Creating the Color Drop Casual Puzzle Game - The Essential Guide to Flash Games - page 353

For update , we loop through all of the Block objects in the board 2D array looking for any that are
not null . This detail is important, because blocks can still be falling into (or out of) place moving
before the entire grid has been replenished with new Block objects. If we do not test for null
values in the array, the game will throw runtime exceptions because of the null object reference. If
the Block is not null , then we test to see if tempblock.isFalling is true . If so, we call
tempBlock.update . Otherwise, we do nothing.
public function update():void {
for (var r:int = 0; r < board.length; r++) {
for (var c:int = 0; c < board[r].length; c++) {
tempBlock = board[r][c];
if (tempBlock != null) {
if (tempBlock.isFalling) {
tempBlock.update();
}
}
}
}
}
The render function is very similar to update . First we check for null values, and then, we call
tempBlock.render if tempBlock.isFalling or tempBlock.isFading is true . We did not test for
tempBlock.isFading in update because tempBlock.update does not handle any of the alpha
fading work for the block.
public function render():void {
for (var r:int = 0; r < board.length; r++) {
for (var c:int = 0; c < board[r].length; c++) {
tempBlock = board[r][c];
if (tempBlock != null) {
if (tempBlock.isFalling || tempBlock.isFading) {
tempBlock.render();
}
}
}
}
}
Waiting for user input
The game state GameStates.STATE_WAITING_FOR_INPUT is set when ColorDrop is in the game loop
waiting for a mouse click. When one of the Block objects is clicked,
CustomEventClickBlock.EVENT_CLICK_BLOCK is dispatched, and the function blockClickListener is
called to handle it (see Figure 8-4).