https://sims4studio.com/thread/4792/unwrap-uv-1-shoes

Introduction

Several people have asked how to create the second UV (uv_1) for shoes. This tutorial will show one method of creating this UV map. Because vertex paint also affects how shoes work with the CAS sliders in the game this tutorial will touch on that topic as well. This Sims 3 to Sims 4 slippers conversion is the example item used for this tutorial:

This tutorial will not show you how to create or map shoes. This tutorial should be used in conjunction with other tutorials that go over how to create and map a mesh and use it to replace an EA mesh.

What you will need

Sims 4 Studio

A mesh that has a correct uv_0 map

Instructions

  1. Open your shoes.blend in Blender, switch to Face select and select the backs of the shoes:

  1. Switch to a front view, select Unwrap, and choose Project From View:

  1. Scale the backs of the shoes to line up with the back side of the legs from EA's UV_1.

  2. Repeat the same but on the front of the shoes. If your mesh, like this one, has tall parts (the kitty ears are tall) they will be in the space of the leg's sliders and will likely cause unwanted deformations with the leg sliders unless you flatten them.

Details on how to line up your mesh with EA's uv_1

Use the UV_1 template I posted in the tutorial section for reference of where to place your map. Note that if you use that you will need to scale your UV map down for it to line up, and scale it back out before importing it into your package (instructions in the thread with the templates).

  1. This is what the front of the slipper looked like when I selected it and chose to project the UV map from the view.
  2. Select the ears and top part of the head that go above the sims foot.
  3. Scale those vertices down on the Y axis (press S then Y then drag the mouse toward the center of the selected area)
  4. Move the scaled part down near the rest of the foot area (press G then Y then move the mouse down)
  5. Select the whole front of that shoe and move it to the area of the sim on the template's foot (the right one in this case)
  6. Scale the entire front of the foot on the X and Y until it fits in the area below the sim's leg 2nd UV