Sunday, September 24, 2006

Is X-Plane on Crack?

I just fixed a bug in the mesh crack-patching code. This is a tricky subject, so here's some information before you file bugs:

Two separate scenery tiles (whether DSF or ENV) may not line up perfectly when placed edge-to-edge. The most common reason is because their elevation data can come from different data sources, but in a few cases files from the same render can have alignment problems.

(In the case of the global scenery, if we have special circumstances like water or airports that must be flat and the features span a tile boundary, the flattening may not work the same way in both tiles. The scenery is also rendered on blocks on different computers, and the blocks may not tile perfectly.)

Whether the error is due to a bug or just two scenery packs together, the sim tries to do its best to fix any gaps in the terrain mesh. (The sim does not try to fix different textures that touch; this is beyond the sim's capabilities of analysis.) X-Plane will take whichever file is loaded most recently and try to realign its edges to match the old edge. When this works right, you can't see a seam. More importantly, if an airport spans that border, you can drive over the border (on a runway) without the plane hitting a bump.

I just fixed a bug in the crack-patching code where it would sometimes incorrectly fix a patch. So if you see a 'crack' in the terrain (basically you would see the sky color showing between terrain triangles as a sliver of light blue or grey) please report it as a bug, but be sure to include the following information:
  • Please include a log.txt file so we can see what you have installed. Be sure to quit x-plane before emailing the log.txt file.
  • Please include a screenshot of the crack. Turn on the framerate, plane lat/lon and camera position datarefs.
  • Please set your sim resolution to 1024x1024 or smaller and send the original PNGs. Please do not crop, process, or compress them. Please do not send JPEGs.
  • Please tell us the nearest ICAO airport so that we can easily go to this location.
As always our bug reporter can be found on a link from

Some crack bugs may be due to a scenery defect (to be addressed the next time we make new scenery), some may be due to sim bugs, and some may be due to the combination of two scenery packages next to each other.

1 comment:

Anonymous said...

It is extremely interesting for me to read that post. Thanx for it. I like such themes and everything that is connected to this matter. BTW, why don't you change design :).