OpenGL questions

[Kevin Camp]

opengl can make some things faster (notably 3d, but also some effects… there is a list of opengl accelerated effects/features in the manual), however it can also lead to instability, so manyusers disable it.

disabling opengl for previews will also allow multiprocessing to be used for preview rendering. so with all 8-cores being used for rendering previews, you may not see much of a slow down in previews… in fact, since there are not too many effects that are accelerated by opengl, you may get better performance in many situations.

Kevin Camp
Senior Designer
KCPQ, KMYQ & KRCW

[Jon Geddes]

Not just instability (which I haven’t really had an issue with), but more importantly, inaccuracy. OpenGL mode often times doesn’t render colors properly.

Every time my comps have gotten really complex and I think to myself that maybe it would render faster if in OpenGL mode, I try enabling it and some of the colors change, particularly in the bright white areas like bright lens flares will turn yellow or something. I would advise against using it.

Jon Geddes
Motion Graphics Designer
http://www.precomposed.com

[Adolfo Rozenfeld]

This is all true.
And that’s why the “OpenGL – Interactive” mode exists for Fast Previews.
It basically provides OpenGL acceleration when you interact (ie, while dragging with your mouse) with layers in the Comp panel, adjust parameters in the Timeline or Effects panel, etc. Then the software renderer kicks in when you release the mouse button and renders that frame.
This mode IMO gives you the best of both worlds, because the OpenGL muscle helps you get a very fast and responsive preview (even if not entirely accurate) and then you do get the actual result from the software renderer. With more powerful graphics cards, you get better results and more advanced features (like preview for Depth of Field, in CS4)
Even for OpenGL – Interactive, if your Comp has non-accelerated effects, it becomes a moot point. It just falls back to software.

The recommendation to turn off OpenGL is so widespread, because OpenGL driver conflicts can lead to instability (especially on the Windows side of things, because of the myriad of drivers available). Sticking to Adobe recommended graphics card and drivers should help. But if you’re not getting corrupt textures or OpenGL-related crashes, there’s no reason to turn it off.

Adolfo Rozenfeld · Adobe

[Tyler Muehlen]

Thanks everyone. You pretty much confirmed my suspicions. I had interactive turned on. The biggest difference I have noticed with it turned off is the view port tended to lag- or get pixalted more often when making changes.

Thanks for clearing this up. Its good to know.