力反馈入门教程

本教程将引导您创建一个简单的触觉模拟，该模拟同时考虑了刚度和阻尼，并模拟了与静态物体（例如一个球体）接触时的物理特性。 完成本教程后，您将获得一个模拟，通过它您可以感知球体的存在，并调整其刚度和阻尼特性以获得不同的触觉体验。

引言

本教程的核心挑战在于开发一个函数，用于计算与同时 具有刚度和阻尼特性的球体接触时产生的力。 在此背景下，刚度的作用类似于弹簧：压缩得越强，产生的力就越大。 而阻尼则描述了物体抵抗运动的能力：运动速度越快，这种阻力就越大。

场景构图

请先按照 《入门指南》 如上所述，并确保该对象的位置、旋转和缩放 触觉起源 auf简体中文（大陆） (0, 0, 0) 或 (1, 1, 1) 已设定。

随后创建一个名为 Sphere 具有以下特点：

• 职位： (0, 0, -0.1) （距离设备约10厘米）
• 缩放： (0.2, 0.2, 0.2) （相当于一个直径为20厘米的球体）

力反馈脚本

将该 GameObject 添加到 球体 一个名为 SphereForceFeedback.cs hinzu。 该脚本用于计算球体与Inverse3 光标接触时作用于光标上的力，并考虑了刚度和阻尼。 请为该脚本设置以下属性：

[SerializeField]
private Inverse3 inverse3;

[Range(0, 800)]
public float stiffness = 300f;
[Range(0, 3)]
public float damping = 1f;

private Vector3 _ballPosition;
private float _ballRadius;
private float _cursorRadius;

只有当光标穿透球体时，才应进行力计算，从而模拟出触摸具有既定刚度和阻尼的物理物体的感觉。 该方法 ForceCalculation 负责此项操作，并同时考虑光标的位置和速度：

private Vector3 ForceCalculation(Vector3 cursorPosition, Vector3 cursorVelocity, float cursorRadius,
    Vector3 otherPosition, float otherRadius)
{
    var force = Vector3.zero;

    var distanceVector = cursorPosition - otherPosition;
    var distance = distanceVector.magnitude;
    var penetration = otherRadius + cursorRadius - distance;

    if (penetration > 0)
    {
        // Normalize the distance vector to get the direction of the force
        var normal = distanceVector.normalized;

        // Calculate the force based on penetration
        force = normal * penetration * stiffness;

        // Apply damping based on the cursor velocity
        force -= cursorVelocity * damping;
    }

    return force;
}

private void OnDeviceStateChanged(object sender, Inverse3EventArgs args)
{
    var inverse3 = args.DeviceController;
    // Calculate the ball force
    var force = ForceCalculation(inverse3.CursorLocalPosition, inverse3.CursorLocalVelocity,
        _cursorRadius, _ballPosition, _ballRadius);

    inverse3.SetCursorLocalForce(force);
}

请在该方法中初始化 Awake _ballPosition, _ballRadius und _cursorRadius, 以配置场景数据：

private void SaveSceneData()
{
    var t = transform;
    _ballPosition = t.position;
    _ballRadius = t.lossyScale.x / 2f;

    _cursorRadius = inverse3.Cursor.Radius;
}

private void Awake()
{
    SaveSceneData();
}

请确保回调函数 OnDeviceStateChanged 在 OnEnable 已注册并位于 OnDisable 需要再次注销，以便在交互过程中正确处理力反馈：

protected void OnEnable()
{
    inverse3.DeviceStateChanged += OnDeviceStateChanged;
}

protected void OnDisable()
{
    inverse3.DeviceStateChanged -= OnDeviceStateChanged;
}

游戏体验

在按住Inverse3 光标的同时，启动“播放模式”，并尝试触碰该球体。 您应该能够感知到球体的存在，并可通过Unity检查器调整其刚度和阻尼特性。这样便能产生一种与虚拟物体进行交互的切实感受。

源文件

该示例的完整场景及所有相关文件均可从 Unity 包管理器的“示例教程”中导入。

SphereForceFeedback.cs

/*
 * Copyright 2024 Haply Robotics Inc. All rights reserved.
 */

using Haply.Inverse.DeviceControllers;
using Haply.Inverse.DeviceData;
using UnityEngine;

namespace Haply.Samples.Tutorials._2_BasicForceFeedback
{
    public class SphereForceFeedback : MonoBehaviour
    {
        public Inverse3Controller inverse3;

        [Range(0, 800)]
        // Stiffness of the force feedback.
        public float stiffness = 300f;

        [Range(0, 3)]
        public float damping = 1f;

        private Vector3 _ballPosition;
        private float _ballRadius;
        private float _cursorRadius;

        /// <summary>
        /// Stores the cursor and sphere transform data for access by the haptic thread.
        /// </summary>
        private void SaveSceneData()
        {
            var t = transform;
            _ballPosition = t.position;
            _ballRadius = t.lossyScale.x / 2f;

            _cursorRadius = inverse3.Cursor.Radius;
        }

        /// <summary>
        /// Saves the initial scene data cache.
        /// </summary>
        private void Awake()
        {
            inverse3 ??= FindObjectOfType<Inverse3Controller>();
            inverse3.Ready.AddListener((device, args) => SaveSceneData());
        }

        /// <summary>
        /// Subscribes to the DeviceStateChanged event.
        /// </summary>
        private void OnEnable()
        {
            inverse3.DeviceStateChanged += OnDeviceStateChanged;
        }

        /// <summary>
        /// Unsubscribes from the DeviceStateChanged event.
        /// </summary>
        private void OnDisable()
        {
            inverse3.DeviceStateChanged -= OnDeviceStateChanged;
            inverse3.Release();
        }

        /// <summary>
        /// Calculates the force based on the cursor's position and another sphere position.
        /// </summary>
        /// <param name="cursorPosition">The position of the cursor.</param>
        /// <param name="cursorVelocity">The velocity of the cursor.</param>
        /// <param name="cursorRadius">The radius of the cursor.</param>
        /// <param name="otherPosition">The position of the other sphere (e.g., ball).</param>
        /// <param name="otherRadius">The radius of the other sphere.</param>
        /// <returns>The calculated force vector.</returns>
        private Vector3 ForceCalculation(Vector3 cursorPosition, Vector3 cursorVelocity, float cursorRadius,
            Vector3 otherPosition, float otherRadius)
        {
            var force = Vector3.zero;

            var distanceVector = cursorPosition - otherPosition;
            var distance = distanceVector.magnitude;
            var penetration = otherRadius + cursorRadius - distance;

            if (penetration > 0)
            {
                // Normalize the distance vector to get the direction of the force
                var normal = distanceVector.normalized;

                // Calculate the force based on penetration
                force = normal * penetration * stiffness;

                // Apply damping based on the cursor velocity
                force -= cursorVelocity * damping;
            }

            return force;
        }

        /// <summary>
        /// Event handler that calculates and send the force to the device when the cursor's position changes.
        /// </summary>
        /// <param name="sender">The Inverse3 data object.</param>
        /// <param name="args">The event arguments containing the device data.</param>
        private void OnDeviceStateChanged(object sender, Inverse3EventArgs args)
        {
            var inverse3 = args.DeviceController;
            // Calculate the ball force
            var force = ForceCalculation(inverse3.CursorLocalPosition, inverse3.CursorLocalVelocity,
                _cursorRadius, _ballPosition, _ballRadius);

            inverse3.SetCursorLocalForce(force);
        }
    }
}