Question

I am writing a match three engine and I succeed in creating the matching with using huge loops to find the matching items. Any ideas on how to fill the empty spaces with the items ( dropping down into the empty spaces ) and creating new items without excessive looping and if statements?

Here is my relavant code so far.

public var rows:uint = 8;
public var cols:uint = 7;
public var cell:Array = new Array();
public var plot:Array = new Array();

public var height:int;
public var width:int;

public var relativePositions:Array = [{name:'top', position:-1}, {name:'bottom', position:1}, {name:'left', position:rows*-1}, {name:'right', position:rows*1}];
public var dictionary:Dictionary = new Dictionary();
public var matches:Array = new Array();

public function createGrid(target:*, displayObject:*, spacer:int) : void {

        var iterator:uint = 0;
        for(var c:uint = 0;c<cols;c++){ 
            for(var r:uint = 0;r<rows;r++){                                         
                cell[iterator] = createGamePiece();
                Sprite(cell[iterator]).name = String(iterator);
                Sprite(cell[iterator]).addEventListener(MouseEvent.CLICK, _handleGamePiece_CLICK);
                Sprite(cell[iterator]).addEventListener(MouseEvent.MOUSE_OVER, _handleGamePiece_MOUSE_OVER);
                Sprite(cell[iterator]).addEventListener(MouseEvent.MOUSE_OUT, _handleGamePiece_MOUSE_OUT);
                cell[iterator].y = cell[iterator].height  * r + (spacer*r);
                cell[iterator].x = cell[iterator].width * c + (spacer*c);
                GamePiece(cell[iterator]).positionX = cell[iterator].x;
                GamePiece(cell[iterator]).positionY = cell[iterator].y;
                GamePiece(cell[iterator]).positionRow = r;
                GamePiece(cell[iterator]).positionCol = c;
                target.addChild(cell[iterator]);
                dictionary[String(iterator)] = cell[iterator]
                iterator++
            }
        } 

    }

public function findRelativeMatches(targetSprite:Sprite) : void {

        targetSprite.alpha = .5;
        var rootPosition:Number = Number(targetSprite.name);

        for ( var i:int = 0; i < relativePositions.length; i ++ ) {
            var key:String = String(rootPosition + relativePositions[i].position);
            // to do >> Not hardcoded to 'Pig'
            if (findSprite(key) != null && GamePiece(targetSprite).color == GamePiece(findSprite(key)).color && GamePiece(findSprite(key)).found == false) {
                var sprite:Sprite = findSprite(key);
                sprite.alpha = .5;
                GamePiece(sprite).found = true;
                matches.push(sprite);
                findRelativeMatches(sprite);
            };
        };

        targetSprite.addEventListener(MouseEvent.MOUSE_OUT, function() : void {
            if ( matches.length != 0 ) {
                for ( var j:int = 0 ; j < matches.length ; j++ ) {
                    Sprite(matches[j]).alpha = 1;
                    GamePiece(matches[j]).found = false;
                }
                matches.splice(0);
            }
        });
    }

public function findSprite(key:String) : Sprite {
        var sprite:Sprite;
        dictionary[key] != undefined ? sprite = dictionary[key] : null;
        return sprite;
    }

protected function _handleGamePiece_CLICK(event:MouseEvent):void
    {
        for ( var j:int = 0 ; j < matches.length ; j++ ) {
            var sprite:Sprite = matches[j];
            view.removeChild(matches[j]);

        }

        matches.splice(0);
    }
public function createGamePiece() : Sprite {
        var gamePiece:GamePiece = new GamePiece();
        return gamePiece;
    }

Answer 1

This is actually what I wanted. A way to collapse WITHOUT iterating over the entire board. This way I JUST loop through the items that have been removed.

protected function _handleGamePiece_CLICK(event:MouseEvent):void
    {
        for ( var j:int = 0 ; j < matches.length ; j++ ) {
            var oldSprite:Sprite = matches[j];
            moveAllPiecesDown(oldSprite);
            view.removeChild(oldSprite);
            oldSprite = null;
        }
        matches.splice(0);
    }

private function moveAllPiecesDown(oldSprite:Sprite):void
    {
        var piecesAbove:int = GamePiece(oldSprite).positionRow;
        var index:int = int(oldSprite.name);

        for( var i:int = 0; i < piecesAbove; i ++ ) {
            var spriteAbove:Sprite = Sprite(view.getChildByName(String(index-(1+i))));
            if(spriteAbove) {
                spriteAbove.y = spriteAbove.y + spriteAbove.height + 1;
                spriteAbove.name = String(Number(spriteAbove.name)+1);
                GamePiece(spriteAbove).textField.text = spriteAbove.name;
                delete dictionary[spriteAbove.name];
                dictionary[spriteAbove.name] = spriteAbove;
            }
        }
    }