Direct SDL bindings to Crystal

This shard allows for the direct use of all unsafe SDL functions. It is designed to use as a low-level foundation for your own libraries.

Note that it is NOT recommended to use these bindings unless you want to write your own wrappers (which are not provided). The bindings here are unsafe and are therefore able to crash your program.

Requirements

You need to have SDL installed or the SDL library files accessible by Crystal for linking and running.

For the other SDL library bindings, you also need to have SDL_image, SDL_mixer and SDL_ttf available.

Depending on the SDL version, you should use either the main branch (for SDL 3) or an sdl2 release (for SDL 2).

Usage

Simply add this shard (sdl-crystal-bindings) to your shard.yml. This repository comes with pre-generated binding files.

Then, use require "sdl-crystal-bindings/sdl3-crystal-bindings".

For the other SDL libraries, you can use require "sdl-crystal-bindings/sdl3-image-bindings", for example. Note that the examples use the relative paths to the respective files.

Regular SDL functions, structs, enums, unions and constants are accessible using the LibSDL namespace, while preprocessor macro functions are accessible using the LibSDLMacro module. This separation is due to the fact that no functions can be added to the Crystal lib modules, which do not already exist in C. Since these are simple macro expressions, they have no real analogon and thus need to be implemented separately.

Note that also the syntax differs from regular SDL in many aspects and is more oriented to Crystal (for example, functions are in snake_case, while structs are in CamelCase).

Examples

There are some examples ported directly from https://examples.libsdl.org/SDL3/ to Crystal. You might have to change the relative paths in the examples for them to work if not started from this directory.

Generating new bindings

To update the bindings, you need to have Ruby, gcc and clang installed on your system (ideally Linux or it might not work).

Just call ruby generate3.rb from the main directory of this shard and the files under src/ will be generated or updated. The script will download the newest SDL headers and generate automated bindings.

If you need to add manual changes, please either use the filters from the script to exclude structs and/or modify the files in the additions3 directory to add specific bindings manually.

If you encounter any problems while generating the bindings, please open an issue.

Changelog

No release for SDL3 yet.

Roadmap

Version 0.3.0

Features

• Support for SDL3
• Many examples for SDL3

Wishlist

Features

• Merging of all functions and macros into one single module (if possible and helpful)
• Even more examples
• Documentation
• Automated binding generation via CI

Usability

• Fix weird formatting in some header files
• Add original C struct/function/constant/macro names as comments