How to extend path on only one side

[Micha5E6D]

Hey guys ,

I am rather new to AI Illustrator and am currently facing the following problem. I hope I can describe it raeasonably clearly: I have 2 shapes, the red one is given and the blue one I want to adjust:

What I want to achieve is that the blue shape starts at the appropriate place at the bottom as well as at the top and has the same arc as the red shape.So roughly speaking something like this: 

Currently I just dragged the arcs manually and estimated the positions, but of course this is not solved cleanly. In principle I would need the option "Move path" but only for the left side of the red shape. How would you solve the problem? 🙂

[Jacob Bugge · Accepted solution]

Micha,

Always make backups of the artwork before any irreversible steps.

One crude way is to start over which implies a rough redoing of the red path; the original can be locked to use as a guide.

If you wish to keep the red path exactly as it is, you can smoothly continue the (leftmost) segments of the top and bottom sides of the red path, then create a path corresponding to the left side.

To continue the (leftmost) segment of the top side, you can (Smart Guides being your friends):

0) Make the blue rectangle much larger so you are free to trim it, you can also extend it to the right to overlap the red path, then Ctrl/Cmd+X+B to place it beneath the red path in the stacking order, then lock it;

1) Click the leftmost part of the top side of the red path, so the corner Anchor Point and the handle is revealed, then with the Line Segment Tool ClickDrag from the Handle into the Anchor Point (Smart Guides say handle and anchor when you are within snapping distance), then delest and ClickDrag the new line by its lower left end Anchor Point to snap to the corner Anchor Point;

Now you have the direction and length of a matching Handle which will ensure a smooth continuation;

2) If you wish to keep the curvature at the corner Anchor Point, skip to 3), if you wish to be able to extend it, click the lower left Reference Point in the Transform panel, then increase the W or H value (you can add *2 or something in the box) and Ctrl/Cmd+Enter to extend;

3) With the Pen Tool, Click and Hold close to the corner Anchor Point/end of line, then press the Spacebar and Drag to snap to the Anchor Point, then let go of the Spacebar and Drag along the line to the far end or as desired, then continue the path by at least one more Anchor Point to shape the top side of the blue path as desired, ensure that the new path extends past it; when drawn you can adjust with the Direct Selection Tool, and hide the line from 1);

4) Repeat 1) - 3) for the bottom side;

Now you have the shapes of the top and bottom sides of the blue path;

5) Trim the blue path by the new paths (you can use Object>Path>Divide Objects Below or Shape Builder or Pathfinder (Divide)), deleting the unwanted bits;

You can make the shape of the right side of the blue path as freely as in 6) or predetermined as you wish, ensure that the new path extends past the top and bottom of the blue path;

To have an equidistant (guide) following (of) the left side of the red path, you can:

5) Direct Select the segment that forms the left side (or hold Shift and select if more than one), then Ctrl/Cmd+C+X+F to bring it to the front (if more than one, Join them), then Object>Path>Offset Path using a, offset that corresponds to the desired gap, then Hide the original segment(s) and delete each straight end part of the offset path with the Direct Selection Tool (remember to deselect first), then delete the rightmost path;

6) If desired, you can edit the path from 5) or just use it as a guide for a new one;

7) Trim the blue path ad in 5).

Now you have all the curved shapes of sides of the blue path related to the red path; if needed/desired, you can create the shape of the left side as desired (straight or curved), and trim again.

[Micha5E6D]

Thank you very much for your detailed answer. Unfortunately, it is somewhat difficult for me to understand. Would it be too much to ask if you make a short VIdeo of the procedure ?:)

[michelew83603738 · Accepted solution]

What @Jacob Bugge is correct and a lot of steps. If this is something you plan to do frequently, AstuteGraphics has a plugin that allows you to extend a path along a curve such as you are trying to to here very quickly. It might e worth checking out and they have a 14 day free trial I believe.

[Kurt Gold]

Micha,

you told that you are rather new to Illustrator. That's just fine.

And at the same time it is one of the most important reasons to learn how to draw with the Pen tool. If you can passably handle this tool, you really do not need over-complicated ways or even plugins. You would just be able to draw it in 20 or 25 seconds.

[Micha5E6D]

Would you mind giving me a short demonstration of how you would solve this task just with the pen tool ?:)

[Kurt Gold]

I could do that, Micha.

But honestly I'm not going to do it. There are already thousands of public tutorials out there that explain how to use the basic drawing tools. Many of them are certainly very useful.

Apart from that, there are always some good instructions at Adobe:

https://helpx.adobe.com/illustrator/using/drawing-pen-curvature-or-pencil.html

Feel free to ask specific questions in case something is unclear or something may confuse you.

[Jacob Bugge]

Micha,

Now that different ways and means have been brought up, to elaborate on the option of starting over, if I were to make such a tricolore (the background being the third colour), I should create the entire outer shape first (more or less based on the existing red shape) to get the best overall appearance, then cut out the shape in the middle, then colour the remaining paths left and right.

[Met1]

Make two rectangles, group, then play with Object→Envelope Distort→Make-with-mesh (or even just Make-with-warp might be enough)...