You definitely want 3 slots for the 3 parts of your shirt! Let's call the shirt an item. The item consists of 3 slots, shirt-left-sleeve
, shirt-right-sleeve
, shirt-torso
. Each slot gets a skin placeholder of the same name. Then you create a new skin, say shirt-blue
, activate it, and drag the images to the correct slot. The shirt-blue
skin then represents the entire shirt, which is easy to manage at runtime when combing skins.
You also want to organize your image folders accordingly. E.g. you have a folder shirts/
, and in it, one folder per concrete shirt version, e.g. shirts/shirt-red/
, shirts/shirt-blue/
. Each of these folders then contains the 3 images making up the shirt. To bring in a new shirt, you create a new folder with the corresponding images, create a new skin, activate it, and attach the 3 images to the skin placeholders. That's it!
To preview combinations of different items directly in Spine, you can use the skin view we've added in 3.7. More info here: Spine 3.7 features rundown - YouTube
To combine the skins for the body, pants, and shirt at runtime in your game or app, you simply merge the attachments from each selected skin into a new skin programmatically. If your character switches an item, you generate a new skin.