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+# Raycast
+
+射线用来求交的
+
+```js
+class Object3D extends EventDispatcher {
+    raycast( /* raycaster, intersects */ ) {}
+}
+class Raycaster {
+
+}
+```
+要想进行拾取操作，就需要实现raycast，新的对象要继承Object3D并实现它，就可以通过Raycaster测试相交
+内部支持的类型有
+Points,
+Line,
+Sprite,
+Mesh,
+InstancedMesh,
+LOD,