设备工作空间转换教程

本教程基于 力反馈入门教程 并演示如何设置设备的位移、旋转和缩放 Inverse3 利用其空间变换特性和方法进行调整。

引言

在设置好基础力反馈场景后，您可能会发现，对触觉原点或触觉控制器进行的调整（例如平移、缩放或旋转）并未如预期那样影响触觉反馈。 该反馈仍然对应于设备前方的一个不可见球体，且不受这些变换的影响。

出现这种偏差的原因在于，力计算使用的是光标的实际（未变换）坐标。 为了解决这个问题，我们使用由Inverse3 控制器组件提供的线程安全的缓存变换矩阵。这样，我们就可以对力反馈的计算应用世界坐标变换。

场景构图

请从“力反馈基础教程”中的场景开始，并确保Inverse3 手柄的左右手设置与您的设备相匹配。 将 手柄旋转至Haply 标志朝向摄像头的方向，并根据需要调整的缩放比例，以扩大光标范围或调整其位置。

对力反馈脚本的修改

复制该脚本 SphereForceFeedback.cs 摘自关于力反馈的基础教程，并在回调中 OnDeviceStateChanged 进行了以下调整：

• 请替换 device.CursorLocalPosition durch device.CursorPosition.
• 请替换 device.CursorLocalVelocity durch device.CursorVelocity.
• 请替换 device.CursorSetLocalForce(force) durch device.CursorSetForce(force).

private void OnDeviceStateChanged(object sender, Inverse3EventArgs args)
{
    var inverse3 = args.DeviceController;
    var force = ForceCalculation(inverse3.CursorPosition, inverse3.CursorVelocity,
        _cursorRadius, _ballPosition, _ballRadius);

    inverse3.SetCursorForce(force);
}

游戏体验

按住Inverse3 光标，启动播放模式。试着像上一个示例中那样触摸球体。 此时，您应该能感受到精确的触觉反馈，该反馈反映了应用于“触觉原点 ”和“触觉控制器”的变换。

源文件

该示例的完整场景及相关文件可从 Unity 的“包管理器”中的“示例教程”中导入。

该示例场景包含用于在运行时调整触觉 控制器和触觉原点的额外脚本。

SphereForceFeedback.cs

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

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

namespace Haply.Samples.Tutorials._3_DeviceSpaceTransform
{
    public class SphereForceFeedback : MonoBehaviour
    {
        // must assign in inspector
        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 ??= FindFirstObjectByType<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. Using 'device.Position' instead of 'device.LocalPosition'
            // ensures the force calculation considers the device's offset and rotation in world space.
            var force = ForceCalculation(inverse3.CursorPosition, inverse3.CursorVelocity,
                _cursorRadius, _ballPosition, _ballRadius);

            // Apply the calculated force to the cursor. Using 'device.CursorSetForce' instead of
            // 'device.CursorSetLocalForce' ensures that the force vector is correctly converted
            // from world space to the device's local space.
            inverse3.SetCursorForce(force);
        }
    }
}