Joining Lines to Arcs

[Soquili]

Some background on Bezier Curves:
http://en.wikipedia.org/wiki/B%C3%A9zier_curve

Info about Splines:
http://en.wikipedia.org/wiki/Spline_(mathematics)

Vector Graphics:
http://en.wikipedia.org/wiki/Vector_graphics

[handrawn]

well like I said, I am not a programmer.... [or a mathematician]

interesting links Bill - thanks, it looks like it could get... complicated

[Soquili]

yes it can become very complicated.

If the imported vector file uses a quadratic approximation for a curve and the native format for the application being used is linear. Making a change to the curve can result in very odd deformation of the curve due to difference in approximations being applied to only a portion of the original curve.

I'm not sure which type of curves are created and editable in Xtreme. Dmitry's SPXE and Xtreme do not seem to share the same type.

[Soquili]

I'm afraid this is all beyond my comprehension. What is it in the definition of a curve that can produce different results if imported from a particular program, when all the visible information about the curve is identical? Why is it that ostensibly identical curves do not exhibit identical behaviour?

Hi Tony,

The curves in the attached .xar look identical, until you look at the edit handles on the points. These are native Xtreme curves so no 3rd party anomalies are being exhibited.

Use the Shape Editor Tool to move one of the curves in the lines (copies are provided at the bottom of the drawing so you can compare to the originals). You will notice the different behaviour exhibited when moving a curve of each line. This is expected because the center point of the curves are different types. One is cusp and the other is smooth.

I hope this helps your comprehension about how the point (node) types can affect how a look alike curve can differ.

Add the different point (node) types that a 3rd party app can add to the mix, things can become very unpredictable. The primary difference is most likely how a particular app defines splines (curves).

[steve.ledger]

Antons XAR file format post has been moved to here:
http://www.talkgraphics.com/showthread.php?t=42257

[tonylondon]

Hi Tony,
Add the different point (node) types that a 3rd party app can add to the mix, things can become very unpredictable. The primary difference is most likely how a particular app defines splines (curves).

What would be logical to me would be that when curves look the same, including having the same "settings" in terms of curve/line (C vs L) and join (S vs. Z) then they would behave exactly the same way. (If they don't then it would suggest that the import filter is not working correctly?) Otherwise it would imply that there is something within the recipient program's definition of the object that is not displayed to the user.
Many thanks Bill for taking the time to explain things; not an easy task in my case!