javascript - 如何从任意点进行光线转换

Question

所以这是我的问题，因为我在一个项目中使用了三个 js，其中用户给出了 x y 坐标，在三个 js 场景上添加了一个点，我需要计算后面碰撞对象的位置/在这一点之前。我尝试使用 Raycaster 但我找不到一个简单的示例来说明如何将 Raycaster 与由点定义的向量一起使用:/ 到目前为止，这是我的代码

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

要从任意点进行光线转换，您可以使用此模式:

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 r.75