[help]centering random rocks

[zervell]

I'm having problems with my ramdom rock generater. It makes all the rocks i need but, when I want to center them to get an even rotation it goes out of wack. how can i center the rocks to get the even rotation?

just copy past code in frame to work it

//total rocks at one time
totalrock = 10;
//rock id number
ir = 0;
//interval that puts out rocks
rocky = setInterval(this, "rockgen", 1000);

function rockgen() {
	var done = false;
	if (ir>=10) {
		ir = 1;
	}
	while (ir<totalrock && !done) {
		ir++;
		if (this["rock"+ir] == null) {
			done = true;
		//create rock
			this.createEmptyMovieClip("rock"+ir, ir);
		//create rock drawing
			this["rock"+ir].createEmptyMovieClip("p", 1);
			
		//Rock drawing
			this["rock"+ir].p.beginFill(0x333333, 100);
			this["rock"+ir].p.lineStyle(3, 0x666666, 100);
			//point x
			this["rock"+ir].p.lineTo(0, 0);
			//point 1
			this["rock"+ir].p.lineTo(ran()+20, ran()+10);
			//point 2
			this["rock"+ir].p.lineTo(ran()+30, ran()+30);
			//point 3
			this["rock"+ir].p.lineTo(ran()+20, ran()+50);
			//point 4
			this["rock"+ir].p.lineTo(0, ran()+60);
			//point 5
			this["rock"+ir].p.lineTo((ran()+20)*-1, ran()+50);
			//point 6 middle
			this["rock"+ir].p.lineTo((ran()+30)*-1, ran()+30);
			//point 7
			this["rock"+ir].p.lineTo((ran()+20)*-1, ran()+10);
			//point x
			this["rock"+ir].p.lineTo(0, 0);
		//Rock drawing end
		
			//center code
			this["rock"+ir].p._x = this["rock"+ir].p._width/2;
			this["rock"+ir].p._y = this["rock"+ir].p._height/2;
			this["rock"+ir]._x = int(Math.random()*400);
			
			//rotation cw or ccw
			var chosse = int(Math.random()*2);
			switch (chosse) {
			case 0 :
				this["rock"+ir].rospeed = int(Math.random()*20);
				break;
			case 1 :
				this["rock"+ir].rospeed = int(Math.random()*20)*-1;
				break;
			}
			
			this["rock"+ir].onEnterFrame = function() {
				var t = this;
				t._y += 20;
				t._rotation += t.rospeed;
				if (t._y>Stage.width) {
					removeMovieClip(t);
				}
			};
		}
	}
}
//retruns a random number
function ran() {
	return int(Math.random()*5);
}

this is the code i use to center the rock

//center code
			this["rock"+ir].p._x = this["rock"+ir].p._width/2;
			this["rock"+ir].p._y = this["rock"+ir].p._height/2;

[LeechmasterB]

Simply add a minus before the half wid pos .

[ImprisonedPride]

Argh, beat me to it... Anything attached or duplicated gets placed at 0,0 so in effect:

this["rock"+ir].p._width/2

is even farther away from 0,0. You need to go negative 1/2 the width for the center of the rock to be at 0,0.

[zervell]

thanks a lot for the help and for responding so quickly. They don't rotate perfectly but there not doing the orbit thing anymore. thanks to both of you.

[mr_malee]

so you want the rocls to rotate around a common center.

first add up all the positions in different components, then divide by the total number of rocks. Record the distance and angle of each rock from this center. Find the angle between the center and the mouse, add the rocks inital angle. Use sin and cos with the distance and angle to move the rocks.