MetaGL

MetaGL
Website	https://metagl.openeggbert.com
Programming language	C++
C++ standard	C++23
Targets	OpenGL ES 3.0+
Used by	EasyGL

MetaGL is a low-level, type-safe C++23 wrapper targeting OpenGL ES 3.0 or higher. It is the foundation layer used by EasyGL and provides:

Runtime OpenGL function loading via a host-supplied GetProcAddress callback
Type-safe enum class wrappers for OpenGL constants (buffer targets, shader types, texture formats, etc.)
Thin inline-style wrapper functions in the metagl namespace (metagl::GlBindBuffer, metagl::GlClear, …)
No windowing, no context creation — the host application owns the GL context lifecycle

Architecture

Host application
      └── provides GL context + GetProcAddress callback
              └── EasyGL   (OOP wrapper, namespace easygl)
                      └── MetaGL  (function pointers + type-safe API, namespace metagl)
                              └── actual OpenGL driver

Public API overview

Header	Contents
`metagl/Types.hpp`	Primitive GL type aliases (`GLuint`, `GLint`, `GlGetProcAddressFn`, …)
`metagl/Enums.hpp`	Type-safe `enum class` wrappers for GL constants
`metagl/Functions.hpp`	Declarations of all `metagl::Gl*` wrapper functions
`metagl/Loader.hpp`	`metagl::Initialize()` / `metagl::IsInitialized()`
`metagl/metagl.hpp`	Umbrella header

Usage

#include <metagl/metagl.hpp>

// Initialize once after host creates the GL context:
metagl::Initialize(my_get_proc_address);

// Use type-safe wrappers:
metagl::GlClearColor(0.2f, 0.3f, 0.3f, 1.0f);
metagl::GlClear(metagl::ClearBufferBit::Color | metagl::ClearBufferBit::Depth);

metagl::GLuint shader = metagl::GlCreateShader(metagl::ShaderType::Vertex);

Design notes

Raw OpenGL values (GL_ARRAY_BUFFER, GL_VERTEX_SHADER, …) stay internal to MetaGL. Callers use enum class values; conversions to GLenum happen inside metagl::detail. No OpenGL headers are exposed in public headers. Plain OpenGL and OpenGL ES older than 3.0 are not supported.

Build

MetaGL is intended to be consumed as a CMake subdirectory:

add_subdirectory(../meta-gl meta-gl)
target_link_libraries(my-target PRIVATE meta-gl::meta-gl)