Bug Report!!!!

[Oldcode]

I'm trying to do a project with lots (26) object as active rigid bodies falling onto a plane as a passive rigid body. I set up the exclusive links and every works, but only for a short time.

As I do my work, making adjustment, trying to get the objects to fall the way I want, some of objects stop working.

They fall through the passive rigid plane as if they have no dynamics at all.

The only way to fix it is to delete the object and re-import it, setting up the dynamics and exclusive links all all over again, which is a major pain!

Anybody else have this problem? Any change this will be fixed in 2013?

[tsn]

Is there a 2D plane in your scene? If so, please use a 3D object instead, e.g. a thin cube. The plane is actually not a rigid body. You can see that when you select the plane and open the "Measure Utility": volume is 0. When RBD is active, the plane's mass is just 0.1 (formally it would be 0).

"Any change this will be fixed in 2013?"

2D objects will remain 2D - even in RF2013

[Oldcode]

Hey Tsn,

Thanks for the reply. Actually, it tried that, using a 3d cube almost flat, but it made no difference.

What did work was loading all the objects I had in to a scene, about 28, and saving it as a setup file, then importing all the objects via the SD file as a multibody. That seems to do the trick.

Later,

[tsn]

Actually it shouldn't make a difference whether you're using individual objects from a SD file or a MultiBody. The main difference is that MultiBodies don't support animation data, so this could be the reason. Did you perform any transformations before export or did you write animation data (even if the objects do not move) to the SD? Glad to hear you've found a solution, but I'm curious why it failed with individual nodes.

[Oldcode]

I simply loaded all 28 objects into a scene, did nothing to them except make sure they were not in contact with each other, and ran the simulation. It was not the animation data I was interested in, I just want all objects to interact with the other objects I want them to interact with.

Then I opened my working scene file, and loaded the objects via the SD animation file. I was then able to run the rigid body simulations without any problems.

You're right, it should not make a difference how I load the objects, but it seems to. If I load them one at a time and setup the dynamics on each, sooner or later, the object dynamics stop working. I don't know why. My only guess is that since there was so many, and the objects are of relatively complicated in shape, the software simply could not handle the dynamics on so many.

[tsn]

Thanks for the explanation of your workflow. 28 objects is actually a pretty low number, but I guess they're very complex with lots of holes, spikes and other small structures. Nevertheless, this can't explain why the simulated failed with individual objects. Just out of curiosity: did you try to simulate with the "Complex hull" method or press the "SD<->Curve" button before running the simulation?

I think I'll pass this over to the RBD team, because they have more insight into the internal processes how SDs are treated. I hope they can shed some light on this issue.

[Oldcode]

Hey tsn,

The objects in my scene are human bone models, about 26 of them, and yeah they are of fairly complicated shapes and about medium polygon count.

No, I've never heard of Complex Hull or the SD Curve. I've been using Real Flow for about yeah, but I'm just a hobbyist, so I can't spend 24/7 on reading the manual.

I'll try to look them up.

[tsn]

No problem. Hobbyists do great things as well and often look deep inside a software's features, because they don't have tight deadlines

You can read more about the "Convex hull" feature here:

http://support.nextlimit.com/display/rf ... Rigid+body
Please look for "Collision primitive" - it's the first parameter explanation.

The "SD<->Curve" button can be found under an object's Node Params > Node > SD<->Curve. The button unlockes an object, makes it editable and removes all animation information that might have been stored with the SD. Maybe you want to give the simulation another try with these changes?

[Oldcode]

Hey tsn,

Thanks for the info. I'll have a look at it, but right now importing all the bones in as a multiobject from the SD file works very well. A nice bonus is I only have to create exclusive links for 1 object and not 28, and if I have to move the objects, I only have to select and move 1.

Check out the clip. I brought the finished scene SD file into Lightwave and rendered it out. I'm pretty happy with how it came out.

Thanks again,

[tsn]

The objects are indeed pretty complex, but the RBD turned out very well. Nice simulation!

If you want to get rid of the mesh flicker you might want to try the standard mesh engine instead of the RenderKit type. The advantages of the MultiBody node are indeed numerous and you will also see a much faster import, especially with large number of objects and polygon-heavy nodes.

Best,
Thomas