private bool CollapseGridItems(ref List <Level.Event> gridUpdateEvents)
{
var movedItems = new List <GridEventItem>();
for (int x = 0; x < Width; x++)
{
for (int y = 1; y < Height; y++) // skip the lowest row
{
// find a filled node
var node = Grid[x, y];
if (!node.IsFilled())
{
continue;
}
// collapse left
var nodeLeft = TryGetGridNodeState(x - 1, y - 1);
if (nodeLeft?.IsEmpty() == true)
{
nodeLeft.SetItemId(node.ItemId);
node.RemoveItem();
// record the event
var movedItem = GridEventItem.Create(nodeLeft, 0, node.Index);
movedItems.Add(movedItem);
continue;
}
// collapse right
var nodeRight = TryGetGridNodeState(x + 1, y - 1);
if (nodeRight?.IsEmpty() == true)
{
nodeRight.SetItemId(node.ItemId);
node.RemoveItem();
// record the event
var movedItem = GridEventItem.Create(nodeRight, 0, node.Index);
movedItems.Add(movedItem);
continue;
}
}
}
if (movedItems.Count > 0)
{
var itemsMovedEvent = new Level.ItemsMovedEvent(movedItems);
gridUpdateEvents.Add(itemsMovedEvent);
return(true);
}
return(false);
}
private bool PullDownGridItems(ref List <Level.Event> gridUpdateEvents)
{
var movedItems = new List <GridEventItem>();
for (int x = 0; x < Width; x++)
{
for (int y = 0; y < Height; y++)
{
// find an empty node
var node = Grid[x, y];
if (!node.IsEmpty())
{
continue;
}
// find an item above
var aboveFilledNode = FindFirstFilledNodeAbove(x, y);
if (aboveFilledNode != null)
{
// pull the item down
node.SetItemId(aboveFilledNode.ItemId);
aboveFilledNode.RemoveItem();
// record the event
var movedItem = GridEventItem.Create(node, 0, aboveFilledNode.Index);
movedItems.Add(movedItem);
}
}
}
if (movedItems.Count > 0)
{
var itemsMovedEvent = new Level.ItemsMovedEvent(movedItems);
gridUpdateEvents.Add(itemsMovedEvent);
return(true);
}
return(false);
}