source/graphics/HFTracer.h

   1 /* Copyright (C) 2014 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  * Determine intersection of rays with a heightfield.
  20  */
  21
  22 #ifndef INCLUDED_HFTRACER
  23 #define INCLUDED_HFTRACER
  24
  25 class CPatch;
  26 class CVector3D;
  27 class CTerrain;
  28
  29 ///////////////////////////////////////////////////////////////////////////////
  30 // CHFTracer: a class for determining ray intersections with a heightfield
  31 class CHFTracer
  32 {
  33 public:
  34         // constructor; setup data
  35         CHFTracer(CTerrain *pTerrain);
  36
  37         // intersect ray with this heightfield; return true if intersection
  38         // occurs (and fill in grid coordinates and point of intersection), or false otherwise
  39         bool RayIntersect(const CVector3D& origin, const CVector3D& dir, int& x, int& z, CVector3D& ipt) const;
  40
  41         /**
  42          * Intersects ray with a single patch.
  43          * The ray is a half-infinite line starting at @p origin with direction @p dir
  44          * (not required to be a unit vector).. The patch is treated as a collection
  45          * of two-sided triangles, corresponding to the terrain tiles.
  46          *
  47          * If there is an intersection, returns true; and if @p out is not NULL, it
  48          * is set to the intersection point. This is guaranteed to be the earliest
  49          * tile intersected (starting at @p origin), but not necessarily the earlier
  50          * triangle inside that tile.
  51          *
  52          * This partly duplicates RayIntersect, but it only operates on a single
  53          * patch, and it's more precise (it uses the same tile triangulation as the
  54          * renderer), and tries to be more numerically robust.
  55          */
  56         static bool PatchRayIntersect(CPatch* patch, const CVector3D& origin, const CVector3D& dir, CVector3D* out);
  57
  58 private:
  59         // test if ray intersects either of the triangles in the given
  60         bool CellIntersect(int cx, int cz, const CVector3D& origin, const CVector3D& dir, float& dist) const;
  61
  62         // The terrain we're operating on
  63         CTerrain *m_pTerrain;
  64         // the heightfield were tracing
  65         const u16* m_Heightfield;
  66         // size of the heightfield
  67         size_t m_MapSize;
  68         // cell size - size of each cell in x and z
  69         float m_CellSize;
  70         // vertical scale - size of each cell in y
  71         float m_HeightScale;
  72 };
  73
  74 #endif