Unity 使用任意一个局部轴指向目标

效果：

主要用于在编辑器中可视化对象的朝向，同时提供了选择不同轴向的功能。在运行时，物体将根据所选择的轴向朝向目标，并在 Scene 视图中绘制一个带箭头的圆环。

定义轴向枚举：

public enum OnlyAxis
{x_Axis,y_Axis,z_Axis
}

• 这是一个用于表示轴向的枚举，包括 x 轴、y 轴和 z 轴。

定义变量：

public Transform target; // 要指向的目标物体
[Header("追踪轴向")]
public OnlyAxis Axis = OnlyAxis.x_Axis; // 选择旋转的轴向
private OnlyAxis CurrentAxis = OnlyAxis.x_Axis; // 当前轴向

• target: 用于指定需要朝向的目标物体。
• Axis: 用于在 Inspector 窗口中选择旋转的轴向。
• CurrentAxis: 用于在运行时跟踪当前的轴向。

主要计算：

private void Update()
{SetAxis(Axis);// 获取目标方向Vector3 targetDirection = target.position - transform.position;Vector3 RotateAxis = transform.up;// 根据选择的轴向，获取目标方向在对应轴上的投影Vector3 axisDirection = Vector3.zero;switch (CurrentAxis){case OnlyAxis.x_Axis:axisDirection = Vector3.ProjectOnPlane(targetDirection, transform.right);break;case OnlyAxis.y_Axis:axisDirection = Vector3.ProjectOnPlane(targetDirection, transform.up);break;case OnlyAxis.z_Axis:axisDirection = transform.forward;Vector3 dirTemp = transform.forward.normalized;RotateAxis = Vector3.ProjectOnPlane(targetDirection, dirTemp);break;}// 计算旋转角度Quaternion newRotation = Quaternion.LookRotation(axisDirection, RotateAxis);transform.rotation = newRotation;
}

• SetAxis 方法用于在运行时更新 CurrentAxis，确保在不同的轴向之间正确切换。
• 在 Update 方法中，获取目标方向，并根据当前选择的轴向计算相应的旋转。最后，将物体的旋转设为新的旋转。

OnDrawGizmosSelected 方法（仅在编辑器中生效）：

#if UNITY_EDITORprivate void OnDrawGizmosSelected(){DrawCircle();}public bool is3DDraw = false;public float radius = 0.1f;public float arrowLength = 0.01f;int segments = 20;private void DrawCircle(){float Radius = is3DDraw ? radius : radius * Vector3.Distance(transform.position, SceneView.lastActiveSceneView.camera.transform.position);float ArrowLength = is3DDraw ? arrowLength : arrowLength * Vector3.Distance(transform.position, SceneView.lastActiveSceneView.camera.transform.position);Gizmos.color = Color.green;Vector3 center = transform.position;Quaternion rotation = transform.rotation;float angleIncrement = 360f / segments;for (int i = 0; i < segments; i++){float angle = i * angleIncrement;Vector3 point = Vector3.zero;float nextAngle = (i + 1) * angleIncrement;Vector3 nextPoint = Vector3.zero;// 根据所选轴向，调整旋转switch (Axis){case OnlyAxis.x_Axis:point = center + rotation * Quaternion.Euler(angle, 0, 0) * (Vector3.up * Radius);nextPoint = center + rotation * Quaternion.Euler(nextAngle, 0, 0) * (Vector3.up * Radius);if (i == 0){Gizmos.DrawLine(nextPoint, center + rotation * Quaternion.Euler(angle + angleIncrement / 2, 0, 0) * (Vector3.up * (Radius + ArrowLength)));Gizmos.DrawLine(nextPoint, center + rotation * Quaternion.Euler(angle + angleIncrement / 2, 0, 0) * (Vector3.up * (Radius - ArrowLength)));}break;case OnlyAxis.y_Axis:point = center + rotation * Quaternion.Euler(0, angle, 0) * (Vector3.right * Radius);nextPoint = center + rotation * Quaternion.Euler(0, nextAngle, 0) * (Vector3.right * Radius);if (i == 0){Gizmos.DrawLine(nextPoint, center + rotation * Quaternion.Euler(0, angle + angleIncrement / 2, 0) * (Vector3.right * (Radius + ArrowLength)));Gizmos.DrawLine(nextPoint, center + rotation * Quaternion.Euler(0, angle + angleIncrement / 2, 0) * (Vector3.right * (Radius + -ArrowLength)));}break;case OnlyAxis.z_Axis:point = center + rotation * Quaternion.Euler(0, 0, angle) * (Vector3.right * Radius);nextPoint = center + rotation * Quaternion.Euler(0, 0, nextAngle) * (Vector3.right * Radius);if (i == 0){Gizmos.DrawLine(nextPoint, center + rotation * Quaternion.Euler(0, 0, angle + angleIncrement / 2) * (Vector3.right * (Radius + ArrowLength)));Gizmos.DrawLine(nextPoint, center + rotation * Quaternion.Euler(0, 0, angle + angleIncrement / 2) * (Vector3.right * (Radius + -ArrowLength)));}break;}if (i != 1) Gizmos.DrawLine(point, nextPoint);}}
#endif

• OnDrawGizmosSelected 方法用于在 Scene 视图中绘制圆环。
• DrawCircle 方法根据选择的轴向，绘制一个圆环并在第一个点上画一个箭头。

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