Question Why not looking out for an external engine?

[ar81]

I am not really familiar with graphical engines in depth, so if I say something silly you may excuse me.

As I see it, Orbiter or addons may give orders to graphical engines to display. You have DirectX, OpenGL and Glide APIs.

Does addon maker code need to communicate using such APIs directly or does it communicate with Orbiter API that controls graphics and interacts with such platform APIs?

 

[Urwumpe]

Does addon maker code need to communicate using such APIs directly or does it communicate with Orbiter API that controls graphics and interacts with such platform APIs?

Add-ons only need to communicate with Orbiter for the 3D graphics and Windows GDI for the 2D graphics.

Optionally, you can use ANY 3D API (DirectX/OpenGL) for rendering images yourself at the same time as Orbiter runs, but the results may depend on the abilities of the graphics card and driver.