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Thread: Fracture - does it only work on convex models?

  1. #1

    Fracture - does it only work on convex models?

    I'm trying to fracture a bridge that is, I'm certain, all closed up and watertight, but I keep getting a few spiky polygon rays that spread out and pass through other arches of the bridge.

    I'm wondering if I've missed something on my model, or if it's a limitation of Fracture.

    It's no problem, happy to break the model up a bit and fracture individual sections, but it would be good to know if I need to do this, or if I need to get better at checking my model!

  2. #2
    Did you make it all tri poly? Its noted in the docs that tri's are preferable for better results.

  3. #3
    Scene Destroyer DrStrik9's Avatar
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    I've had that happen too. Changing Fracture's Random Seed sometimes helps. But like other geometry, I usually just follow the oddities with Select Connected to see if they can be deleted. And of course look in Poly Stats to make sure there are no 2-pointers, etc. -- Don't merge points in Modeler though.

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    Scene Destroyer DrStrik9's Avatar
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    Quote Originally Posted by JamesCurtis View Post
    Did you make it all tri poly? Its noted in the docs that tri's are preferable for better results.
    Tripling before Fracturing doesn't seem to help this problem. I'm also getting "non-closed" sub-objects with Fracture, and 10-12 of these "pointy polys" that extend beyond the originating object, with 180 Cell Count. Attempting to fix the error-filled Fractured (tripled) geometry is not my idea of fun either.

    Think I might send in a bug report on this ...

  5. #5
    Mind if I hijack the thread with another fracture question, does V11 do secondary fracture, as in the main object is fractured and collapsing, and the the fractured parts break once more as they hit the ground or self collide? I watched someone doing this in Max today so I'm curious.

  6. #6
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    Quote Originally Posted by djwaterman View Post
    Mind if I hijack the thread with another fracture question, does V11 do secondary fracture, as in the main object is fractured and collapsing, and the the fractured parts break once more as they hit the ground or self collide? I watched someone doing this in Max today so I'm curious.
    Something like this? Just play with Glue Strength/Breaking Angle/Breaking Distance.
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  7. #7
    Registered User imshadi's Avatar
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    I experienced the same thing. It seems to me that the fracture routine is forgetting to triple things after each iteration or it also may be forgetting to merge points. The little shards and the missing polys I was able to clean up by hand. But it may get cumbersome on an object with too many breaks. I suggested this to Mike Green who also has some Fracture Scripts, including a Voronoi one, but which also failed for the same reason. I hope some one will fix this soon enough.
    Oliver Zúņiga
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  8. #8
    Quote Originally Posted by dee View Post
    Something like this? Just play with Glue Strength/Breaking Angle/Breaking Distance.
    I shouldn't have hijacked the thread, sorry. I see what you are doing but that's not really what I mean, After the first breakage, pieces break away and continue to fracture into smaller bits as they either hit the ground or collide with other pieces. It bogs down the calculation but looks more realistic.

  9. #9
    Eat your peas. Greenlaw's Avatar
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    Like this? (Wait for the second example at around 0:23)

    Lightwave 11 - Fun With Glue

    IMO, calc time is actually quite fast.

    BTW, you can also vary the breaking sensitivity using envelopes and textures. I didn't use it in this example but it can give you a lot of control.

    G.

  10. #10
    That looks better, I followed some of the pieces as they fell and hit the ground, breaking, and then another bit breaks off as it falls over and hits a second time. I should really fool around with this stuff myself to see what it can do. I'm still not sure if that's exactly like the simulation in Max.

  11. #11
    Scene Destroyer DrStrik9's Avatar
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    Unfortunately, Fracture has several problems. I've identified several ways already that can either produce unfixable results, or send Modeler into hyperspace on Mac (needing to be force quit). I had a Fog-Bugz party over here all by myself. Once it's fixed, Fracture will be an extremely valuable tool for Bullet -- withOUT all the manual clean-up and bombing.

    Glue Strength is indeed a FUN toy. I've been doing sims with 99.5%+ Glue Strength and only a .001% or .002% difference between previews, and getting very interesting results. The closer you get to 100% with Breaking Angle and Breaking Distance turned off, the cooler Glue Strength is.

  12. #12
    Senior Constrictor Netvudu's Avatar
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    Geometry mass has quite a dramatic effect on Glue Strength though. You could probably play with much more comfortable values than .001 or .002 by altering the objectīs mass...

    ...then again, you seem to enjoy it so you can disregard my hint...
    3d animation? Hah! Did you take a look through your window?thereīs plenty of it...and pre-rendered!!

  13. #13
    Eat your peas. Greenlaw's Avatar
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    Quote Originally Posted by Netvudu View Post
    ...then again, you seem to enjoy it so you can disregard my hint...
    Thanks for the tip! Sorry, but I'm not going to disregard that.

    G.

  14. #14
    I posted this in another thread, but this seems the better place. Glue is great for keeping a body intact while causing it to move nicely.
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  15. #15
    luxowaver silviotoledo's Avatar
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    Great Puppet!

    How much percent Glued you used?

    May you share your scene?
    Silvio Toledo
    Brazil

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