Cesium 自定义Primitive - 圆

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一、创作思路

        1、创建一个自定义CustomPrimitive

        2、然后根据两个点，生成圆

        3、方便后期绘制圆

二、实现代码

        1、在vue的包中加入turf.

        npm install @turf/turf

        1、创建一个CustomCirclePrimitive类,并加入更新的代码

export default class CustomCirclePrimitive {constructor(options) {this._props = options;/*** 渲染列表* @type {*[]}* @private*/this._primitiveCollection = [];this._dynamicPrimitive = undefined;}updateProperty(options) {this._props = {...this._props,...options,};}/*** 更新* @param frameState*/update(frameState) {this._primitiveCollection.forEach((primitive) => {primitive && !primitive.isDestroyed() && primitive.update(frameState);});if (this._dynamicPrimitive) {this._dynamicPrimitive.update(frameState);}}destroy() {this._primitiveCollection.forEach((primitive) => {primitive && !primitive.isDestroyed() && primitive.destroy();});this._primitiveCollection = undefined;if (this._dynamicPrimitive) {this._dynamicPrimitive.destroy();}this._dynamicPrimitive = undefined;}
}

        2、编写更新代码

updateProperty(options) {this._props = {...this._props,...options,};let positions = this._props.positions;let complete = this._props.complete;if (positions.length > 1) {let dynamicPrimitive = this._dynamicPrimitive;if (dynamicPrimitive) {dynamicPrimitive.destroy();dynamicPrimitive = null;this._dynamicPrimitive = null;}let primitive = this.initCirclePrimitive(positions);if (complete) {this._primitiveCollection.push(primitive);} else {this._dynamicPrimitive = primitive;}}}

        3、编写绘制圆的代码

        设定第一个点为中心点，第二个点为半径上面的点

        半径为第一个点到第二个点的距离

initCirclePrimitive(positions) {let centerP = positions[0];let radiusP = positions[1];let radius = getDistance(centerP, radiusP);let circlePositions = getCircle(centerP, radius);let instance = new GeometryInstance({geometry: new GroundPolylineGeometry({positions: circlePositions,width: 4,}),});return new GroundPolylinePrimitive({geometryInstances: instance,appearance: new PolylineMaterialAppearance({material: new Material({fabric: {type: "Color",uniforms: {color: Color.fromCssColorString("#ff0000"),},},}),}),asynchronous: false,});}

        4、额外的算法代码

        

const ellipsoid = Ellipsoid.WGS84;
/*** 将世界坐标系转换为球面坐标系* @param {Cartesian3} position* @return {{alt: number, lon: number, lat: number}}*/
export const Cartesian3ToWgs84 = (position) => {let cartographic = ellipsoid.cartesianToCartographic(position);let lon = CesiumMath.toDegrees(cartographic.longitude);let lat = CesiumMath.toDegrees(cartographic.latitude);let alt = cartographic.height;return {lon,lat,alt,};
};
/*** 计算分段的距离* @param {Cartesian3} startPoint 起点* @param {Cartesian3} endPoint 终点* @return {number} 平面距离*/
export const getDistance = (startPoint, endPoint) => {let start84 = Cartesian3ToWgs84(startPoint);let end84 = Cartesian3ToWgs84(endPoint);let startPosition = point([start84.lon, start84.lat]);let endPosition = point([end84.lon, end84.lat]);let startToEnd = distance(startPosition, endPosition, options);return startToEnd * 1000;
};
/*** 根据半径和中心点，获取圆形* @param center* @param radius* @return {Cartesian3[]}*/
export const getCircle = (center, radius) => {let center84 = Cartesian3ToWgs84(center);let centerP = [center84.lon, center84.lat];let circleInfo = circle(centerP, radius / 1000.0, options);return circleInfo.geometry.coordinates[0].map((item) => {return Cartesian3.fromDegrees(item[0], item[1]);});
};

        5、测试代码

        

let primitive = new CustomCirclePrimitive();viewer.scene.primitives.add(primitive);let lon = 106;let count = 0;let lat = 26;let centerP = Cartesian3.fromDegrees(lon, lat);let interval = setInterval(() => {let lonTemp = lon + count * 0.00001;let nextP = Cartesian3.fromDegrees(lonTemp, lat);primitive.updateProperty({positions: [centerP, nextP],complete: count === 11,});if (count > 10) {clearInterval(interval);}count++;}, 1000);

三、实现效果

四、代码

import {Cartesian3,Color,GeometryInstance,GroundPolylineGeometry,GroundPolylinePrimitive,Material,PolylineMaterialAppearance,
} from "cesium";
import {getCircle,getDistance,
} from "@/components/MilitaryPlot/utils/PlotUtils";export default class CustomCirclePrimitive {constructor(options) {this._props = options;/*** 渲染列表* @type {*[]}* @private*/this._primitiveCollection = [];this._dynamicPrimitive = undefined;}updateProperty(options) {this._props = {...this._props,...options,};let positions = this._props.positions;let complete = this._props.complete;if (positions.length > 1) {let dynamicPrimitive = this._dynamicPrimitive;if (dynamicPrimitive) {dynamicPrimitive.destroy();dynamicPrimitive = null;this._dynamicPrimitive = null;}let primitive = this.initCirclePrimitive(positions);if (complete) {this._primitiveCollection.push(primitive);} else {this._dynamicPrimitive = primitive;}}}initCirclePrimitive(positions) {let centerP = positions[0];let radiusP = positions[1];let radius = getDistance(centerP, radiusP);let circlePositions = getCircle(centerP, radius);let instance = new GeometryInstance({geometry: new GroundPolylineGeometry({positions: circlePositions,width: 4,}),});return new GroundPolylinePrimitive({geometryInstances: instance,appearance: new PolylineMaterialAppearance({material: new Material({fabric: {type: "Color",uniforms: {color: Color.fromCssColorString("#ff0000"),},},}),}),asynchronous: false,});}/*** 更新* @param frameState*/update(frameState) {this._primitiveCollection.forEach((primitive) => {primitive && !primitive.isDestroyed() && primitive.update(frameState);});if (this._dynamicPrimitive) {this._dynamicPrimitive.update(frameState);}}destroy() {this._primitiveCollection.forEach((primitive) => {primitive && !primitive.isDestroyed() && primitive.destroy();});this._primitiveCollection = undefined;if (this._dynamicPrimitive) {this._dynamicPrimitive.destroy();}this._dynamicPrimitive = undefined;}
}

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