System Support for OpenGL Direct Rendering

OpenGL’s window system support for the X Window System explicitly allows implementations to support direct rendering of OpenGL commands to the graphics hardware. Rendering directly to the hardware avoids the overhead of packing and relaying protocol requests to the X server inherent in indirect rendering. The OpenGL implementation available for Silicon Graphics workstations supports direct rendering using virtualizable graphics hardware in conjunction with the kernel and the X server. The techniques described provide “maximum performance” rendering for OpenGL. Some of the issues are specific to OpenGL, but most of the techniques described are appropriate for the implementation of any high-performance direct rendering graphics interface.