std::vector<Point2D> merge_hull(std::vector<Point2D> set)
{
if(set.size() < 2)
return set;
if (set.size() <= SIZE)
{
return get_hull(set);
}
std::vector<Point2D> set1;
set1.assign(set.begin(), set.begin() + set.size() / 2);
std::vector<Point2D> set2;
set2.assign(set.begin() + set.size() / 2 , set.end());
std::vector<Point2D> hull1 = merge_hull(set1);
std::vector<Point2D> hull2 = merge_hull(set2);
return merge(hull1, hull2);
}
std::vector <int> ConvexHull2D::work()
{
//print_hull(_P, ch2d(_P, _size));
return get_hull(_P, ch2d(_P, _size));
}
//merging of 2 convex hulls
std::vector<Point2D> merge(std::vector<Point2D> set1, std::vector<Point2D> set2)
{
Point2Df p;
std::vector<Point2D> sum;
int is_line1 = is_line(set1);
int is_line2 = is_line(set2);
if(!is_line1)
{
for(int i = 0; i < set1.size() - 2; i++)
{
if(is_left(set1[i], set1[i + 1], set1[i + 2]) != 0)
{
p = centroid(set1[i], set1[i + 1], set1[i + 2]);
break;
}
}
}
else if(!is_line2)
{
for(int i = 0; i < set2.size() - 2; i++)
{
if(is_left(set2[i], set2[i + 1], set2[i + 2]) != 0)
{
p = centroid(set2[i], set2[i + 1], set2[i + 2]);
break;
}
}
}
if(!is_line1 && !is_line2)// 2 polygons
{
if(in_polygon(set2, p) != 0)
{
sum = merge_polygons(set1, set2, p);
return graham_scan(sum);
}
else
{
std::vector<Point2D> clean_set2;
clean_set2 = delete_chain(set2, p);
sum = merge_polygons(set1, clean_set2, p);
return graham_scan(sum);
}
}
else if (!is_line1 && is_line2)//polygon with centroid p and line
{
std::vector<Point2D> clean_set2;
/*
clean_set2 = delete_chain(set2, p);
sum = merge_polygons(set1, clean_set2, p);
*/
if(angle_compare(p, (Point2Df)set2[0], (Point2Df)set2[set2.size() - 1]))
{
clean_set2.push_back(set2[0]);
clean_set2.push_back(set2[set2.size() - 1]);
}
else
{
clean_set2.push_back(set2[set2.size() - 1]);
clean_set2.push_back(set2[0]);
}
sum = merge_polygons(set1, clean_set2, p);
return graham_scan(sum);
}
else if(is_line1 && !is_line2)
{
std::vector<Point2D> clean_set1;
/*
clean_set1 = delete_chain(set1, p);
sum = merge_polygons(clean_set1, set2, p);
*/
if(angle_compare(p, (Point2Df)set1[0], (Point2Df)set1[set1.size() - 1]))
{
clean_set1.push_back(set1[0]);
clean_set1.push_back(set1[set1.size() - 1]);
}
else
{
clean_set1.push_back(set1[set1.size() - 1]);
clean_set1.push_back(set1[0]);
}
sum = merge_polygons(clean_set1, set2, p);
return graham_scan(sum);
}
else // if(is_line1 && is_line2)
{
std::vector<Point2D> clean_set1;
clean_set1.push_back(set1[0]);
clean_set1.push_back(set1[set1.size() - 1]);
clean_set1.push_back(set2[0]);
clean_set1.push_back(set2[set2.size() - 1]);
return get_hull(clean_set1);
}
}