Created
March 31, 2014 15:13
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ol3 particles
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| <!doctype html> | |
| <html lang="en"> | |
| <head> | |
| <title>ol3 particles</title> | |
| <style> | |
| html, body, .map { | |
| margin: 0; | |
| padding: 0; | |
| width: 100%; | |
| height: 100%; | |
| } | |
| </style> | |
| </head> | |
| <body> | |
| <div id="map" class="map"></div> | |
| <script src="http://ol3js.org/en/master/build/ol.js"></script> | |
| <script> | |
| // http://html5hub.com/build-a-javascript-particle-system/ | |
| function randomUniform(a, b) { | |
| return a + Math.random() * (b - a); | |
| } | |
| var vectorSource = new ol.source.Vector(); | |
| var vectorLayer = new ol.layer.Vector({ | |
| source: vectorSource, | |
| style: new ol.style.Style({ | |
| image: new ol.style.Circle({ | |
| radius: 2, | |
| fill: new ol.style.Fill({color: 'yellow'}), | |
| stroke: null | |
| }) | |
| }) | |
| }); | |
| var map = new ol.Map({ | |
| layers: [ | |
| new ol.layer.Tile({ | |
| source: new ol.source.MapQuest({layer: 'sat'}) | |
| }), | |
| vectorLayer | |
| ], | |
| renderer: 'canvas', | |
| target: 'map', | |
| view: new ol.View2D({ | |
| center: [0, 0], | |
| zoom: 1 | |
| }) | |
| }); | |
| var extent = map.getView().getProjection().getExtent(); | |
| for (var i = 0; i < 500; i++) { | |
| var lon = randomUniform(extent[1] / 3, extent[3] / 3); | |
| var lat = randomUniform(extent[0] / 3, extent[2] / 3); | |
| var point = new ol.geom.Point([lon, lat]); | |
| var feature = new ol.Feature(point); | |
| feature.set('velocity', [0, 0]); | |
| feature.set('acceleration', [0, 0]); | |
| vectorSource.addFeature(feature); | |
| } | |
| map.on('postcompose', function(event) { | |
| var features = vectorSource.getFeatures(); | |
| for (var i = 0, ii = features.length; i < ii; i++) { | |
| var feature = features[i]; | |
| var velocity = feature.get('velocity'); | |
| var acceleration = feature.get('acceleration'); | |
| var geometry = feature.get('geometry'); | |
| var coordinates = geometry.getCoordinates(); | |
| velocity[0] += acceleration[0]; | |
| velocity[1] += acceleration[1]; | |
| coordinates[0] += velocity[0]; | |
| coordinates[1] += velocity[1]; | |
| if (ol.extent.containsCoordinate(extent, coordinates)) { | |
| geometry.setCoordinates(coordinates); | |
| } else { | |
| // FIXME | |
| } | |
| } | |
| map.render(); | |
| }); | |
| map.on('singleclick', function(evt) { | |
| var features = vectorSource.getFeatures(); | |
| for (var i = 0, ii = features.length; i < ii; i++) { | |
| var feature = features[i]; | |
| var coordinates = feature.getGeometry().getCoordinates(); | |
| var dx = evt.coordinate[0] - coordinates[0]; | |
| var dy = evt.coordinate[1] - coordinates[1]; | |
| var force = - 1e9 / (dx * dx + dy * dy); | |
| feature.set('acceleration', [dx * force, dy * force]); | |
| } | |
| }); | |
| var prevContext; | |
| vectorLayer.on('render', function(evt) { | |
| var context = evt.context; | |
| if (!prevContext) { | |
| prevContext = document.createElement('canvas').getContext('2d'); | |
| prevContext.canvas.width = context.canvas.width; | |
| prevContext.canvas.height = context.canvas.height; | |
| } | |
| prevContext.globalCompositeOperation = 'destination-out'; | |
| prevContext.fillStyle = 'rgba(0, 0, 0, .1)'; | |
| prevContext.fillRect(0, 0, prevContext.canvas.width, prevContext.canvas.height); | |
| prevContext.globalCompositeOperation = 'lighter'; | |
| prevContext.drawImage(context.canvas, 0, 0); | |
| context.drawImage(prevContext.canvas, 0, 0); | |
| }); | |
| </script> | |
| </body> | |
| </html> |
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