下雪效果-源代码示例 运行 重置

                    <!DOCTYPE html>

<html>
<head>
    <meta charset='UTF-8'/>
    <meta name='viewport' content='initial-scale=1,maximum-scale=1,user-scalable=no'/>
    <link href='http://bigemap.com:9000/bigemap-gl.js/v1.1.0/Widgets/widgets.css' rel='stylesheet'/>
    <script src='http://bigemap.com:9000/bigemap-gl.js/v1.1.0/bigemap-gl.js'></script>
    <style>
        body {
            margin: 0;
            padding: 0;
        }

        #container {
            position: absolute;
            top: 0;
            bottom: 0;
            width: 100%;
        }
        .bmgl-widget-credits{display:none}
    </style>
    <title>part_test</title>
</head>
<body>

<div id='container'></div>

<script>
         bmgl.Config.HTTP_URL = 'http://bigemap.com:9000';
    var viewer = new bmgl.Viewer('container', {mapId:'bigemap.googlemap-satellite',requestRenderMode:false});
    var lat = 30.6;
    var lon = 104.055;
    //取消双击事件
    viewer.BMWidget.screenSpaceEventHandler.removeInputAction(bmgl.ScreenSpaceEventType.LEFT_DOUBLE_CLICK);
    //设置初始位置
    viewer.camera.setView({
        destination: bmgl.Cartesian3.fromDegrees(lon, lat, 300000)
    });

    //定义下雪场景 着色器
    function FS_Snow() {
        return "uniform sampler2D colorTexture;\n\
    varying vec2 v_textureCoordinates;\n\
\n\
    float snow(vec2 uv,float scale)\n\
    {\n\
        float time = czm_frameNumber / 60.0;\n\
        float w=smoothstep(1.,0.,-uv.y*(scale/10.));if(w<.1)return 0.;\n\
        uv+=time/scale;uv.y+=time*2./scale;uv.x+=sin(uv.y+time*.5)/scale;\n\
        uv*=scale;vec2 s=floor(uv),f=fract(uv),p;float k=3.,d;\n\
        p=.5+.35*sin(11.*fract(sin((s+p+scale)*mat2(7,3,6,5))*5.))-f;d=length(p);k=min(d,k);\n\
        k=smoothstep(0.,k,sin(f.x+f.y)*0.01);\n\
        return k*w;\n\
    }\n\
\n\
    void main(void){\n\
        vec2 resolution = czm_viewport.zw;\n\
        vec2 uv=(gl_FragCoord.xy*2.-resolution.xy)/min(resolution.x,resolution.y);\n\
        vec3 finalColor=vec3(0);\n\
        float c = 0.0;\n\
        c+=snow(uv,30.)*.0;\n\
        c+=snow(uv,20.)*.0;\n\
        c+=snow(uv,15.)*.0;\n\
        c+=snow(uv,10.);\n\
        c+=snow(uv,8.);\n\
        c+=snow(uv,6.);\n\
        c+=snow(uv,5.);\n\
        finalColor=(vec3(c)); \n\
        gl_FragColor = mix(texture2D(colorTexture, v_textureCoordinates), vec4(finalColor,1), 0.3); \n\
\n\
    }\n\
";
    }

    var collection = viewer.scene.postProcessStages;
    var fs_snow = FS_Snow();
    var snow = new bmgl.PostProcessStage({
        name: 'czm_snow',
        fragmentShader: fs_snow
    });
    collection.add(snow);
</script>
</body>
</html>                                                                                                                                                                    
源码