我无法理解如何使用JavasScript执行以下数学方程式
我无法理解如何使用JavasScript执行以下数学方程式
提问于 2016-09-26 18:15:52
我无法理解函数labelBox中使用的这行代码this.position = convertlatlonToVec3(cardinal.lat, cardinal.lon).multiplyScalar(radius);。multiplyScalar(radius)是如何工作的。
function convertlatlonToVec3(lat, lon)
{
var cosLat = Math.cos(circle.getCenter().lat() * degrees);
var sinLat = Math.sin(circle.getCenter().lat() * degrees);
var xSphere = radiusEquator * cosLat;
var ySphere = 0;
var zSphere = radiusPoles * sinLat;
var rSphere = Math.sqrt(xSphere*xSphere + ySphere*ySphere + zSphere*zSphere);
var tmp = rSphere * Math.cos(lat * degrees);
xSphere = tmp * Math.cos((lon - circle.getCenter().lng()) * degrees);
ySphere = tmp * Math.sin((lon - circle.getCenter().lng()) * degrees);
zSphere = rSphere * Math.sin(lat * degrees);
var x = -ySphere/circle.getRadius();
var y = (zSphere*cosLat - xSphere*sinLat)/circle.getRadius();
var z = 0;
return new THREE.Vector3(x, y, z);
}
function labelBox(cardinal, radius, root)
{
this.screenvector = new THREE.Vector3(0,0,0);
this.labelID = 'MovingLabel'+ cardinal.ID;
this.position = convertlatlonToVec3(cardinal.lat, cardinal.lon).multiplyScalar(radius);
}回答 1
Stack Overflow用户
回答已采纳
发布于 2016-09-26 18:40:18
Three.js文档
对于THREE.Vector3 multiplyScalar方法，look文档是
.multiplyScalar (S)此
将此向量乘以标量s。
此方法的内容可以在in the THREE.Vector3 class中找到，如下所示：
multiplyScalar: function ( scalar ) {
if ( isFinite( scalar ) ) {
this.x *= scalar;
this.y *= scalar;
this.z *= scalar;
} else {
this.x = 0;
this.y = 0;
this.z = 0;
}
return this;
},页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/39700167
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