Question

let snowParticleSize = scene.drawingBufferWidth / 100.0;
let snowRadius = 100000.0;
let minimumSnowImageSize = new Cesium.Cartesian2(snowParticleSize, snowParticleSize);
let maximumSnowImageSize = new Cesium.Cartesian2(snowParticleSize * 2.0, snowParticleSize * 2.0);
let snowSystem;

let snowGravityScratch = new Cesium.Cartesian3();
function snowUpdate(particle, dt) {
    console.log("update");
    snowGravityScratch = Cesium.Cartesian3.normalize(particle.position, snowGravityScratch);
    Cesium.Cartesian3.multiplyByScalar(snowGravityScratch, Cesium.Math.randomBetween(-30.0, -300.0), snowGravityScratch);
    particle.velocity = Cesium.Cartesian3.add(particle.velocity, snowGravityScratch, particle.velocity);

    let distance = Cesium.Cartesian3.distance(scene.camera.position, particle.position);
    if (distance > snowRadius) {
        particle.endColor.alpha = 0.0;
    } else {
        particle.endColor.alpha = snowSystem.endColor.alpha / (distance / snowRadius + 0.1);
    }
}

snowSystem = new Cesium.ParticleSystem({
    modelMatrix : new Cesium.Matrix4.fromTranslation(scene.camera.position),
    minimumSpeed : -1.0,
    maximumSpeed : 0.0,
    lifetime : 15.0,
    emitter : new Cesium.SphereEmitter(snowRadius),
    startScale : 0.5,
    endScale : 1.0,
    image : './img/snowflake_particle.png',
    emissionRate : 7000.0,
    startColor : Cesium.Color.WHITE.withAlpha(0.0),
    endColor : Cesium.Color.WHITE.withAlpha(1.0),
    minimumImageSize : minimumSnowImageSize,
    maximumImageSize : maximumSnowImageSize,
    updateCallback : snowUpdate
});
scene.primitives.add(snowSystem);

这是Cesium一个示例的代码，核心代码这样的，测试运行可以看到snowSystem添加成功了，但是看不到效果，控制台看updateCallback里面的log也没有运行

Answer 1

粒子特效您可以参考如下示例：

http://support.supermap.com.cn:8090/webgl/examples/editor.html#Particle%20System

Comments

这个和示例挺像的，但是为什么不能运行呢？

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看看是不是没有图片什么的。