I just tried the following code successfully:
var slot = skeletonAnimation.Skeleton.FindSlot(slotName);
slot.SetColor(new Color(1, 0, 0, 1));
If you don't see any effect, please check the script update order as described above. Your script shall run after SkeletonAnimation
and SkeletonRenderer
. If this is already the case, please post the code you are using to set the color.