created as a first working draft.
Tessellates a simple polygon with the earcut algorithm assuming the polygon is almost planar
This commit is contained in:
ganovelli
parent
e98422ee49
commit
4002b9a706
|
|
@ -0,0 +1,142 @@
|
|||
/****************************************************************************
|
||||
* VCGLib o o *
|
||||
* Visual and Computer Graphics Library o o *
|
||||
* _ O _ *
|
||||
* Copyright(C) 2004 \/)\/ *
|
||||
* Visual Computing Lab /\/| *
|
||||
* ISTI - Italian National Research Council | *
|
||||
* \ *
|
||||
* All rights reserved. *
|
||||
* *
|
||||
* 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. *
|
||||
* *
|
||||
****************************************************************************/
|
||||
|
||||
#ifndef __VCGLIB_PLANAR_POLYGON_TESSELLATOR
|
||||
#define __VCGLIB_PLANAR_POLYGON_TESSELLATOR
|
||||
|
||||
#include <assert.h>
|
||||
#include <vcg/space/segment2.h>
|
||||
#include <vcg/math/random_generator.h>
|
||||
|
||||
namespace vcg {
|
||||
|
||||
/** \addtogroup space */
|
||||
/*@{*/
|
||||
/**
|
||||
A very simple earcut tessellation of planar 2D polygon.
|
||||
Input: a vector or Point2<>
|
||||
Output: a vector of faces as a triple of indices to the input vector
|
||||
*/
|
||||
template <class ScalarType>
|
||||
bool Cross( const Point2<ScalarType> & p00,
|
||||
const Point2<ScalarType> & p01,
|
||||
const Point2<ScalarType> & p10,
|
||||
const Point2<ScalarType> & p11)
|
||||
{
|
||||
Point2<ScalarType> vec0 = p01-p00;
|
||||
Point2<ScalarType> vec1 = p11-p10;
|
||||
if ( ( vec0^ (p11-p00)) * ( vec0^ (p10 - p00)) >=0) return false;
|
||||
if ( ( vec1^ (p01-p10)) * ( vec1^ (p00 - p10)) >=0) return false;
|
||||
return true;
|
||||
}
|
||||
|
||||
template <class S>
|
||||
bool Intersect(int cur , int v2, std::vector<int> & next, std::vector<Point2<S> > & points2){
|
||||
for(int i = 0; i < points2.size();++i)
|
||||
if( (next[i]!=-1) && (i!=cur))
|
||||
if( Cross(points2[cur], points2[v2],points2[i],points2[next[i]]))
|
||||
return true;
|
||||
return false;
|
||||
}
|
||||
|
||||
|
||||
template <class POINT_CONTAINER>
|
||||
void TessellatePlanarPolygon2( POINT_CONTAINER & points2, std::vector<int> & output){
|
||||
typedef typename POINT_CONTAINER::value_type Point2x;
|
||||
typedef typename Point2x::ScalarType S;
|
||||
// tessellate
|
||||
// first very inefficient implementation
|
||||
std::vector<int> next,prev;
|
||||
for(int i = 0; i < points2.size(); ++i) next.push_back((i+1)%points2.size());
|
||||
for(int i = 0; i < points2.size(); ++i) prev.push_back((i+points2.size()-1)%points2.size());
|
||||
int v1,v2;
|
||||
// check orientation
|
||||
S orient = 0.0;
|
||||
for(int i = 0 ; i < points2.size(); ++i){
|
||||
v1 = next[i];
|
||||
v2 = next[v1];
|
||||
orient+= (points2[v1] - points2[0]) ^ (points2[v2] - points2[0]);
|
||||
}
|
||||
orient = (orient>0)? 1.0:-1.0;
|
||||
|
||||
int cur = 0;
|
||||
int n_faces = 0;
|
||||
while(output.size()<3*(points2.size()-2)){
|
||||
v1 = next[cur];
|
||||
v2 = next[v1];
|
||||
if( ( (orient*((points2[v1] - points2[cur]) ^ (points2[v2] - points2[cur]))) >= 0.0) &&
|
||||
!Intersect(cur, v2,next,points2))
|
||||
{
|
||||
// output the face
|
||||
output.push_back(cur);
|
||||
output.push_back(v1);
|
||||
output.push_back(v2);
|
||||
|
||||
// readjust the topology
|
||||
next[cur] = v2;
|
||||
prev[v2] = cur;
|
||||
prev[v1] = -1;//unnecessary
|
||||
next[v1] = -1;//unnecessary
|
||||
}
|
||||
else
|
||||
do{cur = (cur+1)%points2.size();} while(next[cur]==-1);
|
||||
}
|
||||
}
|
||||
|
||||
/**
|
||||
A very simple earcut tessellation of planar 2D polygon.
|
||||
Input: a vector or Point3<>
|
||||
Output: a vector of faces as a triple of indices to the input vector
|
||||
|
||||
*/
|
||||
|
||||
template <class POINT_CONTAINER>
|
||||
void TessellatePlanarPolygon3( POINT_CONTAINER & points, std::vector<int> & output){
|
||||
typedef typename POINT_CONTAINER::value_type Point3x;
|
||||
typedef typename Point3x::ScalarType S;
|
||||
Point3x n;
|
||||
|
||||
math::RandomGenerator rg;
|
||||
int i12[2];
|
||||
S bestsn = -1.0;
|
||||
Point3x bestn,u,v;
|
||||
for(int i =0; i < points.size();++i){
|
||||
for(int j = 0; j < 2; ++j){ i12[j] = i; while(i12[j]==i) i12[j] = rg(points.size()-1);}
|
||||
n = (points[i12[0]]-points[i])^(points[i12[1]]-points[i]);
|
||||
S sn = n.SquaredNorm();
|
||||
if(sn > bestsn){ bestsn = sn; bestn = n;}
|
||||
}
|
||||
|
||||
GetUV(n,u,v);
|
||||
// project the coordinates
|
||||
std::vector<Point2<S> > points2;
|
||||
for(int i = 0; i < points.size(); ++i){
|
||||
Point3x & p = points[i];
|
||||
points2.push_back(Point2<S>(p*u,p*v));
|
||||
}
|
||||
TessellatePlanarPolygon2( points2,output);
|
||||
}
|
||||
|
||||
/*@}*/
|
||||
} // end namespace
|
||||
#endif
|
||||
Loading…
Reference in New Issue