anchor.diff:  
   						var normal = geometry.attributes[ "normal" ];
   
  -						if ( attributes["normal"] >= 0 && normal ) {
  +						if ( attributes["normal"] >= 0 && normal != null) {
   
   							var normalSize = normal.itemSize;
   
  
positive.code: 
  						var uv = geometry.attributes[ "uv" ];
  
  						if ( attributes["uv"] >= 0 && uv ) {
  
  							var uvSize = uv.itemSize;
  
  
negative.code: 
  						var color = geometry.attributes[ "color" ];
  
  						if ( attributes["color"] >= 0 && color != null ) {
  
  							var colorSize = color.itemSize;
  
  