correct minor error in particle sizes

src/renderers/Renderer.js

@@ -140,10 +140,10 @@ var Renderer = Class.extend
 				
 				object.screen=object.screen.toVector3();
 				
-				if (object.screen.z >0 && object.screen.z < 1 
+				if (object.screen.z > 0 && object.screen.z < 1 
 				&& object.screen.x+object.zsize > -1 && object.screen.x-object.zsize < 1
 				&& object.screen.y+object.zsize > -1 && object.screen.y-object.zsize < 1){
-					object.zsize *=this.widthHalf;
+					object.zsize *= this.heightHalf;
 					object.screen.x *= this.widthHalf;
 					object.screen.y *= this.heightHalf; 
 					this.renderList.push( object );