Something I’m seeing now that WED is in beta: airport layouts with the entire taxiway structure made from one really complex polygon.
I’m not really sure if this is a good idea. First the potential problems:
- I suspect that the creation of the taxiway layouts can get slow when the number of sides in the airport layout is really huge and there are holes. I don’t know this for a fact because we let the OpenGL libraries do the heavy lifting. Because this loading is done on a second CPU, it might not be noticeable to all users.
- The pavement can have only one texture direction per polygon, so multiple polygons may be necessary.
- Certainly in WED having a few large complex polygons slows down editing — if all else is equal, the tools work better with smaller polygons.
Now…overlapping pavement is generally bad (that is, there is a performance cost), but more sides are also expensive. More thoughts:
- The more square feet of overlap, the worse. So a small overlapping intersection is not so bad, but avoid layering a huge polygon on top of another huge polygon, which just strains the video card.
- Fewer segments are better. Consider two crossing taxiways…8 segments with overlap, but 12 by making a plus.
- But wait – the above example is misleading…if you need to change the light types so the blue taxiway lights don’t cross the intersection then you’ll need to add 4 more segments, so now it’s 12 and 12 – a wash. (In this case, having one big polygon is probably easier to manage.)
And for performance…
- Try going to your layout from far away and watch the last step of loading…if it starts to take a long time to “preload” things it means your layout might be a bit complex.
- Do not expect X-Plane to become faster at loading airport layouts…the limiting factors are proportional to complexity, so if you have a killer polygon now it’ll be pretty expensive later too.
One other note, from a conversation with Tom…WED splits vertices into a fixed number of segments (per zoom level) so splitting a bezier makes it smoother. X-Plane does not! X-Plane splits beziers based on the overall curvature, so adding more nodes without changing the shape has no effect.
So please do not try to use the split command to make X-Plane “smoother”. We’ll provide a rendering setting for this some day. The current value was chosen because anything smaller looks awful and you have to make it a lot bigger (read: a lot slower fps) to get an even marginal visual improvement.
