cesium-在选定的点上绘制一组圆形的线条

Question

我要从点击的点绘制一组圆形的线条。我的代码工作正常，但它绘制的圆形远离点击的点。有人能帮我弄清楚我的错误在哪里吗？

var viewer = new Cesium.Viewer('cesiumContainer'); 
var handler = new Cesium.ScreenSpaceEventHandler(viewer.canvas); 
handler.setInputAction(function(click) { 
    var alertText = ''; 
    function addToMessage(key, value) { 
     alertText += key + ': ' + value + '\n'; 
    } 

    // var pickedObject = scene.pick(click.position); 

     // addToMessage('target', pickedObject.id.id); 
     var position = viewer.camera.pickEllipsoid(click.position); 
     addToMessage('screenX', click.position.x); 
     addToMessage('screenY', click.position.y); 
     addToMessage('didHitGlobe', Cesium.defined(position)); 
     var cartographicPosition = Cesium.Ellipsoid.WGS84.cartesianToCartographic(position); 
     addToMessage('longitude', cartographicPosition.longitude); 
     addToMessage('latitude', Cesium.Math.toDegrees(cartographicPosition.latitude)); 
     terrainSamplePositions = [cartographicPosition]; 
     Cesium.sampleTerrain(viewer.terrainProvider, 9, terrainSamplePositions).then(function() { 
      addToMessage('height', terrainSamplePositions[0].height); 
     }).always(function() { 
      // alert(alertText); 
     }); 

    // var x=Cesium.Math.toDegrees(cartographicPosition.latitude); 
    // var y=Cesium.Math.toDegrees(cartographicPosition.longitude); 
    var y=cartographicPosition.latitude; 
    var x=cartographicPosition.longitude; 
    // alert(x);//35 
    // alert(y);//-101 
    var radius=0.01; 
    var segmants=360; 
    var seg=Math.PI*2/segmants; 
    var origin= new Cesium.Cartesian3(x, y, 0); 
    var shape = []; 
    for (i = 0; i <= segmants; i++) { 
     var teta=seg*i; 
     var a =x+Math.cos(teta)*radius; 
     var b =y+Math.sin(teta)*radius; 
     // shape.push(a); 
     // shape.push(b); 
     var origin= new Cesium.Cartesian3(x, y, 0); 
     console.log(["origin is",origin.y,origin.x]); 

     var direction= new Cesium.Cartesian3(a, b, 0); 
     console.log(["direction is",direction.y,direction.x]); 



     viewer.entities.add({ 
      name : 'Red line on the surface', 
      polyline : { 
       positions : Cesium.Cartesian3.fromCartographicArray([origin.x, origin.y, 
        direction.x, direction.y]), 
       width : 5, 
       material : Cesium.Color.RED 
      } 
     }); 






    } 



    viewer.zoomTo(resultPolygon.position); 
}, Cesium.ScreenSpaceEventType.LEFT_CLICK); 

感谢您的帮助

Answer 1

如果想画一个圆圈，简单与轮廓绘制ellipse geometry。对于圆，将semiMinorAxis设置为与semiMajorAxis相同的值，其值为米。

var position = viewer.camera.pickEllipsoid(click.position); 
var cartographicPosition = Cesium.Ellipsoid.WGS84.cartesianToCartographic(position); 
var y = cartographicPosition.latitude; 
var x = cartographicPosition.longitude; 

var entity = viewer.entities.add({ 
     position: Cesium.Cartesian3.fromRadians(x, y), 
     ellipse : { 
      semiMinorAxis : 10, 
      semiMajorAxis : 10, 
      fill : false,   
      outline: true, 
      material : Cesium.Color.RED, 
      outlineColor : Cesium.Color.RED, 
      outlineWidth : 2 
     } 
}); 
viewer.zoomTo(entity);