This snippet shows how to identify and display digital fully subconvex sets of a grid curve form its tangent bundle.
#include <iostream>
#include "DGtal/base/Common.h"
#include "DGtal/helpers/StdDefs.h"
#include "ConfigExamples.h"
#include "DGtal/topology/KhalimskySpaceND.h"
#include "DGtal/geometry/curves/FreemanChain.h"
#include "DGtal/geometry/curves/GridCurve.h"
#include "DGtal/geometry/volumes/DigitalConvexity.h"
#include "DGtal/io/boards/Board2D.h"
using namespace std;
using namespace Z2i;
int main(
int argc,
char** argv )
{
string S = examplesPath + "samples/contourS.fc";
const Point lowerBound( -200, -200 );
const Point upperBound( 200, 200 );
fstream inputStream( S.c_str(), ios::in );
inputStream.close();
c.initFromPointsRange( fc.
begin(), fc.
end() );
auto points = c.getPointsRange();
std::vector<Point> T( points.begin(), points.end() );
auto midpoints = c.getMidPointsRange();
std::vector<RealPoint> RT( midpoints.begin(), midpoints.end() );
std::vector<Point> T2;
for ( auto && rp : midpoints )
T2.push_back(
Point( (
int) round( 2. * rp[ 0 ] + 1. ),
(int) round( 2. * rp[ 1 ] + 1. ) ) );
aBoard.
setUnit(Board2D::UCentimeter);
Color grey( 200, 200, 200 );
std::set<Cell> pixels;
for ( auto p : T )
{
pixels.insert(
K.
uCell(
Point( 2*p[ 0 ] - 1, 2*p[ 1 ] - 1 ) ) );
pixels.insert(
K.
uCell(
Point( 2*p[ 0 ] + 1, 2*p[ 1 ] - 1 ) ) );
pixels.insert(
K.
uCell(
Point( 2*p[ 0 ] - 1, 2*p[ 1 ] + 1 ) ) );
pixels.insert(
K.
uCell(
Point( 2*p[ 0 ] + 1, 2*p[ 1 ] + 1 ) ) );
}
for ( auto && pixel : pixels )
<< pixel;
aBoard << c;
Point denominator( 2, 2 );
unsigned int last_j = 0;
unsigned int j = 0;
for ( unsigned int i = 0; i < T2.size(); ++i )
{
unsigned int start_j = ( i + 1 ) % T2.size();
for ( j = ( start_j + 1 ) % T2.size(); j != start_j; j = ( j + 1 ) % T2.size() )
{
}
j = ( j + T2.size() - 1 ) % T2.size();
if ( j != last_j )
{
aBoard.
drawLine( RT[i][0], RT[i][1], RT[j][0], RT[j][1] );
}
last_j = j;
}
aBoard.
saveEPS(
"myGridCurve.eps", Board2D::BoundingBox );
return 0;
}