Curved Roads

At this point I can say with 99% confidence that X-Plane 10 will feature bezier curved roads. In X-Plane 9, a road is a line segment; you can simulate curved roads by using a lot of line segments, but the global scenery roads are pretty chunky.

X-Plane 10 allows for a road to be a bezier curve, allowing the specification of smooth curves with a small amount of data. This sets us up to trade off visual quality and performance using a rendering setting.

A few notes for authors:

• Like all of the new v10 road features (and pretty much all of the new v10 scenery features), you don't have to use bezier curves in your roads. They are there as an option if you want them.
• X-Plane 10 will not make curves for you; road data that is defined as line segments in the DSF will be rendered as line segments. (This follows the principle that DSFs contain pre-processed scenery data, and the sim shows DSFs exactly as they are written.)

Pay No Attention to the Documentation

The DSF specification alludes to bezier curved roads; this "old way" of encoding curves was never supported in the sim - all versions of X-Plane ignore this data. The "old way" was how we thought we might do curves some day.

The version 10 curve encoding is different; the "old way" will continue to be ignored in version 10. So: do not use the DSF spec to try to make curved roads now. I will post detailed documentation on curved roads once version 10 is available to authors.