When you drag a limb to the body in Spore and it attaches to the body, not only does the bone rig obviously connect (which allows the limb to move with the body - which I think I mostly know how that works), but the SKIN of the mesh of the limb connects directly to the skin of the mesh on the body seamlessly.
I assume that the limb is a separate mesh from the body, so how do the two meshes become "one"? NOT the bones... that's another question. I'm asking about the skin (the faces, aka the wire-frame, the polygons) of the meshes, how they become one.
What is this called in the 3D modeling world, where the skin of two different meshes connect together when they are brought close to each other? Is there any information online that describes how this might be done in Unity3D?
there are plenty of ways to do it, and none of them are 'magic' per se- take a look at marching cubes, voxel based geometry, or even something as simple as booleans. None of them are fast, but all of them are well within a modern PC's capabilities. Spore used a very specialized engine designed for this purpose, i'm willing to bet you wouldn't be able to get this kind of quality/results with Unity3D without some VERY serious optimization work.
On that note, I saw this on the asset store the other day- it's somewhat related to what you're talking about, and it uses voxels:
answered Jul 05 '11 at 05:38 AM