{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "title": "3D asset",
  "description": "One line of metadata.jsonl: one asset, stored in the folder named by its id.",
  "type": "object",
  "additionalProperties": false,
  "required": [
    "id",
    "file_name",
    "title",
    "category",
    "file",
    "format",
    "size_bytes",
    "sha256",
    "triangles",
    "author",
    "source_url",
    "licence",
    "modified"
  ],
  "dependentRequired": {
    "length_m": [
      "size_source"
    ],
    "width_m": [
      "size_source"
    ],
    "height_m": [
      "size_source"
    ]
  },
  "properties": {
    "id": {
      "type": "string",
      "pattern": "^[a-z0-9_]+$",
      "description": "Folder name; unique."
    },
    "file_name": {
      "type": "string",
      "pattern": "^[a-z0-9_]+/preview\\.png$",
      "description": "Preview image: <id>/preview.png. The Hub shows it beside the row."
    },
    "title": {
      "type": "string",
      "minLength": 1,
      "description": "The author's title."
    },
    "category": {
      "type": "string",
      "minLength": 1,
      "description": "What the object is, lower case: 'general cargo ship', 'lateral mark'."
    },
    "tags": {
      "type": "array",
      "items": {
        "type": "string",
        "pattern": "^[a-z0-9-]+$"
      },
      "uniqueItems": true,
      "description": "Free filters: 'containers', 'photogrammetry', 'low-poly'."
    },
    "description": {
      "type": "string"
    },
    "length_m": {
      "type": "number",
      "exclusiveMinimum": 0,
      "description": "Real overall length, metres."
    },
    "width_m": {
      "type": "number",
      "exclusiveMinimum": 0,
      "description": "Real overall width (beam), metres."
    },
    "height_m": {
      "type": "number",
      "exclusiveMinimum": 0,
      "description": "Real overall height, lowest to highest point (keel to top for a vessel), metres."
    },
    "size_source": {
      "type": "string",
      "minLength": 1,
      "description": "How the real size is known: a reference object, a standard part measured in the mesh, or native units."
    },
    "file": {
      "type": "string",
      "pattern": "^[a-z0-9_]+/[^/]+$",
      "description": "Path of the main file in the repo: <id>/<name>."
    },
    "format": {
      "enum": [
        "glb",
        "gltf",
        "fbx",
        "obj",
        "usdz"
      ]
    },
    "front_axis": {
      "enum": [
        "+z",
        "-z",
        "+x",
        "-x"
      ],
      "default": "+z",
      "description": "Axis of the file the object's front (a vessel's bow) points along. glTF's convention is +z; set it only when the file departs from it."
    },
    "size_bytes": {
      "type": "integer",
      "exclusiveMinimum": 0
    },
    "sha256": {
      "type": "string",
      "pattern": "^[0-9a-f]{64}$"
    },
    "triangles": {
      "type": "integer",
      "exclusiveMinimum": 0
    },
    "textures": {
      "type": "integer",
      "minimum": 0,
      "description": "Number of images."
    },
    "texture_max_px": {
      "type": "integer",
      "exclusiveMinimum": 0,
      "description": "Longest side of the largest image."
    },
    "author": {
      "type": "string",
      "minLength": 1
    },
    "source_url": {
      "type": "string",
      "pattern": "^https://",
      "description": "Page the asset was taken from."
    },
    "licence": {
      "enum": [
        "CC0-1.0",
        "CC-BY-3.0",
        "CC-BY-4.0"
      ],
      "description": "SPDX identifier."
    },
    "modified": {
      "type": "boolean",
      "description": "True if the file differs from what the source offers."
    },
    "added": {
      "type": "string",
      "format": "date"
    }
  }
}