Arena floor

Build a flat arena with an apron, walls with openings and colliders, serve the ground that on-foot and driving kits stand on, and tune it with config and a build hook.

Source: module-kits:kits/world_arena/usage/en.mdView Markdown source

Also read offline — CLI: grip-forge docs world-arenaMCP tool: gripforge_docs { "topic": "world-arena" }

A flat walled play area (world.arena) #

What it is for #

world.arena gives a game a clean flat play area instead of a landscape: a level floor whose top is at height 0, an apron of floor around it, and optional walls with openings (a goal mouth, a gate). Every piece is a static entity with a box collider, so characters and cars stand on the floor and bump into the walls. Use it for a pitch, a ring, a party stage or a training yard. It serves the ground other kits stand on; what happens inside the arena is the business of the other kits.

Turn it on #

gripforge_gamekit_install   { project_id: "gkp_…", id: "world.arena" }
gripforge_gamekit_configure { project_id: "gkp_…", id: "world.arena",
                              config: { "size": [40, 60], "gaps": [{ "side": "north", "width": 8, "height": 3 }] } }

It requires game.engine and physics.port.

First example #

With size [20, 30], apron 2 and one opening on the north wall:

{ "size": [20, 30], "apron": 2, "gaps": [{ "side": "north", "width": 6, "height": 2 }] }

the arena creates one floor entity (tag arena_floor) and six wall pieces (tag arena_wall: the north wall is cut in three, plus the south, east and west walls), and world.arena answers size() with [20, 30].

Settings and defaults #

Setting	Type	Default	Meaning
`size`	`[width, length]`	`[34, 52]`	play area inside the walls in metres (each 4 to 400), centred on the origin; width along x, length along z
`apron`	number 0 to 100	`8`	floor that goes on beyond the walls on every side
`walls`	boolean	`true`	walls around the play area; off gives an open field
`wallHeight`	number 0.2 to 50	`3`	wall height in metres
`wallThickness`	number 0.1 to 10	`1`	wall thickness in metres
`gaps`	list of up to 8	`[]`	openings `{ side, width, height }` centred on a wall
`spawn`	`[x, y, z]`	`[0, 0, 0]`	where the player starts
`spawnYaw`	number	`0`	direction the player faces, in radians (0 faces +z)

side is north (the +z end), south (the -z end), east (the +x side) or west (the -x side). An opening lower than the wall leaves a lintel above it (a goal mouth with its crossbar); an opening as tall as the wall leaves none. An opening wider than the wall removes the wall. All settings are moddable; the kit has no collection.

Services, events #

world.ground (service): flat, height 0 everywhere; its bounds include the apron; also gives the spawn point.
world.arena (service): size() returns [width, length]; inside(p, margin?) says whether a point is inside the walls, margin metres in; walls(), gaps() and apron() return the wall pieces, the openings and the apron width.
world.ready (event): once at mount, after the floor and walls exist, with the size built.

Hooks and modding #

The hook arena.build is asked once per mount, right before the floor and walls are created, with { width, length, walls, wallHeight }. Every field is mutable; it is not cancellable, since a game always has its floor. world.ground, world.arena and world.ready answer for what was built.

{ "id": "open_field", "hook": "arena.build", "set": { "walls": false } }

A mod can override every setting, for example a bigger pitch for a final. Model slots arena_floor and arena_wall dress the pieces; when unbound they show as plain boxes.

Engines #

The floor and walls are one shared implementation for the web and native players; each engine draws the entities with its own renderer.

When it does not do what you expect #

The play area is not the size set: an arena.build tap changed width or length.
Things pass through a wall: a gaps entry opens it; what lies behind it belongs to another kit.
Walls are plain boxes: bind models to the arena_floor and arena_wall slots.

Limits #

Flat only (height 0), one rectangular area centred on the origin, up to 8 openings.

Versions #

Kit world.arena 1.1.0 (the arena.build hook since 1.1.0), requires game.engine@^1 and physics.port@^1.