data structures - Secure usage of Cell_handle in a CGAL Delaunay triangulation after point insertion -

-

i'm planning write algorithm use cgal delaunay triangulation data structure. need insert point triangulation, save reference cells, , make other insertion.

i'm wondering how can store reference cells not invalidated after insertion of new points in triangulation?

it's seems me cell_handle pointer internal structure, it's dangerous store due reallocation of internal container. in other hand can see no way in triangulation_3 interface store index cell_handle.

typedef cgal::exact_predicates_inexact_constructions_kernel k; typedef cgal::triangulation_vertex_base_3<k>             vb; typedef cgal::triangulation_hierarchy_vertex_base_3<vb>  vbh; typedef cgal::triangulation_data_structure_3<vbh>        tds; typedef cgal::delaunay_triangulation_3<k,tds>            dt; typedef cgal::triangulation_hierarchy_3<dt>              dh; typedef dh::vertex_iterator vertex_iterator; typedef dh::vertex_handle   vertex_handle; typedef dh::point           point;  int main(){     dh t;    for(int = 0; < 100; ++i)       t.insert(point(rand()%1000,rand()%1000,rand()%1000));     assert( t.is_valid() );    assert( t.number_of_vertices() == 100 );    assert( t.dimension() == 3 );     typedef dh::cell_iterator celliterator;     std::vector<dh::cell_handle> hnd;    celliterator itend = t.finite_cells_end();    for(celliterator = t.finite_cells_begin(); it!=itend; ++it){       const int dist = std::distance(t.cells_begin(),it);       hnd.push_back(it);    }     const int newp(1000);    for(int = 0; < newp; ++i)       t.insert(point(rand()%1000,rand()%1000,rand()%1000));     int finitec(0),infinitec(0);    for(int = 0; < hnd.size(); ++i){       const int dist = std::distance(t.cells_begin(),hnd[i]);       if(t.is_infinite(hnd[i]))      ++infinitec;   else      ++finitec;    }    assert( t.is_valid() );    return 0; }

this code systematically crash but, , strange me, if change newp 10000, code magically works.

can explain me how handle problem?

since cell can disappear during insertion of new point, handle have saved not guarantee point on expect.

you have crash because use triangulation hierarchy internally creates , remove cells in internal container. if use cgal::delaunay_triangulation_3, not have crash.

for problem, should store quadruplet of vertex_handles , use is_cell function (documented here).


Comments

Post a Comment

Popular posts from this blog

Perl - how to grep a block of text from a file -

-
it can in xml or text format. how in general grep block of text in perl? <track type="ws"> <range> <rangestart>0</rangestart> <rangeend>146.912</rangeend> <locationindex>0</locationindex> <propertyindex>0</propertyindex> </range> </track> <track type="ps" id="1"> <range> <rangestart>0</rangestart> <rangeend>146.912</rangeend> <locationindex>1</locationindex> <propertyindex>1</propertyindex> </range> </track> i want grep type="ps" , till </range> . one solution open file, read line line , match block. open(fh, "file.txt"); foreach $line (<fh>) { if ($line =~ m/type="cc"(.*?)<\/range>/) { print $1; } } but there more optimal solution without reading file line l
Read more

delphi - How to remove all the grips on a coolbar if I have several coolbands? -

-
Image
if set mycoolbar.fixedorder true,only grip on first band hidden. well,if use delphi 7 create vcl forms application,then put coolbar on , create 3 coolbans hold other controls,only grip , top coolbands can hidden setting mycoolbar.fixedorder:=true. i've uploaded picture make things clear. you got fixedorder property wrong. fixed property not allow bands rearranged if set true . setting property of coolbar true keep user changing bands order @ runtime, user can still move , resize bands. can give advice can do, actual solution problem, well, have wait answer. my advice use 3 coolbars in row , setting "fixedorder" property true , bandborderstyle bsnone . way grip hidden on of them. about property, it's not bug of ide, actual preference of property.
Read more

javascript - Animating array of divs; only the final element is modified -

-
this baffling me @ moment. i'm experienced programmer looking throw bit of surprise fiancee on countdown page our wedding. desired effect simulated confetti falling behind main page. setup follows: i have array of divs in javascript. each div absolutely positioned on page. have interval set updates every 50 or milliseconds. on each tick, run loop on array of divs, , calculations , update positions. problem problem having, however, though can see divs created, stored array, , modified (in case, each has slight randomized rotation) during initialization phase, once tick update position starts, div stored in whatever last slot of array gets position updated. tried hard-coding each div index testing purposes, strictly last element update position. upon printing current "left" , "top" style values each div before , after calculations shows value has been changed, no visible change noticeable. here's basic code: javascript var container;
Read more