Glow is an OpenGL binding generator for Go. Glow parses the OpenGL XML API registry to produce a machine-generated cgo bridge between Go functions and native OpenGL functions. Glow is a fork of GoGL2.

Features:

• Go functions that mirror the C specification using Go types.
• Support for multiple OpenGL APIs (GL/GLES/EGL/WGL/GLX/EGL), versions, and profiles.
• Support for extensions (including debug callbacks).

See the open issues for caveats about the current state of the implementation.

Use go get to download and install one of the prebuilt packages. The prebuilt packages support OpenGL versions 3.2, 3.3, 4.1, and 4.4 across both the core and compatibility profiles and include all extensions.

go get github.com/errcw/glow/gl-{core,compatibility}/{3.2,3.3,4.1,4.4}/gl
go get github.com/errcw/glow/gl-core/3.3/gl

Once the bindings are installed you can use them with the appropriate import statements.

import "github.com/errcw/glow/gl-core/3.3/gl"

func main() {
  if err := gl.Init(); err != nil {
    panic(err)
  }
}

The gl package contains the OpenGL functions and enumeration values for the imported version. It also contains helper functions for working with the API. Of note is gl.Ptr which takes a Go array or slice or pointer and returns a corresponding uintptr to use with functions expecting data pointers. Also of note is gl.Str which takes a null-terminated Go string and returns a corresponding *int8 to use with functions expecting character pointers.

A note about threading and goroutines. The bindings do not expose a mechanism to make an OpenGL context current on a different thread so you must restrict your usage to the thread on which you called gl.Init(). To do so you should use LockOSThread.

A simple example illustrating how to use the bindings is available in the examples directory.

If the bindings are generated with extensions included (true by default, or otherwise configured via the -addext and -remext flags) package-global booleans (e.g., gl.ARB_cl_event) indicate whether an extension is available. Availability is determined at Init time based on the ability to load the relevant functions (not via glGetString(GL_EXTENSIONS)).

The procaddr package contains platform-specific functions for loading OpenGL functions. Calling gl.Init() uses the auto subpackage to automatically select an appropriate implementation based on the build environment. If you want to select a specific implementation you can use the noauto build tag and the gl.InitWithProcAddrFunc initialization function.

If the prebuilt, go-gettable packages are not suitable for your needs you can build your own. For example,

go get github.com/errcw/glow
cd $GOPATH/src/github.com/errcw/glow
go build
./glow download
./glow generate -api=gl -version=3.3 -profile=core -remext=GL_ARB_cl_event
go install ./gl-core/3.3/gl

A few notes about the flags to generate:

• api: One of gl, egl, wgl, or glx.
• version: The API version to generate. The all pseudo-version includes all functions and enumerations for the specified API.
• profile: For gl packages with version 3.2 or higher, core or compatibility (explanation).
• addext: A regular expression describing which extensions to include. .* by default, including everything.
• remext: A regular expression describing which extensions to exclude. Empty by default, excluding nothing. Takes precedence over explicitly added regular expressions.
• lenientInit: Flag to disable strict function availability checks at Init time. By default if any non-extension function pointer cannot be loaded then initialization fails; when this flag is set initialization will succeed with missing functions. The generated package exposes Has markers to indicate which functions were successfully loaded. For example if Init cannot load the glAccum function pointer then gl.HasAccum will be false.