Vala Documentation

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OpenGL samples ​

Adapted from the archived GNOME Wiki page Projects/Vala/OpenGLSamples. That page covered GLFW 2, GtkGLExt (GTK 2), GLX, and GLUT. GLFW 2 and GtkGLExt are obsolete; Gtk.GLExt is unmaintained for modern GTK.

This page highlights GLFW 3 with the community glfw3.vapi from vala-extra-vapis for a minimal window and GL context. For libepoxy with Vala, the C library does not ship official vapi files; bindings are described below, and a runnable Meson reference app is ValaGL. Legacy GtkGLExt / GLUT compile lines are summarized at the end for historians digging through the wiki archive.

GLFW 3: window and clear color ​

Modern GLFW uses glfwInit, glfwCreateWindow, glfwMakeContextCurrent, and a core-profile context. The fixed-function glBegin / glEnd triangle from the old wiki is omitted here; use shaders with GLFW 3, or start from the snippet below and follow any current GLFW + OpenGL tutorial.

Vala does not ship GLFW in the default toolchain. Use glfw3.vapi from vala-extra-vapis (GitHub mirror): clone the repo or copy glfw3.vapi, then pass --vapidir /path/to/that/directory with --pkg glfw3. That provides the GLFW namespace below; pkg-config still links the GLFW 3 C library.

vala
using GLib;

int main () {
    if (!GLFW.init ()) {
        return 1;
    }

    GLFW.WindowHint.CLIENT_API.set ((int) GLFW.ClientAPI.OPENGL);
    GLFW.WindowHint.CONTEXT_VERSION_MAJOR.set (3);
    GLFW.WindowHint.CONTEXT_VERSION_MINOR.set (3);
    GLFW.WindowHint.OPENGL_PROFILE.set ((int) GLFW.OpenGLProfile.CORE);

    var win = new GLFW.Window (640, 480, "GLFW 3 + Vala");
    win.make_context_current ();

    /* OpenGL drawing needs a loader (libepoxy) plus Vala bindings — see “ValaGL” below. */

    while (!win.should_close) {
        GLFW.poll_events ();
        win.swap_buffers ();
    }

    GLFW.terminate ();
    return 0;
}

Compile and run ​

  1. Install GLFW 3 development files so pkg-config exposes glfw3 (package names vary by distribution).
  2. Obtain glfw3.vapi: clone vala-extra-vapis or download glfw3.vapi into a folder (for example ./vapi in your project).

Point --vapidir at the directory that contains glfw3.vapi (the cloned repository root, or your vapi/ copy).

shell
valac --vapidir /path/to/vala-extra-vapis --pkg glfw3 -o glfw3-window glfw3-window.vala
./glfw3-window

If the C compiler cannot find GLFW headers, add an explicit include path (for example -X -I/usr/include/GLFW).

Epoxy, gl.vapi, and ValaGL ​

libepoxy is a C library for OpenGL function pointer resolution; it does not include Vala .vapi files in the upstream project.

The fork m-shinder/libepoxy (branch vala-vapi) adds generated Vala bindings: in particular gl.vapi, tied to epoxy/gl.h, with OpenGL entry points exposed under the GL namespace (see that repository’s README for details).

Wiring together GLFW, libepoxy, gl.vapi, and a working render loop is best demonstrated as a Meson project rather than a one-line valac example. For a clear, working reference, see ValaGL: it is a minimal GLFW-based OpenGL skeleton that integrates the necessary dependencies (including a subproject for the Vala-compatible fork of libepoxy), and provides step-by-step documentation for setup and building.