Let's say I have a high-poly face mesh, made in Zbrush,

Not a character artist, but this is my take on how it'd work:

>Sculpt a NEUTRAL expression face.
>Retopo that expressionless face into a game-ready resolution.
>bake neutral face normals
>Rig the face for animation
>plan out how many blendshapes and which.[ optional, but helps ]
>Animate that game res mesh into each of the blend shapes.
>take each low poly blendshape back into zbrush, subdivide and resculpt detail accordingly.
>bake out each blendshape.

Each blendshape will have a unique normal map,
>ie: a smirk would have unique wrinkles on one side of his face/cheek.

Ultimately, an animation triggers and automatically this unique blendshape normal map gets mixed to the neutral/default expression face normal map.

Hope that helps.

>>535054
Well whose fault was it to pose it before retopo?

>>535056
this

do blendshapes and UVs AFTER retopo you mongoloid

>>535054

Are the blend shapes in layers. Retopo and use project all to conform the low to the high and subdivide the low poly. Use project all again on the low for each blendshape. It might fuck up ur geo but it's better to correct it than having to do it by hand.

something something transfer attributes function something something

>>535054

Topogun can do this

>>535112
yeah this might work too, but OP will still be stuck in a shitty workflow.. he'll know for next time kek

Sent from my Android phone

OP here again. I just made a low poly model and baked normals onto it. Then I redid the blendshapes.

I've lost all my detail and wrinkles. Any advice on a workflow to keep those details?

>>535170
Yes, you lose all your detail and wrinkles. This is when you resculpt each time you do a new blendshape. Then you rebake again. Did you even read the first comment?