polygon_simplification.cpp

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#ifndef _POLYGON_SIMPLIFICATION_CPP_
#define _POLYGON_SIMPLIFICATION_CPP_

#include <bo_polygon2d/polygon_simplification.h>


class_polygon_simplification::class_polygon_simplification(void){};
class_polygon_simplification::~class_polygon_simplification(void){};

int class_polygon_simplification::simplify_polygon(PS_CGALPolygon_2* p)
{

        if(!p->is_simple())
        {

                int keep_trying=1;
                int num_attempts=0;

                while(keep_trying)
                {

                        int tt=0;
                        double prev_x=-999999, prev_y=-999999;
                        ROS_WARN("polygon_simplification: polygon is not simple. Printing all vertexes");

                        int tttt=0;
                        for (PS_CGALPolygon_2::Vertex_const_iterator j = p->vertices_begin(); j != p->vertices_end(); ++ j )
                        {
                                //ROS_ERROR("pt%d x=%f y=%f",tttt,j->x(), j->y());      
                                tttt++;
                        }


                        PS_CGALPolygon_2::Vertex_const_iterator begin = p->vertices_begin();
                        PS_CGALPolygon_2::Vertex_const_iterator end = --p->vertices_end();
                        if ( begin->x() == end->x() && begin->y() == end->y())
                        {
                                ROS_WARN("Final and start point are equal. Erasing final point");
                                p->erase(end);  
                        }       


                        for (PS_CGALPolygon_2::Vertex_const_iterator j = p->vertices_begin(); j != p->vertices_end(); ++ j )
                        {
                                if(tt!=0)
                                {
                                        if (prev_x==j->x() && prev_y==j->y())
                                        {
                                                ROS_INFO("Erasing vertex %d",tt);
                                                p->erase(j);    
                                                break;
                                        }
                                        else
                                        {
                                                prev_x = CGAL::to_double(j->x());       
                                                prev_y = CGAL::to_double(j->y());       
                                        }

                                }
                                else
                                {
                                        prev_x = CGAL::to_double(j->x());       
                                        prev_y = CGAL::to_double(j->y());       
                                }


                                //ROS_ERROR("pt%d x=%f y=%f",tt,j->x(), j->y());        
                                tt++;
                        }


                        ROS_WARN("offset polygon %d: result of fix: %d",(int)p->size(), p->is_simple());

                        int ttt=0;
                        for (PS_CGALPolygon_2::Vertex_const_iterator j = p->vertices_begin(); j != p->vertices_end(); ++ j )
                        {
                                //ROS_ERROR("pt%d x=%f y=%f",ttt,j->x(), j->y());       
                                ttt++;
                        }

                        if (p->is_simple()) keep_trying=0;

                        num_attempts++;
                        if (num_attempts>50)
                        {
                                //ROS_ERROR("Could not add polygon. Returning error");
                                return 0;
                        }
                }
        }

        if(!p->is_counterclockwise_oriented()) //check if its counterclockwise. If not reverse
        {
                ROS_INFO("Offset Polygon: ch  (%d points) is not counterclockwise oriented. Reversing orientation",(int)p->size());
                p->reverse_orientation();       
                ROS_INFO("Result Polygon: ch  (%d points)",(int)p->size());
        }


        ROS_INFO("Removing collinear points... %d", (int)p->size());

        int keep_going=true;

        while (keep_going)
        {
                keep_going=false;
                PS_CGALPolygon_2::Vertex_const_iterator j = p->vertices_begin();
                double x2 = CGAL::to_double((*j).x());
                double y2 = CGAL::to_double((*j).y());

                j++;
                double x1 = CGAL::to_double((*j).x());
                double y1 = CGAL::to_double((*j).y());
                j++;

                for (; j != p->vertices_end(); ++ j )
                {
                        double m1 = (y2-y1)/(x2-x1);
                        double m2 = ( CGAL::to_double((*j).y()) - y1)/( CGAL::to_double((*j).x())-x1);

                        if (fabs(m1-m2)<0.01)
                        {
                                j--;
                                p->erase(j);

                                keep_going=true;        
                                break;
                        }

                        x2=x1;
                        y2=y1;
                        x1= CGAL::to_double((*j).x());
                        y1= CGAL::to_double((*j).y());
                }
        }

        ROS_INFO("End removing collinear points... %d", (int)p->size());
        return 1;
}

#endif