I'm working my way through the very basics to learn Houdini, and am having a bit of trouble with the column destruction simulation. Initially, I couldn't get the duplicated columns to recognize the ground plane, so even after I added the GP they would just fall right through. I downloaded the latest build and that seemed to solve that issue.

But now, when I proceed to the point of making the columns breakable and run the simulation, the columns seem to react to the ground plane and, starting at frame 3, all of them explode apart at their bases before the swinging sphere gets anywhere near them. I've gone through the tutorial over and over, even going so far as to delete everything but the column, and duplicate them out and run through all the steps again, making sure I don't miss a step or add an extra one, and no matter what I do it always does the same thing.

Help?

Hi DorkmanScott,

It's been more than a week since you posted for help but I'm gonna answer just in case you haven't found the problem yet.

I downloaded your scene and I'm having the same weird behavior of the objects falling through the floor when using the Bullet solver for RBD simulations. I'm using Houdini 12.1.33, I guess it must be a bug on the Bullet solver on that build.

However, if you go to your AutoDopNetwork and on the rigidbodysolver change the Solver Engine to RBD, your simulation should run fine. Those first steps tutorials were designed with the RBD solver in mind I think, even before the bullet solver was implemented into houdini.

You'll notice also when you run your sim that the colums are split in half still, I guess you're not fusing them correctly after mirroring them.. though i didn't check… thought it would be fun for you to look for that on your own and learn

by the way… to the Houdini world.. hope you enjoy it


*****—EDIT—*****

I checked a bit more cause thought weird that the bullet solver wasn't working well and apparently more people had the same problem on that tutorial… you could check this threads for some hints

http://www.sidefx.com/index.php?option=com_forum&Itemid=172&page=viewtopic&t=25591&sid=890f3ecf762eefb113a7978dc8160032 [sidefx.com]

http://www.sidefx.com/index.php?option=com_forum&Itemid=172&page=viewtopic&t=25540&highlight=Bullet [sidefx.com]


*****—EDIT—*****


Ok… I tested it some more and it was no bug

If you check your normals on the column they are facing inward, that is why its not detecting collisions with the floor.

I added a primitive SOP before the last merge of your column, on the Face/Hull tab I reversed the vertex and that did the job. Now it collides correctly. After doing that I had the same problem that you did when you upgraded Houdini. All columns explode at the third frame, that was solved by raising the substep number on the rigidbodysolver under the Bullets tab.

you can check the fixed scene.

Thank you so much for taking the time to dig into the scene and for your patience explaining it and pointing out a few other resources. I still hadn't sorted it out and I didn't even know where to start, so this helped tremendously. Thanks again!

I wish to also extend my thanks to robonilla for taking time into solving this

It solved a problem I was having in two ways:
A. Increase the Bullet Substep from 10 to 50.
B. (or) Change the solver from Bullet to RBD.