Game Smoke, what's the big deal?

Discussion in 'PC Gaming' started by ECH, Jun 16, 2010.

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  1. ECH

    ECH
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    Why is it that a game's smoke can always reduce frame rates in a game? Is the creation of smoke a driver/CPU issue or is it actually rendered by the GPU? Perhaps something else is going on here.
     
  2. Scott_Arm

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    GPU, lots of overdraw, eats fillrate
     
  3. Grall

    Grall Invisible Member
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    Since smoke is alpha blended, it also eats a lot of memory bandwidth (due to read-modify-write for every pixel, every single layer)...

    Memory is probably the bigger killer of the two, if I were to venture a guess. Current higher-end GPUs have such ridiculous fillrates that you could theoretically do hundreds of full-screen overdraw passes per frame at 100+ fps...
     
  4. ECH

    ECH
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    So the use of smoke is bandwidth/memory limited? Is that way the frame rates tank when smoke instantly appears on the screen (like a smoke bomb) vs a more gradual "already there" (like fog) approach?
     
  5. Neb

    Neb Iron "BEAST" Man
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    Yes although it depends on resolution and amount of layers/particles as for how serious it affects perfomance. Then also if you got MSAA/TSAA then that will further incure a perfomance penalty.

    Reason why all console games have low resolution effects. Also found in some PC games but generally tend to be of quite higher res and some games are brutal with transparency effects like Stalker CS godrays and Metro 2033 godrays being 1:1 with set resolution (and other parts of PP 1:1). Add MSAA/TSAA to the game with full resolution effects and post-proccessing and it gets even heavier.
     
  6. digitalwanderer

    digitalwanderer Dangerously Mirthful
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    Best smoke in a game was still Batman with PhysX. :yep2:
     
  7. ECH

    ECH
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    Thanks for the info!
     
  8. Squilliam

    Squilliam Beyond3d isn't defined yet
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    Causes cancer and reminds Nvidia GPUs of bumpgate... :razz:
     
  9. Simon F

    Simon F Tea maker
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    I think this thread is now done.
     
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