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/* Copyright (C) 2014 Wildfire Games.
* This file is part of 0 A.D.
*
* 0 A.D. is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 2 of the License, or
* (at your option) any later version.
*
* 0 A.D. is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with 0 A.D. If not, see <http://www.gnu.org/licenses/>.
*/
/*
* Determine intersection of rays with a heightfield.
*/
#ifndef INCLUDED_HFTRACER
#define INCLUDED_HFTRACER
class CPatch;
class CVector3D;
class CTerrain;
///////////////////////////////////////////////////////////////////////////////
// CHFTracer: a class for determining ray intersections with a heightfield
class CHFTracer
{
public:
// constructor; setup data
CHFTracer(CTerrain *pTerrain);
// intersect ray with this heightfield; return true if intersection
// occurs (and fill in grid coordinates and point of intersection), or false otherwise
bool RayIntersect(const CVector3D& origin, const CVector3D& dir, int& x, int& z, CVector3D& ipt) const;
/**
* Intersects ray with a single patch.
* The ray is a half-infinite line starting at @p origin with direction @p dir
* (not required to be a unit vector).. The patch is treated as a collection
* of two-sided triangles, corresponding to the terrain tiles.
*
* If there is an intersection, returns true; and if @p out is not NULL, it
* is set to the intersection point. This is guaranteed to be the earliest
* tile intersected (starting at @p origin), but not necessarily the earlier
* triangle inside that tile.
*
* This partly duplicates RayIntersect, but it only operates on a single
* patch, and it's more precise (it uses the same tile triangulation as the
* renderer), and tries to be more numerically robust.
*/
static bool PatchRayIntersect(CPatch* patch, const CVector3D& origin, const CVector3D& dir, CVector3D* out);
private:
// test if ray intersects either of the triangles in the given
bool CellIntersect(int cx, int cz, const CVector3D& origin, const CVector3D& dir, float& dist) const;
// The terrain we're operating on
CTerrain *m_pTerrain;
// the heightfield were tracing
const u16* m_Heightfield;
// size of the heightfield
size_t m_MapSize;
// cell size - size of each cell in x and z
float m_CellSize;
// vertical scale - size of each cell in y
float m_HeightScale;
};
#endif
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