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View Full Version : how much quicker with vbo ?



wizzo
12-04-2003, 09:15 AM
ok, i got the vbo to work, but i'm a bit disapointed....
i'm rendering somethig like a 100 vertice, with texture and per vertex dynamic lightmapping, and i had 100 fps approximatly (i'm running the app on a athlon 2000+ and gf4 ti4200).
after setting up the vbo, i got.... the same

does vbo speed up get noticeable for a large number of vertice only ??
(in fact i have the same problem with the register combiner for the lighting, they didnt really speed up the program....)

wizzo

maximian
12-04-2003, 09:39 AM
Here is what I have found.

For low polygon count, I suggest you use glDrawElements, + VBO for the polygon indices, and a VBO for the vertices. Order the mesh, so that vertices being drawn, do not change much as you loop through the mesh. Ie try to repeat vertices as much as possible in your drawing loop.

For large meshes, ie many thousands, or tens of thousands, you an interleaved array + glDrawArray, and NO indices. I got a 3x improvement with this way.

wizzo
12-04-2003, 12:18 PM
3x improvement sound good to me. i'll try this asap
thanks a lot for the trick =D

wizzo

Zengar
12-04-2003, 03:33 PM
If you have only 100 vertices, CPU->GPU transport will be very fast, because you don't need to send much data. It is very possible that the rasterisation time is much greater. VBO will make sence with thousands of triangles.

DJSnow
12-05-2003, 01:56 AM
@maximian:

>>For large meshes, ie many thousands, or
>>tens of thousands, you an interleaved
>>array + glDrawArray, and NO indices. I
>>got a 3x improvement with this way.
sounds confusing; could you please compile a demo (exe only) and send it to me ?

[This message has been edited by DJSnow (edited 12-05-2003).]