Google maps - draw ellipse based off 4 coordinates - google-maps

Question

I would like to draw an ellipse on google maps based off four coordinates, like the current "rectangle" method available via the API:
var rectangle = new google.maps.Rectangle({
strokeColor: '#FF0000',
strokeOpacity: 0.8,
strokeWeight: 2,
fillColor: '#FF0000',
fillOpacity: 0.35,
map: map,
bounds: new google.maps.LatLngBounds(
new google.maps.LatLng(33.671068, -116.25128),
new google.maps.LatLng(33.685282, -116.233942))
});
(using the bounds paramater).
If that fails, is there an easy way to convert the distance between 2 polygons to a unit of measurement?

Answer 1

You have to calculate the path yourself. This should help:
http://mathworld.wolfram.com/Ellipse.html
Edit: This might be more useful:
http://www.geocodezip.com/v3_MW_example_eshapes.html
A v3 port of Mike Williams' v2 eshapes library, supports ellipse (but not based on the bounds).
Working example that sizes to the map bounds.
proof of concept fiddle
code snippet:
var map = null;
var myOptions = {
zoom: 8,
center: new google.maps.LatLng(43, -79.5),
mapTypeControl: true,
mapTypeControlOptions: {
style: google.maps.MapTypeControlStyle.DROPDOWN_MENU
},
navigationControl: true,
mapTypeId: google.maps.MapTypeId.ROADMAP
}
map = new google.maps.Map(document.getElementById("map"),
myOptions);
google.maps.event.addListenerOnce(map, "bounds_changed", function() {
var bounds = map.getBounds();
var major_axis = google.maps.geometry.spherical.computeDistanceBetween(bounds.getNorthEast(), new google.maps.LatLng(bounds.getSouthWest().lat(), bounds.getNorthEast().lng())) / 2;
var minor_axis = google.maps.geometry.spherical.computeDistanceBetween(
new google.maps.LatLng(bounds.getCenter().lat(), bounds.getSouthWest().lng()),
new google.maps.LatLng(bounds.getCenter().lat(), bounds.getNorthEast().lng())) / 2;
// === Ellipse ===
var point = map.getCenter(); // new google.maps.LatLng(43,-78);
var ellipse = google.maps.Polygon.Ellipse(point, major_axis, minor_axis, 0, "#000000", 2, 1, "#ffff00", 0.5);
ellipse.setMap(map);
});
// This Javascript is based on code provided by the
// Community Church Javascript Team
// http://www.bisphamchurch.org.uk/
// http://econym.org.uk/gmap/
// EShapes.js
//
// Based on an idea, and some lines of code, by "thetoy"
//
// This Javascript is provided by Mike Williams
// Community Church Javascript Team
// http://www.bisphamchurch.org.uk/
// http://econym.org.uk/gmap/
//
// This work is licenced under a Creative Commons Licence
// http://creativecommons.org/licenses/by/2.0/uk/
//
// Version 0.0 04/Apr/2008 Not quite finished yet
// Version 1.0 10/Apr/2008 Initial release
// Version 3.0 12/Oct/2011 Ported to v3 by Lawrence Ross
google.maps.Polygon.Ellipse = function(point, r1, r2, rotation, strokeColour, strokeWeight, Strokepacity, fillColour, fillOpacity, opts) {
rotation = rotation || 0;
return google.maps.Polygon.Shape(point, r1, r2, r1, r2, rotation, 100, strokeColour, strokeWeight, Strokepacity, fillColour, fillOpacity, opts)
}
google.maps.Polygon.Shape = function(point, r1, r2, r3, r4, rotation, vertexCount, strokeColour, strokeWeight, Strokepacity, fillColour, fillOpacity, opts, tilt) {
var rot = -rotation * Math.PI / 180;
var points = [];
var latConv = google.maps.geometry.spherical.computeDistanceBetween(point, new google.maps.LatLng(point.lat() + 0.1, point.lng())) * 10;
var lngConv = google.maps.geometry.spherical.computeDistanceBetween(point, new google.maps.LatLng(point.lat(), point.lng() + 0.1)) * 10;
var step = (360 / vertexCount) || 10;
var flop = -1;
if (tilt) {
var I1 = 180 / vertexCount;
} else {
var I1 = 0;
}
for (var i = I1; i <= 360.001 + I1; i += step) {
var r1a = flop ? r1 : r3;
var r2a = flop ? r2 : r4;
flop = -1 - flop;
var y = r1a * Math.cos(i * Math.PI / 180);
var x = r2a * Math.sin(i * Math.PI / 180);
var lng = (x * Math.cos(rot) - y * Math.sin(rot)) / lngConv;
var lat = (y * Math.cos(rot) + x * Math.sin(rot)) / latConv;
points.push(new google.maps.LatLng(point.lat() + lat, point.lng() + lng));
}
return (new google.maps.Polygon({
paths: points,
strokeColor: strokeColour,
strokeWeight: strokeWeight,
strokeOpacity: Strokepacity,
fillColor: fillColour,
fillOpacity: fillOpacity
}))
}
html,
body,
#map {
height: 100%;
width: 100%;
margin: 0px;
padding: 0px
}
<script src="https://maps.googleapis.com/maps/api/js?libraries=geometry&key=AIzaSyCkUOdZ5y7hMm0yrcCQoCvLwzdM6M8s5qk"></script>
<div id="map"></div>

Answer 2

Not sure if this is what you're looking for, but here's a sample I made(click two points anywhere), it uses a function that takes two latLngs and returns a series of points that describe the ellipse, then adds those to a polygon.
Note that it assumes that the bounding box is relatively small (and away from the poles) to take the points as coplanar.