Cesium 自定义Material 系列 （二十）

对于缩放 圆效果 我们先定义一下他的interface, 方便使用的人知道他的调用参数

export interface PMaterialZoom{

color?: any,

speed?: number,

zoom?: boolean,

}

对于缩放 圆我们叫 MaterialZoom

```javascript

import { MaterialProperty } from "./MaterialProperty";

const defaultOption: PMaterialZoom = {

color: new Cesium.Color(1.0, 0.0, 0.0, 0.7),

speed: 1,

zoom:true//true:放大，false缩小

}

//缩放效果

export class MaterialZoom extends MaterialProperty {

public _getType(option: PMaterialZoom) {

// 由于参数需要动态变动，所以count有变动，认为是新着色器

const { zoom=true } = option;

returnMaterialTrailImage${zoom}

}

constructor(option = defaultOption) {

super(MaterialZoom.prototype, defaultOption, option);

}

protected _getTranslucent(material: any) {

return material.uniforms.color.alpha < 1.0;

}

protected getSource(option: PMaterialZoom): string {

const { zoom=true } = option;

let timeStr;

if(zoom){

timeStr = "float time = fract(czm_frameNumber * speed / 1000.0);";

}else{

timeStr = " float time = 1.0-fract(czm_frameNumber * speed / 1000.0);"

}

return `

uniform vec4 color;

uniform float speed;

czm_material czm_getMaterial(czm_materialInput materialInput){

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