Object interpenetration... is that ok? (image)

olivierth · Jul 2012

Hi, I'm currently modeling some sort of a dragon that will end up in UDK.

I would like to know if it's a bad idea to have the horns modeled separately and just intersecting the head of the dragon?

This is actually not a UDK related question but a general game-engine question.

Can it cause problems?

Thanks!

Will Faucher · Jul 2012

Not really a problem, no. People use floating geometry all the time.

olivierth · Jul 2012

Cool, Thanks for the quick reply Prophecies!

I can now go on with the project.

Ghostscape · Jul 2012

It's typically a bad idea to have interpenetration between two soft-skinned animated objects, though, as you'll get one floating over the other and not looking connected as you animate. If the verts surrounding the horn and the horn itself are 100% weighted to a single bone you'll be OK, otherwise you should merge them.

Olli. · Jul 2012

ghostscape has a point. unless the area where the mesh intersects is rigid, you should merge the meshes if you wish to animate your work.

Ace-Angel · Jul 2012

It's much easier to process and even get the looks of two separate mesh objects, vs. one, especially in ZB, and ESPECIALLY for shaders.

Currently, the Dragons horns wouldn't make sense if they were merged with the skin, you need that hard cut definition between Bone structure and the skin, and why double your work in ZB for that, when you're already halfway there?

It's very much situational, yes I agree, but in this case, this is perfectly fine. All you need to do is work on the skin are around the horns, so that it looks less like a stump/hole with two branches sticking and more like skin which has grown and wrapped around the bone over the years.

I usually suggest peeps to look up other animals or your own teeth in the mirror, since you will see that anything which is exposed and used on a daily basis, which doesn't belong to the skin will have a clear definition of materials, skin simply 'grows' on it, not become part of it.

As for the rigging, same thing, the upper skull of the dragon is not supposed to move, just like that of many animals out there, especially cows, so I don't see the issue in having the end verts of the horns weighted to the node bone in the skull if they're two objects?

If you want the horns to wobble abit, you just wobble them half way from the end verts, rather then the start ones inside the skull, since it wouldn't make sense the other way around, even by physic's standard, bent, snapping or jello horns don't occur randomly inside your skull, they always start form where there is very little support and stop as soon as they have some meat to cover them and absorb most of the laws of physics as padding vest.

olivierth · Jul 2012

Great, thanks for all your insights!

You guys confirmed what I was thinking.

poopipe · Jul 2012

if this is aimed at a game model then the low res would ideally be a single watertight mesh (assuming you don't have special shader requirements on an engine that won't split the meshes for you at render time ). It makes skinning easier as said above but also some engines prefer not to have to clip geometry out.

for your high res - you do whatever you makes life easiest

Object interpenetration... is that ok? (image)

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