Friday, August 10, 2007

Split Beziers Part 3: A Workaround

In my previous post I described a bug where, when we have a split vertex in an apt.dat layout, X-Plane would draw taxiway lights all over the place. Fortunately, there is a workaround.

Remember that a split vertex is represented as two or three colocated vertices with one or two zero-length segments connecting them. The bug is that zero-length segments cause lights and lines to go haywire.

The fix is therefore simple:
  1. Programs that write apt.dat files can simply set the attributes on the zero-length segment to none.
  2. Future versions of X-Plane (with a real bug fix) can join taxiway lines even when there is a zero-length "break" in the attributes.
This picture shows the results - a split vertex with no attributes on the zero-length segment.

The next WED beta will automatically export split vertices this way - there will be no need to patch X-Plane or change your WED layouts.

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