🧊MML

Support for the Metaversal Markup Language

We support interactive interoperable objects created using Metaversal Markup Language (MML). For more information on MML see mml.io.

Compatibility

Each element's compatibility with the rendering engines used by different components of the M² Platform (Unreal and Web) are listed on mml.io. For example: here's the compatibility table for the <m-model> element.

In cases where an mml element contains a media format, <m-video> for instance, we only support formats that are supported by the underlying rendering engine.

MML Avatars

We use MML for Avatar Models. These can come from NFTs, from an in-game editor, or be hand-written and uploaded by a user.

Avatar Format

For an MML file to be a valid avatar it must have a single top-level <m-character> element specifying the source mesh file. It can also optionally contain <m-model> child elements, which you can use to build avatars out of multiple meshes. The skeletons on these meshes must all match the UE5 skeleton. You can also add static meshes as attachments by using the socket attribute.

See here for full details and examples: https://mml.io/docs/reference/elements/m-character

As an example, a single mesh avatar MML is as simple as this:

<m-character src="https://public.mml.io/character-body.glb"></m-character>

Whereas an avatar with multiple meshes and an attachment might look like this:

<m-character src="https://public.mml.io/character-body.glb"
  <m-model src="https://public.mml.io/character-head.glb"></m-model>
  <m-model src="https://public.mml.io/duck.glb" socket="hand_r" rx="180" ry="10" rz="-90" x="-0.15" y="-0.047" z="0.04" sx="0.1" sy="0.1" sz="0.1"></m-model>
</m-character>

To easily make your own compatible GLB mesh files that you can use as part of a valid Avatar MML file, see Creating MML Avatars with Blender and Free Rigging Tools.

Animations don't need to be specified for MML avatars, and will be ignored in the game client. The avatar will be animated using the standard animations for the project (hence the need for meshes to use the correct skeleton).

Using MML Avatars in game

No additional setup is needed to enable MML avatars in the game client. Project blueprints can call JM_ModularCharacterComponent::LoadInteropCharacterFromUrl with the URL of an MML avatar and it will attempt to load it for your player character, and replicate it so it's visible to other players. See WBP_SettingAvatarExample for an example of enabling users to paste an avatar URL into the settings menu.

Players can also have default a MML avatar stored on their profile. By default these won't be loaded in, but if you enable the Character.UseCharacterFromProfile live config flag for your project then any player entering the world will automatically load their custom MML avatar from their profile.

Other MML objects

We also support users dropping custom MML objects directly into worlds. One way of doing this is by using Place mode in the Inventory and Quickbar system. If you're using the default WBP_ItemManagement UI as part of your HUD then you can enable this by ensuring a few live configs are set:

Inventory.HidePlaceMode: false,
Inventory.MaxPlacementSlots: [number greater than 0],
UserCollection.EnabledOnServers: true

The Place tab in the inventory will then show all MML collection items, and you can then use the quickbar to place them into the map.