //sets the plane equation from 3 points on that plane
  45                 void Set(const CVector3D& p1, const CVector3D& p2, const CVector3D& p3);
  46
  47                 //sets the plane equation from a normal and a point on
  48                 //that plane
  49                 void Set(const CVector3D& norm, const CVector3D& point);
  50
  51                 //normalizes the plane equation
  52                 void Normalize();
  53
  54                 //returns the side of the plane on which this point lies
  55                 PLANESIDE ClassifyPoint(const CVector3D& point) const;
  56                 //returns true if this point is on the back side
  57                 inline bool IsPointOnBackSide(const CVector3D& point) const;
  58
  59                 //solves the plane equation for a particular point
  60                 inline float DistanceToPlane(const CVector3D& point) const;
  61
  62                 //calculates the intersection point of a line with this
  63                 //plane. Returns false if there is no intersection
  64                 bool FindLineSegIntersection(const CVector3D& start, const CVector3D& end, CVector3D* intsect) const;
  65                 bool FindRayIntersection(const CVector3D& start, const CVector3D& direction, CVector3D* intsect) const;
  66
  67         public:
  68                 CVector3D m_Norm;       //normal vector of the plane
  69                 float m_Dist;           //Plane distance (ie D in the plane eq.)
  70                 static const float m_EPS;
  71 };
  72
  73 float CPlane::DistanceToPlane(const CVector3D& point) const
  74 {
  75         return m_Norm.X * point.X + m_Norm.Y * point.Y + m_Norm.Z * point.Z + m_Dist;
  76 }
  77
  78 bool CPlane::IsPointOnBackSide(const CVector3D& point) const
  79 {
  80         return DistanceToPlane(point) < -m_EPS;
  81 }
  82
  83 #endif