This is an add-on for debug drawing in 3D and for some 2D overlays, which is written in C++ and can be used with GDScript or C#.
DebugDrawDemoScene.tscn in editor 
    
DebugDrawDemoScene.tscn in play mode 
    
3D:
2D:
Overlay:
Precompiled for:
To download, use the Godot Asset Library or download the archive from the GitHub page by clicking the button at the top of the repository page: Code -> Download ZIP, then unzip it to your project folder. Or use one of the stable versions from the GitHub Releases page (just download one of the Source Codes in assets).
addons/debug_draw_3d to your addons folder, create it if the folder doesn't existYour support adds motivation to develop my public projects.