OCaml OpenGL ES 3.0 bindings

Introduction

This project aims at providing a portable way to write OpenGL (more precisely OpenGL ES) application in OCaml. It comes in three parts:

• Low level bindings allowing direct calls to OpenGL ES functions. These bindings try to remain reasonably type-safe using polymorphic variants to encode enumeration types. The low level bindings also provide some sanity checks for the size of bigarrays which allow to capture quite a lot of errors with clear messages.

• High level bindings providing auxiliary functions like matrix inversion to ease the development. For instance, to use shaders with the high level bindings, you may use compile_shader with the sources code, to get a value of type unit program. Then, you can set the variables of the shaders (uniform or attributes), either as constant or function and get an OCaml function to finally run the shaders.

• A wrapper to open a window, start the main loop and interact. Currently the following framework are supported:

  • X11+EGL
  • Wayland+EGL

  We would like to support different platforms in the future (Windows, Android, iOS, ...) without changing the interface.

Authors

• Alexandre Miquel (initial low level bindings for GLES 2)
• Christophe Raffalli (partial port to GLES 3.0, high-level bindings and examples)
• Rodolphe Lepigre (maze example and port to the dune build system)

Installation

To install from source, clone the repository and run make && make install. Alternatively, you can pin the repository using the following commands (only one of latest two is useful):

opam pin add gles3-stubs.dev https://github.com/craff/gles3.git
opam pin add gles3.dev https://github.com/craff/gles3.git
opam pin add gles3-x11.dev https://github.com/craff/gles3.git
opam pin add gles3-wayland.dev https://github.com/craff/gles3.git

Documentation

The OCaml documentation can be extracted to a webpage using make doc. The generate page is the placed at _build/default/_doc/_html/index.html).

The repository also contains multiple examples:

• examples/flying_cube: a rotating cube.
• examples/curves: a wire-frame cube
• examples/exploding_cube: the names says it all
• examples/cubeTexture: a rotating cube with a texture (including a text).
• examples/cubesAndShapes: rotating cubes and 8 implicit surfaces with simple shadow mapping.
• examples/spheres: many bouncing spheres, using domain to run multicore.
• examples/maze: a maze generator with a simple exploration camera.
• examples/click: illustrates how to use a shader to click on object and get the ID of the object and the position of the clicked point in 3D.
• examples/window: flying_cube in two distinct windows.

To run the examples: to run an example, move to its directory and run one of the two following commands

   BUILD_WAYLAND_EXAMPLES=true dune exec -- <name>_wayland.exe

where name is the name of the file defining the example without extension. example: flying_cube_x11.exe for the first example.

Contributing

Contributions are very welcome!

Things to do:

• Test a lot.
• Write more documentation.
• Complete the low-level bindings (see PRIMITIVES).
• Improve the high-level bindings guided by more examples.
• Provide support for more platforms.
• Find a way to support multiple version of GLES (at least 2.0, 3.0, 3.1, 3,2) with only one OCaml library, and possibly in a transparent way when using the high-level bindings (i.e., the high level bindings should test the version and make the best choice).
• Collect regexp for error message in GLSL for most GLES vendors to give good error messages in all cases (only nouveau/mesa is currently supported). It seems that OpenGL ES does not standardize even error message positions.