javascript - Google maps - get latlng of X% along a straight polyline -


i need latitude/longitude of position @ x percentage along straight polyline segment between 2 other lat/lng points.

the closest have come far using following (for 40% along line):

google.maps.geometry.spherical.interpolate(startlatlng, endlatlng, 0.4);

this works short distances, long polyline segment latlng returned outside of polyline travels, since it's working out shortest distance along earth's surface instead of shortest distance across flat map.

any on appreciated, i'm missing obvious.

there must proven , tested method out there this, here way maps api:

  1. convert lat/lng coordinates pixels
  2. interpolate in pixel plane
  3. convert lat/lng

this pretty straightforward; 1 hassle figuring out how deal lines cross 180 meridian or pole.

here's semi-tested code may give place start:

function mercatorinterpolate( map, latlngfrom, latlngto, fraction ) {     // projected points     var projection = map.getprojection();     var pointfrom = projection.fromlatlngtopoint( latlngfrom );     var pointto = projection.fromlatlngtopoint( latlngto );     // adjust lines cross 180 meridian     if( math.abs( pointto.x - pointfrom.x ) > 128 ) {         if( pointto.x > pointfrom.x )             pointto.x -= 256;         else             pointto.x += 256;     }     // calculate point between     var x = pointfrom.x + ( pointto.x - pointfrom.x ) * fraction;     var y = pointfrom.y + ( pointto.y - pointfrom.y ) * fraction;     var pointbetween = new google.maps.point( x, y );     // project lat/lng     var latlngbetween = projection.frompointtolatlng( pointbetween );     return latlngbetween; }

i'm not 100% sure part handles lines cross 180 meridian, works ok in few quick tests tried.


Comments

Post a Comment

Popular posts from this blog

monitor web browser programmatically in Android? -

i've got tricky question here. need users make payment bank (namely barclaycard) in uk. so, have https url , add parameters (such amount pay, order reference, etc) url, start http connection intent.actionview, redirect user browser can enter credit card details on bank's webpage , make payment our account successfully. far ? the code use below (i changed values privacy reasons) problem is, need app when user has completed/failed/cancelled payment. barclaycardautomatically redirects particular url when payment has succeeded, 1 if failed. there no way of knowing when barclaycard payment has succeeded go android app somehow ? button cardbutton = (button) findviewbyid(r.id.card_button); cardbutton.setonclicklistener(new view.onclicklistener() { @override public void onclick(view arg0) { string prehashstring = new string(); string prohashstring = new string(); string shapassphrase = new string(); shapassphrase = "gsvth£h70zkh...
Read more

Shrink a YouTube video to responsive width -

i have youtube video embedded on our website , when shrink screen tablet or phone sizes stops shrinking @ around 560px in width. standard youtube videos or there can add code make go smaller? you can make youtube videos responsive css. wrap iframe in div class of "videowrapper" , apply following styles: .videowrapper { float: none; clear: both; width: 100%; position: relative; padding-bottom: 56.25%; padding-top: 25px; height: 0; } .videowrapper iframe { position: absolute; top: 0; left: 0; width: 100%; height: 100%; } the .videowrapper div should inside responsive element. padding on .videowrapper necessary keep video collapsing. may have tweak numbers depending upon layout.
Read more

wpf - PdfWriter.GetInstance throws System.NullReferenceException -

i'm trying create pdf document using itextsharp 5.3.4 using following document document = new document(); filestream stm = new filestream(filename, filemode.create); pdfwriter writer = pdfwriter.getinstance(document, stm); i'm getting system.nullreferenceexception following stack trace: system.nullreferenceexception occurred hresult=-2147467261 message=la référence d'objet n'est pas définie à une instance d'un objet. source=itextsharp stacktrace: à itextsharp.text.version.getinstance() innerexception: i've verified neither document nor stm null, , if select "continue" in vs12 document created - exception thrown. updated itextsharp 5.4.0 , it's still occurring. can't find information on anywhere - got ideas? make sure not catching exceptions. nullreferenceexception can 1 caught , handled inside itextsharp, don't care it. fact can continue supports theory. change following setting verify: debug -> exceptions ...
Read more