In the lead up to the semi-annual Autumn Lisp Game Jam I thought I’d look into Phil Hegelberg’s approach to last Aprils Jam, using love2d in concert with fennel. Phil outlines his approach on his blog.
This repo contains the minimal viable setup to get started with Phil Hegelberg’s game design process, plus some additional libraries.
The following commands will clone this project and duplicate its structure into a new folder $PROJECT_NAME
git clone https://gitlab.com/alexjgriffith/min-love2d-fennel.git
./min-love2d-fennel/.duplicate/new-game.sh $PROJECT_NAME
Check out the makefile and conf.lua files in $PROJECT_NAME
, updating them with information relevant to your game.
You can enter love .
in the $PROJECT_NAME
directory to run your game, or make run
.
The following lines with Update
should be changed in the makefile
and love.conf
to reflect your game.
VERSION=0.1.0
LOVE_VERSION=11.4
NAME=change-me # Update
ITCH_ACCOUNT=change-me-too # Update
URL=https://gitlab.com/alexjgriffith/min-love2d-fennel # Update
AUTHOR="Your Name" # Update
DESCRIPTION="Minimal setup for trying out Phil Hagelberg's fennel/love game design process." # Update
GITHUB_USERNAME := $(shell grep GITHUB_USERNAME credentials.private | cut -d= -f2) # Optional (needed for Love V 12.0)
GITHUB_PAT := $(shell grep GITHUB_PAT credentials.private | cut -d= -f2) # Optional (needed for Love V 12.0)
love.conf = function(t)
t.gammacorrect = true
t.title, t.identity = "change-me", "Minimal" -- Update
t.modules.joystick = false
t.modules.physics = false
t.window.width = 720
t.window.height = 450
t.window.vsync = false
t.version = "11.4"
end
Once you install the latest version of fennel-mode, you can run
C-u M-x fennel-repl
followed by love .
to launch a repl.
The make
process as-is will only compile the contents of the root folder and the lib/
folder+subfolders, so make sure to put your game files in either of those.
Specifically, every .fnl
file needed at runtime needs to be situated in the root folder, and every file which is not a .lua
or .fnl
file needs to be put inside lib/
.
In order to use macros, they have to be put in .fnl
files inside lib/
.
If you want a more opinionated layout, you can use pass in a --layout
parameter when creating your project.
./min-love2d-fennel/.duplicate/new-game.sh $PROJECT_NAME --layout=seperate-source
This build uses gamestate
rather than Phil’s approach to scene seperation and puts all your .fnl
files into a /src
directory. It also provides a seperate makefile that handles this layout.
Note, any macros will have to be placed in the root of the project or in the lib
folder (this can be modified in main.lua
)
Presently the only layouts are clone
and seperate-source
. If you want to make your own check out the .duplicate
directory to see how they work.
Use make linux
, make windows
, make mac
, or make web
to create targets for each platform, or make release
to make all four. Check out the makefile for more commands, and remember to edit your game data in it!
You can target the development branch of love (version 12.0) by setting the `LOVE_VERSION` parameter in the makefile to 12.0. Note that because we are working from a github artifact, rather than a release, you will also have to pass in your github username and a github PAT.
To download artifacts created by the Github actions CI you will need to get an access token from “settings -> developer settings -> personal access tokens”. The token needs `workflow` and `actions:read` permissions.
By default the makefile looks for `credentials.private` in the root directory of the project. `*.private` is part of `.gitignore` so personal information stored here will not be part of the git history or get pushed to a remote server.
The contents should look something like this:
GITHUB_USERNAME=username
GITHUB_PAT=PAT
Note: this is presently linux only, however it may be expanded in the future to cover macos and windows.
Phil Hegelberg’s exo-encounter-667 is structured using a modal callback system. Each game state has a mode and each mode has a series of specific callbacks.
If you design your game as a series of states in a very simple state machine, for example start-screen, play and end, with unidirectional progression, you can easily separate the logic for each state into state/mode specific callbacks. As an example, in order to have state dependant rendering that differs between start-screen,play and end you could provide a draw callback for each of those states. Similarly if we need state dependent logic and keyboard input we could provide update and keyboard callbacks. As you iterate you can add and remove callbacks and states/modes as needed with very little friction.