Hi. If you've ever watched tutorials on cc making for ts4, you may know this concept under a different name, "vertex paint".
Multiple things are responsible for how meshes morph when you customize a sim's body or a face in CAS. The main force behind it are Deformation maps. You dont need to know what they look like or how they are applied, but they come in two versions: skintight and robe-like. Vertex paint defines what version a painted area will use.
On the first and third images a skirt is vertex painted with 00FF00, so it morphs using skintight version of Dmaps. As you see, the mesh sinks between the legs and is affected by calf morphs, which is not how it should be ( second and forth images, painted with 3FFF00, robe-like version).
This color in also present in the chest area, but its a bit hard to see a difference on a still image.
Anyway, here are the one I know of:
00ff00 - skintight version. All morphs beside Details mode ones;
3fff00 - robe-like version. Meant for skirts and sometimes between the breasts. Prevents the skirts or loose tops from "sinking" between the legs or breasts. The bottom of the skirts will also not be affected by calf and foot morphs;
000000 - disables all morphing;
007f00 - this color is between 000000 and 00ff00, so you'd expect it to reduce the effect of skintight dmaps by half. I tested it and the area painted with 007f00 morphs just like 00ff00. The only difference is that this area does not highlight when you hover over it. Anyway, this color is used on accessories, the ponytails/jaw-to-chin area of the hair, tips of eyelashes and facial hair;
007f02 - used on root-to-chin area of the hair;
007F3F - enables Details mode morphs. Used on the hairline, roots of facial hair and eyelashes, piercing;
3F7F00 - used on mermaid tails.
How to know what color an area is painted with:
Well, you could switch to vertex paint, change shading to flat and sample it. "Could" in the past tense. You still can but, for some unknown to me and google reason, in 2.8+ the sampled hex is not exact. Now you can paint the mesh with 00FF00, sample the color right away, and it will give you 01FF01 instead.
But this is not a problem. You can either remember the hex for the right category or just transfer vertex paint.
When you make a body accessory, it must move and morph like an area of the body it covers, so you cannot transfer weights and uv_1 from another accessory unless their placement is exact.
This is why you transfer them from a body directly. However, a body highlights when you hover over it, which is not what an accessory should do. So you have 3 options:
- transfer the color from an accessory, not the body, they do not need to overlap for this;
- switch to vertex paint and just flood everything with 007F00;
- delete an existing color attribute and create a new one, flooding everything with a specified color.
The last step is the fastest, so this is what I usually recommend
Face Corner and Byte Color are always the same, color0 for blender 3+, Col for blender 2.7x, the hex differs
