cos and sin plotting

[ericflash]

I have been playing with cos and sin functions and I understand how to plot items around a circle and also make them move in a circular movement. But what I'm not understanding and can't seem to find much about it is how to achieve swirls and moveclip placements like this image.



Here is what I have been trying but its nowhere like the image is showing.

		private function init( evt : Event ) : void
		{
			centerX = stage.stageWidth / 2;
			centerY = stage.stageHeight / 2;
			
			for( var i : int = 0; i < 20; i++ ){
				
				var circ : Shape = new Shape();
				circ.graphics.beginFill(0x333333);
				circ.graphics.drawCircle(0, 0, 20 );
				circ.x = centerX + i * Math.cos(i) * 70;
				circ.y = centerY + i * Math.sin(i) * 70;
		 		//circ.rotation = i * 12;
				addChild(circ);
			}
		}

Can someone please help shine some light how I can plot my items positions like the image with cos and sin.

Thank,

[Schfifty Five]

Well you're taking the sin and cosine of the loop variable (i), which is essentially meaningless (i is not an angle).

Assuming you want the circles to go around in a 360 degree spiral, try something like:

private function init( evt : Event ) : void
        {
            centerX = stage.stageWidth / 2;
            centerY = stage.stageHeight / 2;
            
            for( var i : int = 0; i < 20; i++ ){
                
                var circ : Shape = new Shape();
                circ.graphics.beginFill(0x333333);
                circ.graphics.drawCircle(0, 0, 20 );
                circ.x = centerX + i * Math.cos((i/20)*Math.PI*2) * 70;
                circ.y = centerY + i * Math.sin((i/20)*Math.PI*2) * 70;
                addChild(circ);
            }
        } 

Tweak the numbers a bit to make it look how you want.

[ericflash]

Thanks Schfifty Five
Can you explain this a little.

circ.x = centerX + i * Math.cos((i/20)*Math.PI*2) * 70;

I presume 70 is the radius but not sure why i / 20.
*Math.PI*2 is multiplying by 360 right or the full circle which is Math.PI * 2

Is there somewhere where I can read up on plotting points with cos and sin that shows me how to plot points that are like this and not just in a circle like most tutorials.

[realMakc]

the /20 part is because of your own choice in for( var i : int = 0; i < 20; i++ ), while i goes from 0 to 19, i/20 goes from 0 to (a little less than) 1.

to turn circle into ellipse you obviously need to multiply sin and cos by different numbers, not both 70.

also, I think "i * " part before sin/cos is pointless.

[Schfifty Five]

the /20 part is because of your own choice in for( var i : int = 0; i < 20; i++ ), while i goes from 0 to 19, i/20 goes from 0 to (a little less than) 1.

to turn circle into ellipse you obviously need to multiply sin and cos by different numbers, not both 70.

also, I think "i * " part before sin/cos is pointless.

Yep, what he said.

i/20 gives you a percentage which you multiply by Math.PI*2 (360 degrees) to get a full circle.

The "i *" part is necessary to have a spiral rather than an ellipse.