// Selection logic
// Find the next selectable object in the specified world-space direction.
public SelectableUI 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;
SelectableUI bestPick = null;
for (int i = 0; i < s_List.Count; ++i)
{
SelectableUI sel = s_List[i];
if (sel == this || sel == null)
{
continue;
}
if (!sel.IsInteractable() || sel.navigation.mode == NavigationUI.Mode.None)
{
continue;
}
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 Selectable 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);
}
