Blendshape: low poly character from skinny to muscular

Optey

Hy guys!I was wondering what's the correct and most efficient workflow when it comes to create a game character (low poly) and you need to perform a blendshape (let's say from skinny to muscular) on it?

Usually When I create a character I do all the basic stuff...
1)high poly sculpt
2)retopo to low poly
3)baking
4)texturing

but what about if I need to do a blendshape?I need to create two different meshes (one skinny -high and low- and one muscular -high and low-) and then performing the blendshape? or I can just modify the low poly skinny version to make the different shapes and forms (and in this case What about the different maps as the normal map??) I am a bit confused about the correct workflow about this topic...

Hope someone will help me

Cheers,
Optey

antweiler

I would say, you need two lowpoly meshes to blend between skinny and fat. They need the same topology and vertexcount and id, so one needs to be derived from the other (as you said)
Create nice sculpted normalmaps for both, and blend these, together with the shape, in the engine.

Optey

thanks for the reply antweiler!
correct if I am wrong...I would do this
1)create (for example) the fatty high poly, then create the low poly and bake the maps
2)after that I can create the Skinny High Poly sculpt
3)Then I can import the muscular low poly and match the skinny high poly one in zbrush
4)bake Maps from the skinny High Poly to the skinny Low Poly (created from the fatty Low Poly)
At the end I used the same mesh for the low poly...so I can jump into maya and create blend shape from one to another (the low poly is basically the same)...then I can create also a transition between the two normal maps

antweiler

That sound reasonable, i guess you know the details better than me, since im not a ZBrush expert. Oh, i forgot, for the map blending you obviously need identical UVs on the lowpolies, so keep that in mind when doing 3), matching the muscular lowpoly to the skinny highpoly.
If the topology and vertex ids are identical, its very easy to copy UVs between meshes in Maya.
Do a test first, if the two lowpolies remain blendable in Maya when exported from ZBrush, but i think I did that and it worked...