http://snippets.dzone.com/posts Thu, 24 Jul 2008 20:13:35 GMT DZone Snippets: inside code http://snippets.dzone.com/posts/show/5295 <a href="http://jsfromhell.com/math/is-point-in-poly"> <br />Checks whether a point is inside a polygon. <br />Adapted from: [http://www.ecse.rpi.edu/Homepages/wrf/Research/Short_Notes/pnpoly.html] <br /> <br />[UPDATED CODE AND HELP CAN BE FOUND HERE: Point Inside a Polygon] <br /></a> <br /> <br /> <br /><code> <br />//+ Jonas Raoni Soares Silva <br />//@ http://jsfromhell.com/classes/is-point-in-poly [v1.0] <br /> <br />function isPointInPoly(poly, pt){ <br /> for(var c = false, i = -1, l = poly.length, j = l - 1; ++i < l; j = i) <br /> ((poly[i].y <= pt.y && pt.y < poly[j].y) || (poly[j].y <= pt.y && pt.y < poly[i].y)) <br /> && (pt.x < (poly[j].x - poly[i].x) * (pt.y - poly[i].y) / (poly[j].y - poly[i].y) + poly[i].x) <br /> && (c = !c); <br /> return c; <br />} <br /></code> <br /> <br />Example <br /> <br /><code> <br /><script type="text/javascript"> <br />//<![CDATA[ <br /> <br />points = [ <br /> {x: 0, y: 0}, <br /> {x: 0, y: 50}, <br /> {x: 50, y: 10}, <br /> {x: -50, y: -10}, <br /> {x: 0, y: -50}, <br /> {x: 0, y: 0} <br />]; <br /> <br />alert(isPointInPoly(points, {x: 10, y: 10}) ? "In" : "Out"); <br /> <br />//]]> <br /></script> <br /></code> <br /> Sun, 30 Mar 2008 16:57:56 GMT http://snippets.dzone.com/posts/show/5295 jonasraoni (Jonas Raoni Soares Silva)