My system reports that im using OpenGL 4.2: https://pastebin.com/uXu3BLxX But when i try to use that OpenGL vesion to write a program with it, it fails, the maximum version i can use for that is OpenGL 2.1, why does that happen?

  • e0qdk@kbin.social
    4·
    1 year ago
    • You are running Wayland
    • Your GLFW programs are using EGL, not GLX, to talk to your graphics drivers/hardware
    • glxinfo is talking to a software implementation, not your hardware
    • glxinfo’s output is irrelevant if you want to talk to your hardware with your current configuration; if you want to use the software implementation recompile GLFW targeting GLX and it should match that (but will be VERY slow).
    • One of your old posts describes your GPU as: Intel GMA3100 (G31) – is this the same system you’re running on now? If so, that is ancient. It looks like that came out in 2007 – which predates the existence of OpenGL 3.0; so, getting 2.1 as the newest context available when talking to actual hardware is not surprising…
      • e0qdk@kbin.social
        2·
        1 year ago

        Try compiling GLFW from source against GLX instead of EGL. If glxinfo is talking to a software implementation running on your system, I’d expect GLFW built to use GLX would use the same implementation on your computer.

          • e0qdk@kbin.social
            2·
            1 year ago
            • GLFW is intended to be built with cmake.
            • After unzipping the source, make a build directory, and configure glfw3
            • ^^ I like using ccmake to do this interactively, but you can also just pass flags to cmake if you know what they are
            • You should build with GLFW_USE_WAYLAND and GLFW_USE_OSMESA turned off to get it to try to build against X11.
            • You will probably also want to turn off GLFW_BUILD_DOCS, GLFW_BUILD_EXAMPLES, GLFW_BUILD_TESTS
            • You can adjust CMAKE_INSTALL_PREFIX if you don’t want to use the /usr/local default install path.
            • After generating a Makefile, run make and make install
            • glfw3 generates a pkg-config compatible .pc file as part of its build process that lists flags needed for compilation and linking against the library. Normally, you’d just call pkg-config --cflags --libs --static glfw3 to get this info as part of your own build process (in a Makefile, for example) or else require glfw3 as part of a cmake-based build, but you can read what’s generated in there if that program is not available to you for some reason. In case it’s helpful for comparison, what I get with a custom build of the static library version of glfw3 installed into /usr/local on a slightly old version of Ubuntu is output like -I/usr/local/include -L/usr/local/lib -lglfw -lrt -lm -ldl -lX11 -lpthread -lxcb -lXau -lXdmcp but you may need something different for your particular configuration.

            Basically, something like this, probably, to do the compilation and get the flags to pass to g++:

            wget 'https://github.com/glfw/glfw/releases/download/3.3.8/glfw-3.3.8.zip'
unzip glfw-3.3.8.zip
mkdir build
cd build
cmake -D GLFW_BUILD_DOCS=OFF -D GLFW_BUILD_EXAMPLES=OFF -D GLFW_BUILD_TESTS=OFF -D GLFW_USE_OSMESA=OFF -D GLFW_USE_WAYLAND=OFF -D GLFW_VULKAN_STATIC=OFF ../glfw-3.3.8
make
make install

pkg-config --cflags --libs --static glfw3

            If you want to just compile a single cpp file after building and install, you can do something like

            g++ main.cpp `pkg-config --cflags --libs --static glfw3` -lGL