Display list overhead

Sage
Posts: 1,199
Joined: 2004.10
Post: #1
All

Sometime ago I asked about wether or not it would be faster to draw meshes as a compiled display list or as a VBO.

OSC replied that display lists would be faster by and large, but that there was some sort of per-use penalty.

http://idevgames.com/forum/showthread.php?t=7721

Anyway, I've been sharking to try to clean up some hotspots and am debating wether I should have the shadow volumes of static ( e.g. immobile geometry ) continue to be cached in a display list or wether I should just draw it in immediate mode.

I'll post results, but at the moment I'm curious if anybody has suggestions, or experience to share.
Quote this message in a reply
Moderator
Posts: 916
Joined: 2002.10
Post: #2
everything that has static geometry that isn't a part of my HUD/menu, I use display list
Quote this message in a reply
Sage
Posts: 1,199
Joined: 2004.10
Post: #3
After a quick stab during my lunch break, I've noticed that going from display lists to immediate mode has perked things up noticeably. I'm maxxing at 44fps now, when it was 30 earlier.

Of course, I'm caching the shadow volume geometry -- so it's not being recalculated -- but instead of drawing it via display list I'm just cranking out the cached vertices in immediate mode.
Quote this message in a reply
Moderator
Posts: 916
Joined: 2002.10
Post: #4
how small are these things?
Quote this message in a reply
Sage
Posts: 1,199
Joined: 2004.10
Post: #5
That's a good point. My current quasi-stress-test scenario is a ton ( well, about 250 ) of meshes with about 60 or so triangles apiece. The meshes themselves are drawn via display lists, but it's shadow drawing that's taking up something like 30 percent CPU time. Oddly, it's not the volume projection, but the drawing of the volume that's the big hit ( according to shark ).

Well, I guess that makes sense since the drawing is when the geometry is uploaded.

I'm thinking now that there's probably a threshold point over which display lists become useful, and under which they cost too much. I guess the trick is finding that point...
Quote this message in a reply
Post Reply 

Possibly Related Threads...
Thread: Author Replies: Views: Last Post
  RTS / 2D Overhead Terrain SethWillits 3 5,010 Nov 17, 2007 08:46 PM
Last Post: Skorche
  Roots of Display List Overhead aarku 10 5,811 Apr 12, 2005 12:24 PM
Last Post: FCCovett
  how small is a "small" display list? Diplomtennis 5 4,126 Oct 31, 2004 10:38 AM
Last Post: Hog
  display list generation honkFactory 8 3,574 Mar 13, 2003 11:39 AM
Last Post: honkFactory
  AGL and display list problem kingofsquirrels 2 2,870 Feb 16, 2003 04:18 PM
Last Post: kingofsquirrels