(Tested) OpenGL Geometry Instancing: GeForce GTX 480 vs Radeon HD 5870

Article Index

5 – Quick Conclusion

  • we understand why NVIDIA has called the technique using persistent vertex attributes Pseudo-Instancing (key F4). OpenGL glDrawElements() function is extremly fast and persistent vertex attributes require less overhead than uniforms to be passed to the vertex shader. Both coupled together give this performance boost. Very often, Pseudo-Instancing is almost as fast as HW GI. But Pseudo-Instancing is only fast on NVIDIA hardware.
  • The benefit of hardware geometry instancing is mostly visible with few triangles per instance: 500 faces per instance seems a limit. With many triangles per instance, all techniques are similar.
  • With many triangles per instance (1800 tri) and with many instances (100,000), NVIDIA drivers does not require much CPU power compared to ATI drivers.

Do not hesitate to comment this article and don’t panic if your comments are not quickly approved. I’m moving and I won’t be connected during the next few days. I’ll approve all comments as soon as possible!

See you later my friends!

Moving day
Geometry instancing could help me for my move 😀




19 thoughts on “(Tested) OpenGL Geometry Instancing: GeForce GTX 480 vs Radeon HD 5870”

  1. Pingback: OpenGL Geometry InstancingJeGX's Infamous Lab | JeGX's Infamous Lab

  2. Groovounet

    It would be interesting to see how the test behave with different instancing methods: instanced array, texture buffer, etc. Also 1800 triangles isn’t so much for the maximum.

  3. JeGX Post Author

    Thanks Mr Groove!
    I’ll update this demopack with new techniques next time (at least with instanced array). And I’ll increase the number of polygons per instance 😉

  4. nicolas

    FWIW, note that with more triangles, you’ll be hitting harder the triangle setup bottleneck of one triangle per clock cycle. Don’t know for the NVidia GTX 480, but this limit applies for the ATI R5xxx ; I don’t think that going beyond 180M triangles will bring you anything good for this generation of boards.

    Nice summary of instanciation techniques and perfs though. Did you try to have finer grained timings with ARB_timer_query extension ?

    Cheers

  5. Mars_999

    Yes keep these demo and tutorials coming. I enjoy reading them as it keeps me up to date on the newest features I can do with OpenGL. Plus it’s nice to see the old vs. new method of doing the same thing so once can make his own decision on what to do.

    Thanks!!! keep up the good work!

  6. WacKEDmaN

    20,000 instances x 18 tri/instance = 360,000 tri
    Geforce GTX 470@ 700 core /1800 mem
    – F2: FPS=18, GPU=20%, CPU=30%
    – F3: FPS=40, GPU=21%, CPU=35%
    – F4: FPS=68, GPU=15%, CPU=35%
    – F5: FPS=96, GPU=19%, CPU=35%
    – F6: FPS=101, GPU=24%, CPU=30%

    100,000 instances, 1800 tri/instance = 180,000,000 tri
    Geforce GTX 470@ 700 core /1800 mem
    – F2: FPS=4, GPU=67%, CPU=30%
    – F3: FPS=6, GPU=99%, CPU=24%
    – F4: FPS=6, GPU=99%, CPU=14%
    – F5: FPS=6, GPU=99%, CPU=12%
    – F6: FPS=6, GPU=99%, CPU=10%

    interesting…CPU usage goes down as GPU goes up..i thought the cpu would be less stressed with the lower geometry count…

  7. Matumbo

    I tested with a Radeon HD 2400, Catalyst 10.6.
    The F6 technique half-failed: the asteroids are there, rotating, but all shading on them is turned off (all black). But the middle planet is shaded.
    I suppose this was not intended.
    The driver exposes all the 3 required extensions.

  8. IVXXX

    20,000 instances x 18 tri/instance = 360,000 tri
    ATI HD4770 @ 940 core / 4800 mem
    – F2: FPS=44, GPU=50%, CPU=28%
    – F3: FPS=57, GPU=58%, CPU=30%
    – F4: FPS=54, GPU=40%, CPU=30%
    – F5: FPS=140, GPU=42%, CPU=34%
    – F6: FPS=152, GPU=34%, CPU=30% (no shadinng)

    100,000 instances, 1800 tri/instance = 180,000,000 tri
    ATI HD4770 @ 940 core / 4800 mem
    – F2: FPS=5, GPU=99%, CPU=18%
    – F3: FPS=5, GPU=99%, CPU=16%
    – F4: FPS=5, GPU=99%, CPU=16%
    – F5: FPS=4-8, GPU=99%, CPU=12-28%
    – F6: FPS=1-6, GPU=99%, CPU=6-28% (no shadinng)

  9. ca$per

    Same thing as Matumbo here. But i have Radeon 4850 on Win7 and Cat. 10.5
    F6 – asteroids are all black with all triangle variations (different EXEs).

  10. TopLess3D

    Could you share your source code please (both C++ and GLSL), in order to learn advanced techniques and programming in OpenGL?

  11. krishx007

    hay JeGX R u died or what?????

    Not publishing any new article from 3 to 4 days???

    Fight with GirlFriend?????????

  12. codablank

    where can I find the source of this demo ? or a similar source ? I get very bad performance with glDrawElements() (1000 cube instances max ) and glDrawElementsInstanced gives the same result

    Yet I get a descent FPS when I run your demo (I’m on ATI 4850, opengl 2.1)

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