Hololens入门之手势识别(手检测反馈)

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Hololens入门之手势识别(手检测反馈)

本文实现当使用者手出现在Hololens视野范围内时，跟踪手并给出反馈的效果。

1、在Manager上添加HandsManager脚本组件，用于追踪识别手

HandsManager.cs如下（直接使用HoloTooKit中脚本）

// Copyright (c) Microsoft Corporation. All rights reserved.// Licensed under the MIT License. See LICENSE in the project root for license information.using System.Collections.Generic;using UnityEngine.VR.WSA.Input;namespace HoloToolkit.Unity{    /// <summary>    /// HandsManager determines if the hand is currently detected or not.    /// </summary>    public partial class HandsManager : Singleton<HandsManager>    {        /// <summary>        /// HandDetected tracks the hand detected state.        /// Returns true if the list of tracked hands is not empty.        /// </summary>        public bool HandDetected        {            get { return trackedHands.Count > 0; }        }        private HashSet<uint> trackedHands = new HashSet<uint>();        void Awake()        {            //识别到来源            InteractionManager.SourceDetected += InteractionManager_SourceDetected;            //来源丢失            InteractionManager.SourceLost += InteractionManager_SourceLost;        }        private void InteractionManager_SourceDetected(InteractionSourceState state)        {            // 检测来源是否为手，如果是手则加入跟踪集合            if (state.source.kind != InteractionSourceKind.Hand)            {                return;            }            trackedHands.Add(state.source.id);        }        private void InteractionManager_SourceLost(InteractionSourceState state)        {            // 检测丢失的来源是否为手，如果是手则从跟踪集合中去除            if (state.source.kind != InteractionSourceKind.Hand)            {                return;            }            if (trackedHands.Contains(state.source.id))            {                trackedHands.Remove(state.source.id);            }        }        void OnDestroy()        {            InteractionManager.SourceDetected -= InteractionManager_SourceDetected;            InteractionManager.SourceLost -= InteractionManager_SourceLost;        }    }}

该脚本中使用到了底层API Interaction Input

底层API运行获得输入来源的更多详细信息，例如它在世界中的位置和速度。

如何处理底层交互事件
使用底层交互是很容易的：
1）注册InteractionManager事件
2）处理事件
停止它也很容易：
1）取消注册事件

处理底层交互事件
一旦注册了底层交互事件，在事件发生时你就可以得到回调。你可以使用获取到的时间信息来处理应用行为。

void InteractionManager_SourcePressed(InteractionSourceState state){// state变量里包含以下信息:// 当前凝视射线信息// 来源是否被点击// 位置、速度之类的属性// 来源id和来源类型 （ hand, voice, controller或其他）}

如何停止交互事件
当你不再想要关注一些事件后，只需要取消时间注册即可。

InteractionManager.SourcePressed -= InteractionManager_SourcePressed;

输入源变化事件
这些事件描述了输入源的当前状态：
1) detected（即将激活）
2) lost（即将取消激活）
3) updates（移动或者一些状态在变化）
4) is pressed（点击、按钮按下或者语音选中）
5) is released（点击结束，按钮松开，语音选中结束）

输入源状态
每个事件都会有一个InteractionSourceState参数，这个参数代表了实时输入源状态：
1) 是否是点击状态
2) InteractionSourceProperties包含了输入源位置信息 InteractionSourceLocation，能够获得当前输入源位置和速度信息
3) 凝视射线信息，用于判断事件发生时用户是否在注视目标
4) 来源类型信息，包括hand、voice、controller或者其他类型

2、在Cursor下新建Empty对象，并重命名为CursorBillboard，并添加Billboard脚本组件

Billboard脚本如下(可以直接在HoloToolKit中找到)

// Copyright (c) Microsoft Corporation. All rights reserved.// Licensed under the MIT License. See LICENSE in the project root for license information.using UnityEngine;namespace HoloToolkit.Unity{    public enum PivotAxis    {        // Rotate about all axes.        Free,        // Rotate about an individual axis.        X,        Y    }    /// <summary>    /// The Billboard class implements the behaviors needed to keep a GameObject    /// oriented towards the user.    /// </summary>    public class Billboard : MonoBehaviour    {        /// <summary>        /// The axis about which the object will rotate.        /// </summary>        [Tooltip("Specifies the axis about which the object will rotate (Free rotates about both X and Y).")]        public PivotAxis PivotAxis = PivotAxis.Free;        /// <summary>        /// Overrides the cached value of the GameObject's default rotation.        /// </summary>        public Quaternion DefaultRotation { get; private set; }        private void Awake()        {            // Cache the GameObject's default rotation.            DefaultRotation = gameObject.transform.rotation;        }        /// <summary>        /// Keeps the object facing the camera.        /// </summary>        private void Update()        {            // Get a Vector that points from the Camera to the target.            Vector3 forward;            Vector3 up;            // Adjust for the pivot axis. We need a forward and an up for use with Quaternion.LookRotation            switch (PivotAxis)            {                // If we're fixing one axis, then we're projecting the camera's forward vector onto                // the plane defined by the fixed axis and using that as the new forward.                case PivotAxis.X:                    Vector3 right = transform.right; // Fixed right                    forward = Vector3.ProjectOnPlane(Camera.main.transform.forward, right).normalized;                    up = Vector3.Cross(forward, right); // Compute the up vector                    break;                case PivotAxis.Y:                    up = transform.up; // Fixed up                    forward = Vector3.ProjectOnPlane(Camera.main.transform.forward, up).normalized;                    break;                // If the axes are free then we're simply aligning the forward and up vectors                // of the object with those of the camera.                 case PivotAxis.Free:                default:                    forward = Camera.main.transform.forward;                    up = Camera.main.transform.up;                    break;            }            // Calculate and apply the rotation required to reorient the object            transform.rotation = Quaternion.LookRotation(forward, up);        }    }}

3、在Cursor上添加CursorFeedback脚本组件

1）在HoloToolkit -> Input -> Prefabs中找到HandDetectedFeedback Prefab 并拖到CursorFeedback的hand detected asset上

2）将刚才创建的CursorBillboard拖到CursorFeedback的Feedback Parent上

CursorFeedback脚本如下（(可以直接在HoloToolKit中找到)）

// Copyright (c) Microsoft Corporation. All rights reserved.// Licensed under the MIT License. See LICENSE in the project root for license information.using UnityEngine;namespace HoloToolkit.Unity{    /// <summary>    /// CursorFeedback class takes GameObjects to give cursor feedback    /// to users based on different states.    /// </summary>    public class CursorFeedback : MonoBehaviour    {        [Tooltip("Drag a prefab object to display when a hand is detected.")]        public GameObject HandDetectedAsset;        private GameObject handDetectedGameObject;        [Tooltip("Drag a prefab object to parent the feedback assets.")]        public GameObject FeedbackParent;        void Awake()        {            if (HandDetectedAsset != null)            {                handDetectedGameObject = InstantiatePrefab(HandDetectedAsset);            }            else            {                Debug.LogError("Missing a required game object asset.  Check HandDetectedAsset is not null in editor.");            }        }        private GameObject InstantiatePrefab(GameObject inputPrefab)        {            GameObject instantiatedPrefab = null;            if (inputPrefab != null && FeedbackParent != null)            {                instantiatedPrefab = GameObject.Instantiate(inputPrefab);                // Assign parent to be the FeedbackParent                // so that feedback assets move and rotate with this parent.                instantiatedPrefab.transform.parent = FeedbackParent.transform;                // Set starting state of the prefab's GameObject to be inactive.                instantiatedPrefab.gameObject.SetActive(false);            }            else            {                Debug.LogError("Missing a required game object asset.  Check FeedbackParent is not null in editor.");            }            return instantiatedPrefab;        }        void Update()        {            UpdateHandDetectedState();        }        private void UpdateHandDetectedState()        {            if (handDetectedGameObject == null)            {                return;            }            handDetectedGameObject.SetActive(HandsManager.Instance.HandDetected);        }    }}

4、运行测试

当手出现在Hololens视野中时，手被检测到，在凝视射线处出现一个蓝色的小手（Hololens模拟器中需要处于hold状态才会出现蓝色小手，真机上只要手举起就可以）

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