raylib-pacman

One Pac-Man, written four times against raylib, once per Clojure-family runtime. Each directory is a standalone project you can copy out on its own and run with bb, and nothing here is shared between them on purpose.

The game itself is Michiel Borkent's (@borkdude): all four ports descend from his pacman.clj example in babashka/ffi. See Credits and NOTICE.md.

Example	Runtime	Binding	Build file
babashka-example/	babashka	babashka.ffi	bb.edn
clojure-example/	Clojure on the JVM	raylib-clj, coffi over Panama	deps.edn
jank-example/	jank	cpp/ interop, org.jank-lang.commons/raylib-sys	project.clj
jolt-example/	jolt	net.b12n/raylib, jolt.ffi	deps.edn

babashka	Clojure/JVM
jank	jolt

Same maze, same ghosts, same physics, four different routes into C.

Running one

cd babashka-example && bb pacman     # fastest to start, no build step
cd clojure-example  && bb pacman
cd jank-example     && bb pacman     # first run builds raylib natively
cd jolt-example     && bb pacman

Arrows or WASD steer. ENTER restarts after GAME OVER. Every example also takes two optional arguments, which is what makes them runnable with nobody at the keyboard:

bb pacman 10              # quit after ten seconds of game time
bb pacman 3 out.png 76    # quit after three, capture frame 76 to out.png

From the repository root, bb check-all compiles or loads all four, bb shot-all runs each for three seconds and captures a PNG, and bb doctor-all tells you which toolchain is missing.

Prerequisites

Every example links against a system raylib 6.0 or newer, which none of them bundle:

brew install raylib                       # macOS
sudo pacman -S raylib                      # Arch, and your distro's equivalent

Then per example: babashka needs only bb. The Clojure one needs a JDK 22 or newer, because coffi sits on Panama. jank needs jank and a Leiningen, and jolt needs jolt. None of the four needs the others.

What is the same

The game is. All four carry the same maze, the same physics and the same ghosts, and the interesting part is that this half of the code barely changes between runtimes.

The world is one immutable map. step reads input and returns the next state, nothing under it draws, and draw-state! is a pure function of the state it is handed. Movement is worth reading before the rest: a turn is buffered on the keypress and applied at the next tile centre where it is legal, because deciding a direction anywhere other than a centre is what lets an entity slide into a wall.

The ghosts keep the personalities the 1980 original gave them. Blinky heads straight for Pac-Man's tile. Pinky aims four tiles ahead of him to cut him off. Inky reflects Blinky's tile through a point two tiles ahead of Pac-Man, which is why he seems to change his mind halfway down a corridor. Clyde chases until he is within eight tiles and then breaks for his corner. They alternate scatter and chase on a timer, and a power pellet turns all four blue at once.

What is different

The drawing layer, and the reasons are specific enough to be worth the four copies.

Colour. raylib's Color is a four-byte struct passed by value. raylib-clj hands it over as a plain {:r :g :b :a} map. jolt and babashka both pack it into a single integer instead, which costs nothing: a four-byte all-integer struct rides in one register on both ABIs, so the packed int is the same memory under a cheaper spelling. jank could pass one too, but a jank fn may not return a native value, so colours travel as packed ints and the Color is rebuilt inline at every draw call, which is a position jank does allow.

Pac-Man himself. He is a circle with a wedge missing, and there are two ways to get one. The Clojure and jank ports call DrawCircleSector and sweep from the far lip of the mouth all the way round to the near one, so the mouth is the part the sector never covers. babashka and jolt drop one level down and emit the same shape as an rlgl triangle fan by hand. That is inherited from the original example rather than forced: both FFIs do pass structs by value and both make the DrawCircleSector call correctly, which drawing-pac-man.md shows with the binding for each.

Angles. raylib measures a sector from the positive x axis, and y grows downward, so zero points right and the angle increases clockwise on screen. That makes the heading a plain atan2 in the jank and Clojure ports. The jolt wrapper's sector! puts zero at the top instead, so that port converts, and getting this wrong points Pac-Man's mouth a quarter-turn away from where he is walking while everything still compiles and runs.

The deadline. All four count game time, summed from the clamped per-frame dt, rather than wall time. jank run through Leiningen is why. lein run compiles as it loads, so frame 0 pays for the entire draw path at once: six game-seconds of play took 19.6 seconds of wall clock, of which the first twenty frames were 6.3 of it, and every frame after that ran at a steady 60 FPS. A wall clock charges that one-time cost against the deadline and quits before frame 2, which looks exactly like a game that does not work.

Worth separating from jank itself, because the obvious conclusion is the wrong one. Run the same code as the AOT binary lein leaves in target/ and there is no warm-up at all: a window in about a second, and six game-seconds in 6.4 of wall clock. The cost belongs to the lein run path, not to the language.

Adding another example

Each directory is self-contained, so a new game is a new source file next to pacman, plus a task in that directory's bb.edn. A new runtime is a new <name>-example/ directory with its own build file, its own bb.edn carrying the same info / pacman / shot / check / doctor tasks, and a row in the examples vector at the top of the root bb.edn, which is what check-all and friends walk.

Guide

Longer form, in docs/guide/:

Page	What it covers
the-game.md	The half that barely changes. State, the frame step, tile-centre movement, the ghosts.
crossing-to-c.md	The comparison. How each runtime reaches raylib and what each FFI will not carry.
drawing-pac-man.md	One shape, two implementations, and the angle convention that breaks silently.
running-unattended.md	Deadlines, screenshots, and why the clock is game time.
babashka.md clojure.md jank.md jolt.md	One page per runtime.

Docs site

The guide pages build into a static site with the docs-engine:

bb site:build     # generate _site/
bb site:serve     # build, then serve at localhost:3000
bb site:clean     # delete the build output

Nothing publishes. See docs/site.edn for what wiring the publish half would involve.

Licence

Eclipse Public License 2.0, in LICENSE. The game this repository ports came from MIT-licensed work, and that notice is kept in NOTICE.md alongside the rest of the third-party attribution.

Credits

The game is Michiel Borkent's (@borkdude). All four ports here descend from his examples/pacman.clj in babashka/ffi, which is where the maze, the ghost personalities, the tile-centre movement rule and the rlgl triangle fan came from. The twenty-one maze rows are byte-identical in every port here, so the lineage is easy to check for yourself. What this repository added is the other three runtimes, the drawing layer each of them needs, and the unattended run arguments. babashka/ffi is MIT licensed, and its notice is reproduced in NOTICE.md.

The jolt port arrived by way of the pacman example in jlt-commons/raylib-jlt, which is itself a port of the same original. The jank project layout follows the raylib-sys example in jank's commons repo.

Pac-Man is Namco's, from 1980.

The animated previews were recorded with screen-grab over cgevent, internal b12n tools that are not public yet. Every GIF is committed, so nothing here needs a capture toolchain to build or read.