Grid system specification

Coordinate System

• IJ horizontal grid, K-up. Units are metres.
• World (0, 0, 0) is the centre of the hull footprint at K = 0 and translates to Grid (0, 0, 0).
  • The boat footprint is centred in IJ when viewed top-down.
• Grid(I, J, K) maps directly to World(X, Y, Z) = (I, J, K) in metres, with K as height (Z).

Decks

• Overlapping decks vertical clearance: 2.0 m minimum.
• Non-overlapping deck heights: 0.5 m increments.
• Any floor placed at a Z that is a multiple of 0.5 m constitutes a deck. No predefined deck list.
• Minimum vertical spacing between adjacent decks is 2 m.
  • Stairs/Ramps/Lifts can be used in increments of 0.5 m to go from one deck to another.
• Decks can have any grid-aligned shape; when on the edge of the hull, floors fill the gap.
• Multi-deck volumes are allowed (e.g., theatres). Multiple entrances to the same room can be created on separate decks, as long as agents have access to the required items. Agents will pathfind to the right deck when rooms span multiple decks.
• Decks may have non-standard heights to accommodate atriums. The volume belongs to the deck that contains it, not to surrounding decks.

Grid and Placement

• Primary cell size: 0.5 × 0.5 × 0.5 m sub-cells for placement, masking, and validation. Simulation can aggregate to 1 m where needed for performance.
• Placement grid: 0.5 m increments along I and J. Objects may be positioned and rotated (90° increments) on this 0.5 m sub-grid as long as there is sufficient supporting floor beneath their footprint.
  • Floor support rule: every 0.5 m sub-cell sampled by the object’s footprint must be covered by placed floor on the same deck. No over-void placement.
  • Snapping: object origins snap to the 0.5 m lattice; multi-cell objects sample multiple 0.5 m sub-cells.
• Validation uses discrete masks only; no mesh or bounds collision. Masks are defined at 0.5 m resolution for plan view, with K sampled per 0.5 m step vertically.
• Hard no-overlap rule at 0.5 m resolution: walls, doors, floors, and object footprints cannot occupy the same sub-cell or edge segment simultaneously. Placement fails with a clear reason when conflicts are detected.
• Deck bounds still apply. Odd-shaped boundary cells remain non-placeable for cell-aligned items; sub-grid placement must remain entirely within deck floor coverage.
• Cell layering model (per 0.5 × 0.5 m sub-cell, aggregating to 1 × 1 m for display when helpful):
  • Floor: at most one floor tile occupying the sub-cells that make up the cell area.
  • Object: one object footprint may occupy any subset of sub-cells at 0.5 m resolution.
  • Walls: up to four walls, one per edge (N, E, S, W). Wall thickness is split between adjacent cells. Walls reserve their edge segments at 0.5 m vertical increments.
  • Doors: occupy wall edges, reserve swing/clearance as defined by door style.

Walls, Floors, and Doors

• Floor and wall thickness are split between adjacent cells.
• Walls: placed along cell edges in 0.5 m horizontal segments. Standard heights are multiples of 0.5 m; full-height reference is 2.0 m.
• Doors: 1 m wide, 2 m tall.
  • Door style defines reserved footprint if needed for swing behaviour.
  • Swing space is checked at placement time.

Objects and Footprints

• Objects can span multiple cells. Validation is against the object’s footprint mask at the current rotation.
• Small decorations: see Decorations.

Movement Assumptions (for sizing only)

• Agent width: agents are < 0.5 m wide, allowing two agents to pass through a 1 m door.
• Diagonals: diagonal passage is allowed (subject to future playtest).

Vertical Connectors

• Stairs/lifts: placement on Deck N reserves matching landing cells on Deck N+1 (and additional decks if applicable). See Connectors.