3D Rig Animator

JSON format

Right-handed coordinates, Y up, units roughly metres (1.7 = 170 cm tall). Angles in degrees. Time t in seconds.

1. Polygons (vertices / faces)

{
  "name": "hero",
  "vertices": [[x, y, z], ...],
  "faces": [[0, 1, 2], [4, 5, 7, 6], ...],       // triangles or quads; indices counter-clockwise seen from outside
  "uvs": [[u, v], ...],                          // per-vertex UV (optional)
  "faceUvs": [[[u,v],[u,v],[u,v],[u,v]], ...],   // per-face UV (wins over uvs; for cutting regions out of one atlas)
  "color": [r, g, b],                            // 0-1, colour used when there is no texture (optional)
  "faceColors": [[r, g, b], ...],                // per-face colour (optional)
  "repeat": true,                                // repeat the image when UV exceeds 0-1 (floors, walls)
  "doubleSided": false
}

2. Skeleton (bones / weights)

{
  "bones": [
    {"name": "hips",  "parent": null,   "head": [0, 0.95, 0]},
    {"name": "spine", "parent": "hips", "head": [0, 1.10, 0]},
    ...
  ],
  "weights": [                     // in vertex order, up to 4 bones per vertex
    [["thigh_l", 1]],
    [["chest", 0.7], ["spine", 0.3]],
    {"head": 1},                   // object form also accepted
    ...
  ]                                // omit to bind each vertex to the 2 nearest bones automatically
}

3. Motion (tracks)

{
  "duration": 1.2, "loop": true, "ease": "smooth",     // ease is smooth or linear
  "tracks": {
    "thigh_l": [{"t": 0, "rot": [-32, 0, 0]}, {"t": 0.6, "rot": [32, 0, 0]}, {"t": 1.2, "rot": [-32, 0, 0]}],
    "hips":    [{"t": 0, "pos": [0, 0, 0]}, {"t": 0.3, "pos": [0, -0.03, 0]}, ...]   // pos offsets the bone position
  }
}

4. Camera (keys)

{
  "fov": 50, "size": [640, 480],                       // size is the exported video size
  "style": {"resolution": [320, 240], "nearest": true, "vertexSnap": true,
            "background": "#07080c", "fog": ["#07080c", 3, 9]},
  "keys": [
    {"t": 0, "pos": [2.2, 2.6, 3.0], "look": [0, 0.9, 0]},
    {"t": 4, "pos": [-2.6, 1.3, 2.6], "look": "head", "fov": 32}   // look may also name a bone or an actor
  ]
}

Scene (actors / props / camera)

{
  "world": {"background": "#07080c", "ambient": 0.55, "sun": [0.3, 1, 0.4], "fog": ["#07080c", 3.5, 10]},
  "camera": { ...same as 4... },
  "actors": [
    {"name": "hero", "model": {...1...}, "skeleton": {...2...}, "animation": {...3...},
     "texture": "data:image/png;base64,...",          // Data URL to embed; a file name means load the image separately
     "position": [0, 0, 0], "rotation": [0, 180, 0], "scale": 1,
     "path": [{"t": 0, "pos": [0, 0, 2.8], "rotY": 180}, {"t": 5, "pos": [0, 0, -3], "rotY": 180}]}   // movement path
  ],
  "props": [{"name": "floor", "model": {...1...}, "texture": "data:..."}],   // static objects without bones
  "duration": 5
}

• Joints rotate from parent to child (forward kinematics). Each bone's rotation stacks on its parent's, so turning the thigh carries the shin and foot along.
• Vertices are pulled toward the bone with the larger weight (linear blend skinning). Giving vertices across a joint two bones keeps faces from tearing when it bends.
• Bone names that do not match (present in the motion but not the skeleton) are always listed on the right, never silently dropped.