[ptx] Morphing control points

[Terje Mathisen]

ptx-bounces at email-lists.org wrote:
> Should T1, T2, and T+ control points have valuescalculated for
> morphing?  If yes, how should they be calculated?
> 
> For T1 points (vertical lines, correcting horizontal change) use the
> average x position to make the points vertical.  Only changing the x
> value to line the points one over the other.
> 
> For T2 points ( horizontal lines, correcting vertical change) use the
> average y position to make the points horizontal.  Only changing the y
> value to line the points one beside the other.

Those two make sense.

> 
> For T+ points, modify all the middle points of a set of line points.
> Use the two furthest points to define the line and modify the points
> that are in between.  The middle points need to be moved perpendicular
> to the line.

The proper way to handle a straight line is to calculate a best fit (RMS 
error) line past all the points, and then calculate the error for each 
point as the perpendicular offset.

I.e. use the same distance for the morphing distance as is already used 
for the normal error calculation.

> 
> I generally believe in giving the user the power to do what they want.
> I just don't want to be calculating values that will mostly be of no use.

Good idea. :-)

Terje
-- 
- <Terje.Mathisen at hda.hydro.com>
"almost all programming can be viewed as an exercise in caching"