/sandy/as3/branches/3.0.1/src/sandy/core/data/Polygon.as

/*

# ***** BEGIN LICENSE BLOCK *****

Copyright the original author Thomas PFEIFFER

Licensed under the MOZILLA PUBLIC LICENSE, Version 1.1 (the "License");

you may not use this file except in compliance with the License.

You may obtain a copy of the License at

	http://www.mozilla.org/MPL/MPL-1.1.html

Unless required by applicable law or agreed to in writing, software

distributed under the License is distributed on an "AS IS" BASIS,

WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

See the License for the specific language governing permissions and

limitations under the License.



# ***** END LICENSE BLOCK *****

*/



package sandy.core.data

{

	import flash.display.Sprite;

	import flash.events.Event;

	import flash.events.MouseEvent;

	import flash.geom.Point;

	import flash.geom.Rectangle;

	import flash.utils.Dictionary;

	

	import sandy.core.Scene3D;

	import sandy.core.interaction.VirtualMouse;

	import sandy.core.scenegraph.Geometry3D;

	import sandy.core.scenegraph.IDisplayable;

	import sandy.core.scenegraph.Shape3D;

	import sandy.events.BubbleEvent;

	import sandy.events.BubbleEventBroadcaster;

	import sandy.materials.Appearance;

	import sandy.math.IntersectionMath;

	import sandy.math.Matrix4Math;

	import sandy.math.VectorMath;

	import sandy.util.NumberUtil;

	import sandy.view.Frustum;
	import flash.events.KeyboardEvent;



	/**

	 * Polygon's are the building blocks of visible 3D shapes.

	 *

	 * @author		Thomas Pfeiffer - kiroukou

	 * @author		Mirek Mencel

	 * @since		1.0

	 * @version		3.0

	 * @date 		24.08.2007

	 */

	public final class Polygon implements IDisplayable

	{

	// _______

	// STATICS_______________________________________________________

		private static var _ID_:uint = 0;

		

		/**

		 * This property lists all the polygons.

		 * This is an helping property since it allows to retrieve a polygon instance from its unique ID.

		 * Polygon objects have an unique ID with myPolygon.id.

		 * Using : Polygon.POLYGON_MAP[myPolygon.id] returns myPolygon (for sure this example has no interesst except showing the use of the property.

		 */

		public static var POLYGON_MAP:Dictionary = new Dictionary(true);

	// ______

	// PUBLIC________________________________________________________

		/**

		 * [READ-ONLY] property

		 * Unique polygon ID Number.

		 */

		public const id:uint = _ID_++;



		/**

		 * [READ-ONLY] property.

		 * Link to the Shape3D instance this polygon is related too.

		 */

		public var shape:Shape3D;

		

		/**

		 * [READ-ONLY] property.

		 * Refers to the Scene3D the shape is linked to.

		 */

		public var scene:Scene3D;

		

		/**

		 * [READ-ONLY] property.

		 * Specify if the polygon has been clipped

		 */

		public var isClipped:Boolean = false;

		/**

		 * [READ-ONLY] property.

		 * Array of clipped vertices. Check isClipped property first to see if this array shall be containing the useful data or not.

		 */

		public var cvertices:Array;

		/**

		 * [READ-ONLY] property.

		 * Array of original vertices.

		 */

		public var vertices:Array;

		/**

		 * [READ-ONLY] property.

		 */

		public var vertexNormals:Array;

		/**

		 * [READ-ONLY] property.

		 */

		public var normal:Vertex;

		/**

		 * [READ-ONLY] property.

		 */

		public var aUVCoord:Array;



		/**

		 * [READ-ONLY] property.

		 */

		public var aEdges:Array;



		/**

		 * [READ-ONLY] property.

		 */

		public var caUVCoord:Array;



		/**

		 * [READ-ONLY] property.

		 * This property contains the texture bounds as a Rectangle.

		 */

		public var uvBounds:Rectangle;

		

		/**

		 * [READ-ONLY] property

		 * Array of polygons that share an edge with the current polygon.

		 */

		public var aNeighboors:Array = new Array();

		

		/**

		 * [READ-ONLY] property.

		 * Min values of this polygon

		 */

		public var minBounds:Vector = new Vector();

		/**

		 * [READ-ONLY] property.

		 * Max values of this polygon

		 */

		public var maxBounds:Vector = new Vector();

		/**

		 * [READ-ONLY] property.

		 * Mean values of this polygon

		 */

		public var meanBounds:Vector = new Vector();



		/**

		 * Creates a new polygon.

		 *

		 * @param p_oShape		    The shape this polygon belongs to

		 * @param p_geometry		The geometry this polygon is part of

		 * @param p_aVertexID		The vertexID array of this polygon

		 * @param p_aUVCoordsID		The UVCoordsID array of this polygon

		 * @param p_nFaceNormalID	The faceNormalID of this polygon

		 * @param p_nEdgesID		The edgesID of this polygon

		 */

		public function Polygon( p_oOwner:Shape3D, p_geometry:Geometry3D, p_aVertexID:Array, p_aUVCoordsID:Array=null, p_nFaceNormalID:Number=0, p_nEdgesID:uint=0 )

		{

			shape = p_oOwner;

			m_oGeometry = p_geometry;

			// --

			__update( p_aVertexID, p_aUVCoordsID, p_nFaceNormalID, p_nEdgesID );

			m_oContainer = new Sprite();

			// --

			POLYGON_MAP[id] = this;

		}



		/**

		 * The broadcaster property.

		 *

		 * <p>The broadcaster is the property used to send events to listeners.</p>

		 */

		public function get broadcaster():BubbleEventBroadcaster

		{

			return m_oEB;

		}



		/**

		 * Adds a listener for specifical event.

		 *

		 * @param p_sEvent 	Name of the Event.

		 * @param oL 		Listener object.

		 */

		public function addEventListener(p_sEvent:String, oL:*) : void

		{

			m_oEB.addEventListener.apply(m_oEB, arguments);

		}



		/**

		 * Removes a listener for specifical event.

		 *

		 * @param p_sEvent 	Name of the Event.

		 * @param oL 		Listener object.

		 */

		public function removeEventListener(p_sEvent:String, oL:*) : void

		{

			m_oEB.removeEventListener(p_sEvent, oL);

		}





		/**

		 * Pre-compute several properties of the polygon in the same time.

		 * List of the computed properties :

		 *  - visibility : if the polygon is visible

		 */

		public function computeVisibility():void

		{

			// all normals are refreshed every loop. Face is visible is normal face to the camera

			var l_nDot:Number = ( m_oVisibilityRef.wx * normal.wx + m_oVisibilityRef.wy * normal.wy + m_oVisibilityRef.wz * normal.wz );

			m_bVisible = ( l_nDot < 0 );

		}	

			

		/**

		 * Pre-compute several properties of the polygon in the same time.

		 * List of the computed properties :

		 * <ul>

		 *  <li>mean z depth : the mean z depth used for basic sorting</li>

		 *  <li>max bounds : the maximum bounds of the polygon</li>

		 *  <li>min bounds : the minimum bounds of the polygon</li>

		 *  <li>mean bounds : the mean of each components of the polygon. It is center actually.</li>

		 * </ul>

		 */

		public function precomputeBounds():void

		{

			const l_aVert:Array = vertices;

			// --

			meanBounds.reset();

			minBounds.resetToPositiveInfinity();

			maxBounds.resetToNegativeInfinity();

			// --

			for each ( var v:Vertex in l_aVert )

			{

				if( v.wx < minBounds.x ) minBounds.x = v.wx;

				else if( v.wx > maxBounds.x ) maxBounds.x = v.wx;

				// --

				if( v.wy < minBounds.y ) minBounds.y = v.wy;

				else if( v.wy > maxBounds.y ) maxBounds.y = v.wy;

				// --

				if( v.wz < minBounds.z ) minBounds.z = v.wz;

				else if( v.wz > maxBounds.z ) maxBounds.z = v.wz;

				// -- 

				meanBounds.x += v.wx;

				meanBounds.y += v.wy;

				meanBounds.z += v.wz;

			}

			// -- We normalize the sum and return it

			meanBounds.scale( 1 / l_aVert.length );

		}

		

		/**

		 * Is this face visible?.

		 * The method returns the visibility value pre computed after precompute method call. This getter shall be called afer the precompute call.

		 * @return 	true if this face is visible, false otherwise.

		 */

		public function get visible(): Boolean

		{return m_bVisible;}



		/**

		 * Returns the real 3D position of the 2D screen position.

		 * The 2D position is usually coming from :

		 * <listing version="3.0">

		 * var l_nClicX:Number = m_oScene.container.mouseX;

         * var l_nClicY:Number = m_oScene.container.mouseY;

         * </listing>

         * 

         * @return the real 3D position which correspond to the intersection onto that polygone

         */

		public function get3DFrom2D( p_oScreenPoint:Point ):Vector

		{

			var l_nX:Number = (p_oScreenPoint.x - scene.camera.viewport.width2)/ scene.camera.viewport.width2;

            var l_nY:Number = -(p_oScreenPoint.y - scene.camera.viewport.height2)/scene.camera.viewport.height2;

            var l_oPoint:Vector = new Vector( l_nX, l_nY, 0 );



            // -- on prend la matrice de projection inverse

            var l_oMatrix:Matrix4 = scene.camera.invProjectionMatrix;

            l_oMatrix.vectorMult( l_oPoint );

            l_oMatrix = scene.camera.matrix;

            l_oMatrix.vectorMult( l_oPoint );



            // -- maintenant nous avons la direction du rayon logiquement.

            // -- reste a calculer son intersection avec le polygone

            var l_oNormale:Vector = normal.getVector();

            var l_oOrigineRayon:Vector = scene.camera.getPosition();

                 

            l_oPoint.sub( l_oOrigineRayon );

            //on normalise le vecteur car c'est lui qui sert de vecteur directeur du rayon qui part

            l_oPoint.normalize();

 

            // on chope la constante du plan

            var l_nPlaneConst:Number = VectorMath.dot( (vertices[0] as Vertex).getVector(), l_oNormale );

         

            // Calcul le produit scalaire Normale du plan avec le vecteur directeur du rayon

            var l_nDotNormalePlanRayon:Number = l_oNormale.dot( l_oPoint );



            // In case the ray is parallel to the plane

            if( l_nDotNormalePlanRayon >= -NumberUtil.TOL && l_nDotNormalePlanRayon <= NumberUtil.TOL )

                return null;

         

            // distance from ray to plane

            var l_nDistRayonPlan:Number = (l_oOrigineRayon.dot( l_oNormale ))/(l_oNormale.getNorm());         

     

            // lpane distance

            var t:Number =  - l_nDistRayonPlan / l_nDotNormalePlanRayon

     

            // No collision

            if( t < NumberUtil.TOL )

                return null;

         

            // -- intersection point

          return new Vector( 	l_oOrigineRayon.x + t * l_oPoint.x,

								l_oOrigineRayon.y + t * l_oPoint.y,

                      			l_oOrigineRayon.z + t * l_oPoint.z );;

		}

		

		/**

		 * Get the UVCoord under the 2D screen position after a mouse click or something

		 * The 2D position is usually coming from :

		 * <listing version="3.0">

		 * var l_nClicX:Number = m_oScene.container.mouseX;

         * var l_nClicY:Number = m_oScene.container.mouseY;

         * </listing>

         * 

         * @return the UVCoord under the 2D screen point

         */

		public function getUVFrom2D( p_oScreenPoint:Point ):UVCoord

		{

			var p0:Point = new Point(vertices[0].sx, vertices[0].sy);

            var p1:Point = new Point(vertices[1].sx, vertices[1].sy);

            var p2:Point = new Point(vertices[2].sx, vertices[2].sy);

          

            var u0:UVCoord = aUVCoord[0];

            var u1:UVCoord = aUVCoord[1];

            var u2:UVCoord = aUVCoord[2];

          

            var v01:Point = new Point(p1.x - p0.x, p1.y - p0.y );

           

            var vn01:Point = v01.clone();

            vn01.normalize(1);

           

            var v02:Point = new Point(p2.x - p0.x, p2.y - p0.y );

            var vn02:Point = v02.clone(); vn02.normalize(1);

           

            // sub that from click point

            var v4:Point = new Point( p_oScreenPoint.x - v01.x, p_oScreenPoint.y - v01.y );

            

            // we now have everything to find 1 intersection

            var l_oInter:Point = IntersectionMath.intersectionLine2D( p0, p2, p_oScreenPoint, v4 );

            

            // find vectors to intersection

            var vi02:Point = new Point( l_oInter.x - p0.x, l_oInter.y - p0.y );      

            var vi01:Point = new Point( p_oScreenPoint.x - l_oInter.x , p_oScreenPoint.y - l_oInter.y );



            // interpolation coeffs

            var d1:Number = vi01.length / v01.length ;

            var d2:Number = vi02.length / v02.length;

                     

            // -- on interpole linéairement pour trouver la position du point dans repere de la texture (normalisé)

            return new UVCoord( u0.u + d1*(u1.u - u0.u) + d2*(u2.u - u0.u),

				                u0.v + d1*(u1.v - u0.v) + d2*(u2.v - u0.v));

		}

		

		/**

		 * Returns an array containing the vertices, clipped by the camera frustum.

		 *

		 * @return 	The array of clipped vertices

		 */

		public function clip( p_oFrustum:Frustum ):Array

		{

			isClipped = true;

			// For lines we only apply front plane clipping

			if( vertices.length < 3 )

			{

				clipFrontPlane( p_oFrustum );

			} 

			else

			{

				cvertices = null;

				caUVCoord = null;

				// --	

				cvertices = vertices.concat();

				caUVCoord = aUVCoord.concat();

				// --

				p_oFrustum.clipFrustum( cvertices, caUVCoord );

			}

			return cvertices;

		}



		/**

		 * Perform a clipping against the near frustum plane.

		 *

		 * @return 	The array of clipped vertices

		 */

		public function clipFrontPlane( p_oFrustum:Frustum ):Array

		{

			isClipped = true;

			cvertices = null;

			cvertices = vertices.concat();

			// If line

			if( vertices.length < 3 ) 

			{

				p_oFrustum.clipLineFrontPlane( cvertices );

			}

			else

			{

				caUVCoord = null;

				caUVCoord = aUVCoord.concat();

				p_oFrustum.clipFrontPlane( cvertices, caUVCoord );

			}

			return cvertices;

		}

		

		/**

		 * Updates the vertices and normals for this polygon.

		 *

		 * <p>Calling this method make the polygon gets its vertice and normals by reference

		 * instead of accessing them by their ID.<br/>

		 * This method shall be called once the geometry created.</p>

		 *

		 * @param p_aVertexID		The vertexID array of this polygon

		 * @param p_aUVCoordsID		The UVCoordsID array of this polygon

		 * @param p_nFaceNormalID	The faceNormalID of this polygon

		 * @param p_nEdgesID		The edgesID of this polygon

		 */

		private function __update( p_aVertexID:Array, p_aUVCoordsID:Array, p_nFaceNormalID:uint, p_nEdgeListID:uint ):void

		{

			var i:int=0, l:int;

			// --

			vertexNormals = new Array();

			vertices = new Array();

			for each( var o:* in p_aVertexID )

			{

				vertices[i] = Vertex( m_oGeometry.aVertex[ p_aVertexID[i] ] );

				vertexNormals[i] = m_oGeometry.aVertexNormals[ p_aVertexID[i] ];

				i++;

			}

			// --

			m_oVisibilityRef = vertices[0];

			// -- every polygon does not have some texture coordinates

			if( p_aUVCoordsID )

			{

				var l_nMinU:Number = Number.POSITIVE_INFINITY, l_nMinV:Number = Number.POSITIVE_INFINITY,

									l_nMaxU:Number = Number.NEGATIVE_INFINITY, l_nMaxV:Number = Number.NEGATIVE_INFINITY;

				// --

				aUVCoord = new Array();

				i = 0;

				for each( var p:* in p_aUVCoordsID )

				{

					var l_oUV:UVCoord = UVCoord( m_oGeometry.aUVCoords[ p_aUVCoordsID[i] ] );

					aUVCoord[i] = l_oUV;

					if( l_oUV.u < l_nMinU ) l_nMinU = l_oUV.u;

					else if( l_oUV.u > l_nMaxU ) l_nMaxU = l_oUV.u;

					// --

					if( l_oUV.v < l_nMinV ) l_nMinV = l_oUV.v;

					else if( l_oUV.v > l_nMaxV ) l_nMaxV = l_oUV.v;

					// --

					i++;

				}

				// --

				uvBounds = new Rectangle( l_nMinU, l_nMinV, l_nMaxU-l_nMinU, l_nMaxV-l_nMinV );

			}

			// --

			normal = Vertex( m_oGeometry.aFacesNormals[ p_nFaceNormalID ] );

			// If no normal has been given, we create it ourself.

			if( normal == null )

			{

				var l_oNormal:Vector = createNormal();

				var l_nID:Number = m_oGeometry.setFaceNormal( m_oGeometry.getNextFaceNormalID(), l_oNormal.x, l_oNormal.y, l_oNormal.z );

				normal = Vertex( m_oGeometry.aFacesNormals[ l_nID ] );

			}

			// --

			aEdges = new Array();

			for each( var l_nEdgeId:uint in  m_oGeometry.aFaceEdges[p_nEdgeListID] )

			{

				var l_oEdge:Edge3D = m_oGeometry.aEdges[ l_nEdgeId ];

				l_oEdge.vertex1 = m_oGeometry.aVertex[ l_oEdge.vertexId1 ];

				l_oEdge.vertex2 = m_oGeometry.aVertex[ l_oEdge.vertexId2 ];

				aEdges.push( l_oEdge );

			}

		}



		/**

		 * Clears the container of this polygon from graphics.

		 */

		public function clear():void

		{

			m_oContainer.graphics.clear();

		}



		/**

		 * Displays this polygon on its container if visible.

		 *

		 * @param p_oScene The current scene this polygon is rendered into

		 * @param p_oContainer	The container to draw on

		 */

		public function display( p_oScene:Scene3D, p_oContainer:Sprite = null ):void

		{

			scene = p_oScene;

			// --

			const lCont:Sprite = (p_oContainer)?p_oContainer:m_oContainer;

			if( m_bVisible )

			{

				m_oAppearance.frontMaterial.renderPolygon( p_oScene, this, lCont );

			}

			else

			{

				m_oAppearance.backMaterial.renderPolygon( p_oScene, this, lCont );

			}

		}



		/**

		 * The container for this polygon.

		 */

		public function get container():Sprite

		{

			return m_oContainer;

		}



		/**

		 * @private

		 */

		public function get depth():Number

		{

			return meanBounds.z;

		}



		/**

		 * The z depth of this polygon.

		 */

		public function set depth( p_nDepth:Number ):void

		{

			meanBounds.z = p_nDepth;

		}



		/**

		 * Returns a string representing of this polygon.

		 *

		 * @return	The string representation.

		 */

		public function toString():String

		{

			return "sandy.core.data.Polygon::id=" +id+ " [Points: " + vertices.length + "]";

		}



		/**

		 * Enables or disables object events for this polygon.

		 *

		 * <p>If a value of true is passed, the object events onPress, onRollOver and onRollOut are enabled.<br />.

		 * To use them, you have to add listeners for the events.</p>

		 *

		 * @param b 	Pass true to enable the events, false to disable.

		 */

		public function set enableEvents( b:Boolean ):void

		{

	        if( b && !mouseEvents )

	        {

	        	container.addEventListener(MouseEvent.CLICK, _onInteraction);

	    		container.addEventListener(MouseEvent.MOUSE_UP, _onInteraction);

	    		container.addEventListener(MouseEvent.MOUSE_DOWN, _onInteraction);

	    		container.addEventListener(MouseEvent.ROLL_OVER, _onInteraction);

	    		container.addEventListener(MouseEvent.ROLL_OUT, _onInteraction);

	    		

				container.addEventListener(MouseEvent.DOUBLE_CLICK, _onInteraction);

				container.addEventListener(MouseEvent.MOUSE_MOVE, _onInteraction);

				container.addEventListener(MouseEvent.MOUSE_OVER, _onInteraction);

				container.addEventListener(MouseEvent.MOUSE_OUT, _onInteraction);

				container.addEventListener(MouseEvent.MOUSE_WHEEL, _onInteraction);

    

			}

			else if( !b && mouseEvents )

			{

				container.removeEventListener(MouseEvent.CLICK, _onInteraction);

				container.removeEventListener(MouseEvent.MOUSE_UP, _onInteraction);

				container.removeEventListener(MouseEvent.MOUSE_DOWN, _onInteraction);

				container.removeEventListener(MouseEvent.ROLL_OVER, _onInteraction);

				container.removeEventListener(MouseEvent.ROLL_OUT, _onInteraction);

				

				container.removeEventListener(MouseEvent.DOUBLE_CLICK, _onInteraction);

				container.removeEventListener(MouseEvent.MOUSE_MOVE, _onInteraction);

				container.removeEventListener(MouseEvent.MOUSE_OVER, _onInteraction);

				container.removeEventListener(MouseEvent.MOUSE_OUT, _onInteraction);

				container.removeEventListener(MouseEvent.MOUSE_WHEEL, _onInteraction);

	    	}

	    	mouseEvents = b;

		}

		

		public function get enableEvents():Boolean

		{ return mouseEvents; }



		protected function _onInteraction( p_oEvt:Event ):void

		{m_oEB.broadcastEvent( new BubbleEvent( p_oEvt.type, this, p_oEvt ) );}

		

		protected function _startMouseInteraction( e : MouseEvent = null ) : void

		{

			container.addEventListener(MouseEvent.CLICK, _onTextureInteraction);

			container.addEventListener(MouseEvent.MOUSE_UP, _onTextureInteraction);

			container.addEventListener(MouseEvent.MOUSE_DOWN, _onTextureInteraction);

			

			container.addEventListener(MouseEvent.DOUBLE_CLICK, _onTextureInteraction);

			container.addEventListener(MouseEvent.MOUSE_MOVE, _onTextureInteraction);

			container.addEventListener(MouseEvent.MOUSE_OVER, _onTextureInteraction);

			container.addEventListener(MouseEvent.MOUSE_OUT, _onTextureInteraction);

			container.addEventListener(MouseEvent.MOUSE_WHEEL, _onTextureInteraction);

			

			container.addEventListener(KeyboardEvent.KEY_DOWN, _onTextureInteraction);

			container.addEventListener(KeyboardEvent.KEY_UP, _onTextureInteraction);

			

			m_oContainer.addEventListener( Event.ENTER_FRAME, _onTextureInteraction );

		}

		

		protected function _stopMouseInteraction( e : MouseEvent = null ) : void

		{

			container.removeEventListener(MouseEvent.CLICK, _onTextureInteraction);

			container.removeEventListener(MouseEvent.MOUSE_UP, _onTextureInteraction);

			container.removeEventListener(MouseEvent.MOUSE_DOWN, _onTextureInteraction);

			

			container.removeEventListener(MouseEvent.DOUBLE_CLICK, _onTextureInteraction);

			container.removeEventListener(MouseEvent.MOUSE_MOVE, _onTextureInteraction);

			container.removeEventListener(MouseEvent.MOUSE_OVER, _onTextureInteraction);

			container.removeEventListener(MouseEvent.MOUSE_OUT, _onTextureInteraction);

			container.removeEventListener(MouseEvent.MOUSE_WHEEL, _onTextureInteraction);

			m_oContainer.removeEventListener( Event.ENTER_FRAME, _onTextureInteraction );

			

			container.removeEventListener(KeyboardEvent.KEY_DOWN, _onTextureInteraction);

			container.removeEventListener(KeyboardEvent.KEY_UP, _onTextureInteraction);

			

		}

		

		public function set enableInteractivity( p_bState:Boolean ):void

		{

			if( p_bState != mouseInteractivity )

			{

				if( p_bState )

				{

					container.addEventListener( MouseEvent.ROLL_OVER, _startMouseInteraction, false );

					container.addEventListener( MouseEvent.ROLL_OUT, _stopMouseInteraction, false );

				}

				else

				{

					_stopMouseInteraction();

				}

				// --

				mouseInteractivity = p_bState;

			}

		}

		

		public function get enableInteractivity():Boolean

		{ return mouseInteractivity; }

		

		

		protected function _onTextureInteraction( p_oEvt:Event = null ) : void

		{

			if ( p_oEvt == null || !(p_oEvt is MouseEvent) ) p_oEvt = new MouseEvent( MouseEvent.MOUSE_MOVE, true, false, 0, 0, null, false, false, false, false, 0);

			

		    //	get the position of the mouse on the poly

			var pt2D : Point = new Point( scene.container.mouseX, scene.container.mouseY );

			var uv : UVCoord = getUVFrom2D( pt2D );

			

			VirtualMouse.getInstance().interactWithTexture( this, uv, p_oEvt as MouseEvent );

			_onInteraction( p_oEvt );

		}

				

		/**

		 * Calculates and returns the normal vector of the polygon.

		 *

		 * @return	The normal vector

		 */

		public function createNormal():Vector

		{

			if( vertices.length > 2 )

			{

				var v:Vector, w:Vector;

				var a:Vertex = vertices[0], b:Vertex = vertices[1], c:Vertex = vertices[2];

				v = new Vector( b.wx - a.wx, b.wy - a.wy, b.wz - a.wz );

				w = new Vector( b.wx - c.wx, b.wy - c.wy, b.wz - c.wz );

				// we compute de cross product

				var l_normal:Vector = VectorMath.cross( v, w );

				// we normalize the resulting vector

				VectorMath.normalize( l_normal ) ;

				// we return the resulting vertex

				return l_normal;

			}

			else

			{

				return new Vector();

			}

		}



		/**

		 * The appearance of this polygon.

		 */

		public function set appearance( p_oApp:Appearance ):void

		{

			m_oAppearance = p_oApp;

			// --

			p_oApp.frontMaterial.init( this );

			p_oApp.backMaterial.init( this );

		}



		/**

		 * @private

		 */

		public function get appearance():Appearance

		{

			return m_oAppearance;

		}



		/**

		 * Changes which side is the "normal" culling side.

		 *

		 * <p>The method also swaps the front and back skins.</p>

		 */

		public function swapCulling():void

		{

			//TODO Check the acuracy of this method

			// reverse the normal

			var v:Vector = normal.getVector();

			var m:Matrix4 = Matrix4Math.axisRotation( vertices[0].x - vertices[1].x, vertices[0].y - vertices[1].y, vertices[0].z - vertices[1].z, 180 );

			m.vectorMult3x3( v );

			v.normalize();

			normal.x = v.x;

			normal.y = v.y;

			normal.z = v.z;

			v = null;

			m = null;

		}



		/**

		 * Destroys the sprite attache to this polygon.

		 */

		public function destroy():void

		{

			clear();

			// --

			if( m_oContainer.parent ) m_oContainer.parent.removeChild( m_oContainer );

			if( m_oContainer ) m_oContainer = null;

			// --

			cvertices = null;

			vertices = null;

			m_oEB = null;

		}





	// _______

	// PRIVATE_______________________________________________________



		/** Reference to its owner geometry */

		private var m_oGeometry:Geometry3D;

		private var m_oAppearance:Appearance;

		/** array of ID of uv coordinates in geometry object */

		private var m_aUVCoords:Array;

		private var m_bVisible:Boolean = false;



		protected var m_oContainer:Sprite;

		protected var m_oVisibilityRef:Vertex;



		protected var m_oEB:BubbleEventBroadcaster = new BubbleEventBroadcaster();



		/** Boolean representing the state of the event activation */

		private var mouseEvents:Boolean = false;

		private var mouseInteractivity:Boolean = false;

	}

}