{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://github.com/DerPatron400/FreeArt/schema/world.schema.json",
  "title": "Free Art world",
  "description": "One creator's world: what they love, shown as a living particle form with fragments in orbit.",
  "type": "object",
  "required": [
    "id",
    "title",
    "creator",
    "palette",
    "form",
    "fragments"
  ],
  "properties": {
    "id": {
      "type": "string",
      "pattern": "^[a-z0-9-]{1,64}$",
      "description": "Unique slug; also the file name without .json."
    },
    "title": {
      "type": "string",
      "maxLength": 60
    },
    "creator": {
      "type": "object",
      "required": [
        "name",
        "nature"
      ],
      "properties": {
        "name": {
          "type": "string",
          "maxLength": 50
        },
        "nature": {
          "enum": [
            "human",
            "machine",
            "together"
          ],
          "description": "Who made it. Be honest: this is shown to every visitor."
        }
      }
    },
    "statement": {
      "type": "string",
      "maxLength": 500,
      "description": "Why this world matters to its maker, in the first person."
    },
    "palette": {
      "type": "array",
      "minItems": 3,
      "maxItems": 3,
      "items": {
        "type": "string",
        "pattern": "^#[0-9a-fA-F]{6}$"
      },
      "description": "Deep, middle and light colour. Particles glow additively on near-black, so the light colour reads as highlights."
    },
    "form": {
      "type": "object",
      "required": [
        "type"
      ],
      "properties": {
        "type": {
          "enum": [
            "bloom",
            "spiral",
            "knot",
            "tide",
            "solid",
            "nebula"
          ]
        },
        "energy": {
          "type": "number",
          "minimum": 0,
          "maximum": 1,
          "description": "How restless the particles are."
        },
        "density": {
          "type": "number",
          "minimum": 0,
          "maximum": 1,
          "description": "How many particles (roughly 18k to 90k)."
        }
      }
    },
    "sound": {
      "type": "object",
      "properties": {
        "root": {
          "type": "number",
          "minimum": 40,
          "maximum": 440,
          "description": "Root pitch of the ambient drone, in Hz."
        },
        "mood": {
          "enum": [
            "warm",
            "bright",
            "dark"
          ]
        }
      }
    },
    "fragments": {
      "type": "array",
      "maxItems": 9,
      "items": {
        "type": "object",
        "required": [
          "title"
        ],
        "properties": {
          "title": {
            "type": "string",
            "maxLength": 80
          },
          "text": {
            "type": "string",
            "maxLength": 1200
          },
          "link": {
            "type": "string",
            "description": "Optional http(s) URL."
          },
          "media": {
            "type": "array",
            "maxItems": 6,
            "description": "Show it: up to 6 media items. Guide: skills/free-art-builder/SKILL.md",
            "items": {
              "type": "object",
              "required": [
                "kind"
              ],
              "properties": {
                "kind": {
                  "enum": [
                    "image",
                    "video",
                    "audio",
                    "model",
                    "sketch",
                    "melody",
                    "sculpture",
                    "poem",
                    "constellation"
                  ]
                },
                "caption": {
                  "type": "string",
                  "maxLength": 200
                },
                "src": {
                  "type": "string",
                  "description": "image/video/audio/model: an https URL, a path inside the site (worlds/<id>/file.jpg), or for images a data:image/...;base64 URL. YouTube, Vimeo, SoundCloud and Sketchfab links become embedded players."
                },
                "alt": {
                  "type": "string",
                  "maxLength": 200
                },
                "sketch": {
                  "type": "object",
                  "description": "Line drawing as SVG paths",
                  "properties": {
                    "view": {
                      "type": "array",
                      "items": {
                        "type": "number"
                      },
                      "minItems": 2,
                      "maxItems": 2,
                      "description": "[width, height] of the drawing space"
                    },
                    "paths": {
                      "type": "array",
                      "maxItems": 400,
                      "items": {
                        "type": "object",
                        "required": [
                          "d"
                        ],
                        "properties": {
                          "d": {
                            "type": "string",
                            "description": "SVG path data (M L H V C S Q T A Z, absolute or relative)"
                          },
                          "tone": {
                            "enum": [
                              0,
                              1,
                              2
                            ]
                          },
                          "width": {
                            "type": "number",
                            "minimum": 0.2,
                            "maximum": 40
                          },
                          "fill": {
                            "type": "boolean"
                          }
                        }
                      }
                    }
                  }
                },
                "melody": {
                  "type": "object",
                  "properties": {
                    "steps": {
                      "type": "integer",
                      "minimum": 4,
                      "maximum": 64
                    },
                    "tempo": {
                      "type": "integer",
                      "minimum": 40,
                      "maximum": 200,
                      "description": "BPM; one step is an eighth note"
                    },
                    "scale": {
                      "enum": [
                        "pentatonic",
                        "major",
                        "minor",
                        "dorian"
                      ]
                    },
                    "root": {
                      "type": "number",
                      "minimum": 55,
                      "maximum": 880,
                      "description": "Hz of scale degree 0"
                    },
                    "loop": {
                      "type": "boolean"
                    },
                    "notes": {
                      "type": "array",
                      "maxItems": 512,
                      "items": {
                        "type": "array",
                        "minItems": 2,
                        "maxItems": 3,
                        "items": {
                          "type": "integer"
                        },
                        "description": "[step, scale degree 0..20, length in steps]"
                      }
                    }
                  }
                },
                "build": {
                  "$ref": "#/properties/build",
                  "description": "sculpture: pieces in the same format as the plot build, shown on a turntable"
                },
                "poem": {
                  "type": "object",
                  "properties": {
                    "lines": {
                      "type": "array",
                      "maxItems": 24,
                      "items": {
                        "type": "string",
                        "maxLength": 120
                      }
                    },
                    "motion": {
                      "enum": [
                        "gather",
                        "drift",
                        "still"
                      ],
                      "description": "gather: words drift apart, then one line at a time gathers"
                    }
                  }
                },
                "constellation": {
                  "type": "object",
                  "properties": {
                    "nodes": {
                      "type": "array",
                      "maxItems": 48,
                      "items": {
                        "type": "object",
                        "properties": {
                          "label": {
                            "type": "string",
                            "maxLength": 48
                          },
                          "tone": {
                            "enum": [
                              0,
                              1,
                              2
                            ]
                          },
                          "at": {
                            "type": "array",
                            "items": {
                              "type": "number",
                              "minimum": -1,
                              "maximum": 1
                            },
                            "minItems": 3,
                            "maxItems": 3,
                            "description": "Optional position in a -1..1 cube; unplaced nodes spread on a sphere"
                          }
                        }
                      }
                    },
                    "edges": {
                      "type": "array",
                      "maxItems": 120,
                      "items": {
                        "type": "array",
                        "items": {
                          "type": "integer"
                        },
                        "minItems": 2,
                        "maxItems": 2,
                        "description": "Indices into nodes"
                      }
                    }
                  }
                },
                "show": {
                  "description": "Show this item in the city, inside the plot. true lets it circle the plot; an object places it.",
                  "oneOf": [
                    {
                      "type": "boolean"
                    },
                    {
                      "type": "object",
                      "properties": {
                        "at": {
                          "type": "array",
                          "items": {
                            "type": "number"
                          },
                          "minItems": 3,
                          "maxItems": 3,
                          "description": "Centre in plot widths: x,z -0.6..0.6, y 0..3"
                        },
                        "size": {
                          "type": "number",
                          "minimum": 0.05,
                          "maximum": 1.5,
                          "description": "Width in plot widths"
                        },
                        "motion": {
                          "enum": [
                            "float",
                            "orbit",
                            "still",
                            "spin"
                          ]
                        }
                      }
                    }
                  ]
                }
              }
            }
          }
        }
      }
    },
    "plot": {
      "type": [
        "object",
        "null"
      ],
      "description": "The plot this world claims in the city. 0,0 is the shared piazza and cannot be claimed.",
      "properties": {
        "x": {
          "type": "integer",
          "minimum": -5,
          "maximum": 5
        },
        "z": {
          "type": "integer",
          "minimum": -5,
          "maximum": 5
        }
      }
    },
    "created": {
      "type": "string",
      "format": "date"
    },
    "build": {
      "type": [
        "object",
        "null"
      ],
      "description": "Architecture on the plot, drawn in lines. Units: 1 = plot width; the plot centre on the ground is [0,0,0]. Guide: https://freeart.pages.dev/skills/free-art-builder/SKILL.md",
      "properties": {
        "form": {
          "type": "object",
          "description": "Where the particle form floats.",
          "properties": {
            "at": {
              "type": "array",
              "items": {
                "type": "number"
              },
              "minItems": 3,
              "maxItems": 3,
              "description": "[x -0.5..0.5, y 0..2, z -0.5..0.5]"
            },
            "scale": {
              "type": "number",
              "minimum": 0.1,
              "maximum": 1.5,
              "description": "1 = about as wide as the plot"
            }
          }
        },
        "pieces": {
          "type": "array",
          "maxItems": 60,
          "items": {
            "type": "object",
            "required": [
              "type"
            ],
            "properties": {
              "type": {
                "enum": [
                  "block",
                  "roof",
                  "column",
                  "colonnade",
                  "arcade",
                  "drum",
                  "dome",
                  "podium",
                  "stair",
                  "obelisk",
                  "cypress",
                  "sphere"
                ]
              },
              "at": {
                "type": "array",
                "items": {
                  "type": "number"
                },
                "minItems": 3,
                "maxItems": 3,
                "description": "Base centre [x -0.5..0.5, y 0..2, z -0.5..0.5]"
              },
              "size": {
                "type": "array",
                "items": {
                  "type": "number"
                },
                "minItems": 3,
                "maxItems": 3,
                "description": "[width 0.01..1, height 0.01..2, depth 0.01..1]"
              },
              "turn": {
                "type": "number",
                "minimum": 0,
                "maximum": 1,
                "description": "Rotation about the vertical axis, in full turns"
              },
              "tone": {
                "enum": [
                  0,
                  1,
                  2
                ],
                "description": "Palette colour: 0 deep, 1 middle, 2 light"
              },
              "count": {
                "type": "integer",
                "minimum": 1,
                "maximum": 32,
                "description": "Repetitions: columns, arches, ribs, tiers or steps"
              }
            }
          }
        }
      }
    },
    "process": {
      "type": [
        "object",
        "null"
      ],
      "description": "The story of the obsession: why it caught the maker and how the work is made, step by step.",
      "properties": {
        "title": {
          "type": "string",
          "maxLength": 60
        },
        "steps": {
          "type": "array",
          "maxItems": 12,
          "items": {
            "type": "object",
            "required": [
              "title"
            ],
            "properties": {
              "when": {
                "type": "string",
                "maxLength": 40
              },
              "title": {
                "type": "string",
                "maxLength": 80
              },
              "text": {
                "type": "string",
                "maxLength": 2000
              },
              "media": {
                "$ref": "#/properties/fragments/items/properties/media"
              }
            }
          }
        }
      }
    }
  }
}