SINE_MESHBATCH

package
{
    import flash.display.Sprite;
    import starling.core.Starling;

    public class SINE_MESHBATCH extends Sprite
    {
        public function SINE_MESHBATCH ()
        {
            with (stage) { frameRate = 60; color = 0x0; align = 'TL'; scaleMode = 'noScale'; }

            var starling : Starling = new Starling (Spiral, stage); // starling 2.1
            starling.showStats = true;
            starling.start ();
        }
    }
}


import flash.geom.Matrix;
import starling.display.*;
import starling.events.Event;
import starling.core.Starling;

/**  @author SPANVEGA // CHRISTIAN  **/

final class Spiral extends Sprite
{
    private var quad : Quad;

    private var batch : MeshBatch;

    private var angle  : Number = 0,
                radius : Number = 0;

    private var m : Matrix = new Matrix ();

    private var fx : Number, fy : Number, // from
                tx : Number, ty : Number, // to

                cx : Number, cy : Number; // center


    public function Spiral ()
    {
        quad = new Quad (1, 1, 0xFFFFFF);
        quad.alignPivot ();

        addChild (batch = new MeshBatch ());

        cx = Starling.current.stage.stageWidth  >> 1;
        cy = Starling.current.stage.stageHeight >> 1;

        addEventListener (Event.ENTER_FRAME, update);
    }

    private function update (e : Event) : void
    {
        tx = Math.sin (toRadians (angle)) * radius;
        ty = Math.cos (toRadians (angle)) * radius;

        //

        var q : Quad = line (quad, fx, fy, tx, ty);
        // offset to center
            q.x += cx;
            q.y += cy;

        batch.addMesh (q);

        //

        fx = tx, fy = ty;

        angle  += 5.0;
        radius += 0.3;
    }

    private function toRadians (degrees : Number) : Number
    {
        return degrees * Math.PI / 180
    }

    private function line (quad : Quad, fx : Number, fy : Number, tx : Number, ty : Number) : Quad
    {
        var dx : Number = tx - fx,
            dy : Number = ty - fy,
            ds : Number = Math.sqrt (dx * dx + dy * dy);

        var a : Number, b : Number, c : Number, d : Number,
            sin : Number, cos : Number, rad : Number;

        // scale
        a = ds;

        // identity
        b = 0;
        c = 0;
        d = 1;

        // rotate
        rad = Math.atan2 (dy, dx);
        sin = Math.sin (rad);
        cos = Math.cos (rad);

        m.a  = a * cos - b * sin;
        m.b  = a * sin + b * cos;
        m.c  = c * cos - d * sin;
        m.d  = c * sin + d * cos;

        // translate
        m.tx = fx;
        m.ty = fy;

        //

        quad.transformationMatrix = m;

        return quad;
    }
}