Asynchronous conditional graphics rendering

A graphics processing unit implements conditional rendering by putting itself in a state in which it does not execute any rendering commands. Once the graphics processing unit is placed in this state, all subsequent rendering commands are ignored until another rendering command explicitly removes the graphics processing unit from this state. Conditional rendering commands enable the graphics processing unit to place itself in and out of this state based upon the value of a flag in memory. Conditional rendering commands can include conditions that must be satisfied by the flag value in order to change the state of the graphics processing unit. The value of the flag can be set by the graphics processing unit itself, a second graphics processing unit, a graphics coprocessor, or the central processing unit. This enables a wide variety of conditional rendering methods to be implemented.