And I am wondering do you use .fx files as well or do you inject your DL into the scenery using couatl?
Yes, we updated all our sceneries that use PBR ( non-PBR scenery don't require that ) to use V5-specific .FX files.
And yes, Couatl has everything to do with the fact you see almost ZERO impact of DL in our airports, compared to every other developers airports, that don't have much control over how DL lights are created. While almost everybody just places all the DL in a .BGL, hoping for the best, we have a fairly complex "hybrid" method, which works this way:
- The .BGL contains a few basic DL lights, not not have the scenery be entirely pitch black at night, and these are made in the traditional way, and are always on.
- When you approach close to gates, we use what we call the "collision system", which is a system provided by Couatl ( runs in the background, with zero effect on fps ), so we can trigger things to appear only when the airplane is inside a specific area, not just a rectangle or a radius, but a polygon with a precise shape, nothing you see on screen, it's a logical polygon.
This way, we create/destroy additional DL lights, which are the ones with the biggest impact on fps because, instead of having 150-200 DL all visible at the same time, which would be the case if we used just the .BGL format, we only have the generic ones + the one on the terminal closest to you, even the right side so, typically, we don't have more than 6-7 DL lights in addition to the generic ones, so the overall count of lights in the scenery is always way lower than any other comparable scenery.
We use this kind of optimization for lots of things, like visible passengers inside terminals ( KORD and LFSB ), or the active Gate Panels ( KORD ), and for some of the ground traffic too ( KMEM, KSDF, KCLT ). The DL optimization is used for all our sceneries that comes with DL, so all of them from KCLT onward.