masterq32 / zig-opengl

OpenGL binding generator based on the opengl registry

Zig OpenGL Binding

This is a pragmatic binding to different OpenGL versions.

It uses the official OpenGL Registry by Khronos to generate the Zig code.

Right now, it does minimal adjustments like removing the gl prefix from functions or the GL_ prefix from constants. Everything else is the same as the C API.

There is a single non-OpenGL function exported:

pub fn load(load_ctx: anytype, get_proc_address: fn(@TypeOf(load_ctx), [:0]const u8) ?*FunctionPointer) !void {

This function will load all OpenGL entry points with the help of get_proc_address. It receives the load_ctx as well as the function name.

NOTE: Please do not reference zig-opengl as a submodule or a package. Generate a binding and copy the output of that into your repository and update the file on demand. The OpenGL Registry is just too huge to be used conveniently.

Cloning submodules is required, so use --recursive:

git clone --recursive https://github.com/MasterQ32/zig-opengl.git

Example

This example uses ZWL by @Aransentin.

const zwl = @import("zwl");

const Platform = zwl.Platform(…);

pub fn initAndDraw(window: Platform.Window) !void {
  try gl.load(window.platform, Platform.getOpenGlProcAddress);

  while(true) {
    gl.clearColor(1, 0, 1, 1);
    gl.clear(gl.COLOR_BUFFER_BIT);

    try window.present();
  }
}

Usage with mach-glfw

There is an example of mach-glfw + zig-opengl usage available here: https://github.com/hexops/mach-glfw-opengl-example

Pregenerated Loaders

This repository contains pre-generated bindings for all extension-free OpenGL versions.

Generating your own loader

From source

To generate your own loader, you have to clone this repository and build the generator with dotnet:

user@machine:~/zig-opengl$ dotnet run
Usage: generator <registry> <result> <api_version> [<extension>] [<extension>] ...
user@machine:~/zig-opengl$ dotnet run OpenGL-Registry/xml/gl.xml gl3v3.zig GL_VERSION_3_3
Final API has 344 commands and 818 enums types.
user@machine:~/zig-opengl$

dotnet run \
  OpenGL-Registry/xml/gl.xml \ # path to the opengl registry
  my_binding.zig             \ # path to the generated file
  GL_VERSION_3_3             \ # feature level, options listed below
  …                            # Add your extensions here, each as a single arg. Or let them out, you don't need extensions

Possible feature levels (at the time of writing) are:

• GL_VERSION_1_0
• GL_VERSION_1_1
• GL_VERSION_1_2
• GL_VERSION_1_3
• GL_VERSION_1_4
• GL_VERSION_1_5
• GL_VERSION_2_0
• GL_VERSION_2_1
• GL_VERSION_3_0
• GL_VERSION_3_1
• GL_VERSION_3_2
• GL_VERSION_3_3
• GL_VERSION_4_0
• GL_VERSION_4_1
• GL_VERSION_4_2
• GL_VERSION_4_3
• GL_VERSION_4_4
• GL_VERSION_4_5
• GL_VERSION_4_6
• GL_VERSION_ES_CM_1_0
• GL_ES_VERSION_2_0
• GL_ES_VERSION_3_0
• GL_ES_VERSION_3_1
• GL_ES_VERSION_3_2
• GL_SC_VERSION_2_0

Contribution

This library uses a small C# script that generates the Zig bindings. It is located in src/Generator.cs

What is missing right now?

• Option to specify core or compatibility profile.

zig-opengl's Issues

Make it accessible from build.zig (like Snektron/vulkan-zig)

Basically add some type of API for Zig's build system to generate the code from the build script so the bindings are accessible from everywhere in the code.

Clarify license for generated code

Does the EUPL apply to generated bindings, or just the generator program? glad for example licenses the generator under The MIT License, but generated code as "any of Public Domain, WTFPL or CC0." I think it would be helpful to either make the same distinction for zig-opengl, or explicitly state that generated bindings are also covered under EUPL.

Split repo in generator and generated Zig files

It would be nice to keep the generated Zig files in a separate and lean repo so they can be easily included using package managers like gyro and zigmod.

Make it compatible with self-host compiler

there's a lot function decals break down

Type is Used as a Parameter Name

type is used as a parameter name in a couple of functions, which prevents the bindings from compiling without modification. Presumably the code that generates the bindings could automatically rename these to something like gltype to make everything work out of the box.