ShowLocalAxis.cs

using UnityEngine;

// Displays lines for the Local Axis of a game object evenwhen the object is not selected.
public class ShowLocalAxis : MonoBehaviour
{
    // This is used by the CustomTransformComponent class
    // and the custom inspector for this class so that we can tag the script component
    // for deletion at the proper time. We're hiding it in the inspector since it shouldn't
    // be modified by the user, but needs to be publically accessible by other classes.
    [HideInInspector]
    public bool destroyWhenSafe = false;

    // This is the length of the lines to be displayed.
    // I've set a range here to prevent them from being overly long or too short.
    // The range tag will make the inspector draw a slider for the value instead of a field box.
    [Range(1f,100f)]
    public float handleLength = 10f;

    // This method is run by Unity when gizmos should be drawn in the Scene view.
    public void OnDrawGizmos()
    {
        // First we need to set the gizmo matrix from the transform's local values.
        Gizmos.matrix = transform.localToWorldMatrix;
        Gizmos.color = Color.blue; // We define the gizmo color before each line.
        Gizmos.DrawLine(Vector3.zero, Vector3.forward * handleLength); // Then we draw the line along the axis.
        Gizmos.color = Color.red;
        Gizmos.DrawLine(Vector3.zero, Vector3.right * handleLength);
        Gizmos.color = Color.yellow;
        Gizmos.DrawLine(Vector3.zero, Vector3.up* handleLength);
    }
}