vcglib/vcg/complex/intersection.h

#include<vector>
#include<vcg/space/point3.h>
#include<vcg/space/plane3.h>
#include<vcg/space/segment3.h>
#include<vcg/space/intersection3.h>
#include<vcg/space/index/grid_static_ptr.h>

#include<vcg/complex/trimesh/base.h>
using namespace std;

namespace vcg{

/** \addtogroup complex */
/*@{*/
/** 
    Function computing the intersection between  a grid and a plane. It returns all the cells intersected
*/
template < typename  GridType,typename ScalarType>
bool Intersect(   GridType & grid,Plane3<ScalarType> plane, vector<typename GridType::Cell *> &cells){					
	Point3d p,_d;
	Plane3d pl;
	_d.Import(plane.Direction());
	pl.SetDirection(_d);
	pl.SetOffset(plane.Offset());
	for( int ax = 0; ax <3; ++ax)
			{ int axis = ax;
				int axis0 = (axis+1)%3;
				int axis1 = (axis+2)%3;
				int i,j;
				Point3i pi;

				Segment3<double> seg;
				seg.P0().Import(grid.bbox.min);
				seg.P1().Import(grid.bbox.min);
				seg.P1()[axis] = grid.bbox.max[axis];

				for(i = 0 ; i <= grid.siz[axis0]; ++i){
					for(j = 0 ; j <= grid.siz[axis1]; ++j)
						{
							seg.P0()[axis0] = grid.bbox.min[axis0]+ (i+0.01) * grid.voxel[axis0] ;
							seg.P1()[axis0] = grid.bbox.min[axis0]+ (i+0.01) * grid.voxel[axis0];
							seg.P0()[axis1] = grid.bbox.min[axis1]+ (j+0.01) * grid.voxel[axis1];
							seg.P1()[axis1] = grid.bbox.min[axis1]+ (j+0.01) * grid.voxel[axis1];
							if ( Intersection(pl,seg,p))
								{
									pi[axis] =	min(max(0,floor((p[axis ]-grid.bbox.min[axis])/grid.voxel[axis])),grid.siz[axis]);
									pi[axis0] = i;
									pi[axis1] = j;
									grid.Grid(pi,axis,cells);
								}
						}
					}
			}
		sort(cells.begin(),cells.end());
		cells.erase(unique(cells.begin(),cells.end()),cells.end());
		
		return false;
	}

/*@}*/

/** \addtogroup complex */
/*@{*/
/** 
    Function computing the intersection between  a trimesh and a plane. It returns an EdgeMesh.
		Note: This version always returns a segment for each triangle of the mesh which intersects with the plane. In other
		words there are 2*n vertices where n is the number of segments fo the mesh. You can run vcg::edge::Unify to unify
		the vertices closer that a given value epsilon. Note that, due to subtraction error during triangle plane intersection,
		it is not safe to put epsilon to 0. 
// TODO si dovrebbe considerare la topologia face-face della trimesh per derivare quella della edge mesh..
*/
template < typename  TriMeshType, typename EdgeMeshType, class ScalarType>
bool Intersection(	TriMeshType & m, 
					Plane3<ScalarType>  pl,
					EdgeMeshType & em,
					double& ave_length,
					typename GridStaticPtr<typename TriMeshType::FaceContainer> *grid,
					typename vector< typename GridStaticPtr<typename TriMeshType::FaceContainer>::Cell* >& cells)
{
	typedef typename TriMeshType::FaceContainer FaceContainer;
	typedef GridStaticPtr<FaceContainer> GridType;
	EdgeMeshType::VertexIterator vi;
	TriMeshType::FaceIterator fi;
    vector<TriMeshType::FaceType*> v;
	v.clear();
	Intersect(*grid,pl,cells);
	Segment3<ScalarType> seg;
	ave_length = 0.0;
	vector<GridType::Cell*>::iterator ic;
	GridType::Cell fs,ls;
	for(ic = cells.begin(); ic != cells.end();++ic)
		{
			grid->Grid(*ic,fs,ls);
			GridType::Link * lk = fs;
			while(lk != ls){
				TriMeshType::FaceType & face = *(lk->Elem());
					if(!face.IsS())
					{
						face.SetS();
						v.push_back(&face);
						if(vcg::Intersection(pl,face,seg))// intersezione piano triangolo
							{
								face.SetS();
								// add to em
								ave_length+=seg.Length();
								vcg::edge::Allocator<EdgeMeshType>::AddEdges(em,1);
								vi = vcg::edge::Allocator<EdgeMeshType>::AddVertices(em,2);
								(*vi).P() = seg.P0();
								em.edges.back().V(0) = &(*vi); 
								vi++;
								(*vi).P() = seg.P1();
								em.edges.back().V(1) = &(*vi); 
							}
					}//endif 
					lk++;
				}//end while
		}
	ave_length/=em.en;
	vector<TriMeshType::FaceType*>::iterator v_i;
    for(v_i=v.begin(); v_i!=v.end(); ++v_i) (*v_i)->ClearS();

	return true;
}
/*****************************************************************/
/*INTERSECTION    RAY - MESH                                     */
/*                                                               */
/* Intersection between a Ray and a Mesh. Returns a 3D Pointset! */
/*****************************************************************/
template < typename  TriMeshType, class ScalarType>
bool IntersectionRayMesh(	
	/* Input Mesh */		TriMeshType * m, 
	/* Ray */				const Line3<ScalarType> & ray,
	/* Intersect Point */	Point3<ScalarType> & hitPoint)
{
	//typedef typename TriMeshType::FaceContainer FaceContainer;
	TriMeshType::FaceIterator fi;
	bool hit=false;

	if(m==0) return false;

	//TriMeshType::FaceIterator fi;
	//vector<TriMeshType::FaceType*>::iterator fi;

	ScalarType bar1,bar2,dist;
	Point3<ScalarType> p1;
	Point3<ScalarType> p2;
	Point3<ScalarType> p3;
	for(fi = m->face.begin(); fi != m->face.end(); ++fi)
	{
		p1=vcg::Point3<ScalarType>( (*fi).P(0).X() ,(*fi).P(0).Y(),(*fi).P(0).Z() );
		p2=vcg::Point3<ScalarType>( (*fi).P(1).X() ,(*fi).P(1).Y(),(*fi).P(1).Z() );
		p3=vcg::Point3<ScalarType>( (*fi).P(2).X() ,(*fi).P(2).Y(),(*fi).P(2).Z() );
		if(Intersection<ScalarType>(ray,p1,p2,p3,bar1,bar2,dist))
		{
			hitPoint= p1*(1-bar1-bar2) + p2*bar1 + p3*bar2;
			hit=true;
		}
	}

	return hit;
}
/*@}*/
} // end namespace vcg