OpenGL.GL.SGIX.async

OpenGL extension SGIX.async

This module customises the behaviour of the OpenGL.raw.GL.SGIX.async to provide a more Python-friendly API

Overview (from the spec)

This extension provides a framework for asynchronous OpenGL commands. It also provides commands allowing a program to wait for the completion of asynchronous commands.

Asynchronous commands have two properties:

1) Asynchronous commands are non-blocking. For example, an asynchronous ReadPixels command returns control to the program immediately rather than blocking until the command completes. This property allows the program to issue other OpenGL commands in parallel with the execution of commands that normally block.

2) Asynchronous commands may complete out-of-order with respect to other OpenGL commands. For example, an asynchronous TexImage command may complete after subsequent OpenGL commands issued by the program rather than maintaining the normal serial order of the OpenGL command stream. This property allows the graphics accelerator to execute asynchronous commands in parallel with the normal command stream, for instance using a secondary path to transfer data from or to the host, without doing any dependency checking.

Programs that issue asynchronous commands must also be able to determine when the commands have completed. The completion status may be needed so that results can be retrieved (e.g. the image data from a ReadPixels command) or so that dependent commands can be issued (e.g. drawing commands that use texture data downloaded by an earlier asynchronous command). This extension provides fine-grain control over asynchronous commands by introducing a mechanism for determining the status of individual commands.

Each invocation of an asynchronous command is associated with an integer called a "marker." A program specifies a marker before it issues an asynchronous command. The program may later issue a command to query if any asynchronous commands have completed. The query commands return a marker to identify the command that completed. This extension provides both blocking and non-blocking query commands.

This extension does not define any asynchronous commands. See SGIX_async_pixel for the asynchronous pixel commands.

The official definition of this extension is available here: http://www.opengl.org/registry/specs/SGIX/async.txt