Develop Reference

I have a polygon , and I know all of 4 points. How do I determine if a given point is inside the polygon with OpenLayers?

I referred this post
How to determine if a point is inside a 2D convex polygon?
But I want to do the same in OSM with Open Layers.Please help me.
[Link](http://jsfiddle.net/Sanju5390/3tpLs6w3/)

You can do this with turf.js using turf.inside:
var polygon = new ol.Feature(new ol.geom.Polygon([[[-5e6, -1e6], [-4e6, 1e6],
[-3e6, -1e6], [-5e6, -1e6]]]));
var point = new ol.Feature(new ol.geom.Point([-4e6, 0e6]));
var format = new ol.format.GeoJSON();
var isInside = turf.inside(
format.writeFeatureObject(point),
format.writeFeatureObject(polygon));
console.log(isInside);
http://jsfiddle.net/d6o81vc7/22/

LatLngBounds more than 2 parameters [duplicate]

This question already has answers here:
How to use containsLocation in Google maps geometry library.
(2 answers)
Closed 8 years ago.
in my javascript code, i have code like this :
var myLocation = new google.maps.LatLng(52.585701,20.453212);
var allowBounds = new google.maps.LatLngBounds(
new google.maps.LatLng(52.584903,20.451171),
new google.maps.LatLng(52.589701,20.463865)
);
if (allowBounds.contains(myLocation))
console.log('allowed');
else
console.log('disallowed');
it's work, the result is 'allowed', because i just use 2 parameter for allowBounds (southWest and northEast point).
now i have kml file with polygon coordinats more than 2 coordinat. i want use those coordinats for allowBounds paramater. because i want to check whether myLocation coordinat is in polygon location/area or not. mybe like this :
var allowBounds = new google.maps.LatLngBounds(
new google.maps.LatLng(52.584903,20.451171),
new google.maps.LatLng(52.589701,20.463865),
new google.maps.LatLng(52.629701,20.413865),
new google.maps.LatLng(52.572190,20.963865)
);
that is possible?? if not, can you give me some advice to check myLocation coordinat is in polygon area or not without use google.maps.LatLngBounds??
thank you for your helped.

According to the documentation you can't put more than 2 coordinates in the constructor. However, you can add more than 2 coordinates to a LatLngBounds object by using the .extend(point:LatLng) function.
var markers = [
new google.maps.LatLng(1.234, 5.678),
new google.maps.LatLng(1.234, 5.678),
new google.maps.LatLng(1.234, 5.678)
];
var bounds = new google.maps.LatLngBounds();
for (index in markers) {
bounds.extend(markers[index]);
}

OpenStreetMap point not showing on map with open layers

var map;
var vectors;
var point;
var drag;
Any long and Lat can be used
function mapCreate(lon,lat){
map = new OpenLayers.Map("map1");
var osm = new OpenLayers.Layer.OSM();
//create a vector
vectors = new OpenLayers.Layer.Vector("Vector Layer");
map.addLayer(osm);
var center = new OpenLayers.LonLat(lon,lat).transform(
new OpenLayers.Projection("EPSG:4326"),
map.getProjectionObject()
);
Assign a lat long to the point
point = new OpenLayers.Geometry.Point(lat,lon);
Add point to vectors
vectors.addFeatures([new OpenLayers.Feature.Vector(point)]);
map.setCenter(center, 15);
//add vectors to map
map.addLayer(vectors);
}
Am I missing something?

Are you looking at the full map? There's a high chance that you're setting the point's location as lat/lon. The OpenLayers LonLat object is so named only to trick innocent users like you into thinking that it automatically converts latitude longitude, or expects them, or something. Don't trust it, reproject into the projection of your map.

I thought Collection were necessary, but looks like you have lat & lon swapped. A point must have lon, then lat.
feature = new OpenLayers.Feature.Vector(new OpenLayers.Geometry.Collection([new OpenLayers.Geometry.Point(0, 0)]), {});
vectors.addFeatures([feature]);

Setting a Google Maps viewport to automatically fit pane for locations of (n) markers of various locations

The approach I took thus far has been:
function addMarker( query ) {
var geocoder = new google.maps.Geocoder();
var afterGeocode = $.Deferred();
// Geocode 'query' which is the address of a location.
geocoder.geocode(
{ address: query },
function( results, status ){
if( status === 'OK' ){
afterGeocode.resolve( results ); // Activate deferred.
}
}
);
afterGeocode.then( function( results ){
var mOptions = {
position: results[0].geometry.location,
map: map
}
// Create and drop in marker.
var marker = new google.maps.Marker( mOptions );
marker.setAnimation( google.maps.Animation.DROP );
var current_bounds = map.getBounds(); // Get current bounds of map
// use the extend() function of the latlngbounds object
// to incorporate the location of the marker
var new_bounds = current_bounds.extend( results[0].geometry.location );
map.fitBounds( new_bounds ); // fit the map to those bounds
});
}
The problem I'm running into is that the map inexplicably zooms out by some amount, no matter if the new marker fits within the current viewport or not.
What am I doing wrong?
ADDENDUM
I added logs and an additional variable to capture the map bounds after the transition was made (new_new_bounds)
current_bounds = // Map bounds before anything is done.
{-112.39575760000002, 33.60691883366427},
{-112.39295444655761, 33.639099}
new_bounds = // From after the extend
{-112.39295444655761, 33.60691883366427},
{-112.39575760000002, 33.639099}
new_new_bounds = // From after the fitbounds
{-112.33942438265382, 33.588697452015374},
{-112.44928766390382, 33.657309727063996}

OK, so after much wrangling, it turns out that the problem was a map's bounds are not the same as a map's bounds after fitBounds(). What happens (I presume), is Google takes the bounds you give it in the fitBounds() method, and then pads them. Every time you send the current bounds to fitBounds(), You're not going to fit bounds(x,y), you're going to fit bounds(x+m,y+m) where m = the arbitrary margin.
That said, the best approach was this:
var current_bounds = map.getBounds();
var marker_pos = marker.getPosition();
if( !current_bounds.contains( marker_pos ) ){
var new_bounds = current_bounds.extend( marker_pos );
map.fitBounds( new_bounds );
}
So, the map will only fit bounds if a marker placed falls outside the current map bounds. Hope this helps anyone else who hits this problem.

A possible explanation is that you randomly placed your new marker into the gap of the z-curve. A z-curve recursivley subdivide the map into 4 smaller tiles but that's also the reason why there are gaps between the tiles. A better way would be to use a hilbert curve or a moore curve for map applications. There is a patented search algorithm covering this issue, I think it is called multidimensional range query in quadtrees. You want to look for Nick's hilbert curce quadtree spatial index blog.

Google Maps v3 - Why is LatLngBounds.contains returning false

I have the following code in which I would expect the contains method to return true, but it returns false:
var bounds = new google.maps.LatLngBounds(
new google.maps.LatLng(55.38942944437183, -2.7379201682812226),
new google.maps.LatLng(54.69726685890506, -1.2456105979687226)
);
var center = bounds.getCenter(); // (55.04334815163844, -1.9917653831249726)
var x = bounds.contains(center); // returns false
On the same page, where map is a reference to the Map object, the following code returns true as expected:
map.getBounds().contains(map.getBounds().getCenter())
Why might my call to bounds.contains be returning false?

Ah, brilliant. The google.maps.LatLngBounds constructor expects SouthWest and NorthEast LatLng parameters. I have somehow bungled up my coordinates and passed in NorthWest and SouthEast instead!
var bounds = new google.maps.LatLngBounds(
new google.maps.LatLng(54.69726685890506,-2.7379201682812226),
new google.maps.LatLng(55.38942944437183, -1.2456105979687226)
);
var center = bounds.getCenter(); // still returns (55.04334815163844, -1.9917653831249726)
var x = bounds.contains(center); // now returns true
Lesson learned: getCenter doesn't care if you created the LatLngBounds with NorthWest and SouthEast instead, but if you want contains to return a useful answer you better pass in the suggested SouthWest and NorthEast!

I guess its easier to try this. It works for me without having to worry about NE orSW
var bounds = new google.maps.LatLngBounds();
bounds.extend(54.69726685890506,-2.7379201682812226);
bounds.extend(55.38942944437183, -1.2456105979687226);
var center = bounds.getCenter(); // still returns (55.04334815163844, -1.9917653831249726)
var x = bounds.contains(center); // now returns true
I know this post is old, but I came searching for answers here, so thought of updating from what I have learnt.

This is the way that it worked for me:
var bounds = new google.maps.LatLngBounds();
bounds.extend(54.69726685890506,-2.7379201682812226);
bounds.extend(55.38942944437183, -1.2456105979687226);
map.fitBounds(bounds);