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jimbotini
10-14-2013, 07:56 PM
Although I'm not totally new to the 3d world, I'm bran-spanking new to lightwave. I'm attempting to use bullet dynamics' soft body deformer on a "cloth" skirt (shirt, too but that is a lesser problem) on a figure imported through FBX from DAZ. Things seem fine until I try to use a bone to move a limb. It seems as if the collision points on the figure don't follow the figure when deformed using bones. I'm obviously doing something wrong and/or missing some crucial step. I would appreciate any help anyone could offer. I can't help but think it has something to do with the bones imported with FBX.

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VermilionCat
10-14-2013, 11:05 PM
If you're using the model as the collision object then it must be deforming body as well.

Greenlaw
10-15-2013, 03:29 PM
The easiest and most reliable way to do this is the parent collision objects for each limb to the bones and use Kinematic mode. Each limb can be as simple as a squashed sphere or a pill object. If you need the body collision with cloth to be more accurate, you might optionally consider cutting up your character and parenting the limbs to the bones. IMO, using primitives for collision limbs is perfectly acceptable most of the time--many production studios do it this way to speed up the dynamics calculations.

Alternatively, you might get more accurate collision results if you use a baked MDD with the original mesh as your collision object, and use the Rigid setting in Bullet. TBH, I'm not 100% sure this actually works--it's been a while since I tried something like this--but if it does work, my guess is that it's going to be too slow to calculate if your mesh is very dense. FYI, MDD objects do work with Bullet but it might not be the most practical solution in this case.

That said, normally, I like to go with the first suggestion and be done with it. That approach is more interactively tweakable and often produces good results. I only use another method when I run into a major problem with the first method, and there is time/budget available to set this up.

G.

Greenlaw
10-15-2013, 03:49 PM
Here's an example of the first method. Scrub to 0:54.

Sister Motion Test (http://www.youtube.com/watch?v=jASC8IOsIqY)

Here I'm using four 'pill' objects for the arms and shoulders. The pills are set to Kinematic mode to move around the hair guides, and the guides are set to Deformable mode. You can see the effect of the collision when the character raises her arms. Oh yeah, here's another tip: use only as many collision objects as needed to speed up the calculations. In this case, I could have left out the lower limbs from Bullet since they're not actually colliding with anything.

G.

jimbotini
10-15-2013, 09:32 PM
I figured trying the deforming body was a quick thing to try, however after watching the figure turn to a gelatinous state I realized I had to change the shape retention to 100%... then she fell over after rubbing all the skin on her feet of on the ground plane. I could still be doing something wrong. Spline or null control for the hip (root) bone?

Next attempt is the "pill" collision objects. This one makes the most sense to me, but I don't understand why it would make a difference making another object for collisions. I thought setting up the mesh as a whole as a kinematic object makes it all a giant collision object. It works as long as I don't deform the body.

Although I'm figuring it out, it turns out I fail more at metric than modeling. I'll have to continue this tomorrow.

Thanks for your help so far.

jimbotini
10-15-2013, 10:06 PM
OK, so I couldn't help myself. I created more of a zeppelin rather than pills just out of laziness and speed placed and parented to her thigh (I'm coining the phrase "zeppelin thighs") and it appears better but tremendous poke-through. A quick attempt at collision margin up to 25mm didn't seem to help. Perhaps I'll "drug up" her thighs tomorrow to see if a higher polly count and better fit will help.

Any other things I should try?

117677

Greenlaw
10-15-2013, 10:47 PM
Check your mass distribution for the cloth object. If the fabric has no thickness, you may need to set this property to Surface or Vertices for it to work properly.

For the skirt, are you using a weight map in Mesh Filter around the waist? This should help control the motion. You also want to use Shape Retention to get the skirt to go back into it's shape when it's not moving around. For example, in the video above, I use Shape Retention to get Sister's hair to go back to it's combed state after it's been vigorously shaken. You'll want to use that on clothing, especially cloth that moves around a lot like a skirt or dress.

Regarding Kinematic mode, its main use is for animating collision objects parented to bones. This feature isn't meant to pass mesh deformation to other objects--for that, you should use MDD. But if you have bones animation, parenting proxy objects is generally a better way to go with LightWave Bullet dynamics.

Hope this helps. Good luck! :)

G.

Greenlaw
10-15-2013, 10:51 PM
Also, make sure the character mesh is not part of the Bullet calculation--you don't need it if you're using proxies for collision. In fact, the character mesh doesn't need to be in the scene at all unless it's to check for penetration. Leaving the mesh out of the scene during calculation may speed things up. To remove the mesh, use Replace with Null rather than deleting it. Then, when you're done and you have baked your cloth sim to MDD, you can use Replace Object to replace to the null with with original object--this way is cleaner and there's less chance of breaking things. (Naturally, this assumes that the character mesh and clothing are separate objects.)

G.

Greenlaw
10-15-2013, 10:59 PM
Getting back to the Sister demo, I forgot to mention that there is also a 'head' collision object. This is a simplified head-only object parented to the head bone. The neck of the object is sealed so I can use Solid mode with it--unnecessary details, like eyes and ears, have been left out of the collision object to improve the speed and stability of the simulation.

G.

Greenlaw
10-16-2013, 02:26 AM
One more thing to check: if the skirt is really low-poly, try sub-dividing it to give it more density for the collision to work with. I'm not 100% certain but I think Bullet ignores an object's sub-patched shape and uses its original polygon shape when it calculates--this might make the simulation appear to be less accurate.

I'm might be wrong about that but it's worth a try anyway. Let me know how it goes--curious to hear what happens.

G.

Danner
10-16-2013, 02:52 AM
... it turns out I fail more at metric than modeling... The metric system is quite easy, much more logical, but you don't have to use it in LW. You can change the units to "english" in the options pannel (shortcut "o"). Or just input any value as inches or feet and LW will automatically convert it to metric, just add ' or " at the end of the number.

Surrealist.
10-17-2013, 05:40 AM
Man I was too lazy to read the whole thread. I think my eyes glossed over at the point where Greenlaw said the easiest way.... and parent a collision object to each limb....:D

OK I do know that technique and I am not being critical of the great help. Just trying to add some humor.

But for something like character cloth it is not sounding like Bullet cloth is that great of a tool for the job. I thought you could deform the bullet cloth with a boned mesh. Is this not the case? Is it really that convoluted to set up?

It kinda sounds like in a case like this the classic cloth solution is far more appropriate. You will get very predictable results, have a set up that makes sense and it is tired and true. The only missing ingredient would be self collision which does not look like you'd need in this case. You would however have to simulate the skirt first and then the blouse after it.

I used this technique in the cloth sim that is in my reel. (brown dress green blouse)

If you do want to go that route, I have a set up that will get you there in minutes and save hours of frustration. It is all documented on this site.

Here is one thread that seems to have all of the steps laid out for your reference should you need it:

http://forums.newtek.com/showthread.php?126654-Is-Cloth-simulation-in-LW-still-bad

jimbotini
10-17-2013, 12:38 PM
I will look over that thread with more detail and give it a try. I started with the clothFX first because that is where all the tutorials I found pointed me. When I had problems with several collision objects (legs and chair when the figure sits down) I tried bullet.

The collision object attached to the bone makes sense to me and I'm working on an object to parent to the bones in question, but now I'm talking about collision objects for pretty much the whole figure if I do some full body outfit. I would have to agree with you, Surrealist, that I thought bullet was supposed to allow bone deformed meshes as opposed to only bone moved meshes. I wonder if just slicing off a thigh and scaling it slightly would make the collision object creation go faster. That of course brings up an interesting question, that I believe I asked before, why do creating collision objects attached to bones that deform another mesh make a difference?

With the ClothFX approach, I can make the waist on the skirt "fixed" and the figure a collision object and the test I did before would work fine. Switched to bullet, I make collision objects attached to bones, what do I do to hold the skirt up if I don't use the figure as a kinematic body? Another collision object? The collision object worked better or I would be continuing on this path, but it does seem a pain. Lightwave has such marvelous features and they keep boasting "easy to use" and "save time" so I can't help but think I'm just doing something wrong or the FBX import from DAZ3d was bad. QQ

Perhaps I just need to invest in some training on lightwave. Any suggestions? I've seen the rigging videos on this site and a few on some other sites.

Greenlaw
10-17-2013, 01:20 PM
why do creating collision objects attached to bones that deform another mesh make a difference?
There's a heck of a lot less calculation involved with simply translating rigid collision objects in space (parented to the bones) compare to deforming a dense mesh with a rigged skeleton, and it's even more so if IK is involved with that skeleton. Alternatively, you could MDD your character which would leave out the extra calculation involved with bones deformation. MDD, as mentioned above, does read correctly in Bullet and gives you the same deformation, but it's a lot faster since the 'motion' is baked in. This will still be much slower than proxies parented to bones though.

FWIW, I did the same when I used to use ClothFX--normally, I can't afford the time for calculating full meshes for dynamics during production. The difference in time can literally be a few minutes vs. many hours for a solution.

Hope that answers your question. :)

G.

Surrealist.
10-17-2013, 01:39 PM
I can not really comment on Bullet because it is another animal that I have not really gotten into. I just have seen a lot of threads end with no solutions that I could see for good character stuff. But classic cloth went that way for a lot of years too. There has been a lot of requests for new dynamics and Bullet was the answer.

Have you seen this?:

https://www.lightwave3d.com/learn/article/lightwave-115-cloth-dynamics-revealing-a-lamborghini/

Nothing to do with character stuff but it does go into a way to fix the cloth to something moving.

It could be someone just needs to come along and crack this. Greenlaw has been very good a documenting stuff so maybe the answer is in there someplace.

I am not 100 percent sure that even the Bullet soft body even the initial library is the best solution for character cloth. Seems that the cloth dynamics solution has more character related settings.

What will happen in any cloth solution (syflex, ncCoth etc) when you try and make the character sit, is that the radius around the collision objects will intersect and the cloth, caught in the middle, will go nuts. This can happen under the arms too and nCloth at least has a push out value and self trapped check which intends to solve this and does pretty good for clothing draped on an animated body. I have not tried it for a sitting character though.

So I think if you issue is sitting you will have to try and work around it somehow no matter which way you go. But that is out of my experience so far so I can not give any tips other than the logic of how the cloth sim is working that I gave you.

EDIT:

The mdd solution does sound like a viable alternative. :)

jimbotini
10-17-2013, 02:03 PM
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.

Surrealist.
10-17-2013, 05:37 PM
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.

wesleycorgi
11-01-2013, 06:40 AM
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.

jimbotini
11-01-2013, 09:14 PM
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.

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Surrealist.
11-01-2013, 10:03 PM
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.

wesleycorgi
11-03-2013, 02:59 PM
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.

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).

hdace
11-03-2013, 07:50 PM
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.

Surrealist.
11-03-2013, 08:54 PM
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.php?133474-Bullet-Deforming-Body-Collision-mesh-cannot-hold-its-shape

hdace
11-03-2013, 09:19 PM
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.

Surrealist.
11-03-2013, 09:27 PM
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.

Surrealist.
11-03-2013, 09:30 PM
Forum acting up again... sorry.

jimbotini
11-03-2013, 09:52 PM
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.

VermilionCat
11-04-2013, 12:03 AM
Yeah, in my addendum page 83 there is... But there's no mention of MDD so beware.

bazsa73
10-05-2014, 04:47 AM
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.

Greenlaw
10-05-2014, 12:27 PM
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.

Greenlaw
10-05-2014, 03:03 PM
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.

bazsa73
10-05-2014, 03:05 PM
it works at last but looks crap, clothFx makes better results

Greenlaw
10-05-2014, 03:21 PM
I'll post a couple of scenes to demonstrate. Hold on.

G.

bazsa73
10-05-2014, 03:24 PM
I'll post a couple of scenes to demonstrate. Hold on.

G.

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

Greenlaw
10-05-2014, 03:45 PM
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.

Greenlaw
10-05-2014, 03:52 PM
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.

bazsa73
10-06-2014, 03:57 AM
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

Greenlaw
10-06-2014, 10:23 AM
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. :)

bazsa73
10-06-2014, 11:53 AM
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.

cyclopse
10-07-2015, 10:42 PM
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.

jimbotini
10-07-2015, 11:11 PM
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.

Greenlaw
10-08-2015, 03:30 PM
No... it's not. Using 2015.3....OK... rant over.

Don't know what to say because it's working here:

130233

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.

3dbr
10-09-2015, 03:37 AM
Greenlaw, could you show your example where the work Bullet and mdd?

Greenlaw
10-09-2015, 03:17 PM
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.

Greenlaw
10-09-2015, 03:21 PM
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.

chikega
10-10-2015, 08:05 AM
Thanks G. for all the hints and suggestions. Simplicity is the order of the day. I'm looking forward to the day that LWG will activate 'memory' in the Bullet soft body dynamics (similar to Houdini), in which the soft body will 'remember' it's deformation, so we can do effects like foot steps in the snow. :)

PS: Looks like we joined the forum during the same time period, July 2003 :)

Greenlaw
10-10-2015, 10:45 AM
That sounds interesting but I'm not sure I understand. How does 'memory' work in Houdini?

chikega
10-10-2015, 11:13 AM
Memory as in the object retaining it's deformed state after a collision with another object, otherwise known as plastic deformation. Crumpling metal is another good example:

130276130277130278

Greenlaw
10-10-2015, 11:36 AM
Ah, okay, thanks!

That's pretty cool. I can recall a few jobs where I cheated that effect by baking the 'crunch' state of the mesh to an endomorph, but now I'm curious to try it without the cheat. :)

G.

Greenlaw
10-10-2015, 02:24 PM
BTW, I posted a 'quick and dirty' animated example of clothing on a character over in this thread:

http://forums.newtek.com/showthread.php?148347-ClothFX-UUUUUGGGHH!/page2&highlight=bullet

Scroll down to post #24 to see the first video.

This animation wasn't meant to be 'final' quality, it was just something I threw together this morning to see what issues I might face for an upcoming project, which has characters wearing somewhat blouse-like shirts and skirts. I think the test shows that LightWave Bullet is certainly capable of making credible clothing effects quickly and with just a little effort.

I've also posted some tips there that I hope will be helpful.

G.