Creating the Color Drop Casual Puzzle Game - The Essential Guide to Flash Games - page 339

as a parameter is the value used to decrement the alpha value of the Block when render is called
by Game .
public function startFade(fadeValue:Number):void {
this.fadeValue = fadeValue;
isFading=true;
}
This update function is much like the update functions we have already written in this topic. It
looks to see if the Block 's isFalling variable equals true , and if so, it updates nextYLocation to
the current y position plus speed . The fading of the Block is not affected by render .
public function update():void {
if (isFalling) {
nextYLocation = y + speed;
}
}
The render function is only slightly more complicated than update . If the Block is falling, update
sets y to nextYLocation . If fallEndY is reached, the function makes sure the Block ends in the
correct location by setting it exactly to the value in fallEndY . We do this because the last time the
block moved, there is a good chance that that it overshot fallEndY , so we simply move it to
where it should land. The isFalling property is set to false , so ColorDrop can test to see if all
Block objects have stopped falling.
If the block is fading , we update the alpha value of the Block by subtracting the fadeValue . If the
alpha value is reached (or goes negative), we set it to 0 and set isFading to false , so ColorDrop
can test to see if all the fading Blocks are finished.
public function render():void {
if (isFalling) {
y = nextYLocation;
if (y >= fallEndY) {
y = fallEndY;
isFalling = false;
}
}
if (isFading) {
alpha -= fadeValue;
if (alpha <= 0) {
alpha = 0;
isFading = false;
}
}
}
The onMouseDownListener function is called when the player clicks on the Block with the mouse.
This function dispatches a custom event that we will create in the next section of this chapter. The
CustomEvent sends a reference to itself as the second parameter. ColorDrop will listen for this
event, so it can start processing the Block objects to see which ones it should remove from the
screen.