How to rig your mesh and make it game-ready (weight transfer, uv_1 & vertex paint)
Hi, I wanted to write this short tutorial on how make your CAS mesh game-ready using Sims 4 Studio & Blender, going over meshgroups, weight transfer, uv_1, and vertex paint. This tutorial assumes some knowledge about blender but it is beginner-friendly.
This applies to any mesh you can make in CAS, from clothes to accessories.Â
Prerequisites: You have a new mesh ready, with a UV+texture that fits within the Sims 4 body UV space, and you are using Blender 2.78 or Blender 2.7.
(1) Meshgroups/Cuts
In order for your mesh to show in studio, it has to have the same number of meshgroups/cuts as the .package you cloned has (these are the s4studio_mesh_x meshes in blender). You can check the cut number for a mesh on the scene tab in blender
When creating a new package, I highly recommend cloning a clothing with one cut, as explained in this mini tutorial by @theslydââ. This saves you from having to cut your mesh up into parts before importing and saves a lot of time.
For some accessories and other items there arenât options you can clone with one cut, for which you just need to work with and keep the same number of cuts.
(2) Weight Transfer
STEP 1: Append either a nude top/bottom, or reference ea mesh into blender. Most of the time I use the nude meshes to transfer from because itâs easier/quicker. You can download this mesh pack I made that contains all the male and female nude meshes to save time.
You can delete any extra rigs and bone shapes.
STEP 2 (optional): Subdivide the EA mesh, especially important if your mesh is high poly. This isnât neccessary to do but if your morphs arenât looking smooth ingame, you need to do this,
STEP 3: Holding shift, select the EA mesh, and then your mesh, and go to weight paint, and on the left side bar (press T if itâs not open), on the tool tab, click the button âTransfer Weightsâ
Make sure âAuto Normalizeâ is checked before you transfer weights!!!
Skip the next step if youâre using Blender 2.70
STEP 3: After clicking âTransfer Weightsâ, set the Source Layer to âBy nameâ, and Destination to âAll Layersâ, and then Click the âCleanâ button, and set the Subset to âAll groupsâ.Â
This procedure fully transfers all the weights, and deletes any weights that are set to 0 (these weights break the animations ingame).
Now your weights are transferred properly and your mesh is rigged to the skeleton, so it will move when your sim moves.
STEP 4 (optional):Â If your mesh is oversized or big there may be glitches/bad looking areas.
These are fixed via manual editing, @theslydâ has tutorial that goes over this, but my advice is that the blur tool is your best friend. I recommend adding the armature modifier to your mesh if itâs not there and linking it to the rig, because then you can pose your mesh in Blender and check for weight glitches without entering the game.
(3) UV_1 Transfer
This REQUIRES Blender 2.78, older versions cannot be used for the uv_1 transfer.
This is also assuming your EA mesh (the one you appended earlier) is still in your blender file after weight transferring.
STEP 1: On the Data tab (the upside down triangle), scroll down to UV maps, create a new UV map and rename it to uv_0.
STEP 2: Select your mesh, go to the modifiers tab and add a Data Transfer modifier.
STEP 3: Make the Source Object the EA mesh, check âFace Corner Data Transferâ, click UVs, change All Layers to uv_1, change By Name to uv_1, and then click Apply.
Now your mesh will morph properly ingame when a sim is fat/thin. You can delete the EA mesh now if you donât need to use it anymore.
For some accessories and parts of meshes, they do not need a uv_1 if you donât want them to morph with the sim, like the pendant on a necklace, or zips on clothing.
For example, if thereâs a zip on your clothes you donât want to morph, go to the UV editor with the uv_1 selected, and then find where the zip is, press L to select that uv island and then size it down really small. This will make it not morph if a sim is fat/thin, with the rest of the clothing morphing like normal.
(4) Vertex Paint
STEP 1: Select your mesh, and go to the vertex paint mode.
STEP 2: On the left side panel (press T if itâs not there), click the colour box and on the Hex tab, set the colour to 00FF00.
STEP 3: With the green colour entered, press shift+k to colour your entire mesh green. You donât need any other colours like blue or yellow (as said in other tutorials), it wonât make a difference.
And thatâs the vertex paint done! Vertex paint is crucial for your mesh to work ingame with sliders and for the other rigging parts to work, and with that the whole rigging process is finished.Â
Your mesh should be ready to use ingame, properly morphing and moving with the sim. I also have a tutorial on LODs if you want to continue finishing your CC for release. LODs are super important for making your CC optimised, and is the other step of making your creation completely game-ready.Â
If you need more info or help with common weight and uv_1 issues, I highly recommend @mauvemornâââs tutorials. You can also post on the creatorâs help section on the s4s forums if you need more specific help, I and other creators check there often to help people out.
Hopefully the helped! Feel free to ask any questions through asks/dms :)