OpenGL Registry

Parses the Khronos OpenGL registry into a standardized and user-friendly data structure that can be walked through, providing an essential need for tools that generate code to create an OpenGL wrapper/bindings, for any language. Given an API name, version, and profile, is capable of filtering and grouping data structures that cover that specific subset of definitions, using a typical Ruby object-oriented approach.

Add this line to your application's Gemfile:

gem 'opengl-registry'

And then execute:

$ bundle install

Or install it yourself as:

$ gem install opengl-registry

You can either download the latest copy of gl.xml directly from the Khronos repo, or fetch it through the API.

require 'opengl-registry'

GL::Registry.download('/path/to/save/gl.xml')

For successive runs, you can simply check that the version you have is up to date.

if GL::Registry.outdated?('/path/to/gl.xml')
  # Download updated copy
end

First step is to create the registry, which is essentially a container that stores every definition defined for OpenGL, OpenGLES (Embedded Systems), and OpenGLSC (Security Critical).

registry = GL::Registry.load('/path/to/gl.xml')

Alternatively, if you have the XML as a string...

registry = GL::Registry.parse(xml_string)

In order to filter results and definitions by a subset of the API, version, profile, etc, create a new spec.

extensions = ['GL_ARB_get_program_binary', 'GL_ARB_texture_storage']
spec = GL::Spec.new(registry, :gl, 3.3, :core, extensions)

The created spec object can be then used to enumerate through every definition that this subset defines. The data will automatically be filtered and sorted, allowing for easy inspection of each entity.

spec.functions.each do |function|
  # Print out the function name and return type
  puts "#{function.name} (#{function.type})"
    
  # Loop through argument definitions
  function.arguments.each do |argument|
    puts "  #{argument.name} (#{argument.type})"
  end
end

spec.enums.each do |enum|
  # Enums also define "groups" for creating C-style enumeration types, etc
  puts "#{enum.name} = #{enum.value}"
end

There are many helper functions throughout for detailed filtering, and retrieving any relevant information that might be required, such as generating bindings for a particular language, etc. See the documentation for more details.

The gem is available as open source under the terms of the MIT License.