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defun-games / claylib

A Common Lisp 2D/3D game toolkit built on top of Raylib 4.5.
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common-lisp game-development game-engine gamedev lisp raylib

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claylib

A Common Lisp 2D/3D game toolkit built on top of Raylib 4.5 and Raygui 3.6.

Quick Start

Claylib is not yet in Quicklisp. Load claylib.asd and run (ql:quickload :claylib/examples) or similar to load all of the available packages. See the next section for what those packages are and how you might use them.

To see the examples in action, just run e.g. (claylib/examples/basic-window:main). Hit Escape to exit. At the time of this writing, most of the core examples are done, as well as a handful from other categories. GUI examples are very work-in-progress.

Tested only on Linux, so far. There's no obvious reason it can't work on other platforms, but you might need to build Raylib and Raygui yourself.

Systems

There's also claylib/wrap and claylib/makewrap if you're interested in digging into the claw wrappers. Otherwise, there's no reason to touch them.

Current Status

The project should be considered beta. While the API is mostly stable at this point, the possibility of changes still exists.

claylib/ll should be highly usable, as a thin wrapper over Raylib and Raymath. Raygui is sparsely tested but usable if you know what you're doing; examples are in progress.

For claylib, you're best off reviewing the examples as a survey of what's done and what's not. 2D support is largely complete; 3D support, a bit less complete. If any piece is particularly important to you, please file an issue and we will prioritize it!

Using claylib

Walking through the first texture example will give a "boilerplate" of how you might make a game with claylib. (This is certainly not the only way, just a way.)

with-window

(defun main ()
  (with-window (:title "raylib [textures] example - texture loading and drawing")
    ...))

The with-window macro initializes a new Raylib window and takes care of freeing stray C memory when it closes. Here we set the window title with the :title keyword. Other keywords:

Scenes

(let* ((image-size 256)
       (scene (make-scene ((texass (make-texture-asset ...)))
                          ((texture (make-texture texass ...))
                           (text (make-text ...))))))
  ...)

"Scenes" are a new concept in Claylib that don't really exist in Raylib. Scenes aim to make it easier to create groups of objects and assets, and allocate your memory up front wherever possible. Using scenes well will also maximize REPL interactivity while you develop your game; more on this in the do-game-loop section below. make-scene takes two lists -- a list of game assets and a list of game objects.

Assets are where you load your models, textures, audio, etc. from files. You'll use these pre-loaded assets later, as components of this scene's game objects, background music, and so on. When defining an asset, you specify a path and can either pass :load-now t to load it immediately, or let with-scenes do it automatically later on. Important note: Modifying an asset will modify all objects composed of that asset! This is usually discouraged.

Objects, in a nutshell, are things that get drawn on the screen. Technically you can put things in here that can't be drawn, but there probably aren't many reasons to, and it could break your draw loop if you aren't careful. Sometimes you'll want to compose objects from an already defined asset, such as via make-texture.

Under the hood, make-scene is a macro that includes a let* so you can reference previous bindings within the same definition. (This does mean, however, that the assets and objects share a namespace and must all have unique names.) In this case, scene will contain two game objects named text and texture, with the latter being formed from the asset texass. There is also a :gc keyword, a boolean that toggles garbage collection when the scene closes out. This is t by default.

make-whatever

(make-texture-asset
 (claylib/examples:claylib-path
  "examples/textures/resources/raylib_logo.png"))
(make-texture texass
              (/ (- (get-screen-width) image-size) 2.0)
              (/ (- (get-screen-height) image-size) 2.0))
(make-text "this IS a texture!"
            360 370
            :size 10
            :color +gray+)

As mentioned above, make-texture-asset takes a required pathname and a :load-now keyword argument.

make-texture requires a texture-asset, and X and Y coordinates for where the texture should be drawn. The drawing can be modified via a number of keyword arguments: :width, :height, :tint, etc. (Most fall under the category of "you'll know them if you need them.")

make-text takes three required arguments -- a text string, and the X and Y coordinates where the text should be drawn. In practice you'll frequently pass :size and :color but they do have sane defaults for the lazy, as does :spacing. You can also pass your own font object via :font... but let's not get ahead of ourselves.

claylib exports a number of make-whatever functions for these game objects, which you are recommended to use where available. Not every class has such a corresponding function yet.

with-scenes

(with-scenes scene ()
  ...)

The with-scenes macro takes a single scene or a list of scenes; for each scene it loads your assets if you passed any and prepares your game objects. In the parens you can pass a :gc argument, which will either force or disable garbage collection at the end of the body regardless of scene-specific settings. If :gc is not passed, the scene setting is used (i.e. GC will run if at least one scene requests it).

do-game-loop

(do-game-loop (:livesupport t)
  ...)

The do-game-loop macro is your main loop, where your game will spend most of its time and where performance and consing matter the most. It's just a fancy do form, so you can pass corresponding :vars, :end, and :result keywords. The end form has an implied (or (window-should-close-p) ...) which means the loop will always terminate when you hit Escape, in addition to whatever conditions you pass.

As for :livesupport: claylib uses the excellent livesupport library to provide better interactive development. With it enabled, you can run your game and see your changes at the REPL reflected in real-time. This is where scenes come in, as all you need to do is setf a scene object's properties and watch that object be drawn differently. Any functions that are called from your game loop can be similarly live-modified. It is recommended to keep :livesupport enabled for development and disable it when you ship your game.

with-drawing

(with-drawing () ...)

A simple macro that encloses the body in a drawing mode. By default it clears the *claylib-background* color at the beginning, or you can pass :bgcolor in the parens to clear a different one. Other similar macros:

draw-scene-*

(draw-scene-all scene)

Draw every game object in the passed scene, in the order those objects were put into the scene. For greater specificity, use one of the other functions:

Claylib-only Features

In addition to scenes, we've added a few other niceties to Claylib that don't exist in Raylib.

Allocation Pools

Repeatedly allocating new objects within the game loop is a Bad Thing™. Ideally you will use scenes to define and allocate objects upfront as much as possible, but it's not always feasible to do that. Sometimes you just need to access a pool of pre-allocated objects, either globally, or tied to something that isn't a scene. Claylib handles this in a simple but effective way:

(defvar *my-pool* (make-alloc-pool))

(get-alloc 'foo *my-pool* 'vector2)
(get-alloc 'bar *my-pool* 'vector3)
(get-alloc 'foo *my-pool*) ; Same vector2 you previously created

You could use allocation pools just like this, but a more probable use case is attaching a pool to some object for vector and matrix calculations -- a lot of Raymath functions want single-use vectors/matrices and it can be a pain to set these up outside the game loop. Call (alloc-pool my-object) to get or create a pool for a given object.

Use make-alloc-pool, alloc-pool, set-alloc, get-alloc, and rem-alloc. See the docstrings for more details.

Linking and Triggers

You can link a parent object and a child object with a trigger to update the child object when the parent object is changed. This is similar to how you might use a scene graph in mainstream game engines, but arguably more flexible. Consider the following highly contrived example:

(defvar *circle-1* (make-circle 20 20 5 +blue+))
(defvar *circle-2* (make-circle 50 50 8 +red+))

(defun move-circles (x y)
  (incf (x *circle-1*) x)
  (incf (y *circle-1*) y)
  (incf (x *circle-2*) x)
  (incf (y *circle-2*) y))

The two circles are meant to move together, but when you have many objects tied together like this, it can be annoying to keep them all in sync. Fortunately, there's a more scalable way:

(defvar *circle-1* (make-circle 20 20 5 +blue+))
(defvar *circle-2* (make-circle 50 50 8 +red+))

(dolist (writer '(x y))
  (link-objects (pos *circle-1*) writer (list (pos *circle-2*) writer :incf)))

(defun move-circles (x y)
  (incf (x *circle-1*) x)
  (incf (y *circle-1*) y))

What we're doing here is linking the x and y slots of *circle-1*'s position vector with the corresponding slots of *circle-2*'s position vector. :incf is the trigger: The child circle's position is incremented by the same amount as the parent's. Supported triggers are :incf, :setf, :scale, and an arbitrary function that takes five arguments (parent writer, parent object, value, child writer, and child object).

While this is admittedly more verbose than something like (link-objects *circle-1* *circle-2*), that's made up for with flexibility. It's just as easy to have x tied to y, or have the parent's position tied to the child's radius, or have a function that changes the child's color, etc.

Use link-objects and unlink-objects. See the docstrings for more details.