Stochastic Pruning (2)

Posted: February 7th, 2010 | Tags: | 5 Comments »

A quick update for anyone who was having problems running my stochastic pruning demo on NVIDIA cards, I've updated the demo with a fix (I had forgotten to disable a vertex array).

While I was at it I added some grass:

The grass uses stochastic pruning but still generates a lot of geometry, it's just one grass tile flipped around and rendered multiple times. I wanted to see if it would be practical for games to render grass using pure geometry but really you'd need to be much more aggressive with the LOD (Update: apparently the same technique was used in Flower, see comments).

Kevin Boulanger has done some impressive real time grass rendering using 3 levels of detail with transitions. Cool stuff and quite practical by the looks of it.

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5 Comments on “Stochastic Pruning (2)”

  1. 1 korak said at 2:15 am on March 12th, 2010:

    no any trees on NVidia ^(

  2. 2 mmack said at 9:39 am on March 12th, 2010:

    Hey Korak, sorry about that, I've only been able to test it on my home NV260 and my work NV5800 Quadro which seems to be OK.

    I threw a whole load of asserts in there to try and catch any driver issues so if there's anymore debug information let me know and I'll look into it.

    Seriously considering switching to DirectX at this stage.

  3. 3 hornet said at 3:59 am on March 16th, 2010:

    I believe this paper does something similar - unfortunately it's not publicly available.

    http://akpeters.metapress.com/content/r8p4l210071w5717/

  4. 4 John Edwards said at 5:33 pm on July 25th, 2010:

    Hey Miles,

    Cool blog. Just thought I'd throw out that we rendered all the grass in our PSN game Flower with geometry, and we basically used stochastic pruning to do it (though we didn't have that name for it at the time). For grass, though, we found that scaling up distant blades uniformly looked weird, so we biased the scale to be on the width of the blade much more than the height. The basic notion of render fewer, bigger things in the distance was preserved, though.

  5. 5 mmack said at 6:32 pm on July 30th, 2010:

    Hi John, thanks a lot for posting some info on what you did for the grass in Flower.

    I also found modifying the height looked a bit strange so ended up just scaling the blade width.

    Pleased to hear it works on much bigger scales too, I certainly didn't notice any artifacts when I was playing the game!


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