Repulsive Shells [video]

Paper: https://www.cs.cmu.edu/~kmcrane/Projects/RepulsiveShells/ind...

The ending was unexpected but great haha. I'm curious if the algo is fast enough for real time or if it's only for renders.

"So.. what will the world do with this knowledge?"

"Something something, rule 34."

Is there a standard underwear man model like the teapot? I find it's use hilarious considering there's no reason for model to be in underwear. Same with the butt/hip model at the end. Chefs kiss.

I was hoping that this would be about computational geometry (and not, say, about the C shell or Powershell), and I am glad it indeed was.

TL;DR: they are talking about approach to 3D geometry which avoids self-intersection by design, which is something useful for modeling solid bodies.

However, I hope someone makes a video about shells that are hard to use too :)

> I'm curious if the algo is fast enough for real time or if it's only for renders.

Yeah, likewise. It definitely looks like it's formulated for optimizing paths rather than, say, simulating real-time physics, so I'm guessing not yet. From a quick scan of the paper, I didn't see anything on the complexity (O(N logN) or O(N^2) or whatever), but there were some timings:

> Figures 11 [clasped hands] and 15 [underwear model] each took first 10 minutes to find a coarse trajectory, then 5 and 2-3 minutes, respectively, to refine [to 60 fps].

I clicked thinking it would be either electron shells or really ugly animal shells.

Does this have implications for gaming? I know character models with lots of "accessories" clip into walls and the character body very often, and from what I gathered, the belief was that this was a hard and manual problem to solve.

The main example is a dude moving his arms around, and the repulsing shell/surface kind of interpolates through the motion semi smoothly.

I could totally see something like this being useful or interesting for destructive physics in video games. Like, oh, this surface/shell is about to repulse a rocket slamming into it, deform it for this hit. It's be a very different application but there's a kernel of morphology here feels similar ish, of this kind of softbodied-at-a-distance simulation.

Based on other comments though it sounds way too slow to consider for realtime games though.

Those numbers don't mean much beyond "minutes are better than days", because this contribution is a quality improvement via a new algorithm. Optimizing performance and maximizing choice of hardware power is another effort.

And here I thought groovysh was a repulsive shell.

It was kind of repulsive

Haven't read the paper, but guessing, in the limit, this is simulating the electromagnetic interaction between electron shells of atoms?

That triggered my Watership Down childhood PTSD.

That space has seen major improvements over the past few years, but this method would be a great addition to the toolkits and games out there.

Might speed up the animation pipeline so artists can get to something physically plausible quicker but it doesn't seem like it's feasible to run in real time.

First thing that came to mind upon seeing the title was Powershell --- or as some like to call it, powersHell. ;-)

Why not? The skeleton model doesn’t appear to be doing full skin simulation, it simulates repulsion of the skeleton.

Because it takes minutes to run.