cesium-wind.rar_cesium 风_cesium 绘制风场_cesium-wind_curiousx2p_渲染中

//define([ 'windy/Particle', 'windy/WindField'], function ( Particle, WindField) { var _primitives = null; var SPEED_RATE = 0.15; //var PARTICLES_NUMBER =2000;//默认2000 var PARTICLE_MULTIPLIER = 1 / 300; // particle count scalar (completely arbitrary--this values looks nice) const PARTICLE_REDUCTION = (Math.pow(window.devicePixelRatio, 1 / 3) || 1.6); // multiply particle count for mobiles by this amount var MAX_AGE = 10; var BRIGHTEN = 1.5; var Windy = function (json, cesiumViewer) { this.windData = json; this.windField = null; this.particles = []; this.lines = null; _primitives = cesiumViewer.scene.primitives; this._init(); }; Windy.prototype = { constructor: Windy, _init: function () { // 创建风场网格 this.windField = this.createField(); /*var particleCount = Math.round( bounds.width * bounds.height * PARTICLE_MULTIPLIER); if (this.isMobile()) { particleCount *= PARTICLE_REDUCTION; }*/ var particleCount = 2000; // 创建风场粒子 for (var i = 0; i < particleCount; i++) { this.particles.push(this.randomParticle(new Particle())); } }, createField: function () { var data = this._parseWindJson(); return new WindField(data); }, animate: function () { var self = this, field = self.windField, particles = self.particles; var instances = [], nextX = null, nextY = null, xy = null, uv = null; particles.forEach(function (particle) { if (particle.age <= 0) { self.randomParticle(particle); } if (particle.age > 0) { var x = particle.x, y = particle.y; if (!field.isInBound(x, y)) { particle.age = 0; } else { uv = field.getIn(x, y); nextX = x + SPEED_RATE * uv[0]; nextY = y + SPEED_RATE * uv[1]; particle.path.push(nextX, nextY); particle.x = nextX; particle.y = nextY; instances.push(self._createLineInstance(self._map(particle.path), particle.age / particle.birthAge)); particle.age--; } } }); if (instances.length <= 0) { this.removeLines(); } self._drawLines(instances); }, _parseWindJson: function () { var uComponent = null, vComponent = null, header = null; this.windData.forEach(function (record) { var type = record.header.parameterCategory + "," + record.header.parameterNumber; switch (type) { case "2,2": uComponent = record['data']; header = record['header']; break; case "2,3": vComponent = record['data']; break; default: break; } }); return { header: header, uComponent: uComponent, vComponent: vComponent }; }, removeLines: function () { if (this.lines) { _primitives.remove(this.lines); this.lines.destroy(); } }, //求路径上点 _map: function (arr) { var length = arr.length, field = this.windField, dx = field.dx, dy = field.dy, west = field.west, south = field.north, newArr = []; for (var i = 0; i <= length - 2; i += 2) { newArr.push( west + arr[i] * dx, south - arr[i + 1] * dy ) } return newArr; }, _createLineInstance: function (positions, ageRate) { var colors = [], length = positions.length, count = length / 2; for (var i = 0; i < length; i++) { colors.push(Cesium.Color.WHITE.withAlpha(i / count * ageRate * BRIGHTEN)); } return new Cesium.GeometryInstance({ geometry: new Cesium.PolylineGeometry({ positions: Cesium.Cartesian3.fromDegreesArray(positions), colors: colors, width: 1.5, colorsPerVertex: true }) }); }, _drawLines: function (lineInstances) { this.removeLines(); var linePrimitive = new Cesium.Primitive({ appearance: new Cesium.PolylineColorAppearance({ translucent: true }), geometryInstances: lineInstances, asynchronous: false }); this.lines = _primitives.add(linePrimitive); }, randomParticle: function (particle) { var safe = 30, x, y; do { x = Math.floor(Math.random() * (this.windField.cols - 2)); y = Math.floor(Math.random() * (this.windField.rows - 2)); } while (this.windField.getIn(x, y)[2] <= 0 && safe++ < 30); particle.x = x; particle.y = y; particle.age = Math.round(Math.random() * MAX_AGE);//每一次生成都不一样 particle.birthAge = particle.age; particle.path = [x, y]; return particle; }, isMobile: function () { return (/android|blackberry|iemobile|ipad|iphone|ipod|opera mini|webos/i).test( navigator.userAgent); } }; //return Windy; //})