PhysX Clo0th With Convex Hull


https://forum.reallusion.com/Topic557736.aspx
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By Rampa - Last Year
I discovered today how to use the tapered cylinder shape for PhysX cloth that the PhysX engine supports. It was amazingly simple! The shape just has to be very basic. So cylinders with different sized/shaped ends, and cones can work. As long as the edges connecting the ends are only a single segment. End caps are not needed either. Using custom imported, oddly shaped, cylinders works great!



Since the default character collision shapes are only box, sphere, and capsule; this method can be used to fine tune collision shapes that you then attach to the character yourself.
By Rampa - Last Year
And taking advantage of the fact that is creating convex hulls, you can strategically adjust the model to get it to create a somewhat domed end. I adjusted 4 points upwards and merged them, then 4 more points upward and scaled smaller. It then happily a convex hull as if there were no geometry gaps. Nice trick! :)

By 4u2ges - Last Year
The problem with Convex Hull (aside from being unstable and crash a lot), is that no more that 1 collision object with fairly high poly count to make a decent leg enclosure would work with a single Soft Cloth mesh.
Meaning it's not useful for character cloths.
NVIDIA seems already has support for tapered capsules, but it was never implemented in iClone

By Rampa - Last Year
You can have many of these. I am actually not quite correct in the video, since I was figuring it out as I experimented with it. 60 tri's or less for a collision shape will work with convex hull. So basically the convex hull shapes are just a way to use varying shapes to replace the existing collision shapes. So you create a tapered hip to knee collision shape, for instance. It would use about the same number of tri's s the current capsule that does not taper.
By 4u2ges - Last Year
Yes, but with 60 tris you may only use one or two collisions per dress, which is quite limited (for long dresses, capes, coats.. etc).

Here is to compare.
A Convex Hull cylinder with 16 tris each (no caps) only allows to interact with the total of 3 shapes, compare to Capsule where I can have max of 16 shapes.



Moreover, 30-32 tris cylinder with (no caps) would crash iClone while simulating with any cloth (it does not like those numbers for whatever reason).


By Rampa - Last Year
Got it. Bummer it has such different capacities. Oh well.