如何從任意點Raycast

Question

所以這裏是我的問題，因爲我在一個項目中使用三個js，用戶給出x y座標一個點被添加到三個js場景，我需要計算碰撞對象的位置/在這一點之前。我試着用Raycaster，但我無法找到如何使用Raycaster由點定義的矢量一個簡單的例子：/ 這是我到目前爲止的代碼

var projector = new THREE.Projector(); 
    var directionVector = new THREE.Vector3(); 
    /* how could i use a vector defined by my origin point 

    var origin = new THREE.Vector3(x, y, 0); 

    instead of the camera vector as used below ? 
    */ 
    projector.unprojectVector(directionVector, camera); 
    directionVector.sub(camera.position); 
    directionVector.normalize(); 
    var ray = new THREE.Raycaster(); 
    ray.set(camera.position,directionVector) 
    var intersects = ray.intersectObjects(scene.children); 
     if (intersects.length > 0) { 
      console.log(intersects); 
     } 

Answer 1

從任意角度光線投射，你可以使用這個模式：

var raycaster = new THREE.Raycaster(); // create once, and reuse 
var origin = new THREE.Vector3(); // reuse it 
var direction = new THREE.Vector3(); // reuse it 
... 

origin.set(x, y, z); 
direction.set(0, 0, - 1).normalize(); // direction vector must have unit length 
raycaster.set(origin, direction); 
var intersects = raycaster.intersectObjects(objects, recursiveFlag); 
if (intersects.length > 0) {  
    // your code   
} 

three.js所r.75