javascript - Which segment of a polyline was clicked? -

-

i have set sample polyline 5 segments, , i'm allowing new markers created when user clicks on polyline.

i'd know if there's foolproof way determine whether new marker between markers 0 , 1, or 1 , 2 ... or between 4 , 5. i've considered checking if new marker inside bounding box, , point-in-line formulas, neither 100% precise.

as google maps uses mercator projection projecting gps coordinates, can't use 'line equation' gps coordinates, because projection not linear gps points.but instead can use world coordinates linear. here have used parametric form of line equation check whether point on segment: 

function ispointonsegment( map, gpspoint1, gpspoint2, gpspoint ){      var p1 = map.getprojection().fromlatlngtopoint( gpspoint1 );      var p2 = map.getprojection().fromlatlngtopoint( gpspoint2 );      var p = map.getprojection().fromlatlngtopoint( gpspoint );      var t_x;      var t_y;      //parametric form of line equation is:      //--------------------------------      //      x = x1 + t(x2-x1)      //      y = y1 + t(y2-y1)       //--------------------------------      //'p' on [p1,p2] segment,if 't' number [0,1]      //-----case 1----      //      x = x1      //      y = y1      //---------------      if( p2.x-p1.x == 0 && p2.y-p1.y == 0){         return p.x == p1.x && p.y == p1.y;      }else       //-----case 2----      //      x = x1      //      y = y1 + t(y2-y1)      //---------------      if( p2.x-p1.x == 0 && p2.y-p1.y != 0){         t_y = (p.y - p1.y)/(p2.y-p1.y);         return p.x == p1.x && t_y >= 0 && t_y <= 1;      }else      //-----case 3----      //      x = x1 + t(x2-x1)      //      y = y1       //---------------      if( p2.x-p1.x != 0 && p2.y-p1.y == 0){         t_x = (p.x - p1.x)/(p2.x-p1.x);         return p.y == p1.y && t_x >= 0 && t_x <= 1;      }      //-----case 4----      //      x = x1 + t(x2-x1)      //      y = y1 + t(y2-y1)       //---------------      t_x = (p.x - p1.x)/(p2.x-p1.x);      t_y = (p.y - p1.y)/(p2.y-p1.y);      return ( t_x == t_y && t_x >= 0 && t_x <= 1 && t_y >= 0 && t_y <= 1); }

by having clicked point , segments of polyline, use above implemented function , retrieve segment looking for.


Comments

Post a Comment

Popular posts from this blog

c++ - OpenCV Error: Assertion failed <scn == 3 ::scn == 4> in unknown function, -

-
i read alot other solution still confused should mine... #include <opencv2/objdetect/objdetect.hpp> #include <opencv2/highgui/highgui.hpp> #include <opencv2/imgproc/imgproc.hpp> #include <iostream> #include <stdio.h> using namespace std; using namespace cv; int main(int argc, const char** argv) { //create cascade classifier object used face detection cascadeclassifier face_cascade; //use haarcascade_frontalface_alt.xml library face_cascade.load("haarcascade_frontalface_alt.xml"); //setup video capture device , link first capture device videocapture capturedevice; capturedevice.open(0); //setup image files used in capture process mat captureframe; mat grayscaleframe; //create window present results namedwindow("outputcapture", 1); //create loop capture , find faces while (true) { //capture new image frame capturedevice >> captureframe; ...
Read more

php - render data via PDO::FETCH_FUNC vs loop -

-
i've been using 2 methods render data. the first one: function name($id,$name){ return '<div id="'.$id.'">'.$name.'</div>'; } echo implode($pdo->query("select id,name user")->fetchall(pdo::fetch_func,'name')); the second one: $users = $pdo->query("select id,name user")->fetchall(pdo::fetch_obj); foreach($users $user){ echo name($user->id,$user->name); } i don't understand how pdo::fetch_func works. tried figure out. however, not well-documented. could please explain fetch mode? , also, 1 performs better? thank you. both methods wrong , have learn how use templates , how separate business logic presentation logic. $users = $pdo->query("select id,name user")->fetchall(pdo::fetch_obj); tpl::assign('users', $users); is code business logic part. then in template <?php foreach $users $row): ?> <div id="<?=$...
Read more

The canvas has been tainted by cross-origin data in chrome only -

-
uncaught securityerror: failed execute 'getimagedata' on 'canvasrenderingcontext2d': canvas has been tainted cross-origin data i getting above error in chrome. code(following) works fine in mozilla. have not corss domain issue. why above error in chrome? var wheel_canvas, wheel_context, can_w, can_h, wheel_grd; var large_radius = 160; var small_radius = 120; var wheel_canvas = document.getelementbyid('wheel_canvas'); var wheel_context = wheel_canvas.getcontext('2d'); var can_w = $(wheel_canvas).width(); var can_h = $(wheel_canvas).height(); var centerx = can_w / 2, centery = can_h / 2; var wheel_grd = null; test('#ff0000'); function test(hex) { $('#clrpicker').css({'left': 210, 'top': 210 }); inverted = hexbw(hex); $('#color_val_show').val(hex); current_color_hex_val_selected = hex; $('#color_val_show').css({'color':inverted,'background':hex}); fillgradient...
Read more