User programmable primitive engine

A fixed function engine and method are described for processing a set of primitive commands. One embodiment of the fixed function engine includes a means for receiving one or more primitive commands, where each such primitive command includes information for processing vertex data using a user-developed program or subroutine. The fixed function engine also includes a means for determining a set of related primitive commands from the received primitive commands and a means for identifying a first primitive command to process from that set. In addition, the fixed function engine includes a means for transmitting a first program command, which is related to the first primitive command, to a processing engine for processing.