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I have two lines that are not intersecting, but I would like to extend them until they touch.

Screenshot of two non-intersecting lines

What's the best way to go about this?

Greenonline
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CodeZealot
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2 Answers2

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Edit: So you say that it's a bezier curve, in that case you can't do this operation, unless you convert to mesh then back to bezier.

First thing, in the options enable Auto Merge and Split Edges & Faces:

enter image description here

Then select a vertex, press GG to slide, and C to extend the slide beyond the limit. When the edges will cross it will automatically create a vertex thanks to the options:

enter image description here

moonboots
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    Wow, I didn't even know this existed. Good answer – Duarte Farrajota Ramos Apr 17 '23 at 15:31
  • Thanks for your answer. But unfortunately, I do not see those options available. Do you have an addon by any chance?

    The only options I see are three check boxes. One for 'Origins', 'Locations' and 'Parents'.

     – CodeZealot Apr 17 '23 at 16:01
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    You need to be in Edit mode – moonboots Apr 17 '23 at 16:12
  • So I managed to turn on 'Auto Merge' and 'Split Edges & Faces', but when I double press G after clicking the vertex of my line, my line is still following my cursor and not staying on its current course. Any idea why that may be the case? – CodeZealot Apr 17 '23 at 17:09
  • Could it be because I'm using a Bezier curve? – CodeZealot Apr 17 '23 at 17:16
  • Yes you didn't precise, in that case, convert your curve to mesh, do the operation, then back to bezier – moonboots Apr 17 '23 at 17:19
  • Using your steps, I managed to get edge slider working and can extend lines. However, the 'intersecting vertex' is not being made. Both Auto-Merge and Split Edges & Faces are ticked. Both lines were converted to mesh too

    There is a step I'm missing somewhere. When I open a new project, here's what I do.

    1. Tick auto-merge and split edges and faces.
    2. Bring in two Bezier curves.
    3. Convert both Bezier lines to poly lines (to make them straight).
    4. Convert both lines to mesh.
    5. Use the 'GG' + 'C' to extend both lines to get an intersection.

    But the vertex still doesn't appear.

     – CodeZealot Apr 18 '23 at 12:05
  • The 2 edges need to overlap, in my case they are aligned on the Z axis, otherwise no vertex can be created. So first thing maybe select all in Edit mode and press SZ0 – moonboots Apr 18 '23 at 12:09
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    I found my mistake. I had them both as separate items in my scene collection. After joining them with CTRL-J. I now get my vertex. Sorry for sending you on a wild goose chase. – CodeZealot Apr 18 '23 at 12:13
  • Oh ok great then ;) – moonboots Apr 18 '23 at 12:17
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@moonboot's way, the straight-up, straightforward use of tools, is preferable, IMO.. but if you had to do this repeatedly, then the shipped add-on Mesh:tinyCAD has a 'VTX|AUTO' operator that will extend coplanar edges to their intersection:

enter image description here

Robin Betts
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