Multiple Materials Management

RRemDust · 4 giu 2023

Hello guys !

I've been thinking about how to manage multiple materials for the same spine character in Unity.
The easiest way is to export my Atlas by Folders and not Attachments as in Spine Editor I'm using a sub-folder structure to keep images/attachments organised but...

It result in a big number of Textures and Materials (about 15).

While it's very easy to manage (I can set any material/shader to any "folder" (specific for body, weapons etc) it seems very unoptimised (I have different folders for arms, legs etc when they should be exported as a "body" atlas and have one shared material )

I learnt recently about "GetRepackedAttachments" but I'm not sure how to use it on so many folders or if there is a better way of doing this ?

I suppose that FX and Materials management on a character is pretty commun so please tell me if there is a common way of dealing with it, as I haven't found any real documentation about it.

Thanks a lot !

Harald · 5 giu 2023

RemDust I learnt recently about "GetRepackedAttachments" but I'm not sure how to use it on so many folders or if there is a better way of doing this ?

Could you please explain what you mean by "you're not sure how to use GetRepackedAttachments on many folders"? In general GetRepackedAttachments is called on a list of Attachments, no matter what atlas page texture they are coming from. Folders where these attachmentr originally came from are not relevant here in any way.

In general, GetRepackedAttachments like GetRepackedSkin serves to pack those given attachments to a single new atlas page texture.

RemDust While it's very easy to manage (I can set any material/shader to any "folder" (specific for body, weapons etc) it seems very unoptimised (I have different folders for arms, legs etc when they should be exported as a "body" atlas and have one shared material )

I'm not aware of your typical skeleton setup, whether you can mix any type of arm with any type of leg. Nevertheless, attachments should ideally be grouped according to which will likely be used

1) in combination and
2) in succession in regards to draw order.

So it does not sound too efficient to have one atlas page for arms, one for legs, one for chests, one for heads, and so on, if you end up always requiring all 15 of the atlas page textures in the end for a complete skeleton. You might instead want to group by typical combination, like having the base skin-underlayer ("real" skin) on one atlas page, low-tier armor on another atlas page (leather armor), separate from high-tier armor in another (obsidian armor) atlas page. Then you might additionally also think about grouping by draw order, which groups skin and underwear together, and groups "outer" items like gloves, helmets and weapons together as well.

If your game allows any combination of arm / leg / head / helmet from all your current atlas pages (folders), then you might want to give repacking a go to combine them to a single atlas page.

RRemDust · 11 giu 2023

Thanks for the reply Harald,
It makes sense.

The reason why I have many subfolders is that I have a lot of attachments variants and I prefer to keep them in separate folders in Spine editor.
And the reason why I export in Unity by folder is that I can then apply shaders and FX on specific skeleton parts.

So if I want to use GetRepackedAttachments correctly to create a single Texture2D "Body" with its new associated material I should get all the attachments contained in the different Texture2D body parts ? I'm not too sure about how to do that... Something like the follow code (but with the different Texture2D i need to pack) ?

List<Attachment> attachments = new List<Attachment>();
foreach (AtlasRegion region in atlas.Regions)
{
    if (region.page.rendererObject == textureToPack)
    {
        Attachment attachment = region.GetAttachment();
        if (attachment != null)
        {
            attachments.Add(attachment);
        }
    }
}

If this is correct, I suppose I would just have to assign the newly created texture to a new material then ?

Harald · 12 giu 2023

RemDust And the reason why I export in Unity by folder is that I can then apply shaders and FX on specific skeleton parts.

If you only need to override materials and shader on a few parts, it might make more sense to use
CustomMaterialOverride or CustomSlotMaterials as described here. Artificially arranging parts to atlases to have a single atlas per body part seems like a rather costly workaround.

So if I want to use GetRepackedAttachments correctly to create a single Texture2D "Body" with its new associated material I should get all the attachments contained in the different Texture2D body parts ?

The code that you have posted does not make a lot of sense to me. Here you seem to repack attachments of an atlas if they are on a single texture already. Even without the
if (region.page.rendererObject == textureToPack)
check (if you intended to say "is one of a set of textures to repack") it would make things more complicated to iterate over the atlas attachments. Instead you would likely want to iterate over the attachments equipped at your skeleton (what you are actually using), and then repack those. Unless I misunderstood what you wanted to achieve with your code above, maybe you could share your thoughts on what you had in mind.