performance difference between VA and CVA

Graphics and GPU Programming Programming

Started by bondi January 30, 2002 06:26 AM

7 comments, last by bondi 22 years, 2 months ago

122

Author

January 30, 2002 06:26 AM

Hi, I''ve a question about vertex array and compiled vertex array. My machine: AMD Athlon 850 Mhz and GEforce2MX. I draw an object that contains 2,5k triangles and is textured, with glDrawArrays(...); and notice the frame rate. Later I use the extension GL_EXT_compiled_vertex_array and redraw the same object. and notice no difference in the frame rate. [using: LockArraysEXT(...); glDrawArrays(...), UnLockArraysEXT();] My question: Is there a performance difference between VA and CVA?

Lev Povalahev

122

January 30, 2002 06:37 AM

Check the GF performance FAQ on NVIDIA site - there you should find the information how to use CVA with NVIDIA cards properly.

-Lev

bondi

122

Author

January 30, 2002 06:58 AM

I''ve also read the GF performance FAQ on NVIDIA site. And use the
specifed format. I don''t know why there is any performance difference between VA and CVA on my program.

Should if I use glDrawElements instead of glDrawArray(), if I use
CVA?

Anonymous

January 30, 2002 09:26 AM

Try drawing the mesh two times with VA and then same with CVA

If the draw calls for CVA are placed between Lock and Unlock calls, you should notice a difference.

Witchcraven

564

January 30, 2002 10:37 PM

As I understand it, CVA is primarily for multipass rendering.

rickpeek

122

January 31, 2002 03:47 AM

quote:Original post by bondi
My question:
Is there a performance difference between VA and CVA?

no tnl Voodoo3 CVA support, 350 mhz, 13 k detailed triangles per frame

GL_TRIANGLES

without CVA normal VA
30-35 fps

with CVA
60-80 fps

zedzeek

529

January 31, 2002 03:04 PM

i believe VAR needs glDrawElements(..)
cva is useful when u share a lot of vertices in a model (eg multipass or a cube)
btw when u are testing for this make your window small eg 200x100 so youre not fillrate bound

http://uk.geocities.com/sloppyturds/gotterdammerung.html

Captain Courgette, eat more veg

python_regious

929

January 31, 2002 06:10 PM

Where can I find tutorials on using CVA''s? The extension spec I looked at was from 1996 ( which said it was unfinished! ), so can anyone point me somewhere?

Cheers