package org.papervision3d.core.culling {	import org.papervision3d.core.geom.renderables.Triangle3D;	import org.papervision3d.core.geom.renderables.Vertex3DInstance;	import org.papervision3d.core.proto.MaterialObject3D;	import org.papervision3d.objects.DisplayObject3D;		public class DefaultTriangleCuller implements ITriangleCuller	{				private static var x0:Number;		private static var y0:Number;		private static var x1:Number;		private static var y1:Number;		private static var x2:Number;		private static var y2:Number;				public function DefaultTriangleCuller()		{					}			public function testFace(face:Triangle3D, vertex0:Vertex3DInstance, vertex1:Vertex3DInstance, vertex2:Vertex3DInstance):Boolean		{			//Material checks & backface culling			if(vertex0.visible && vertex1.visible && vertex2.visible){				var material:MaterialObject3D = face.material ? face.material : face.instance.material;								if(material.invisible){					return false;				};								x0 = vertex0.x;				y0 = vertex0.y;				x1 = vertex1.x;				y1 = vertex1.y;				x2 = vertex2.x;				y2 = vertex2.y;								if( material.oneSide ){					if( material.opposite ){						if( ( x2 - x0 ) * ( y1 - y0 ) - ( y2 - y0 ) * ( x1 - x0 ) > 0 )						{							return false;						}					}else{						if( ( x2 - x0 ) * ( y1 - y0 ) - ( y2 - y0 ) * ( x1 - x0 ) < 0 )						{							return false;						}					}				}				return true;			}			return false;		}			}}