vcglib/vcg/space/index/grid_util.h

/****************************************************************************
* VCGLib                                                            o o     *
* Visual and Computer Graphics Library                            o     o   *
*                                                                _   O  _   *
* Copyright(C) 2005                                                \/)\/    *
* Visual Computing Lab                                            /\/|      *
* ISTI - Italian National Research Council                           |      *
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* All rights reserved.                                                      *
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* This program 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.                                       *
*                                                                           *
* This program 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 (http://www.gnu.org/licenses/gpl.txt)          *
* for more details.                                                         *
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History

$Log: not supported by cvs2svn $
Revision 1.9  2005/12/02 00:27:22  cignoni
removed excess typenames

Revision 1.8  2005/10/03 16:21:10  spinelli
erase wrong assert on boxToIbox function

Revision 1.7  2005/10/02 23:16:26  cignoni
English comment and moved typedef to public scope

Revision 1.6  2005/09/30 13:12:46  pietroni
basic grid class is derived from Indexing base class defined in base,h

Revision 1.5  2005/09/16 11:56:38  cignoni
removed wrong typename and added ending \n

Revision 1.4  2005/08/02 11:01:05  pietroni
added IPToP and IBoxToBox functions, modified BoxToIBox function in order to use PToIP function

Revision 1.3  2005/07/28 06:11:12  cignoni
corrected error in GridP (did not compile)

Revision 1.2  2005/07/01 11:33:36  cignoni
Added a class BasicGrid with some utility function that are scattered among similar classes

Revision 1.1  2005/03/15 11:43:18  cignoni
Removed BestDim function from the grid_static_ptr class and moved to a indipendent file (grid_util.h) for sake of generality.


****************************************************************************/
#ifndef __VCGLIB_GRID_UTIL
#define __VCGLIB_GRID_UTIL

#include<vcg/space/index/base.h>
#include<vcg/space/box3.h>
#include <vcg/space/index/space_iterators.h>

namespace vcg {

	/** BasicGrid
	
	Basic Class abstracting a gridded structure in a 3d space;
	Usueful for having coherent float to integer conversion in a unique place:
	Some Notes:
		- bbox is the real occupation of the box in the space;
		- siz is the number of cells for each side

	OBJTYPE:      Type of the indexed objects.
	SCALARTYPE:   Scalars type for structure's internal data (may differ from
	              object's scalar type).

	*/

template <class OBJTYPE, class SCALARTYPE> 
class BasicGrid:public SpatialIndex<OBJTYPE,SCALARTYPE> 
{
public:

	typedef SCALARTYPE ScalarType;
	typedef Box3<ScalarType> Box3x;
	typedef Point3<ScalarType> CoordType;
	typedef OBJTYPE ObjType;
	typedef OBJTYPE* ObjPtr;
	typedef BasicGrid<OBJTYPE,SCALARTYPE> GridType;

	Box3x bbox;

	CoordType dim;		/// Spatial Dimention (edge legth) of the bounding box
	Point3i siz;		/// Number of cells forming the grid
	CoordType voxel;	/// Dimensions of a single cell

	/* Given a 3D point, returns the coordinates of the cell where the point is
	 * @param p is a 3D point
	 * @return integer coordinates of the cell
	 */
	inline Point3i GridP( const Point3<ScalarType> & p ) const 
	{
		Point3i pi; 
		PToIP(p, pi);
		return pi;
	}

	/* Given a 3D point p, returns the index of the corresponding cell
	 * @param p is a 3D point in the space
	 * @return integer coordinates pi of the cell
	 */
	inline void PToIP(const CoordType & p, Point3i &pi ) const
	{
		CoordType t = p - bbox.min;
		pi[0] = int( t[0] / voxel[0] );
		pi[1] = int( t[1] / voxel[1] );
		pi[2] = int( t[2] / voxel[2] );
	}

	/* Given a cell index return the lower corner of the cell
	 * @param integer coordinates pi of the cell
	 * @return p is a 3D point representing the lower corner of the cell
	 */
	inline void IPToP(const Point3i & pi, CoordType &p ) const
	{
		p[0] = ((ScalarType)pi[0])*voxel[0];
		p[1] = ((ScalarType)pi[1])*voxel[1];
		p[2] = ((ScalarType)pi[2])*voxel[2];
		p += bbox.min;
	}

	/* Given a cell in <ScalarType> coordinates, compute the corresponding cell in integer coordinates
	 * @param b is the cell in <ScalarType> coordinates
	 * @return ib is the correspondent box in integer coordinates
	 */
	void BoxToIBox( const Box3x & b, Box3i & ib ) const
	{
		PToIP(b.min, ib.min);
		PToIP(b.max, ib.max);
		//assert(ib.max[0]>=0 && ib.max[1]>=0 && ib.max[2]>=0);	
	}

	/* Given a cell in integer coordinates, compute the corresponding cell in <ScalarType> coordinates
	 * @param ib is the cell in integer coordinates
	 * @return b is the correspondent box in <ScalarType> coordinates
	 */
	/// Dato un box in voxel ritorna gli estremi del box reale
	void IBoxToBox( const Box3i & ib, Box3x & b ) const
	{
		IPtoP(ib.min,b.min);
		IPtoP(ib.max,b.max);
	}
};

	/** Calcolo dimensioni griglia.
	Calcola la dimensione della griglia in funzione
	della ratio del bounding box e del numero di elementi
	*/
	template<class scalar_type>
	void BestDim( const int elems, const Point3<scalar_type> & size, Point3i & dim )
	{
		const int mincells   = 1;		// Numero minimo di celle
		const double GFactor = 1;	// GridEntry = NumElem*GFactor
		double diag = size.Norm();	// Diagonale del box
		double eps  = diag*1e-4;		// Fattore di tolleranza

		assert(elems>0);
		assert(size[0]>=0.0);
		assert(size[1]>=0.0);
		assert(size[2]>=0.0);


		int ncell = int(elems*GFactor);	// Calcolo numero di voxel
		if(ncell<mincells)
			ncell = mincells;

		dim[0] = 1;
		dim[1] = 1;
		dim[2] = 1;

		if(size[0]>eps)
		{
			if(size[1]>eps)
			{
				if(size[2]>eps)
				{
					double k = pow((double)(ncell/(size[0]*size[1]*size[2])),double(1.0/3.f));
					dim[0] = int(size[0] * k);
					dim[1] = int(size[1] * k);
					dim[2] = int(size[2] * k);
				} 
				else 
				{
					dim[0] = int(::sqrt(ncell*size[0]/size[1]));
					dim[1] = int(::sqrt(ncell*size[1]/size[0]));
				}
			}
			else
			{
				if(size[2]>eps)
				{
					dim[0] = int(::sqrt(ncell*size[0]/size[2]));
					dim[2] = int(::sqrt(ncell*size[2]/size[0]));
				}
				else
					dim[0] = int(ncell);
			}
		}
		else
		{
			if(size[1]>eps)
			{
				if(size[2]>eps)
				{
					dim[1] = int(::sqrt(ncell*size[1]/size[2]));
					dim[2] = int(::sqrt(ncell*size[2]/size[1]));
				}
				else
					dim[1] = int(ncell);
			}
			else if(size[2]>eps)
				dim[2] = int(ncell);
		}
		dim[0] = math::Max(dim[0],1);
		dim[1] = math::Max(dim[1],1);
		dim[2] = math::Max(dim[2],1);
	}
}
#endif