LensFlare shader for Godot?

Hello, Can I ask if anyone tried or have a lens flare shader for great sunny scenes?

Maybe you just get screen coordinates of light source in screen space like X and Y where they are -1..1

Then you multiply those by some coefficients and draw sprites on screen

Seems really simple, but I do not yet know how to get screen coordinates from get_global_transform()

I believe it is more efficient than using a shader