Line data    Source code

       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             : #include "precompiled.h"
      26             : 
      27             : #include "Plane.h"
      28             : #include "MathUtil.h"
      29             : 
      30             : const float CPlane::m_EPS = 0.001f;
      31             : 
      32         370 : CPlane::CPlane()
      33             : {
      34         370 :     m_Dist = 0.0f;
      35         370 : }
      36             : 
      37             : //sets the plane equation from 3 points on that plane
      38           0 : void CPlane::Set(const CVector3D& p1, const CVector3D& p2, const CVector3D& p3)
      39             : {
      40           0 :     CVector3D D1, D2;
      41           0 :     CVector3D Norm;
      42             : 
      43             :     //calculate two vectors on the surface of the plane
      44           0 :     D1 = p2-p1;
      45           0 :     D2 = p3-p1;
      46             : 
      47             :     //cross multiply gives normal
      48           0 :     Norm = D2.Cross(D1);
      49             : 
      50           0 :     Set(Norm, p1);
      51           0 : }
      52             : 
      53             : //sets the plane equation from a normal and a point on
      54             : //that plane
      55           0 : void CPlane::Set(const CVector3D& norm, const CVector3D& point)
      56             : {
      57           0 :     m_Norm = norm;
      58             : 
      59           0 :     m_Dist = - (norm.X * point.X + norm.Y * point.Y + norm.Z * point.Z);
      60             : 
      61             : //  Normalize ();
      62           0 : }
      63             : 
      64             : //normalizes the plane equation
      65          24 : void CPlane::Normalize()
      66             : {
      67          24 :     float Scale = 1.0f/m_Norm.Length();
      68             : 
      69          24 :     m_Norm.X *= Scale;
      70          24 :     m_Norm.Y *= Scale;
      71          24 :     m_Norm.Z *= Scale;
      72          24 :     m_Dist *= Scale;
      73          24 : }
      74             : 
      75             : //returns the side of the plane on which this point
      76             : //lies.
      77           0 : PLANESIDE CPlane::ClassifyPoint(const CVector3D& point) const
      78             : {
      79           0 :     float Dist = DistanceToPlane(point);
      80             : 
      81           0 :     if (Dist > m_EPS)
      82           0 :         return PS_FRONT;
      83           0 :     else if (Dist < -m_EPS)
      84           0 :         return PS_BACK;
      85             : 
      86           0 :     return PS_ON;
      87             : }
      88             : 
      89             : //calculates the intersection point of a line with this
      90             : //plane. Returns false if there is no intersection
      91          12 : bool CPlane::FindLineSegIntersection(const CVector3D& start, const CVector3D& end, CVector3D* intsect) const
      92             : {
      93          12 :     float dist1 = DistanceToPlane(start);
      94          12 :     float dist2 = DistanceToPlane(end);
      95             : 
      96          12 :     if( (dist1 < 0 && dist2 < 0) || (dist1 >= 0 && dist2 >= 0) )
      97           4 :         return false;
      98             : 
      99           8 :     float t = (-dist1) / (dist2-dist1);
     100           8 :     *intsect = Interpolate(start, end, t);
     101             : 
     102           8 :     return true;
     103             : }
     104             : 
     105           0 : bool CPlane::FindRayIntersection(const CVector3D& start, const CVector3D& direction, CVector3D* intsect) const
     106             : {
     107           0 :     float dot = m_Norm.Dot(direction);
     108           0 :     if (dot == 0.0f)
     109           0 :         return false;
     110             : 
     111           0 :     *intsect = start - (direction * (DistanceToPlane(start)/dot));
     112           0 :     return true;
     113           3 : }