class SnowEffect {
|
constructor(viewer, options) {
|
if (!viewer) throw new Error("no viewer object!");
|
options = options || {};
|
this.snowSize = Cesium.defaultValue(options.snowSize, 0.02); // ❄️大小，最好小于0.02
|
this.snowSpeed = Cesium.defaultValue(options.snowSpeed, 100.0); // 速度
|
this.snowColor = Cesium.defaultValue(options.snowColor, new Cesium.Color(1.0, 1.0, 1.0, 1.0)); // 颜色
|
this.viewer = viewer;
|
this.init();
|
}
|
|
init() {
|
this.snowStage = new Cesium.PostProcessStage({
|
name: "czm_snow",
|
fragmentShader: this.snow(),
|
uniforms: {
|
snowSize: () => {
|
return this.snowSize;
|
},
|
snowSpeed: () => {
|
return this.snowSpeed;
|
},
|
snowColor: () => {
|
return this.snowColor;
|
},
|
},
|
});
|
this.viewer.scene.postProcessStages.add(this.snowStage);
|
}
|
|
destroy() {
|
if (!this.viewer || !this.snowStage) return;
|
this.viewer.scene.postProcessStages.remove(this.snowStage);
|
const isDestroyed = this.snowStage.isDestroyed();
|
// 先检查是否被销毁过，如果已经被销毁过再调用destroy会报错
|
if (!isDestroyed) {
|
this.snowStage.destroy();
|
}
|
delete this.snowSize;
|
delete this.snowSpeed;
|
}
|
show(visible) {
|
this.snowStage.enabled = visible;
|
}
|
|
snow() {
|
return "uniform sampler2D colorTexture;\n\
|
in vec2 v_textureCoordinates;\n\
|
uniform float snowSpeed;\n\
|
uniform float snowSize;\n\
|
uniform vec4 snowColor;\n\
|
float snow(vec2 uv,float scale)\n\
|
{\n\
|
float time=czm_frameNumber/snowSpeed;\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)*snowSize);\n\
|
return k*w;\n\
|
}\n\
|
out vec4 fragColor;\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=smoothstep(1.,0.3,clamp(uv.y*.3+.8,0.,.75));\n\
|
float c=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) * snowColor.rgb);\n\
|
fragColor=mix(texture(colorTexture,v_textureCoordinates),vec4(finalColor,1),.5);\n\
|
}\n\
|
";
|
}
|
}
|
export default SnowEffect;
|
