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Thread: Bullet Dynamic soft body

  1. #31
    Eat your peas. Greenlaw's Avatar
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    Additional note: I just tried out my example above--it works pretty much as described, although you may want to leave Shape Retention to 0%, otherwise the cubes don't really fall completely away from each other if you allow the sim to run its course. I normally use some Shape Retention for items that need to partially or fully return to their initial shape and position. This is especially important for hair and clothing on a character. In the case of the free falling squishy cubes described above, probably so much.

  2. #32
    it works at last but looks crap, clothFx makes better results
    Last edited by bazsa73; 10-05-2014 at 04:19 PM.

  3. #33

  4. #34
    Quote Originally Posted by Greenlaw View Post
    I'll post a couple of scenes to demonstrate. Hold on.

    G.
    Thanks but you shouldn't bother, I think I stick to ClothFx.

  5. #35
    Eat your peas. Greenlaw's Avatar
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    Okay, here you go.

    The first scene is called twoSquishyBoxes.lws. This is the example described above. The two cubes have Bullet Deforming (cloth) applied, they are dropped on top of each other and they react. The bullet cache should load when you open the scene, but if it doesn't, Reset and recalculate the sim. It should only take a few seconds.

    The second scene is called mddCollision.lws. This one has two cubes, one driven entirely by MDD with Bullet Deforming enabled, the other driven only by Bullet with Deforming enabled. When you play the animation, the MDD pushes the first cube into the second and knocks if off the ground block. You can see the cloth dynamics effecting both boxes as they collide.

    Also included is a video preview render for each scene to show how it looks here, just in case the scenes are running differently on your system.

    Hope this helps. Granted these are simple examples but they demonstrate the fundamental principals. I do this sort of thing often with characters and creatures at work and I can assure you that similar setups do work with more complex meshes and rigs.

    G.
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  6. #36
    Eat your peas. Greenlaw's Avatar
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    I used ClothFX for about 10 years for hair and cloth sims and stopped using it not long after Bullet Deforming became available in Lightwave. ClothFX is still useful, but I rarely use it these days--when I do, it's mainly just to scan meshes so I can use FX MetaLink. Bullet Deforming is generally much faster than ClothFX and easier to setup, and these days I use Bullet almost exclusively for hair and fabric animations.

    Obviously the tool you choose really depends on what you're trying to accomplish--one dynamics tool can be better suited than another for certain tasks.

    G.

  7. #37
    Thanks Greenlaw.
    I could succesfully setup a softcube scene on my own but I'm not happy with the Bullet(MDD character + deforming cloth) solution.
    I'm sure it requires more research on my side but must admit that I was happier with the ClothFx result than the Bullet.
    Now I have to concentrate on other tasks and for the time being I'm happy with ClothFx.
    Cheers

  8. #38
    Eat your peas. Greenlaw's Avatar
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    No problem. When you posted that collision was not working with deforming and mdd objects in Bullet, I had to check for myself. Since I use this feature at work from time to time, I became concerned that it got broken in the latest release. I was relieved to see that it's still working.

  9. #39
    Quote Originally Posted by Greenlaw View Post
    No problem. When you posted that collision was not working with deforming and mdd objects in Bullet, I had to check for myself. Since I use this feature at work from time to time, I became concerned that it got broken in the latest release. I was relieved to see that it's still working.
    I just wonder why my bullet cloth wiggles nervously as if it was irritated by the underlying object. It is a very high frequency but low amplitude wiggling.

  10. #40
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    Quote Originally Posted by Greenlaw View Post
    No problem. When you posted that collision was not working with deforming and mdd objects in Bullet, I had to check for myself. Since I use this feature at work from time to time, I became concerned that it got broken in the latest release. I was relieved to see that it's still working.
    No... it's not. Using 2015.3. Made an MDD of my character, loaded the MDD, and used that object as a deformer with 100% retension. Used my character's blouse as a deformer, and the blouse fell right through. Change the character to a static object, and the blouse sits just fine. I'm just not seeing what good bullet is if you can't use boned objects for cloth. My character is wearing a silk blouse that I want to hug her mesh as she moves. ClothFX sucks. And I truly mean that! I feel like I might as well burn some sage and drop chicken bones to see if it will work. Bullet would be awesome if I could actually use my boned geometry as a collision object.

    It's not lost on me that there are absolutely ZERO tutorials out there on making actual clothes for characters that are actual humans (and not Pokemon LOD) with Bullet.

    I just switched back to Lightwave from Maya (switched away at 6.5). I'm thinking it was a complete and total waste of money and time! I originally moved away from Lightwave to get away from Kludgy work-arounds because nothing worked the way it was supposed to. I don't want to spend all my time figuring out work arounds.

    OK... rant over.

  11. #41
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    I'd love to make what you ask about bone-deformed human figure controlling collision with soft body clothing and have it all work right. The best I found for procedure is actually in the Layout manual that ships with Lightwave (11.6 addendum page 120 ... sorry, I don't have 2015 handy). I think you might have been missing some of those settings or perhaps the blouse was set to retract too much and pulled through the mesh. The last part was a suggestion to avoid all the collision calculations by just using smaller objects and exploiting the object hierarchy. Other parse spread around the manual indicate that subdivision order and amount of geometry on any of the objects can make a difference like that.

    I have also seen folks using weight maps to make only part of the the clothing controlled by bullet and using bones from the human figure to control the rest of the clothing. You don't need all the dynamics on shirt sleeves or pant legs like you would on a flappy collar or dress, for example.

    One thing I found in my travels through converting objects from one format to another is that some exporters don't actually connect all the geometry as you might expect. Putting the figure in Modeler and merging points might help, too.

    Of course if you find the magic numbers and settings to do as you describe without objects exploding or dancing, please enlighten me.

    -- Cut from user manual --
    Using a Deforming object for Collision
    When using a character or anything else deformed by bones, morphs or displacement as a softbody collider, you need to transform the mesh itself (or part of it) into a Bullet Deforming body.
    If you want to maintain the original shape of the deformed object, you need to set some parameters in the Bullet Softbodies panel:
    Shape Retention must be set to 100%
    Shape Lock must be set to Translation & Rotation
    Both Linear and Angular Stiffness must be set to 0
    Volume Conservation must be set to 0.

    Use simple kinematic shape objects parented to the bones of characters to create effective softbody colliders. Capsules are perfect for this.

  12. #42
    Eat your peas. Greenlaw's Avatar
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    Quote Originally Posted by cyclopse View Post
    No... it's not. Using 2015.3....OK... rant over.
    Don't know what to say because it's working here:

    Click image for larger version. 

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    The worm thingie was posed with bones and then baked to mdd. Both objects are set to Deforming in Bullet. I ran the sim and the cloth conformed the the shape of the worm thingie pretty closely. Using Lightwave 2015.3.

    Could you post the scene you're having trouble with?

    G.

  13. #43
    Registered User 3dbr's Avatar
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    Greenlaw, could you show your example where the work Bullet and mdd?
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  14. #44
    Eat your peas. Greenlaw's Avatar
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    That's what the above example is. The 'worm' is being deformed by .mdd, not bones. The bones are only there for the initial deformation before baking.

    That said, I don't recommend using mdd for collision because the calc times are not practical for many production schedules. It's often much better to use proxies. IMO, you should only use mdd for collision if you absolutely can't make the sim work using more efficient methods.

    G.

  15. #45
    Eat your peas. Greenlaw's Avatar
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    The last 'real world' example I can recall was a creature feature I worked on a couple of years ago that had a shark breaking out of ice. Originally I used an .mdd of the shark as the collision object to break the ice element but the calc time was going to take hours. I switched to proxy objects and this drop the calc time down to a few seconds. That was perfect because I only had a single day scheduled to complete that shot.

    G.

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