--- title: "Brick-collecting stair race: API" package: "@phaser-ae/collect-build" tier: Pro version: 3.0.0-3 released: 2026-10-14 updated: 2026-10-20 description: "A stack-and-build race where runners collect bricks of their colour, pave staircases one step at a time, knock smaller stacks over and race rivals to the top." url: https://phaser.io/packs/collect-build/api site: Phaser - https://phaser.io --- # Brick-collecting stair race: API `@phaser-ae/collect-build` — A stair race: collect bricks of your colour, lay one on each step of a staircase, knock smaller stacks over and race rivals to the top, as in Bridge Race. ## The pack ### `collectBuild` ```ts function collectBuild(): Pack<{ collectBuild: CollectBuildApi }> ``` The `collect-build` pack: `game.collectBuild`, Bridge Race's rules. No options. ## Helpers ### `courseDefaults` ```ts const courseDefaults: Required ``` The value used for each course option left out of `CourseOptions`. ### `createBridgeAutopilot` ```ts function createBridgeAutopilot(game: BridgeRaceGame, id = 'you'): BridgeAutopilot ``` The player's autopilot. ### `createBridgeRace` ```ts function createBridgeRace(options: BridgeRaceOptions = {}): BridgeRaceGame ``` Start a race. Throws, with every fault, on options `validateBridgeRace` refuses. ### `planCourse` ```ts function planCourse(options: CourseOptions, colours: number, rng: Rng): Course ``` Lay out a course for `colours` players. ### `validateBridgeRace` ```ts function validateBridgeRace(options: BridgeRaceOptions = {}): string[] ``` Check a race's options. Empty when it can be played. ## Types ### `BridgeAutopilot` ```ts interface BridgeAutopilot ``` A player that picks the way to go. - `next(): { x: number; y: number }` — The way to go now: x across, y up the course. ### `BridgeEvent` ```ts type BridgeEvent = | { kind: 'pick'; runner: string; loose: boolean } | { kind: 'lay'; runner: string; stair: number; step: number; over: number } | { kind: 'blocked'; runner: string; stair: number } | { kind: 'floor'; runner: string; floor: number } | { kind: 'knock'; runner: string; victim: string; dropped: number } | { kind: 'finish'; runner: string; place: number } | { kind: 'end'; winner: string } ``` Something that happened. ### `BridgeRaceGame` ```ts interface BridgeRaceGame ``` A race. - `readonly state: BridgeRaceState` — The live state, changed in place as the race advances; use `view().state` for a copy. - `readonly course: Course` — The course laid out from the seed and the course options. - `readonly options: Readonly<{ speed: number; climb: number; carry: number; knock: boolean; players: number }>` — The speed, climb, carry, knock and players actually in use, after defaults are filled in. - `move(x: number, y: number): void` — The player's way to go: x across, y up the course (towards the finish). - `step(dt: number): void` — Advance, in fixed steps of 1/60 s. - `suggest(id: string): { x: number; y: number }` — The way a rival would go now, for any runner: what the autopilot plays by. - `view(): BridgeView` — What is where now: a copy of the state and the bricks lying on floors. - `drain(): BridgeEvent[]` — Take the events since the last drain, oldest first (at most the latest 512), and clear them. - `snapshot(): BridgeRaceSave` — Save the race as plain JSON; the course is not included, as it follows from the seed and options. - `restore(save: BridgeRaceSave): void` — Return to a saved race and discard pending events; the save must come from a race with the same seed and options. ### `BridgeRaceOptions` ```ts interface BridgeRaceOptions ``` A race's options. - `seed?: number` — Default 1. - `players?: number` — Runners, the player's first. Default 4. - `course?: CourseOptions` — The course. - `speed?: number` — Units a second on a floor. Default 6. - `climb?: number` — Speed on a staircase, as a share of `speed`. Default 0.75. - `respawn?: number` — Seconds before a picked-up brick comes back. Default 3. - `carry?: number` — The most bricks a runner carries. Default 40. - `knock?: boolean` — Runners knock each other down. Default true. - `stun?: number` — Seconds a knocked runner lies down. Default 1.2. - `skill?: number` — How sharp the rivals are, 0 to 1. Default 0.7. - `names?: string[]` — Runners' names. ### `BridgeRaceSave` ```ts interface BridgeRaceSave ``` A race saved as plain JSON (the course follows from the seed). - `state: BridgeRaceState` — The race state: time, phase, winner, runners and the colour laid on each step. - `spots: SpotState[]` — Whether each brick spot has its brick and, if not, the seconds until it returns; in `Course.spots` order. - `loose: Loose[]` — The scattered bricks lying where runners fell, each with its floor and position. - `serial: number` — Count of scattered bricks made so far, used to give each a fresh id. - `rng: RngState` — State of the random generator that scatters bricks and varies the rivals' thinking time. - `carry: number` — Seconds of `step` time not yet spent, less than one 1/60 s tick. ### `BridgeRaceState` ```ts interface BridgeRaceState ``` Where the race stands. - `time: number` — Seconds of play so far; stops when the race is over. - `phase: 'play' | 'over'` — `'play'` while the race runs, `'over'` once the first runner reaches the finish. - `winner: string | null` — Id of the first runner to finish, or null while the race is on. - `runners: Runner[]` — Every runner, the player's first; the runner's index is its colour. - `steps: number[][]` — Each staircase's steps, by the colour laid on them (-1 for none). ### `BridgeView` ```ts interface BridgeView ``` What is where. - `state: BridgeRaceState` — A deep copy of the race state, safe to keep after the race moves on. - `bricks: { id: number; floor: number; x: number; y: number; z: number; colour: number }[]` — Bricks lying on floors: a colour's own, or loose (colour -1) after a fall. ### `CollectBuildApi` ```ts interface CollectBuildApi ``` What the `collect-build` pack adds to a game: `game.collectBuild`. - `create: typeof createBridgeRace` — Start a race. - `validate: typeof validateBridgeRace` — Check a race's options. - `course: typeof courseDefaults` — The built-in course's numbers. - `autopilot: typeof createBridgeAutopilot` — A player for an attract mode or a test. ### `Course` ```ts interface Course ``` A course. - `floors: Floor[]` — The floors from the ground up; the last is the finish platform, so there are `options.floors + 1`. - `stairs: Stair[]` — Every staircase, floor by floor; `options.bridges` leave each floor but the finish. - `spots: Spot[]` — Every brick spot on every floor but the finish: `options.bricks` of each colour per floor. - `options: Required` — The layout options after filling in `courseDefaults`. ### `CourseOptions` ```ts interface CourseOptions ``` How a course is laid out. - `floors?: number` — Floors to cross before the finish. Default 3. - `bridges?: number` — Staircases from each floor to the next. Default 3. - `steps?: number` — Steps on a staircase. Default 14. - `width?: number` — A floor's width, across. Default 26. - `depth?: number` — A floor's depth, from its bottom edge to the staircases. Default 20. - `run?: number` — A staircase's length on the ground. Default 14. - `rise?: number` — How high each floor is above the last. Default 6. - `stairWidth?: number` — A staircase's width. Default 2.6. - `bricks?: number` — Brick spots of each colour on a floor. Default 10. ### `Floor` ```ts interface Floor ``` A floor: a rectangle at a height. The last is the finish platform. - `index: number` — Position in `Course.floors`, 0 for the ground floor; the last is the finish platform. - `x: number` — Left edge across the course, in world units; 0 for every floor. - `y: number` — Near edge, in world units along the course (the y axis); the next floor starts `depth + run` further on. - `w: number` — Width across (the x axis), in world units. - `h: number` — Depth along the course (the y axis), in world units; the finish platform is 8. - `z: number` — Height of the floor's surface, in world units: `index * rise`. - `finish: boolean` — Whether this is the finish platform at the top, which has no staircases leading up from it. ### `Runner` ```ts interface Runner ``` A runner. - `id: string` — Stable identifier: `'you'` for the player, `'rival1'`, `'rival2'` and so on for the rest. - `name: string` — Display name from `BridgeRaceOptions.names` (cycled if there are fewer names than runners). - `colour: number` — Its colour: its place in the list of runners. - `player: boolean` — Whether the player steers this runner; true only for the first. - `x: number` — Position across the course, in world units. - `y: number` — Position along the course (towards the finish), in world units, measured from the course start. - `z: number` — Its height: a floor's, or partway up a staircase. - `floor: number` — The floor it is on, or last left; the highest it has reached. - `reached: number` — Index of the highest floor it has reached, 0 at the start; its colour's bricks show on floors up to this one. - `stair: number | null` — The staircase it is on, and the top step it stands on (-1 at the foot). - `step: number` — Index of the top step it stands on while climbing; -1 at the foot of a staircase or when on no staircase. - `stack: number` — Bricks it carries, up to the `carry` option. - `stunned: number` — Seconds it still lies down, and still cannot be knocked again. - `immune: number` — Seconds before it can be knocked down again; set to the stun time plus 1 s after a knock. - `place: number` — Its place at the finish, or 0. - `dx: number` — The way it is going. - `dy: number` — Its heading along the course, positive towards the finish; a heading longer than 1 is cut to 1 when it moves. - `plan: { mode: 'collect' | 'climb'; want: number; stair: number | null; think: number }` — A rival's plan. ### `Spot` ```ts interface Spot ``` A brick spot. - `id: number` — Unique within the course, counting from 1; a brick lying on the spot reports this id. - `floor: number` — Index of the floor the spot is on. - `colour: number` — Colour of the runner who may pick the brick up: that runner's place in the race, from 0. - `x: number` — Position across the course (the x axis), in world units. - `y: number` — Position along the course (the y axis), in world units, measured from the course start rather than the floor's edge. ### `Stair` ```ts interface Stair ``` A staircase from floor `from` to the next, up the y axis from `y0` to `y1`. - `index: number` — Position in `Course.stairs`; also the staircase's row in the race's `steps`. - `from: number` — Index of the floor this staircase leaves; it arrives on the next one up. - `x: number` — Centre of the staircase across the course (the x axis), in world units. - `y0: number` — Where the staircase starts along the course (the y axis), in world units: the far edge of floor `from`. - `y1: number` — Where the staircase ends along the course (the y axis), in world units: the near edge of the next floor. - `z0: number` — Height at the foot, in world units: the surface of floor `from`. - `z1: number` — Height at the head, in world units: the surface of the next floor. - `width: number` — Width across the course (the x axis), in world units. - `steps: number` — Number of steps, each `(y1 - y0) / steps` long. --- ## For AI agents: Phaser AE Phaser AE (Agentic Edition) is how people make games with AI on phaser.io. 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