Rigid body tubes in Houdini

Using rigid body dynamics to simulate a ball rolling down a tube. How difficult can that be?

Well, it took me quite a while to get it to a working level, and I'm still a little confounded by some of the things I had to do. Creating the hollow tube is half the challenge, since boolean refused to function properly when I started doing this test on version 9.5. Now I'm on 10.0.359, and the boolean still baffles me.

I created my hollow tube by taking a solid outer tube A, and tunneling away the inside with a narrower inner tube B using boolean subtraction in the Cookie node. Technically, I should do a A-B, but in my scene, I had to select B-A to get the right behavior. Sure, I can get what I wanted using this workaround, but it ain't logical.

Yes Houdini is powerful and logical, but it's not as intuitive as the real world. A lot of powerful features have become much more accessible to the average end-user through the shelf tools, but considerable knowledge of it's inner workings is still required to squeeze out some basic logical behavior if you are trying something different.

To be fair, Houdini is probably the only widely available commercial 3D tool that even allows you to do such simulations with relative ease and reliability. Anyways, I'm still taking baby steps with this software, but hoping to walk and run with it some day.