cubiccube

There are some good example hip files inside of the support materials for Solaris in the h18 docs that might answer some of your questions. The download link is buried in here: https://www.sidefx.com/docs/houdini/solaris/tutorials.html

Do the materials keep their assignments? I'm able to bring materials into lops with the scene import lop but still have to manually reassign them to their respective groups.

This just made my day. Thanks Milan!

Searching for "variable viscosity" on here should point you in the right direction. If you've got more questions just post a hip file of your setup.

Stack a couple Voronoi split sops with a grid piped into input 2.

A Point Replicate Procedural geometry shader w/proper CVEX logic could probably achieve this. You might find this recent thread helpful too: http://forums.odforce.net/topic/19359-is-there-a-way-to-create-uniform-evenly-sized-voronoi-pieces-in-h13/?hl=voronoi

Here's a simple setup for a timer inside a simulation context. I like using a "state" attribute where 0 = ready, 1 = active, and -1 = dead. This is handy for controlling things like debris emission too. simple_timer_v01.hipnc

In order to get your "neighbour" attribute to write properly, it needs to be created and fed into the while loop. Check out the attached file (go to frame 2). sopsolver_pointcloud_fix1.hipnc

As always, thanks for all your great work!

The technique you're describing is a good way to determine when to start emitting debris (when two points or prims that started off as neighbors become pulled apart --> emit debris) but I'm not sure you want to use this kind of distance based logic to stop emissions. Consider two faces that stay within the distance threshold will continue emitting indefinitely. A timer might be more useful here, as it guarantees you'll stop emitting at some point. Regardless, you can do distance calculations pretty easily in VEX using point cloud lookups. Be sure to store initial neighbors as attributes first.

There are a lot of ways you could go about offsetting the timing (duplicating your foreach sops and staggering the timing of their switches or something along those lines), but I'm not sure this is the best way to solve the "linear" look you're talking about. You'll get a more seamless effect if, instead of scattering points on top of the actual geometry, use the property point position (with a very small random offset, +/-.1) as the origin for your new piece points (you can use a line or add sop to make the initial points or, in H13, use Attrib Wrangle).That way everything originates from the same spot and explodes outward instead of appearing in midair. Not exactly the answer you're looking for but give it a shot and see if it helps. Also, you scene will simulate much more quickly if you bring the polygon count on your geometry way down. Pipe the initial geometry into a shrink sop to generate a convex hull (what Bullet converts your geometry into anyway) and play with the sliders until you get something closer to 100 polys. Good luck!

I like VEX for this sort of thing, especially now that we can add/delete geometry with Attrib Wrangle. Here's an example file. delete_inside_faces_v01.hipnc

Nice! Thanks for this!

You can get that kind of jitter using basic sine functions. You could also use some noise. Or both: use sine functions to get your oscillations and use noise to vary the frequency and amplitude. You could do these with expressions if you wanted but imo a vopsop or wrangle node is more quick and clean. The other component to the jitter in your reference is that it builds as the boxes get closer to splitting. In my example file I was assigning a randomized counter to each box once its velocity dropped below a certain threshold. You could use that same counter (or another based on different logic) to drive the ramping up of the jitter. Now, implementing it with BulletSOP might be a little tricky since you can only animate static (mass = 0) objects. I believe there's an example in the hip file Milan includes with each release that shows how to get around this by stashing your objects mass and swapping it out when you want it to become active.

What Houdini build are you using? And what BulletSOP version? BulletSOP should be v2.0.9 and Houdini 12.5.469 is recommended (though I'm on 12.5.536 without problems).