Flah mx Space Invaders Problem

patmul

Doing a project in flash at the minute in Space Invaders but don't really know too much about flash mx. The problem I have is that when i shoot the attackers from my ship they're not blowing up and I don't know how the code to do this .My code at the minute for shooting is
onClipEvent(load){

moveSpeed=10;

}
onClipEvent (enterFrame) {

if (Key.isDown(Key.RIGHT)) {
this._x+=moveSpeed;
} else if (Key.isDown(Key.LEFT)) {
this._x-=moveSpeed;
}
}

// when the mouse cliks
onClipEvent(mouseDown)
{
// duplicate the bullet mc
_root.bullet.duplicateMovieClip("bullet" + bulletNum,bulletNum);
// set the coords to the mouse clik
eval("_root.bullet" + bulletNum)._x = this._x;
eval("_root.bullet" + bulletNum)._y = this._y;
// increment the bullet number
bulletNum++;
// if more than 50 bullets , start again at 0
if(bulletNum>50)
bulletNum = 0;
}

and for the attacker is
onClipEvent(load){
this._y =0;
speed=10;
}
onClipEvent(enterFrame){
if(this._x <0)
{
// set direction to right
speed=10;
// drop down
this._y +=30;
}
if(this._x > Stage.width)
{
// set direction to left
speed=-10;
// drop down
this._y += 30;
}
// move horizontal
this._x += speed;

}

If anyone could help me with some of the code I would much appreciate it

SantaHoe

I've never used actionscript (or whatever flash is using nowdays) so I'll see if I can help in pseudocode
I haven't a clue what the flash coordinate system is like, so this could very well make no sense at all... just something I had to do before in C.

I think you'd want to start with some kind of collision detection for the enemy units... a reasonable way of doing this would be to take the x/y position of an enemy unit and from that define a sort of box around it... you'd do this by taking the size of the sprite used and figuring out what size would make sense for a hitbox.
For example, say the sprite for an enemy is 20x20 pixels and the unit is on the screen at 200x 100y and the x/y coordinate describes its center... you'd define the hitbox by something like this:

IF (bullet_x_position > (enemy_x_position - 10)) AND (bullet_x_position < (enemy_x_position +10)) AND (bullet_y_position > (enemy_y_position - 10)) AND (bullet_y_position < (enemy_y_position + 10))
THEN killenemy();

You're basically checking the position of the bullet against the position of the enemy (with a plus or minus range a few pixels in each direction because the sprite doesn't just cover one point in space, it spans a few in each direction) ... if all of the conditions are true, then the bullet is definitly in the same x/y position as somewhere on the sprite and a hit should be registered.
And then you can adopt this for many enemies and many bullets by sticking in whatever arrays of x/y positions that you want and using the one function to check them all every tick.

Again, I don't know if this makes any sense in a Flash context, but I hope it's at least food for thought if nothing else.

impr0v

There's a tutorial on creating a space invaders type game, including collision detection, at http://www.video-animation.com/flash_12.shtml .

I'd say it suits your purposes, since the code is so similar to your own, uncannily similar in fact.