View Full Version : How Would you ---- Fill a Burlap Sack

11-04-2013, 04:22 PM
I'm needing to fill up a burlap sack with grain. I'm thinking of using bullet some how, but am lost on how I would get particles to interact and quote morph the sack into a full sack. Anyone with thoughts?

11-04-2013, 04:34 PM
Do you actually need to see the action of the grain filling up the sack? Meaning, does it have to be technically accurate? You could have the grain fall in and then slowly morph the sack...so it'll give the appearance that the abundance of grain is making the sack's shape change when in reality it's not. Just need to convince the user that action A is resulting in B.

11-04-2013, 04:42 PM
we'll actually I was wanting to do the bullet to get a more realistic result on the finished sack displacement. I didn't' want to morph and sculpt, as I'm not skilled in that area of modeling.

In short, No I don't have to see the grain actually filling up the sack.

11-04-2013, 05:36 PM
Dunno, but it sounds fun. I might have a play tomorrow! :)

11-04-2013, 07:27 PM
i think this might be an actual valid use of the.... uhhhhh..... "Bulge" (????) Effector?

OR, use gradients/nodes to vary a morph based on the geometry's distance to a null. SplineGod did a whole DVD on this effect. In this case, since distances is spherical, it neatly matches the bag. Is the bag HANGING from some support, like a garbage bag? You'd make an empty bag and a full bag as endomorphs, run the null up the center to execute the morph. (OR, it may make more sense to UNmorph the mesh-- whatever works.)

I also think you could base it on "Whatever is -y from this null". All this was possible with Gradients, so with Nodes it should be even more flexible, if a bit more technical.

BTW: kudos for a GOOD subject line!

11-04-2013, 07:42 PM
Here's one I made with bullet. It's pretty much thrown together, but it might be a good starting point?

Ryan Roye
11-04-2013, 08:21 PM
See this tutorial also. Though it uses Hardfx, the same technique could just as easily be applied via bullet dynamics.


11-05-2013, 03:12 AM
Swampy, do you ever sleep? :D

11-05-2013, 04:14 AM
Swampy, do you ever sleep? :D

Yep. But not for very long... life's too interesting! What did you think of the sack?


11-05-2013, 04:20 AM
Nice. Shame you can't animate the weight map so the top corners aren't still pinned after the sack falls. Or can you? :D

11-05-2013, 09:27 AM
I havn't looked at the scene, but you can pin with nulls instead of weights and then it's animatable.