skeleton.SetAttachement and skins

EventSpawn

So I have been successfully using the SetAttachment method to switch out props on a character at runtime but now I am running into an exception when using attachments and Skins.

So situational overview I have gotten a character that has three skins (Light, Dark, Normal) the character also has two arms (normal, muscular)

Because of the different skins slot F_Arm_Small has three attachments F_Arm_Small, F_Arm_Small_Light, F_Arm_Small_Dark. But due to them being attached to a certain skin only one of them shows up in the inspector, as is expected

now I have a property

private bool smallArms

public bool SmallArms{
     get { return smallArms; }
     set {
          smallArms = value;
          if(smallArms){
               //disable the large arms
               skeleton.SetAttachment("F_Arm_Large", null);

           //enable the small arms
           List<Attachment> posAttachements = new List<Attachment>();
           skeleton.Skin.FindAttachmentsForSlot(skeleton.FindSlotIndex("F_Arm_Small"), posAttachements);
           skeleton.SetAttachment("F_Arm_Small", posAttachements[0].Name);           
      }
 }
}

Now it is skeleton.SetAttachment("F_Arm_Small", posAttachements[0].Name); that is throwing the exception

Exception: Attachment not found: F_Arm_Small_Dark, for slot: F_Arm_Small
Spine.Skeleton.SetAttachment (System.String slotName, System.String attachmentName) (at Assets/Spine/spine-csharp/Skeleton.cs:433)
LoK.FemaleClothingController.set_UseSmallBoobs (Boolean value) (at Assets/Scripts/SharpClawVillage/Animation/FemaleSC/FemaleClothingController.cs:513)
LoK.FemaleClothingController.Start () (at Assets/Scripts/SharpClawVillage/Animation/FemaleSC/FemaleClothingController.cs:79)

I have been looking into the code behind the SetAttachment and the problem lies in the attachments dictionary.
When reading the json data these methods are used (SkeletonJson.cs lines 254 and 255)

Attachment attachment = ReadAttachment((Dictionary<String, Object>)entry.Value, skin, slotIndex, entry.Key);
if (attachment != null) skin.AddAttachment(slotIndex, entry.Key, attachment);

In this case the Key to the attachement dictionary is constructed from the slotIndex (correct) and the entry.Key F_Arm_Small
Here is the excerpt from the Json file

"F_Arm_Small": {
"F_Arm_Small": { "name": "F_Arm_Small_Dark", "type": "linkedmesh", "skin": "Normal", "parent": "F_Arm_Small", "width": 158, "height": 532 }
}

When we then get to the SetAttachment method It runs down trough a couple of functions until it gets to the GetAttachment function in skin.cs

public Attachment GetAttachment (int slotIndex, String name) {
   Attachment attachment;
   attachments.TryGetValue(new AttachmentKeyTuple(slotIndex, name), out attachment);
   return attachment;
}

The problem is that the key that is constructed now uses the name that is given (F_Arm_Small_Dark) to construct the Key to the dictionary. This obviously fails to match the Key constructed previous with the entry.Key So it returns null and thus throwing the error

What am I missing? or is it something my animator has done wrong when constructing the various skins?

EventSpawn

Pharan

Thanks for your interest in the inner workings of the Spine runtime!

Here are a few quick facts that might clarify:
(1)

The problem is that the key that is constructed now uses the name that is given (F_Arm_Small_Dark) to construct the Key to the dictionary.

This is true. It's also your code, so all you need to do is not use the attachment name. Instead, have it as a constant "F_Arm_Small" and it should work.
This is assuming "F_Arm_Small" is the name of the skin placeholder in Spine Editor which has different attachments per skin. There's no need to use the attachment name.
The attachment name actually unrelated to attachment lookups in skins and is more often used when the atlas region data is mapped onto the attachment.

(2) skeleton.SetAttachment(slotName, attachmentName)
This is a convenience method. Each of its steps, you could probably define or replace yourself to be more specific to your needs, or skip them altogether.
Step 1: FindSlot which goes through all of the skeleton's slots and finds a slot name string match.
Step 2: GetAttachment which queries the currently active skin (Skeleton.skin) to get a matching attachment name in the slot in step 1. In Spine editor, this is the name of the Skin Placeholder, not the name of the attachment.
Step 3: slot.Attachment = attachment

Attachments not inside skin placeholders in Spine Editor are placed in the Skeleton.Data.DefaultSkin.
In the default skin, the attachment name is used as the attachment key.
In actual skins, the skin placeholder name is used.

(3) So your property should actually just be:

public bool SmallArms {
   get { return smallArms; }
   set {
      smallArms = value;
      if (smallArms) {
         skeleton.FindSlot("F_Arm_Large").Attachment = null;
         skeleton.SetAttachment("F_Arm_Small", "F_Arm_Small");
      }
   }
}

Of course, by no means is that necessarily the best, safest or fastest implementation.
But it'll work. You can add checks and reference caching to your class as necessary.

EventSpawn

Hi Pharan,

Yes the property as you described will work. That was one of the solutions I came up with on my own as well :p but as you said it is hardly generic and reusable.

The disconnect for me comes from the fact that when you use the FindAttachmentsForSlot(index, list) method it returns a correct list with names. But when you then use this name to set the attachement it fails, because when dealing with skins you need the parent key name and not the actual attachment name.

This makes it kind of difficult to make a more generic method as (as far as I can see) there is no way to get said parent key from an attachment ...

I have discussed this with the animator and he has just made more skins so that the large and the small arms reside in their own skin. Unless we want a character to go super saiyan at runtime we wont need to swap out the arms anyway 😃
But it was an interesting read of some code. It is always fun to read other peoples code 😃

Pharan

The fact of the matter is simply that FindAttachmentsForSlot is not so you can get a list of names. You get a list of Attachments.
You can use any of those attachments to say:

slot.Attachment = listOfAttachments[0];

and not need to use any string comparisions/operations.
I'm actually not sure why one would need a list of Attachments for a slot. (I didn't design this API. :p)

I think what you want is Skin.FindNamesForSlot : spine-runtimes/Skin.cs at master
Use those returned strings in your GetAttachment call, not the attachment names.