在Cesium中给管道添加水流效果

添加效果前后对比：


关键代码：

/*** 水流粒子，目前支持向上或者向下的效果* @param {Number} x* @param {Number} y* @param {Number} z* @param {Number} options* @example* options = {*    color: Cesium.Color.AZURE,*    emissionRate: 5, //影响水流速度*    direction: "upword",*    heightReference : Cesium.HeightReference.RELATIVE_TO_GROUND* }*/renderWaterParticle(x, y, z, options = {}) {options = this.defaultParticleOptions(options);if (options.heightReference === Cesium.HeightReference.RELATIVE_TO_GROUND) {//获取当前位置的地形高程const terrainHeight = this._viewer.scene.globe.getHeight(Cesium.Cartographic.fromDegrees(x, y));z += terrainHeight;}const translationOffset = Cesium.Matrix4.fromTranslation(this.particlesOffset, new Cesium.Matrix4());const planePosition = Cesium.Cartesian3.fromDegrees(x, y, z);const translationOfPlane = Cesium.Matrix4.fromTranslation(planePosition, new Cesium.Matrix4());const particlesModelMatrix = Cesium.Matrix4.multiplyTransformation(translationOfPlane,translationOffset,new Cesium.Matrix4());// creating the particle systemsconst rocketOptions = {numberOfSystems: 20.0,iterationOffset: 0.5,cartographicStep: 0.0000001,baseRadius: 0.000005,...options,};const rocketSystems = [];this.createParticleSystems(rocketOptions, rocketSystems, particlesModelMatrix);this.showAll(rocketSystems, true);this.particleSystems.push(...rocketSystems);}createParticleSystems(options, systemsArray, particlesModelMatrix) {const matrix4Scratch = new Cesium.Matrix4();let scratchAngleForOffset = 0.0;const scratchOffset = new Cesium.Cartesian3();const imageSize = new Cesium.Cartesian2(8.0, 8.0);const length = options.numberOfSystems;for (let i = 0; i < length; ++i) {scratchAngleForOffset = (Math.PI * Math.random() * 2) / options.numberOfSystems;scratchOffset.x += options.baseRadius * Math.cos(scratchAngleForOffset);scratchOffset.y += options.baseRadius * Math.sin(scratchAngleForOffset);const emitterModelMatrix = Cesium.Matrix4.fromTranslation(scratchOffset, matrix4Scratch);const color = options.color;const force = this.forceFunction(options, i);const item = this._viewer.scene.primitives.add(new Cesium.ParticleSystem({image: this.getImage(),startColor: color,endColor: color.withAlpha(0.0),particleLife: 1,speed: 0.0000005,imageSize: imageSize,emissionRate: options.emissionRate,emitter: new Cesium.CircleEmitter(1),lifetime: 1,updateCallback: force,modelMatrix: particlesModelMatrix,emitterModelMatrix: emitterModelMatrix,}));systemsArray.push(item);}}showAll(systemsArray, show) {const length = systemsArray.length;for (let i = 0; i < length; ++i) {systemsArray[i].show = show;}}