Monday, April 25, 2011


During the last three weeks I've spent most of my spare time writing a GUI for Jose's amazing ApiTrace project. ApiTrace is a project to trace, analyze and debug graphics api's. Both OpenGL and Direct3D. To some extend inspired by gDEBugger and Windows PIX. We wanted a tool that would let us slice through huge games and CAD apps to the exact call which causes problems and be able to inspect the entire graphics state, including the shaders, textures and all the buffers. We ended up doing that, plus a lot more and we're just getting started. In other words it's the best thing since "Human/Robot Emancipation Act of 3015".

You begin by tracing your target application. You can do that either from the console or from the GUI. A trace file is created and we can do some amazing things with it. You can open it in a GUI and
  • Inspect the state frame by frame, draw call by draw call:
  • Replay the trace file:
  • Check every texture:
  • Every bound framebuffer:
  • Every shader:
  • Every vertex buffer:
  • You can see if OpenGL threw an error at any point during the replay and if so what was it:
  • And to go completely nuts, as graphics developers like to do, you get to edit any shader, any uniform and large chunks of the state to immediately see the effects it would have on the rendering:

As a driver developer you no longer have to install all the games just to debug a problem, the report can simply include a short trace which you can use to immediately figure out what's wrong. As an application developer you can inspect every graphics call your app makes, you can analyze your api usage and you could automatically produce standalone testcases which you can send to driver developers.

ApiTrace is hosted on github and it's BSD licensed. It works on Linux and Windows (we're planning to add OSX support as well). Gui is written using Qt and requires the QJson library.

Jose just announced the first release so let us know if there's anything that would make your life a lot easier. Next is support for multiple GL contexts, ability to export just a single frame from a trace (either as a trace file or a standalone C application), ability to start and stop tracing on a hot key and lots of other features soon. So whether you're a driver developer, working on games, CAD apps or 2D scene-graphs this is a tool that should make your life significantly easier and better.