Page 1 of 2 12 LastLast
Results 1 to 15 of 16

Thread: Bullet Chains

  1. #1
    Newbie Member maschinsky's Avatar
    Join Date
    Feb 2004
    Location
    Bad Voeslau, Austria
    Posts
    55

    Bullet Chains

    Hi!

    http://www.youtube.com/watch?v=Qs5UcOJsg8k

    I have made this scene using Bullet dynamics to have the collider object roll down the plane and hit the chains. generally I'm quite happy with it, but I think that the chains feel a bit too stiff. I recon Glue Strenght governs that stiffness, no? but if I set the "Glue Strength" to anything other than 100% the chains fall apart.

    Any tips of how I can make the chains behave more "chainy"?!

    Chains are parts objects with the following settings:

    Friction: 5%
    Bounciness 0%
    Linear Dampening: 1%
    Angular Dampening 1%
    Glue Strenght 100%
    __________________________________________________ __________________________
    LW 11.5, OSX 10.8.2, MacPro Dual 6 core 2.66GHz Xeon, 48GB Ram, Nvidia Quadro 4800

  2. #2
    Space Monkey 3DGFXStudios's Avatar
    Join Date
    Sep 2005
    Location
    Earth
    Posts
    3,121
    Video is private. Can't watch it.

  3. #3
    Newbie Member maschinsky's Avatar
    Join Date
    Feb 2004
    Location
    Bad Voeslau, Austria
    Posts
    55
    Sorry. Switched it to public now.
    __________________________________________________ __________________________
    LW 11.5, OSX 10.8.2, MacPro Dual 6 core 2.66GHz Xeon, 48GB Ram, Nvidia Quadro 4800

  4. #4
    Can you share the object/scene file.

  5. #5
    Super Member XswampyX's Avatar
    Join Date
    Aug 2010
    Location
    Kernow
    Posts
    2,078
    Here's my take on the scene/objects. Each chain link is a separate bullet object (just a clone). Moved around in layout to make the long chains.
    Attached Files Attached Files

  6. #6
    Newbie Member maschinsky's Avatar
    Join Date
    Feb 2004
    Location
    Bad Voeslau, Austria
    Posts
    55
    Thanks for posting the project. I'll dissect it later today, because your chains behave more realistically. Here is my project in case you want to look at it: Chains.zip
    __________________________________________________ __________________________
    LW 11.5, OSX 10.8.2, MacPro Dual 6 core 2.66GHz Xeon, 48GB Ram, Nvidia Quadro 4800

  7. #7
    gold plated 3D Chrusion's Avatar
    Join Date
    Mar 2003
    Location
    Chatannooga, TN
    Posts
    1,080
    Quote Originally Posted by XswampyX View Post
    Each chain link is a separate bullet object (just a clone). Moved around in layout to make the long chains.
    Is this absolutely required? Isn't that what the Parts object type is for, to eliminate the need to clone, move, and rotate individual objects to create what can be done in a single layer in Modeler?

    Maybe it is and I'm not understanding Parts object type, because when I do the above (make a straight chain in a single layer in Modeler) and make it a Parts type, I CANNOT get it to collide with itself and other single link objects set at either Static or Kinematic without the chain dropping thru these single links in other layers or they initially minimally affect the chain, such as the immediate link collides, but then the rest of the chain breaks into separate links as it falls (even with minimal gravity... like -12").

    Baffled and scratching my head wondering why there aren't any tutorials. The Bullet interface seems straight forward enough that you wouldn't need one (thus probably why the lack), but my chain attempt is simply wildly unstable (as in barely ANY self-collision and if any, every thing breaks and flies apart, no matter what bounce, friction, glue, and collision distance/thickness is). I just can't fathom how your chains remains intact and self-collide all over the place despite all sorts of "internal" and external movement.
    Dean A. Scott, mfa
    Senior 3D Animator and Graphic Design Illustrator, @ Astec, Inc.
    Owner / Lead Artist @ chrusion | FX

  8. #8
    TD/Animator lino.grandi's Avatar
    Join Date
    Jun 2003
    Location
    Rome
    Posts
    1,701
    Quote Originally Posted by Chrusion View Post
    Is this absolutely required? Isn't that what the Parts object type is for, to eliminate the need to clone, move, and rotate individual objects to create what can be done in a single layer in Modeler?
    Yes, parts objects are ideal for this kind of work.

    Quote Originally Posted by Chrusion View Post
    Maybe it is and I'm not understanding Parts object type, because when I do the above (make a straight chain in a single layer in Modeler) and make it a Parts type, I CANNOT get it to collide with itself and other single link objects set at either Static or Kinematic without the chain dropping thru these single links in other layers or they initially minimally affect the chain, such as the immediate link collides, but then the rest of the chain breaks into separate links as it falls (even with minimal gravity... like -12").

    Baffled and scratching my head wondering why there aren't any tutorials. The Bullet interface seems straight forward enough that you wouldn't need one (thus probably why the lack), but my chain attempt is simply wildly unstable (as in barely ANY self-collision and if any, every thing breaks and flies apart, no matter what bounce, friction, glue, and collision distance/thickness is). I just can't fathom how your chains remains intact and self-collide all over the place despite all sorts of "internal" and external movement.
    There's a bullet chain scene using parts objects in the 11 content.
    Lino Grandi
    3D Development, LightWave 3D Group/NewTek, Inc.

    https://www.lightwave3d.com/

    LightWave 3D Group YouTube channel:

    http://www.youtube.com/user/Official...?feature=watch

    My YouTube Channel:

    http://www.youtube.com/user/linograndi?feature=mhee

  9. #9
    gold plated 3D Chrusion's Avatar
    Join Date
    Mar 2003
    Location
    Chatannooga, TN
    Posts
    1,080
    Thanks, Lino.

    I see the key item I was missing was the Shape Type. Not mesh, but Convex Pieces. I was going to say that I found I can easily break the chains by simply turning the static link into kinematic and keying it on X one direction, then the other over 200 frames such that the chains whip upwards, break near the middle, and spin end over end as they fall, BUT then it occurred to me to up the calc frame rate from 180 to 400 fps and that fixed it.
    Dean A. Scott, mfa
    Senior 3D Animator and Graphic Design Illustrator, @ Astec, Inc.
    Owner / Lead Artist @ chrusion | FX

  10. #10
    TD/Animator lino.grandi's Avatar
    Join Date
    Jun 2003
    Location
    Rome
    Posts
    1,701
    Quote Originally Posted by Chrusion View Post
    Thanks, Lino.

    I see the key item I was missing was the Shape Type. Not mesh, but Convex Pieces. I was going to say that I found I can easily break the chains by simply turning the static link into kinematic and keying it on X one direction, then the other over 200 frames such that the chains whip upwards, break near the middle, and spin end over end as they fall, BUT then it occurred to me to up the calc frame rate from 180 to 400 fps and that fixed it.
    In general more the objects you're simulating are little, more precision it's needed.
    Lino Grandi
    3D Development, LightWave 3D Group/NewTek, Inc.

    https://www.lightwave3d.com/

    LightWave 3D Group YouTube channel:

    http://www.youtube.com/user/Official...?feature=watch

    My YouTube Channel:

    http://www.youtube.com/user/linograndi?feature=mhee

  11. #11
    gold plated 3D Chrusion's Avatar
    Join Date
    Mar 2003
    Location
    Chatannooga, TN
    Posts
    1,080
    Would this precision (fps) be basically proportional to object size, that is a direct correlation btwn absolute size and fps? For example, my links are 0.6" long and made of 0.1" diameter material, so is it just trail and error to find the right Dynamics Framerate (precision) value or is there a specific number you should start with based on a given object size? Also, please clarify... if Collision Margin = 0, does that mean the surfaces of two colliding objects are allowed to touch, but not intersect, and if set greater than 0 it means the colliding surfaces are that much apart (like a cushion of air between)?
    Dean A. Scott, mfa
    Senior 3D Animator and Graphic Design Illustrator, @ Astec, Inc.
    Owner / Lead Artist @ chrusion | FX

  12. #12
    Quote Originally Posted by Chrusion View Post
    Would this precision (fps) be basically proportional to object size, that is a direct correlation btwn absolute size and fps? For example, my links are 0.6" long and made of 0.1" diameter material, so is it just trail and error to find the right Dynamics Framerate (precision) value or is there a specific number you should start with based on a given object size? Also, please clarify... if Collision Margin = 0, does that mean the surfaces of two colliding objects are allowed to touch, but not intersect, and if set greater than 0 it means the colliding surfaces are that much apart (like a cushion of air between)?
    I'm curious about this too. We are constantly reminded that it is best to model in real world proportions and yet the chains scene included in the content has chain links that are 5 feet long. :/ ? I'm trying to do hand cuffs and not succeeding.
    64 bit Win 7 Enterprise
    Dual Intel(R) Xeon Quad Core 2.93GHz
    RAM 24.0 GB
    NVIDIA Quadro FX 5800
    Driver Version 259.81

  13. #13
    Quote Originally Posted by hunter View Post
    I'm curious about this too. We are constantly reminded that it is best to model in real world proportions and yet the chains scene included in the content has chain links that are 5 feet long. :/ ? I'm trying to do hand cuffs and not succeeding.
    I've been wondering about this as well; I have a scene with a large amount of coins/poker chips being poured out, and these are to scale (around 30mm wide, 1-2mm thick). I have to really overcrank the *time resolution* to minimize the "buzzing" somewhat, and then keyframe the Time Scale down to 0 in order to get them to settle instead of vibrate as they sit there. (Bullet doesn't support "stiction", which baffles me, as one of the very first things anybody does when trying out dynamics is to spill a bunch of objects and expect them to stand still when they come to rest).

    But why no spatial resolution option to go with the temporal option?

  14. #14
    When I use "parts for the chain, and set up the chain links in one layer..leaving space..nothing happens! Gonna try the clone option.

    BTW, thanks for the thread. real help!

  15. #15
    Super Member akaracquel's Avatar
    Join Date
    Jul 2011
    Location
    Where The Wombats Live
    Posts
    317
    Blog Entries
    1
    Quote Originally Posted by PeteS View Post
    When I use "parts for the chain, and set up the chain links in one layer..leaving space..nothing happens!
    Same thing happened to me as well ...but my objects were in sub-D. Noticed the chain parts in all the scenes + LW content were not sub-D - parts method is working for polygonal chains at this end.

Page 1 of 2 12 LastLast

Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •