[CS3] Drag to fire Balls.

Basically Im trying to recreate this game called shuffle found on the shockwave site. http://www.shockwave.com/gamelanding/shuffle.jsp

Ive taken a fantastic bit of code from http://www.krazydad.com/bestiary/ called "Superball" which gives a basic ball environment simular to the one in the game. I have edited it a little but am struggling to convert it now.

At the moment you "toss" the balls around the screen but I need to edit this into a drag back and release to select the power and direction, like the above game.

Code:

---

MovieClip.prototype.pressBall = function()
{
        this.isDragging = true;
        this.vx = this.vy = 0;
        this.lmx = _root._xmouse;
        this.lmy = _root._ymouse;
        this.startDrag(false);
}

MovieClip.prototype.releaseBall = function()
{
        this.isDragging = false;
        this.stopDrag();
}

MovieClip.prototype.moveBall = function()
{
        // compute forces on ball
        if (!this.isDragging) {
                this.vx *= dampK;        // damping due to air resistance
                this.vy *= dampK;

                this.vy += gravK;        // gravity
               
                // bounce off floor and ceiling
                if (this._y+ballRadius + this.vy >= SH ||
                        (this._y-ballRadius) + this.vy < 0)
                {
                        this.vy *= -dampCollision;
                }
                // bounce off right and left walls
                if ((this._x-ballRadius) + this.vx <= 0 ||
                        this._x+ballRadius + this.vx >= SW)
                {
                        this.vx *= -dampCollision;
                }
                this._x += this.vx;
                this._y += this.vy;
        }
        else {
                // Set vx,vy to correspond to mouse movement, enabling user to 'toss' ball
                this.vx *= dampK;
                this.vy *= dampK;
                this.vx = _root._xmouse - this.lmx;
                this.vy = _root._ymouse - this.lmy;
                this.lmx = _root._xmouse;
                this.lmy = _root._ymouse;
        }
}

---

I think this is the relevent peice of code. Any ideas from anyone?

There are basically three fixes you need to do. First, comment out the lines that read

this.startDrag(false);

and

this.stopDrag();

Next, near the bottom of the script there are two lines that read:

Code:

---

                this.vx = _root._xmouse - this.lmx;
                this.vy = _root._ymouse - this.lmy;

---

Change then to something like:

Code:

---

                this.vx = (this.lmx - _root._xmouse) * 1.5;
                this.vy = (this.lmy - _root._ymouse) * 1.5;

---

This reverses the direction of the force (as in the game you are trying to emulate) and magnifies the force 1.5 times.

You'll also need to add code that renders an arrow that begins at this._x and this._y and whose point is centered on this._x + this.vx, this._y + this.vy.

I'll let you figure that part out.

Thats excellent. Is there a way I could change it so it doesnt react to the speed that the mouse is moved back and rather the distance it is from the ball?

Also, while im here, am I going about recreating that game in the correct way? What would you recommend?

To react to relative mouse position, use this

Code:

---

this.vx = (this._x - _root._xmouse) * 1.5;
this.vy = (this._y - _root._ymouse) * 1.5;

---

To answer your second question. I'm not sure there is a correct way.

I'm a bit concerned that you're using this code without truly understanding it - this may cause you trouble in the future. You should take the time to gain understanding of what the code is doing. For example, why did the fixes I gave you work? I could tell you, but can you figure this out on your own?

If there is a correct way, you will only truly discover it by stumbling around a bit in the dark, that is, through experience.

:)

hey jbum! nice to see you here, man ;)

that's it. Take care

gparis