machin-game-demo-2048

name	machin-game-demo-2048
description	Build, run, and modify machin-game-demo-2048 — the 2048 puzzle as a native raylib desktop app written in machin (MFL). Use when working on this repo, or as a worked example of driving a GUI / graphics library from machin through the C FFI (window, rectangles, text, keyboard).

machin-game-demo-2048

The 2048 sliding-puzzle as a real native desktop window, written in machin (MFL) and rendered with raylib over machin's C FFI. It is the reference example for GUI / graphics programs in machin (the terminal counterpart is machin-game-demo-snake).

The shared game-dev setup, build-and-verify workflow, and the cross-cutting caveats/gotchas (esp. the int/float rule) live in the canonical machin-gamedev skill. This file is 2048's specifics.

Build & run

./build.sh                 # machin encode game2048.src -> game2048.mfl, then machin build -> ./machin-game-demo-2048
./machin-game-demo-2048

Needs machin, a C compiler, raylib, and a display.

• System raylib (apt-get install libraylib-dev, brew install raylib, …): build.sh detects it via pkg-config/headers and builds the committed system-style source directly.
• No root: build.sh downloads raylib's prebuilt static release into vendor/ and injects cflags "-I… -L…" + link ":libraylib.a" into a throwaway copy of the encoded .mfl — the committed game2048.src stays system-style.
• MACHIN=/path/to/machin ./build.sh to use a specific compiler.

Controls: ←↑→↓ or WASD to slide, R restart, Esc quit.

How it maps to the FFI

The whole extern "raylib" { … } block is the only thing crossing into C; everything else is pure MFL. It uses just FFI Phases 1–2 — scalars and one by-value struct — exactly like machin/examples/gui:

MFL	raylib C	FFI feature
cstruct Color { r u8 g u8 b u8 a u8 }	Color{ unsigned char r,g,b,a; }	by-value struct
fn DrawText(string,i32,i32,i32,Color)	void DrawText(const char*,int,int,int,Color)	scalars + struct arg
fn MeasureText(string,i32) i32	int MeasureText(const char*,int)	scalar return (text centering)
fn IsKeyPressed(i32) bool	bool IsKeyPressed(int)	scalar return (input)
link "raylib" link "GL" …	-lraylib -lGL … (in order)	multi-lib linking

raylib is immediate-mode and polls input via functions, so no opaque handles or callbacks are needed. raylib key codes used: 263/262/265/264 = Left/Right/Up/Down, 65/68/87/83 = A/D/W/S, 82 = R. (Esc is raylib's default window-close key, caught by WindowShouldClose().)

Patterns worth copying

• One slide routine, four directions. lane_index(dir, lane, pos) maps direction + lane + travel-position → flat board index; move_lane then compacts non-zeros, merges each equal pair once, and pads. No four-way copy-paste.
• Mutate a slice in place across calls. move_lane/spawn/reset take the board slice and write board[i] = …; the writes hit the shared backing array, so the caller sees them. They return only summaries (gained, moved, ok).
• str(bool) is fine (machin v0.42.0+): str(true) → "true". On older compilers str was numeric-only, so keep bools in control flow if you must target those.
• Random without a PRNG builtin. rand_bytes(2) then % len(empties) picks a cell; a second byte < 26 gives the ~10% chance of a 4.
• Center text. MeasureText(s, fs) then x + (CELL - tw)/2; shrink the font as the number widens so 4-digit tiles still fit.

Modifying

• Board size is wired to 4×4 (the % 4 / * 4 indexing and the 16-cell loops); changing it touches lane_index, has_moves, and the render loop.
• Window / tile geometry: the WIN_W/WIN_H/BX/BY/GAP/CELL helper funcs.
• Colors: tile_color(v) (per-value palette) and text_color(v).
• Win detection (reaching 2048) isn't enforced — play continues; add a check in the move handler if you want a win banner.
• After any edit to game2048.src, re-run ./build.sh (never hand-edit game2048.mfl — it is generated).