Cesium雾效果

本文是一个下雾的效果

1. 下雾效果的类代码：

class FogEffect {
    constructor(viewer, options) {
        if (!viewer) throw new Error('no viewer object!');
        options = options || {};
        this.visibility = Cesium.defaultValue(options.visibility, 0.1);
        this.color = Cesium.defaultValue(options.color,
            new Cesium.Color(0.8, 0.8, 0.8, 0.5));
        this._show = Cesium.defaultValue(options.show, !0);
        this.viewer = viewer;
        this.init();
    }

    init() {
        this.fogStage = new Cesium.PostProcessStage({
            name: 'czm_fog',
            fragmentShader: this.fog(),
            uniforms: {
                visibility: () => {
                    return this.visibility;
                },
                fogColor: () => {
                    return this.color;
                }
            }
        });
        this.viewer.scene.postProcessStages.add(this.fogStage);
    }

    destroy() {
        if (!this.viewer || !this.fogStage) return;
        this.viewer.scene.postProcessStages.remove(this.fogStage);
        this.fogStage.destroy();
        delete this.visibility;
        delete this.color;
    }

    show(visible) {
        this._show = visible;
        this.fogState.enabled = this._show;
    }

    fog() {
        return "uniform sampler2D colorTexture;\n\
         uniform sampler2D depthTexture;\n\
         uniform float visibility;\n\
         uniform vec4 fogColor;\n\
         varying vec2 v_textureCoordinates; \n\
         void main(void) \n\
         { \n\
            vec4 origcolor = texture2D(colorTexture, v_textureCoordinates); \n\
            float depth = czm_readDepth(depthTexture, v_textureCoordinates); \n\
            vec4 depthcolor = texture2D(depthTexture, v_textureCoordinates); \n\
            float f = visibility * (depthcolor.r - 0.3) / 0.2; \n\
            if (f < 0.0) f = 0.0; \n\
            else if (f > 1.0) f = 1.0; \n\
            gl_FragColor = mix(origcolor, fogColor, f); \n\
         }\n";
    }
}

2. 页面使用方式
   引入上面的js即可

new Cesium.FogEffect(viewer, {
            visibility: 0.2,
            color: new Cesium.Color(0.8, 0.8, 0.8, 0.3)
        });

3. 效果图

   
   
   cesium_fog.png