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MOPs explode with point deform

Posted: Wed Feb 10, 2021 10:41 am
by g.bailey
I was working last week to create an exploding effect on a fairly dense animated mesh. Since MOPs explode recalculates each frame and is pretty expensive, I ended up point deforming a static version of the exploded mesh. It worked pretty well for what I needed, but there were small gaps as the mesh deformed.

It got me thinking where there was a way to clean up those gaps. Some way to store the original point positions and retransfer. I could unpack, but then I'm losing all the benefits of MOPs. Just wondering if there's a way to do it to the packed prims?

Thanks for any ideas.


Re: MOPs explode with point deform

Posted: Wed Feb 10, 2021 11:39 am
by toadstorm
This is a tricky one, because the original mesh is deforming so there's going to sometimes be gaps no matter what because the exploded primitives are effectively "rigid" and can't be deformed, only transformed. Additionally, areas where the mesh nearly collides (elbows and other tight intersections) are going to have trouble knowing what source they're bound to when computing capture weights.

You can minimize the deformation weighting problems by providing Point Deform with a "Piece Attribute" in 18.5. I'm using Connectivity to create a class attribute on points, transferring that to the exploded packed primitives, and then using that as the Piece Attribute for the Point Deform. I'm also taking the capture radius way, way down so that individual primitives are less likely to have their orientations influenced by neighbors. Attaching the scene file here.

Re: MOPs explode with point deform

Posted: Wed Feb 10, 2021 1:10 pm
by g.bailey
Thanks. That helps a lot. Gets it as close as I was hoping.