function (val) {
			var self = this;
			console.log("zooming to " + val + "...");
			self.pix_per_sec = val;
			self.render();
		}
function (val) {
			var self = this;
			console.log("zooming to " + val + "...");
			self.pix_per_sec = val;
			self.render();
		}
function ( val ) { var self = this ; console . log ( "zooming to " + val + "..." ) ; self . pix_per_sec = val ; self . render ( ) ; }
change the zoom level and re-render
change the zoom level and re - render