RE: Index16 vs Index32 for index buffer

You should use 16 bits whenever possible, mainly to save memory. Under some
circunstances, the driver is able to determine that 16 bits are enough to
index your geometry and to save bandwidth it will convert the indices while
transfering them to the hardware. To make sure that this optimization
happens, you should use glDrawRangeElements instead of glDrawElements.

--
Ignacio Castaño
[email protected]


Remy Saville <[email protected]> wrote:
> During Homeworld 2 I did some benchmarks and found on some nv1x cards
> there was a small boost when we switched to 16 from 32.  I didn't notice
> any difference on any other cards I tested with though.
>  
> 
> -----Original Message-----
> Igor Kravtchenko
> Sent: August 16, 2005 11:24 AM
> To: Multiple recipients of list OPENGL-GAMEDEV-L
> 
> I wondered if there is some issues and important things to know about 
> optimisation
> between the fact to use Int16 or Int32 for its index buffer under
> OpenGL.
> By having used Direct3D for a very long time, I'm used to Int16 which is
> 
> the only
> supported index depth bits on today's video card.
> Nevertheless, OpenGL allows to use Int32 as well as Int16. In a general 
> manner,
> is it "bad" to use Int32 for its index buffer? Does just the driver 
> convert them back
> to Int16 without any performance loss?
> 
> Any remark or hint are welcome.
> Thanks,
> 
> Igor.
> 
> 
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> -- 
> Author: Igor Kravtchenko
>   INET: [email protected]
> 
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> -- 
> Author: Remy Saville
>   INET: [email protected]
> 
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