| 1 | import { STACKS_PER_SIDE, WALL_SIZE, WALL_STACKS } from './tiles'; |
| 2 | import type { SeatId } from './types'; |
| 3 | |
| 4 | /** |
| 5 | * What the wall square looks like right now. |
| 6 | * |
| 7 | * The square is eaten from both ends at once — normal draws come off the front, |
| 8 | * kong and flower replacements off the back — so how much of it is left is not |
| 9 | * one number but a per-stack question, and two things want the answer: the |
| 10 | * drawing of it (ui/WallRing) and the physics (table/geometry), since a stack |
| 11 | * still standing is something a thrown tile has to get past. |
| 12 | * |
| 13 | * Deliberately typed against the fields it reads rather than `GameState`, so it |
| 14 | * stays a function of the wall and nothing else. |
| 15 | */ |
| 16 | export interface WallProgress { |
| 17 | drawnFront: number; |
| 18 | drawnBack: number; |
| 19 | rules: { wallReserve: number }; |
| 20 | /** Who threw the dice, and what they came up. See `breakAt`. */ |
| 21 | dealer: SeatId; |
| 22 | dice: number[]; |
| 23 | } |
| 24 | |
| 25 | export interface Stack { |
| 26 | /** Tiles still in this stack: 2 full, 1 half, 0 spent. */ |
| 27 | count: 0 | 1 | 2; |
| 28 | /** Part of the 16-tile 底牌 tail that ends the hand. */ |
| 29 | dead: boolean; |
| 30 | /** The break point — the stack the next draw comes off. */ |
| 31 | next: boolean; |
| 32 | } |
| 33 | |
| 34 | /** |
| 35 | * Position 0 is the break point. Stack `i` holds positions `2i` and `2i+1`, and |
| 36 | * a position is still there if it is past the front and short of the back. |
| 37 | */ |
| 38 | export function wallStacks(s: WallProgress): Stack[] { |
| 39 | const front = s.drawnFront; |
| 40 | const back = WALL_SIZE - s.drawnBack; |
| 41 | const deadFrom = back - s.rules.wallReserve; |
| 42 | |
| 43 | return Array.from({ length: WALL_STACKS }, (_, i) => { |
| 44 | const a = i * 2; |
| 45 | const b = a + 1; |
| 46 | const live = (p: number) => p >= front && p < back; |
| 47 | const count = ((live(a) ? 1 : 0) + (live(b) ? 1 : 0)) as 0 | 1 | 2; |
| 48 | return { count, dead: b >= deadFrom, next: front === a || front === b }; |
| 49 | }); |
| 50 | } |
| 51 | |
| 52 | /** |
| 53 | * Whether a stack is something a thrown tile has to get past. |
| 54 | * |
| 55 | * A stack of two stands as tall as the tile being thrown at it. One of one is |
| 56 | * low enough to sail over, and a spent one is not there at all — so only a full |
| 57 | * stack is a barrier. This is the rule behind both halves of the throw: the |
| 58 | * colliders the pile bounces off, and whether a seat may flick at all. |
| 59 | */ |
| 60 | export const isBarrier = (s: Stack) => s.count === 2; |
| 61 | |
| 62 | /** The four sides in the order WallRing lays them out, clockwise from the top. */ |
| 63 | export const WALL_SIDES = ['top', 'right', 'bottom', 'left'] as const; |
| 64 | export type WallSide = (typeof WALL_SIDES)[number]; |
| 65 | |
| 66 | /** |
| 67 | * Which side of the square sits in front of each seat — the one a seat has to |
| 68 | * throw over. Seats run bottom, right, top, left (see ui/rotation.ts) and the |
| 69 | * sides are drawn top, right, bottom, left, so the two orders are not the same. |
| 70 | */ |
| 71 | export const SEAT_WALL_SIDE: Record<SeatId, number> = { 0: 2, 1: 1, 2: 0, 3: 3 }; |
| 72 | |
| 73 | /** The stacks making up one quarter of the square as it was built. */ |
| 74 | export function sideStacks(stacks: Stack[], side: number): Stack[] { |
| 75 | return stacks.slice(side * STACKS_PER_SIDE, (side + 1) * STACKS_PER_SIDE); |
| 76 | } |
| 77 | |
| 78 | /** How many stacks a side of the square holds, once the middle is measured. */ |
| 79 | export interface RingCapacity { |
| 80 | /** Along the top and the bottom. */ |
| 81 | h: number; |
| 82 | /** Down the left and the right. */ |
| 83 | v: number; |
| 84 | } |
| 85 | |
| 86 | /** Dealt out before anybody looks at the table: sixteen tiles, four ways. */ |
| 87 | const DEALT = 64; |
| 88 | /** |
| 89 | * How much wall is left once a hand has been dealt. The square is built to the |
| 90 | * whole hundred and forty-four now rather than to this — see `RING` — so this |
| 91 | * is only a fact about the wall, and what the tests measure a fresh deal |
| 92 | * against. |
| 93 | */ |
| 94 | export const DEALT_STACKS = WALL_STACKS - DEALT / 2; |
| 95 | |
| 96 | /** |
| 97 | * The square is the whole wall: eighteen stacks of two a side, four sides, the |
| 98 | * hundred and forty-four tiles, exactly as it is built on a table. |
| 99 | * |
| 100 | * It used to be rebuilt to what was *left* after a hand had been dealt — barely |
| 101 | * half of it — because eighteen full-size stacks a side wants about 560px and no |
| 102 | * ordinary window has that between the top and bottom strips. That bought a |
| 103 | * square, at the price of it not being the wall: a side ran out of stacks before |
| 104 | * it reached its corner, so the four of them never met. |
| 105 | * |
| 106 | * What gives instead is the tile. A wall tile is not a hand tile — on a table it |
| 107 | * is the same tile, but on a screen the wall has to fit the middle and the hand |
| 108 | * has to be readable, and those are two different jobs. See `wallSquare`. |
| 109 | */ |
| 110 | export const RING: RingCapacity = { h: STACKS_PER_SIDE, v: STACKS_PER_SIDE }; |
| 111 | |
| 112 | /** The square, in pixels, once the room it has to fit has been measured. */ |
| 113 | export interface WallSquare { |
| 114 | /** A stack's short side — the wall's own tile width. */ |
| 115 | cell: number; |
| 116 | /** One wall, end to end: eighteen stacks. */ |
| 117 | len: number; |
| 118 | /** How deep a wall stands, which is a stack's long side. */ |
| 119 | thick: number; |
| 120 | /** The opening left in the middle: where the discards go. */ |
| 121 | open: number; |
| 122 | /** What the whole thing takes up, walls included. */ |
| 123 | outer: number; |
| 124 | } |
| 125 | |
| 126 | /** |
| 127 | * How big the square comes out, given the tile it is built from. |
| 128 | * |
| 129 | * Four walls of eighteen stacks, laid down square and nothing turned. Each is |
| 130 | * pinned at the corner it is built from and runs its whole length from there, |
| 131 | * which carries it one wall-depth past the far corner and over the end of the |
| 132 | * next wall along — the same way round each time. That is the pinwheel, and it |
| 133 | * is why the corners are covered rather than mitred. |
| 134 | * |
| 135 | * So the whole thing measures a wall's length *plus* one depth across, and |
| 136 | * leaves that length *less* one depth in the middle. |
| 137 | * |
| 138 | * The tile is the given, and the square is whatever that comes to. It used to |
| 139 | * be solved the other way about — the room across the table was the given and |
| 140 | * the tile was what gave — which bought a square that fitted at the price of |
| 141 | * the one thing about a wall tile that is not negotiable: it is the tile you |
| 142 | * are playing with. A tile that changed size between the wall and your hand |
| 143 | * read as a different, smaller set of tiles sitting in the middle. `--tile-w` |
| 144 | * in styles.css is the one size, and this follows it. |
| 145 | */ |
| 146 | export function wallSquare(cell: number, ratio: number): WallSquare { |
| 147 | const len = cell * STACKS_PER_SIDE; |
| 148 | const thick = cell * ratio; |
| 149 | return { cell, len, thick, open: len - thick, outer: len + thick }; |
| 150 | } |
| 151 | |
| 152 | /** |
| 153 | * Where the four walls actually stand, in tiles from where the square built |
| 154 | * them: found by pushing them about on a real table, which is what the drag in |
| 155 | * `ui/WallRing` is for. `x` is across the table and `y` down it, both in tiles |
| 156 | * so the placement carries to any window. Nought is the wall left where it was |
| 157 | * built. In `WALL_SIDES` order. |
| 158 | * |
| 159 | * A ladder, as it stands: the two flat walls drawn in towards each other until |
| 160 | * the band they leave between them is the room the four strips actually leave, |
| 161 | * and the two upright ones pushed out past the ends of it. Eighteen full-size |
| 162 | * stacks is longer than the middle of a table is deep, so something has to |
| 163 | * overhang; this is a choice about *what* does. |
| 164 | */ |
| 165 | export const WALL_PLACED: WallNudge[] = [ |
| 166 | { x: -0.47, y: 5.06 }, |
| 167 | { x: 1.29, y: -0.76 }, |
| 168 | { x: 0.88, y: -4.31 }, |
| 169 | { x: -1.6, y: 1.13 }, |
| 170 | ]; |
| 171 | |
| 172 | /** How far a wall has been pushed from where it was built, in tiles. */ |
| 173 | export interface WallNudge { |
| 174 | x: number; |
| 175 | y: number; |
| 176 | } |
| 177 | |
| 178 | /** 擲骰 — the three dice a Taiwanese dealer throws to open a hand. */ |
| 179 | export type Dice = [number, number, number]; |
| 180 | |
| 181 | /** Three of them, from the same seeded rng that shuffled the wall. */ |
| 182 | export function rollDice(rng: () => number): Dice { |
| 183 | return [0, 0, 0].map(() => 1 + Math.floor(rng() * 6)) as Dice; |
| 184 | } |
| 185 | |
| 186 | /** |
| 187 | * Where the wall is broken, as a place in the square. |
| 188 | * |
| 189 | * The dealer throws, and the total does two jobs at once. It counts round the |
| 190 | * table — the dealer themself is one, then on round to their right, which is |
| 191 | * the way play goes — to pick *whose* wall is opened. Then the same number |
| 192 | * counts stacks in from the right-hand end of that wall, and the break is |
| 193 | * behind them: the tile drawn first is the next one along, and the drawing runs |
| 194 | * away to the left from there, on round the square. |
| 195 | * |
| 196 | * The square makes that easy to say. Every wall is laid down from the corner |
| 197 | * its own player's right hand falls on — that is what the pinwheel is — so the |
| 198 | * run of 72 places already starts at the right end of each side, and the break |
| 199 | * is simply so many places into the side the dice picked. |
| 200 | * |
| 201 | * Nothing about the *tiles* turns on it: the wall was shuffled before it was |
| 202 | * built, so which stack is drawn first is decided either way. What it moves is |
| 203 | * where in the middle of the table the gap opens, and which player has to reach |
| 204 | * furthest for the next draw — which is the whole of what it does at a table |
| 205 | * too, and is worth having because it is what a hand looks like. |
| 206 | */ |
| 207 | export function breakAt(dealer: SeatId, dice: number[]): number { |
| 208 | const total = dice.reduce((n, d) => n + d, 0); |
| 209 | if (total <= 0) return 0; |
| 210 | // One is the dealer, and the count goes the way the turn does. |
| 211 | const whose = ((dealer + total - 1) % 4) as SeatId; |
| 212 | return (SEAT_WALL_SIDE[whose] * STACKS_PER_SIDE + total) % WALL_STACKS; |
| 213 | } |
| 214 | |
| 215 | /** A stack and which of the 72 it is — the index is what the physics reads. */ |
| 216 | export interface Placed { |
| 217 | index: number; |
| 218 | stack: Stack; |
| 219 | } |
| 220 | |
| 221 | /** |
| 222 | * Where what is left of the wall actually goes. |
| 223 | * |
| 224 | * Four walls of eighteen full-size stacks want about 560px a side, and the |
| 225 | * middle of the table is nothing like that in both directions at once — so a |
| 226 | * square built to the tile is a square that hangs out under the players. What |
| 227 | * saves it is that by the time anyone is looking, four hands have been dealt |
| 228 | * off the front and there is nothing like a whole wall left: only what is still |
| 229 | * standing is drawn, and it is laid out around a ring cut to the middle rather |
| 230 | * than to the tile. Players push the remaining stacks about to keep them tidy |
| 231 | * for exactly this reason. |
| 232 | * |
| 233 | * The rebuilt square is the size of the wall as it is dealt, so at the start |
| 234 | * the run fills it exactly, and from then on it is simply *eaten*: the tail is |
| 235 | * pinned to the end of the square and normal draws take stacks off the front, |
| 236 | * which leaves a growing gap where they were and moves nothing else. Kong and |
| 237 | * flower replacements come off the other end and shorten it from there. Both |
| 238 | * ends are where they would be on a table, and the square keeps the size it was |
| 239 | * built at — a square that shrank every draw would close in on the discards |
| 240 | * lying inside it. |
| 241 | * |
| 242 | * `from` is the break: which place in the square the first tile drawn comes |
| 243 | * off, from `breakAt`. Every place is returned whether or not there is still a |
| 244 | * stack standing on it, because with the break anywhere but the corner a wall |
| 245 | * is eaten from its *middle* — a row that closed the gap up would drag the |
| 246 | * whole tail of the wall along the table behind it. |
| 247 | */ |
| 248 | export function ringLayout(stacks: Stack[], cap: RingCapacity, from = 0): Placed[][] { |
| 249 | const sides: Placed[][] = [[], [], [], []]; |
| 250 | const lengths = [cap.h, cap.v, cap.h, cap.v]; |
| 251 | const slots = 2 * (cap.h + cap.v); |
| 252 | if (slots <= 0) return sides; |
| 253 | |
| 254 | // Each stack has its own place in the square and keeps it: the far end is the |
| 255 | // far end of the square, and everything counts back from there. Draws off the |
| 256 | // front open a gap at the break point, draws off the tail shorten the other |
| 257 | // end, and no tile that is still standing ever has to move. |
| 258 | const offset = WALL_STACKS - slots; |
| 259 | |
| 260 | const run: (Placed | null)[] = Array.from({ length: slots }, () => null); |
| 261 | for (let index = 0; index < stacks.length; index++) { |
| 262 | // A wall too long for its square only happens before a hand is dealt, and |
| 263 | // then only for the frame it takes to deal it. What falls off the start is |
| 264 | // the part about to be drawn anyway. |
| 265 | const at = index - offset; |
| 266 | if (at < 0 || at >= slots) continue; |
| 267 | run[(at + from) % slots] = { index, stack: stacks[index] }; |
| 268 | } |
| 269 | |
| 270 | let p = 0; |
| 271 | for (let side = 0; side < 4; side++) { |
| 272 | for (let i = 0; i < lengths[side]; i++, p++) { |
| 273 | const place = run[p]; |
| 274 | if (place) sides[side].push(place); |
| 275 | } |
| 276 | } |
| 277 | return sides; |
| 278 | } |