I am working with a 2GB Raspberry Pi 4 with the very latest edition of the OS which was shipped with the Pi kit I bought (Debian 10.2, kernel 4.19.75-v7l+).
Long long ago (around the time of the first Pi Zero IIRC), I succeeded in getting GLES functional in a command-line environment without X. Unfortunately, somewhere along the way I lost all that (probably re-imaged the wrong SD card without a backup...). Recently I've started afresh, but things aren't going very well.
It's difficult to make this long story shorter, but ultimately I came across the advice published here, involving combining EGL and dispmanx.
What my problem seems to boil down to is EGL_BAD_NATIVE_WINDOW returned by eglCreateWindowSurface. According to khronos.org, this error "...may be generated if native_window is not a valid window for the same platform as display." If I am honest, I must admit I have almost no idea what that means.
What other info should I provide in order to get help on this?
Thanks in advance!