Page 2 of 4 FirstFirst 1234 LastLast
Results 16 to 30 of 50

Thread: Bullet Dynamic soft body

  1. #16
    Registered User
    Join Date
    Sep 2013
    Location
    Texas
    Posts
    46
    ok, so we're talking grand time savings by lowering the poly count and removing mesh deformation from bones. Most of what I'm doing at the moment is getting cloth deformations to reimport into DAZ studio as morphs to include in some products. As a hobbyist I'm having a hard time buying additional tools when the ones I have should be doing the trick. As long as I have a system that works, I don't mind setting it up and letting it run for a day to get a figure-sit-down-pose for something.

    I have seen the discussion of using MDD. DAZ3d with the AniMate2 plugin can export MDD files as a cheap alternative, but I don't know if there is something that is more professional (and somewhat cheap) and/or better to use.

    Perhaps I'll try later this evening tuning down the collision radius to prevent that "field squish" thing you mentioned. Both the figure and the skirt are pretty high poly count, thanks to DAZ and Marvelous Designer. Alternatively, is there a poly reducing function that I haven't found in Modeler? So many options, stop this spin from rooming.

    You guys are awesome, by the way.

  2. #17
    A few things come to mind with this information that might be a help. One is I think there will be a trial version of Crono Sculpt when they release in a few weeks and also you can buy a pre-release version now.

    The next thing is that if this is for a still image sit down pose it gives you a lot more options. Even if it is an animation from a sitting position.

    What I would do in either case is make use of "save trans object" which will freeze and object in its dynamic state on that frame. Having a frozen start position for cloth is a good workflow.

    This would allow you to do it in stages. First get the character in a sitting position with no chair collision. Save trans the object, load it in, "use bones from" and fix the waist as you did before and apply the cloth modifier.

    And then using that, add the chair collision and raise/slide it into position with animation but consider using another object as the collision object. This way you can adjust the radius so it looks right falling over the chair but not intersect with the other radius.

    Then save trans that and now you have a character sitting in a chair with proper collisions and you could then animate the character from there for poses or even animation.

    Some kind of workflow like that would be worth giving a shot.

    EDIT: And an additional workflow to this is once you get the cloth in the sitting position with the chair in place, save trans that and then remove the collision object but fix the points that are trapped between the chair and body, letting the rest fall free. Would stabilize it considerably.
    Last edited by Surrealist.; 10-17-2013 at 06:42 PM.

  3. #18
    Top Dog
    Join Date
    Aug 2005
    Location
    Los Angeles
    Posts
    1,077
    I've been playing with Bullet Dynamics recently for a simple table cloth on a table. I can't seem to find the secret sauce to get a snug fit without poke thrus. Cloth Fx works well but it takes a long time to solve.

    The easiest and quickest way I found was Marvelous Designer, a bit expensive if you don't use much. But if your thing is clothing Daz content, MarvDes kicks butt.

  4. #19
    Registered User
    Join Date
    Sep 2013
    Location
    Texas
    Posts
    46
    I've noticed that with both bullet and cloth dynamics, the less complex the better. It has also been said that the collision radius has to be set carefully. By default with cloth fx (can't recall with bullet) the collision object has 0 radius and the cloth has something like 5-10 mm. The cloth has to start at least that far away. If you get poke through, increase either the collision radius or equalize the poly count between your cloth and collision object.

    As for my purposes, I have had more success with cloth fx simply because bullet seems to not care about meshes deformed by bones, only meshes moved by bones. Bullet seems to currently need collision objects assigned to leg and arm bones on a figure to deform clothing. Although it has advantages, my purposes don't benefit from them.

    I have Marvelous Designer. I tried v2 a while back and didn't care for some of its annoying "features" but rather liked the v3 beta, bought it, and now regretting it with their "updates" that has left it unusable with constant crashing. If it weren't for its awesome way to create clothing and hope that they might fix it, I'd say Marvelous Designer is worthless. Otherwise, anything created in modeler that looks like it could be clothing can be draped either way in lightwave.

    What I currently have for a process to create clothing content for DAZ characters is to model in MD3 (if it works) over an OBJ exported DAZ character, export the clothing to lightwave to do draping over the same DAZ character imported with FBX with all the body joint movements, importing the obj trans objects as joint controlled morphs in DAZ. So far everything looks great and only needs a few extra morphs to accommodate some oddities that the JCMs exhibit. Below is a quick image of a genesis 2 female with the skirt I've been playing around with. Only the figure was posed, everything else was joint controlled morphs to better conform the skirt. Not bad for DAZ with a lack of cloth draping capabilities.

    Click image for larger version. 

Name:	skirt draping 1.png 
Views:	495 
Size:	80.4 KB 
ID:	117941

  5. #20
    Another thing to keep in mind is how the collisions actually happen with Cloth fx. Not sure about Bullet. But nCloth for example gives you options, two of which are points and faces. In CLoth FX is is limited to points. So the cloth object can not collide with a face. Vertex is the least accurate and the fastest method. So the only way to improve the accuracy is to increase the resolution of both the cloth object and the collision object and adjust the radius. For this reason it is also better for a character that the collision object (body) be subpatches or otherwise dense and smooth, or sharp pointy contours will poke though. Also if memory serves correct, I believe it is the cloth object radius I would leave at 0. And adjust only the collision radius or the collision object. Keeps it simple and it works well. For animation you also can not forget the resolution setting in the etc tab. As low as possible to get a proper final simulation. I think that might be scene scale dependent as it is in meters.

  6. #21
    Top Dog
    Join Date
    Aug 2005
    Location
    Los Angeles
    Posts
    1,077
    Quote Originally Posted by jimbotini View Post

    I have Marvelous Designer. I tried v2 a while back and didn't care for some of its annoying "features" but rather liked the v3 beta, bought it, and now regretting it with their "updates" that has left it unusable with constant crashing. If it weren't for its awesome way to create clothing and hope that they might fix it, I'd say Marvelous Designer is worthless. Otherwise, anything created in modeler that looks like it could be clothing can be draped either way in lightwave.

    Click image for larger version. 

Name:	skirt draping 1.png 
Views:	495 
Size:	80.4 KB 
ID:	117941

    That's good to know about MD3. I still use MD2 and was part of the MD3 beta program but never had but a few minutes to try out before they released.

    I brought the same models (of a table and table cloth) into Modo 701 and tried their soft body bullet. Modo had better results with poke-thru and solving in general. However, I was crashing quite a bit (not sure if it is a Mavericks issue — since I don't think Lux/Foundry have official support yet).

  7. #22
    Melancholy&MysteryStreet hdace's Avatar
    Join Date
    Mar 2006
    Location
    Kansas
    Posts
    950
    Quote Originally Posted by VermilionCat View Post
    If you're using the model as the collision object then it must be deforming body as well.
    I've been trying to use Bullet to do cloth dynamics for months now and I still can't understand why this is the case. There's no logical reason why an arm inside a shirt should be a deforming body. It should be a kinematic object. Setting up a system whereby the arm may get deformed by the shirt is like setting up a system whereby the dog is wagged by the tail.
    "There can be no true beauty without decay." --Latin proverb. Nothing digital is beautiful?
    Our new movie is here: http://epistrophypictures.com

  8. #23
    I am pretty sure It is because a Kinematic body has to do with an object that moves through world space and the position of the object along with the volume of the object is calculated for collision. Where as a deforming body is something that gets deformed on the point level dynamically as in bones etc. So it is a different way to calculate collisions.

    Where as with classic Cloth FX it does not matter if the mesh is deformed or not because collisions are always based on points at the lowest level.

    So in classic dynamics it would be the same as using a mesh as opposed to a collision object

    And then of course you can deform an arm or body part with another object in the simulation such as an object striking a soft body but that that soft body could also be a collision object and affect other soft bodies.

    If I am wrong please correct me, but that is my understanding so far.


    http://forums.newtek.com/showthread....hold-its-shape
    Last edited by Surrealist.; 11-03-2013 at 09:58 PM.

  9. #24
    Melancholy&MysteryStreet hdace's Avatar
    Join Date
    Mar 2006
    Location
    Kansas
    Posts
    950
    Okay, I can see that. But why not just have a button or selectable item that basically says, "This item will deform other stuff but it will not get deformed by the other stuff too"? The manual lists five different settings that have to be exactly correct to ensure the item will only get deformed the regular ways but not by the other deforming body. Not only is it annoying and confusing, it's just bad workflow.

    Anyway, thanks very much, Surrealist, for finally clearing up that mystery for me.
    "There can be no true beauty without decay." --Latin proverb. Nothing digital is beautiful?
    Our new movie is here: http://epistrophypictures.com

  10. #25
    You are welcome and I agree. The only other light to shed on it is that perhaps it has to do with the fact that character work is a specific area of application for Bullet. Whereas by design it is for special effects. So in SFX you have all kinds of potential situations that is is open for. And the settings reflect that vast array of effects you might want to achieve. Where as for most character work you don't need that.

    One day you'll want the character to melt out of his suit and there you are.

  11. #26
    Forum acting up again... sorry.

  12. #27
    Registered User
    Join Date
    Sep 2013
    Location
    Texas
    Posts
    46
    Manual? There is a manual? I got the addendum on the download page, but I have yet to actually see a manual. Where is this alleged manual so that I might clear up a whole slew of questions? I'd love me some manual.

  13. #28
    Yeah, in my addendum page 83 there is... But there's no mention of MDD so beware.

  14. #29
    Two deforming object in Bullet won't collide so it will not work with a character mesh driven by MDD. Only Greenlaw's "pill" method works.
    Last edited by bazsa73; 10-05-2014 at 06:54 AM.

  15. #30
    Eat your peas. Greenlaw's Avatar
    Join Date
    Jul 2003
    Location
    Los Angeles
    Posts
    7,290
    Quote Originally Posted by bazsa73 View Post
    Two deforming object in Bullet won't collide so it will not work with a character mesh driven by MDD. Only Greenlaw's "pill" method works.
    Deforming objects certainly can collide in Bullet. Make two divided cubes and make them deformable and hang them over a static floor collision object (a non-divided cube should be fine.) Make sure the deforming cubes have some volume conservation and maybe a tiny bit of Shape Retention (1% might be plenty.) Set Shape Lock to Translation and Rotation. Now, drop one cube on top of the other. The cubes should squish and bounce against each other.

    You can do the same with MDD driven deforming objects too but it's gonna be slow as molasses. This is why it's highly recommended that you use separate proxy objects and kinematic when using characters as collision objects. (If the animation was done in another package, like Maya for example, use FBX to export a skeleton to parent the proxy collision objects to. You can still use the MDD version for render.) The difference in calculation time can be minute vs. hours and in many situations, the results can be more or less the same.

    G.

Page 2 of 4 FirstFirst 1234 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
  •