注意点：
1、开启射线检测
cc.director.getPhysics3DManager().enabled = true;
2: 响应射线的物体要加3D碰撞盒 BoxCollider3D，勾选3d,且节点大小用scale控制（width=100改为scaleX=100）
3:响应射线的物体分组group要设置为3D，分组管理里需要勾选3D和3D的碰撞

demo下载：
https://download.csdn.net/download/K86338236/89527924

const { ccclass, property } = cc._decorator;

@ccclass
export default class CameraTouchCtrl extends cc.Component {

    @property(cc.Camera)
    camera: cc.Camera = null;//3D相机

    @property(cc.Node)
    touchNode: cc.Node = null;//2D触摸节点
    start() {
        //开启射线检测
        cc.director.getPhysics3DManager().enabled = true;
        this.touchNode.on(cc.Node.EventType.TOUCH_START, this.onTouchStart, this);
    }

    /**检测射线 */
    onTouchStart(event) {
        let touchLoc = event.touch.getLocation();
        let ray = this.camera.getComponent(cc.Camera).getRay(touchLoc);
        let maxDistance = 1000;//检测的最远距离，如果物体远，需要改大数值
        let rayColliderGroupName = "3D";//碰撞分组，分组管理里需要勾选3D和3D动碰撞
        //响应射线的物体要加3D碰撞盒 BoxCollider3D，分组group设置为3D
        const result = cc.director.getPhysics3DManager().raycastClosest(ray, rayColliderGroupName, maxDistance, false);
        if (result) {
            let box = result.collider.node
            box.scale += 0.01
        }
    }
}