Rune wrote:
> 
> "Ron Parker" wrote:
> > I see it.  I'm not sure what's causing this.  The strange
> > thing is that it applies to the edges, whose behavior I
> > thought I understood.
> 
> Uh-oh. This doesn't sound good.
> 
> Anywhere else I can seek help?

Not only do the points in question have to be co-planar,
but the control points at the edge of the patch must lie on
the line between the two adjacent interior points.

A1   A2   A3   A4/B1   B2   B3   B4
A5   A6   A7   A8/B5   B6   B7   B8
A9   A10  A11  A12/B9  B10  B11  B12
A13  A14  A15  A16/B13 B14  B15  B16

In this example, the point A8/B5 (shared between the two patches)
must lie along the line running from A7 to B6.  Likewise, the
shared point A12/B9 must lie along the line from A11 to B10.

It seems to be that whenever you cross from one patch to another, the
border point *must* lie on the line between its adjacent points, and in
the case of corners, it must line on the lines going in both directions.

If you fire up Moray and play with a 2x2 Bezier sheet, you'll note that
some of the control points are not manipulable by the user; they're
set from the other points in order to keep things smooth.

Regards,
John

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