Much of the understanding for supporting direct rendering of OpenGL came from the implementation of its predecessor, the IRIS GL. The work of Jeff Doughty, John Giannandrea, Luther Kitahata, Paul Mielke, Jeff Weinstein, and others on IRIS GL's resource management laid the basis for the facilities described here. We would like to acknowledge all those at Silicon Graphics who helped ensure OpenGL's successful implementation, notably Kurt Akeley, Peter Daifuku, Simon Hui, Phil Karlton, Mark Stadler, Paula Womack, and David Yu.