// Select on enable and add to the list.
protected override void OnEnable()
{
//Check to avoid multiple OnEnable() calls for each selectable
if (m_EnableCalled)
{
return;
}
base.OnEnable();
if (s_SelectableCount == s_Selectables.Length)
{
BaseSelectable[] temp = new BaseSelectable[s_Selectables.Length * 2];
Array.Copy(s_Selectables, temp, s_Selectables.Length);
s_Selectables = temp;
}
m_CurrentIndex = s_SelectableCount;
s_Selectables[m_CurrentIndex] = this;
s_SelectableCount++;
isPointerDown = false;
DoStateTransition(currentSelectionState, true);
m_EnableCalled = true;
}
// Selection logic
/// <summary>
/// Finds the selectable object next to this one.
/// </summary>
/// <remarks>
/// The direction is determined by a Vector3 variable.
/// </remarks>
/// <param name="dir">The direction in which to search for a neighbouring BaseSelectable object.</param>
/// <returns>The neighbouring BaseSelectable object. Null if none found.</returns>
/// <example>
/// <code>
/// using UnityEngine;
/// using System.Collections;
/// using UnityEngine.UI; // required when using UI elements in scripts
///
/// public class ExampleClass : MonoBehaviour
/// {
/// //Sets the direction as "Up" (Y is in positive).
/// public Vector3 direction = new Vector3(0, 1, 0);
/// public Button btnMain;
///
/// public void Start()
/// {
/// //Finds and assigns the selectable above the main button
/// BaseSelectable newSelectable = btnMain.FindSelectable(direction);
///
/// Debug.Log(newSelectable.name);
/// }
/// }
/// </code>
/// </example>
public BaseSelectable FindSelectable(Vector3 dir)
{
dir = dir.normalized;
Vector3 localDir = Quaternion.Inverse(transform.rotation) * dir;
Vector3 pos = transform.TransformPoint(GetPointOnRectEdge(transform as RectTransform, localDir));
float maxScore = Mathf.NegativeInfinity;
BaseSelectable bestPick = null;
for (int i = 0; i < s_SelectableCount; ++i)
{
BaseSelectable sel = s_Selectables[i];
if (sel == this)
{
continue;
}
if (!sel.IsInteractable() || sel.navigation.mode == Navigation.Mode.None)
{
continue;
}
#if UNITY_EDITOR
// Apart from runtime use, FindSelectable is used by custom editors to
// draw arrows between different selectables. For scene view cameras,
// only selectables in the same stage should be considered.
if (Camera.current != null && !UnityEditor.SceneManagement.StageUtility.IsGameObjectRenderedByCamera(sel.gameObject, Camera.current))
{
continue;
}
#endif
var selRect = sel.transform as RectTransform;
Vector3 selCenter = selRect != null ? (Vector3)selRect.rect.center : Vector3.zero;
Vector3 myVector = sel.transform.TransformPoint(selCenter) - pos;
// Value that is the distance out along the direction.
float dot = Vector3.Dot(dir, myVector);
// Skip elements that are in the wrong direction or which have zero distance.
// This also ensures that the scoring formula below will not have a division by zero error.
if (dot <= 0)
{
continue;
}
// This scoring function has two priorities:
// - Score higher for positions that are closer.
// - Score higher for positions that are located in the right direction.
// This scoring function combines both of these criteria.
// It can be seen as this:
// Dot (dir, myVector.normalized) / myVector.magnitude
// The first part equals 1 if the direction of myVector is the same as dir, and 0 if it's orthogonal.
// The second part scores lower the greater the distance is by dividing by the distance.
// The formula below is equivalent but more optimized.
//
// If a given score is chosen, the positions that evaluate to that score will form a circle
// that touches pos and whose center is located along dir. A way to visualize the resulting functionality is this:
// From the position pos, blow up a circular balloon so it grows in the direction of dir.
// The first BaseSelectable whose center the circular balloon touches is the one that's chosen.
float score = dot / myVector.sqrMagnitude;
if (score > maxScore)
{
maxScore = score;
bestPick = sel;
}
}
return(bestPick);
}