How to check for OpenGL support?

[timart]

What is the best way to check for OpenGL support when my JUCE app/plugin opens? If a computer does not support OpenGL, I want my app to show a warning pop-up and render without OpenGL.

Is this approach reported by @reuk still the best method for checking OpenGL support?

How to test for OpenGL?

An approach I’ve used is to: Create a test component with 1x1 px size, positioned in the corner of the window. This component should hold an OpenGLContext. Give the OpenGLContext a custom renderer. This renderer will simply check some of the context’s extension function pointers in the first paint callback, and then use MessageManager::callAsync to report back whether or not the context supports all the features that are required. When the callback is fired, the owner of the test component can…

[jrlanglois]

It’s not terribly straightforward. Feel free to have a look at a class I wrote that handles applying GL 3 or removing the context if GL isn’t found (or too old):

• squarepine_core/HighPerformanceRendererConfigurator.h at main · SquarePine/squarepine_core · GitHub
• squarepine_core/HighPerformanceRendererConfigurator.cpp at main · SquarePine/squarepine_core · GitHub

Note that you have to attach (or “configure” in this case) on the main thread, and depending on the system you might only be able to attach a bit later than construction time of your editor.

Loosely speaking, you can do this with the configurator (you’ll probably want to use a SafePointer):

  MessageManager::callAsync ([&]()
  {
      configurator.configureWithOpenGLIfAvailable (*this);

      if (auto* context =  configurator.context.get())
          context->executeOnGLThread ([&] (OpenGLContext& c)
          {
              configurator.paintCallback();
          }, false);
  });