Breakout hitbox system - actionscript-3

Question

I've been working on this for several weeks now and I can get it to work as It to work. It's almost there I guess there is just something I'm missing. I basically cant get the collision detection betwen the blocks and the ball to work like I wnat them to work.
Dump SWF
The ball still has a chance to plow loads of block within seconds. I would love to hear form people who have had a similiar problem.
Here's the code;
private function checkCollision():void
{
grdx = Math.floor((ball.x) / 28);
grdy = Math.floor((ball.y) / 14);
ngrdx = Math.floor((ball.x + dx) / 28);
ngrdy = Math.floor((ball.y + dy) / 14);
if (grdy <= level.length - 1 && ngrdy <= level.length - 1 && grdy >= 0 && ngrdy >= 0)
{
if(level[grdy][ngrdx] > 0)
{
level[grdy][ngrdx] = 0;
bnm = "Block_" + grdy + "_" + ngrdx;
if (this.getChildByName(bnm) != null)
{
this.removeChild(this.getChildByName(bnm));
dx *= -1;
totalBreaks++;
trace("Hit on X");
trace("Block: " + totalBreaks + " / " + totalBlocks);
}
}
else if(level[ngrdy][grdx] > 0)
{
bnm = "Block_" + ngrdy + "_" + grdx;
level[ngrdy][grdx] = 0;
if (this.getChildByName(bnm) != null)
{
this.removeChild(this.getChildByName(bnm));
dy *= -1;
totalBreaks++;
trace("Hit on Y");
trace("Block: " + totalBreaks + " / " + totalBlocks);
}
}
if(level[ngrdy][ngrdx] > 0)
{
bnm = "Block_" + ngrdy + "_" + ngrdx;
level[ngrdy][ngrdx] = 0;
if (this.getChildByName(bnm) != null)
{
this.removeChild(this.getChildByName(bnm));
dy *= -1;
dx *= -1;
totalBreaks++;
trace("hit on X,Y");
trace("Block: " + totalBreaks + " / " + totalBlocks);
}
}
}
}

Answer 1

I'm not sure I got this right but I think one problem can be with your if else if statements.
From your example, a call to checkCollision() might change twice your dx and dy vars, resulting in the ball keep going in the same direction while it hit a brick.
If I'm right then you may refactor your if statements like the following:
if (level[ngrdy][ngrdx] > 0)
{
[...]
}
else if (level[grdy][ngrdx] > 0)
{
[...]
}
else if (level[ngrdy][grdx] > 0)
{
[...]
}
Besides, it's a good practice to enclose simple tests into parenthesis. So instead of writing that:
if (grdy <= level.length - 1 && ngrdy <= level.length - 1 && grdy >= 0 && ngrdy >= 0)
I would write this :
if ((grdy <= level.length - 1) && (ngrdy <= level.length - 1) && (grdy >= 0) && (ngrdy >= 0))
thus making the code more readable.
Good work though, keep going on!
EDIT:
As your comment suggest it is not a correct answer, I dig a bit more and I now have another suggestion, using some booleans to check whether the direction should be flipped on both axes. I also did a bit of refactoring:
private function checkCollision():void
{
grdx = Math.floor((ball.x) / 28);
grdy = Math.floor((ball.y) / 14);
ngrdx = Math.floor((ball.x + dx) / 28);
ngrdy = Math.floor((ball.y + dy) / 14);
var flipX:Boolean = false;
var flipY:Boolean = false;
if ((grdy <= level.length - 1) && (ngrdy <= level.length - 1) && (grdy >= 0 && ngrdy >= 0))
{
if (testBlock(grdx, ngrdy))
{
flipY = true;
}
if (testBlock(ngrdx, grdy))
{
flipX = true;
}
if (testBlock(ngrdx, ngrdy))
{
flipX = true;
flipY = true;
}
dx *= flipX ? -1 : 1;
dy *= flipY ? -1 : 1;
}
}
private function testBlock(xPos:int, yPos:int):Boolean
{
if (level[yPos][xPos] > 0)
{
trace("hit on X,Y");
level[yPos][xPos] = 0;
breakBlock("Block_" + yPos + "_" + xPos);
trace("Block: " + totalBreaks + " / " + totalBlocks);
return true;
}
return false;
}
private function breakBlock(blockName:String):void
{
if (this.getChildByName(blockName))
{
this.removeChild(this.getChildByName(blockName));
totalBreaks++;
}
}
If it happened to be the correct solution, I'd clean this answer...