Use the Ray Casting algorithm for checking if a point (marker) lies inside of a polygon: function isMarkerInsidePolygon(marker, poly) { var polyPoints = poly.getLatLngs(); var x = marker.getLatLng().lat, y = marker.getLatLng().lng; var inside = false; for (var i = 0, j = polyPoints.length – 1; i < polyPoints.length; j = i++) { var xi = … Read more
This is for Pillow, a more maintained fork of PIL. http://pillow.readthedocs.org/ If you want to draw polygons that are transparent, relative to each other, the base Image has to be of type RGB, not RGBA, and the ImageDraw has to be of type RGBA. Example: from PIL import Image, ImageDraw img = Image.new(‘RGB’, (100, 100)) … Read more
Arash Partow’s FastGEO library contains implementations of many interesting algorithms in computational geometry. Polygon intersection is one of them. It’s written in Pascal, but it’s only implementing math so it’s pretty readable. Note that you will certainly need to preprocess your edges a little, to get them into clockwise or counterclockwise order. ETA: But really, … Read more
Let’s assume you want to draw an N-sided polygon of radius r, centred at (0,0). Then the n vertices are given by: x[n] = r * cos(2*pi*n/N) y[n] = r * sin(2*pi*n/N) where 0 <= n < N. Note that cos and sin here are working in radians, not degrees (this is pretty common in … Read more
If all you need is the coordinates here is a drawing tool I like to use – move the polygon or re-shape it and the coordinates will display right below the map: jsFiddle here. Also, here is a Codepen JS var bermudaTriangle; function initialize() { var myLatLng = new google.maps.LatLng(33.5190755, -111.9253654); var mapOptions = { … Read more
There are many algorithms for this problem. It is called “minimum bounding box”. You will find solutions too searching for “convex hull”, especially here. One way is to find the leftmost point and then repeat to search for a point where all other points are to the right of the line p(n-1)p(n).
Edit As of 2013, most links below are not functional anymore. However, I’ve found the cited paper, algorithm included, still available at this (very slow) server. Here you can find a project dealing exactly with your issues. Although it works primarily with an area “filled” by points, you can set it to work with a … Read more