A constrained surface is a reference surface constrained by a cloud of points, normals
and optional U′V′ parameters. Use a constrained surface as a reference to create
windscreen layers and curved parameterised windscreen antenna elements.
Surface parameters (U′ and V′) define the outline and internal grid lines of a
constrained surface.
Define the same U′ value at a set of points to force a single U′ grid line to
flow through the points. Similarly, define the same V′ value at a set of points to force a
single V′ grid line.
The range of values assigned to the U′ or V′ grid lines only determine relative
distances in the U′V′ space.
For example, setting the range of the U′ grid lines as -1...1, 0...1 or 0...100
will only influence the relative U′ distance between the adjacent U′ grid
lines.
