8 Replies Latest reply on Sep 22, 2009 7:29 PM by RogerPaine

# shorten a curve by a specified amount

I'm looking for an easy way to chop a specified amount off a curve or an arc - specifically shorten the length of the line by a given amount rather than shortening by the length of the cord of the arc; sometimes the curve is not an arc which makes the calculation rather complex.

Another way of saying it might, for example, be "I have a wiggly line that I need to cut 3mm off the end of".

• ###### 1. Re: shorten a curve by a specified amount

That would be a great feature also a very complex one perhaps. But not possible in Illy unless you were very good at scripting and i do think it can be handle by a script though it would have be a very thorough one and quite cleaver to it would first have to calculate the radius of the curved section you want to shorten, which Illustrator should be able to do then it have to figure out the the angle that a marker could be set at for an anchor point to be 3 mm from the selected end of the path in order to isolate a segment that it would them add the anchor point to and the select that segment and delete it.

I believe Illustrator can do the calculations but hoe to properly tell it to do so and act on it might be difficult however it might just as well be a piece of case and the place to find out would be Illustrators Scripting Forum. There may already be  such a script in existence.

• ###### 2. Re: shorten a curve by a specified amount

Roger, would you accept a method which sometimes may be slightly inaccurate?

For example, instead of 20 mm it would be 20,011 mm or 19,997 mm?

• ###### 3. Re: shorten a curve by a specified amount

Yes Kurt, I think I can cope with a few 100ths of a mm. Let's see your plan!

cheers

Roger

• ###### 4. Re: shorten a curve by a specified amount

Roger,

Please describe a real-world situation in which you need to do this. How often do you need to do this?

JET

• ###### 5. Re: shorten a curve by a specified amount

The debug panel might help a little. When you know the length of a path, you could kinda guesstimate how much you need to chop off...

Mylenium

• ###### 6. Re: shorten a curve by a specified amount

Download, unzip and open the following Illustrator file (AI 10 format, ca. 30 kb).

Shorten Paths

In that file there are 21 graphic styles based on Pattern brushes. Now:

1. Select the path
2. Copy and Paste in front
3. Apply one of the graphic styles
4. Object > Expand Appearance (do not deselect)
5. View > Guides > Make Guides
6. While smart guides are enabled, zoom in, get the Scissors tool and cut according to the guides you created at point 5.

Note that this method is not 100 % accurate and on some/many paths you'll need to modify the pattern brush in order to get more accurate results (for example, see graphic style 'exceptions')

If you need other lenghts, then you would have to create your own graphic styles.

• ###### 7. Re: shorten a curve by a specified amount

Jetaimage - I am an eyewear designer and a cyclist. In the first instance, I want to be able to shorten paths by a specified amount to correctly draw cross sections of lens/frame designs and secondly, to simplify the process of route planning for group rides - I have a scanned scale map of the region over which I have traced the roads (mostly auto-traced), Cadtools "cadtracker" shows the length of a path to scale but does not provide a way to cut it accurately to length. It would be nice if I could add a point 40mm (or whatever) from the end of a path so I can plan rides to specific distances. Currently, I have a guess, cut the path, check the length of the bit I want in cadtracker; if it is not close enough I undo and take another guess etc.

• ###### 8. Re: shorten a curve by a specified amount

Kurt - very clever

cheers

Roger

So, actually, you can make a straight path whatever length you want to either chop off or end up with, make it into a pattern brush with "add space to fit" selected. Copy>paste in front (the path you want to shorten) > apply the brush > expand and use it to cut the original path... or miss out the copy and paste part and just delete the bit you don't want after expanding. No worries.