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How to Create circular path animation

We will use  Lathe class , this class allows you to define extrusion on a circular path defining starting angle, ending angle, radius, rotation axis ...

Download the classes lathe.zip

AS code:

package {
	import flash.display.Sprite;
	import flash.display.StageAlign;
	import flash.display.StageQuality;
	import flash.display.StageScaleMode;
	import flash.events.*;
    import flash.ui.*;
	import flash.geom.Point;

	import sandy.core.Scene3D;
	import sandy.core.scenegraph.Camera3D;
	import sandy.core.scenegraph.Group;
	import sandy.core.scenegraph.Shape3D;
	import sandy.materials.*;
	import sandy.materials.attributes.*;
	import sandy.primitive.Box;
	import sandy.primitive.Line3D;
	import sandy.extrusion.Extrusion;
	import sandy.extrusion.data.*;
	import sandy.core.data.*;

	public class Example046 extends Sprite {

		private var scene:Scene3D;
		private var camera:Camera3D;
		private var c:Box;
		private var ext:Extrusion;

		public function Example046() {

			camera = new Camera3D(stage.stageWidth, stage.stageHeight);
			scene = new Scene3D("myScene", this, camera , new Group("root"));

			var arrayElm:Array = new Array();
			arrayElm[0] = new Point(0,-10);	arrayElm[1] = new Point(0,10);	arrayElm[2] = new Point(30,10); arrayElm[3] = new Point(30,0);
			arrayElm[4] = new Point(20,0);	arrayElm[5] = new Point(20,5);	arrayElm[6] = new Point(10,5); arrayElm[7] = new Point(10,-10);
			arrayElm[8] = new Point(0,-10);

			var sectionElm:Polygon2D = new Polygon2D(arrayElm);

			var lathe1:Lathe = new Lathe (new Vector, new Vector (1, 1, 1), new Vector (1, 0, 0), 0, 4, 0.05);

			// create extrusion
			ext = new Extrusion ("ext0", sectionElm, lathe1.toSections ());
			ext.appearance = new Appearance (new ColorMaterial (0x990000, 1,
				new MaterialAttributes (new LightAttributes( true, 0.1))));
			ext.appearance.frontMaterial.lightingEnable = true;
            ext.pan = -40;
			ext.rotateX = -80;
			ext.pan = -40;
			ext.x = 20;
			ext.z = -100; 

			scene.root.addChild(ext);

			stage.addEventListener(MouseEvent.MOUSE_MOVE, mouseMovedHandler);
			addEventListener(Event.ENTER_FRAME, render);
		}

		private function render(event:Event):void {
			scene.render();
			//ext.rotateX += 4;
		}

		private function mouseMovedHandler(event:MouseEvent):void {
           //ext.pan=(event.stageX-550/2)/5;
		   //ext.tilt=(event.stageY-400/2)/20;

        }
	}
}

We start by defining a simple polygon2D that we want to extrude in a circular way:

var arrayElm:Array = new Array();
arrayElm[0] = new Point(0,-10);	arrayElm[1] = new Point(0,10);
arrayElm[2] = new Point(30,10); arrayElm[3] = new Point(30,0);
arrayElm[4] = new Point(20,0);	arrayElm[5] = new Point(20,5);
arrayElm[6] = new Point(10,5); arrayElm[7] = new Point(10,-10);
arrayElm[8] = new Point(0,-10);

var sectionElm:Polygon2D = new Polygon2D(arrayElm);

How to use the Lathe class

var lathe1:Lathe = new Lathe (new Vector, new Vector (1, 1, 1), new Vector (1, 0, 0), 0, 4, 0.05);

Since there is not much to do, probably it's better to list here the parameters of the Lath class:
* Generates circular, spiral or helix arc.

@param	center Arc center.
@param	axis Axis of revolution.
@param	reference A vector that specifies direction to count angle from. Must be non-collinear to axis.
@param	angle0 Start angle.
@param	angle1 End angle.
@param	step Angle step.
@param	radius0 Start radius.
@param	radius1 End radius.
@param	height0 Start height.
@param	height1 End height.
@param	scale0 Start scale.
@param	scale1 End scale.

public function Lathe (center:Vector, axis:Vector, reference:Vector,
angle0:Number = 0, angle1:Number = Math.PI, step:Number = 0.3,
radius0:Number = 100, radius1:Number = 100, height0:Number = 0,
height1:Number = 0, scale0:Number = 1, scale1:Number = 1)
Now see your project :