14. The method according to claim 13 , wherein the generated data structure comprises a list of the intermediate representations being generated, each entry in the created list referencing a corresponding one of the intermediate representations and is associated with a state variable defining the progress of generating the corresponding intermediate representation.
14. The method according to claim 13 , wherein the generated data structure comprises a list of the intermediate representations being generated, each entry in the created list referencing a corresponding one of the intermediate representations and is associated with a state variable defining the progress of generating the corresponding intermediate representation. 15. The method according to claim 14 , wherein the least two intermediate representations consecutive in z-order are selected based on the list and the associated state variables.