What is the relationship between EGL and OpenGL?

Question

I\'m writing an implementation for OpenVG and OpenGL|ES in Go, both of which depend on the Khronos EGL API, supposedly to ease portability I guess.

I\'m writing an

Answer 1

You can bind EGL_OPENGL_API as the current API for your thread, via the eglBindAPI(EGLenum api); a subsequent eglCreateContext will create an OpenGL rendering context.

From the EGL spec, p42:

Some of the functions described in this section make use of the current rendering API, which is set on a per-thread basis by calling

EGLBoolean eglBindAPI(EGLenum api);

api must specify one of the supported client APIs , either EGL_OPENGL_API, EGL_OPENGL_ES_API, or EGL_OPENVG_API

The caveat is that the EGL implementation is well within its rights not support EGL_OPENGL_API and instead generate an EGL_BAD_PARAMETER error if you try to bind it.

It's also hard to link to libGL without picking up the AGL/WGL/GLX cruft; the ABI on these platforms require that libGL provides those entry points. Depending on what platform you're playing with this may or may not be a problem.