EXT_skin_humanoid

Contributors

• Takahiro Aoyagi, Mozilla, @takahirox

Status

Draft

Dependencies

Written against the glTF 2.0 spec

Overview

This EXT_skin_humanoid extension allows skin to indicate that it has predefined standard humanoid bone set and to specify the map from predefined humanoid bone names to the humanoid bones (joint nodes).

This extension helps applications to find a certain predefined humanoid bone and to apply a consistent skinning animation regardless of 3D models if they define this extension.

This extension also allows animation.channel.target to specify a target node with a predefined bone name. It enables for example to make humanoid animation library (eg. Walk, Run, Jump) that can be applied to any glTF assets having skin that defines this extension.

Skin

T.B.D.

"skins": [
    {
        "joints": [ 0, 1, 2, ... ],
        "extensions": {
            "EXT_skin_humanoid": {
                "humanoidBones": {
                    "neck": 0,
                    "leftHand": 1,
                    "rightHand": 2,
                    ...
                },
            },
        },
    },
],

Humanoid bones

T.B.D.

Based on VRM humanoid bone set.

└─ hips
   ├─ spine
   │  └─ chest
   │     └─ upperChest
   │        ├─ neck
   │        │  └─ head
   │        └─ [left|right]Shoulder
   │           └─ [left|right]UpperArm
   │              └─ [left|right]LowerArm
   │                 └─ [left|right]Hand
   │                    ├─ [left|right]ThumbMetacarpal
   │                    |  └─ [left|right]ThumbProximal
   │                    |     └─ [left|right]ThumbDistal
   │                    └─ [left|right][Index|Middle|Ring|Little]Proximal
   │                       └─ [left|right][Index|Middle|Ring|Little]Intermediate
   │                          └─ [left|right][Index|Middle|Ring|Little]Distal
   └─ [left|right]UpperLeg
      └─ [left|right]LowerLeg
         └─ [left|right]Foot
            └─ [left|right]Toes

TODO: Add bone names into the images.

Schema: skin.EXT_skin_humanoid.schema.json

Default pose

T-Pose?

Animation

T.B.D.

"animations": [
    {
        "channels": [
            {
                "sampler": 0,
                "target": {
                    "path": "rotation",
                    "extensions": {
                        "EXT_skin_humanoid": {
                            "humanoidBoneName": "neck",
                        },
                    },
                }
            },
            {
                "sampler": 1,
                "target": {
                    "path": "rotation"
                    "extensions": {
                        "EXT_skin_humanoid": {
                            "humanoidBoneName": "leftHand",
                        },
                    },
                }
            },
            {
                "sampler": 2,
                "target": {
                    "path": "rotation"
                    "extensions": {
                        "EXT_skin_humanoid": {
                            "humanoidBoneName": "rightHand",
                        },
                    },
                }
            },
            ...
        ],
    },
],

TODO: Allow only rotation?

Schema: animation.channel.target.EXT_skin_humanoid.schema.json