OpenGL.GL.SGIX.instruments

OpenGL extension SGIX.instruments

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

Overview (from the spec)

This extension allows the gathering and return of performance measurements from within the graphics pipeline by adding instrumentation.

There are two reasons to do this. The first is as a part of some type of fixed-frame-rate load management scheme. If we know that the pipeline is stalled or struggling to process the amount of data we have given it so far, we can reduce the level of detail of the remaining objects in the current frame or the next frame, or adjust the framebuffer resolution for the next frame if we have a video-zoom capability available. We can call this type of instrumentation Load Monitoring.

The second is for performance tuning and debugging of an application. It might tell us how many triangles were culled or clipped before being rasterized. We can call this simply Tuning.

Load Monitoring requires that the instrumentation and the access of the measurements be efficient, otherwise the instrumentation itself will reduce performance more than any load-management scheme could hope to offset. Tuning does not have the same requirements.

The proposed extension adds a call to setup a measurements return buffer, similar to FeedbackBuffer but with an asynchrounous behavior to prevent filling the pipeline with NOP's while waiting for the data to be returned.

Note that although the extension has been specified without any particular instruments, defining either a device dependent or device independent instrument should be as simple as introducing an extension consisting primarily of a new enumerant to identify the instrument.

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