Layering QML on top of OpenGL scene

[bam80]

Hi, thank you for the project!
For similar https://github.com/organicmaps/organicmaps app, we have an idea to adopt QML UI as alternative to currently in use Qt Widgets one.
What I see from Dependencies, your project draws a map purely from within QML, using QML wrappers for Mapbox GL/MapLibre.

Organic Maps has it's own C++/OpenGL engine to render maps, so intended approach there is slightly different - the main idea is to place an overlay with QML controls on top of OpenGL layer with map. QML scene should probably spawn a full window to handle gestures. That should support transparency and input events pass-through.

Do you have an idea how to best achieve that from Qt/C++ point of view?

[rinigus]

You will probably need a layer similar to https://github.com/rinigus/mapbox-gl-qml. Something that can be between C++/OpenGL and QML by exposing your map handling.