public static PickingObject PickGameObject(Vector2 mousePosition)
{
s_RetainHashes = true;
var enumerator = GetAllOverlapping(mousePosition).GetEnumerator();
if (!enumerator.MoveNext())
{
return(PickingObject.Empty);
}
PickingObject topmost = enumerator.Current;
var pickingBase = topmost.TryGetComponent(out Transform trs)
? HandleUtility.FindSelectionBaseForPicking(trs)
: null;
// Selection base is only interesting if it's not the topmost
PickingObject selectionBase = new PickingObject(pickingBase);
PickingObject first = selectionBase.target == null ? topmost : selectionBase;
int topmostHash = topmost.GetHashCode();
int prefixHash = topmostHash;
if (Selection.activeObject == null)
{
// Nothing selected
// Return selection base if it exists, otherwise topmost game object
s_PreviousTopmostHash = topmostHash;
s_PreviousPrefixHash = prefixHash;
return(first);
}
if (topmostHash != s_PreviousTopmostHash)
{
// Topmost game object changed
// Return selection base if exists and is not already selected, otherwise topmost game object
s_PreviousTopmostHash = topmostHash;
s_PreviousPrefixHash = prefixHash;
return(Selection.activeObject == selectionBase.target ? topmost : first);
}
s_PreviousTopmostHash = topmostHash;
// Pick potential selection base before topmost game object
if (Selection.activeObject == selectionBase.target)
{
if (prefixHash == s_PreviousPrefixHash)
{
return(topmost);
}
s_PreviousPrefixHash = prefixHash;
return(selectionBase);
}
s_ActiveObjectFilter.Clear();
s_ActiveObjectFilter.Add((PickingObject)Selection.activeObject);
// Check if active game object will appear in selection stack
PickingObject picked = HandleUtility.PickObject(mousePosition, false, null, s_ActiveObjectFilter);
if (picked == ((PickingObject)Selection.activeObject))
{
// Advance enumerator to active game object
while (enumerator.Current != ((PickingObject)Selection.activeObject))
{
if (!enumerator.MoveNext())
{
s_PreviousPrefixHash = topmostHash;
return(first); // Should not occur
}
UpdateHash(ref prefixHash, enumerator.Current);
}
}
if (prefixHash != s_PreviousPrefixHash)
{
// Prefix hash changed, start over
s_PreviousPrefixHash = topmostHash;
return(first);
}
// Move on to next game object
if (!enumerator.MoveNext())
{
s_PreviousPrefixHash = topmostHash;
return(first); // End reached, start over
}
UpdateHash(ref prefixHash, enumerator.Current);
if (enumerator.Current == selectionBase)
{
// Skip selection base
if (!enumerator.MoveNext())
{
s_PreviousPrefixHash = topmostHash;
return(first); // End reached, start over
}
UpdateHash(ref prefixHash, enumerator.Current);
}
s_PreviousPrefixHash = prefixHash;
return(enumerator.Current);
}
static void UpdateHash(ref int hash, PickingObject obj)
{
hash = unchecked (hash * 33 + obj.GetHashCode());
}