Bizarre trim and combine paths problem

So lately, I've run into a really weird - and incredibly annoying - problem.

I've got two rivers close to each other that I want to combine. One of these rivers also has a portion that needs to be trimmed off (say, I moved a coastline inward, so now the river overhangs it). So I trim that river, then I use "smooth to straight" on both of them, and then combine paths to join them.

When I get to that third step, using combine paths, suddenly the part I trimmed is back. And the end of the other river (the one that wasn't trimmed) wants to connect to that end, the end that only exists again because CC3+ decided to bring my trimmed portion back to life when I hit combine paths.

Naturally, when this happens, I just hit escape to back out and try to fix this mess. In SOME cases - not always, but sometimes - when I hit esc to get out of the "combine paths" operation, things get even weirder when the trim gets reversed! The part I trimmed remains back, and the part I DIDN'T trim disappears entirely.

The only way to get around this, I've found, is to do my trim, then save and close CC3+ entirely, then reopen it. If I do that, then the trimmed portion will usually stay gone when I then use combine paths after reopening the map.

Anyone have any idea what could be causing this, or how to fix it? Thanks!

EDIT: Now it's doing it several operations later. I trimmed, saved, closed, reopened, smooth to straight, combine paths, straight to smooth, success... did some other unrelated stuff, saved, came back to this river, added an entirely new portion to it, and when I try to combine paths to connect THAT portion, suddenly the trimmed part from like twenty minutes ago is reappearing during the "combine paths" operating and wreaking havoc. Any help is appreciated, this is driving me batty, lol

Comments

  • This happens to me, if I try this while the rivers are 'smooth'. So I first 'straighten' them, do the edit, then 'resmooth' them.
  • LoopysueLoopysue ProFantasy 🖼️ 40 images Cartographer
    Yep. Same here. If you want to edit smooth lines its always best to make them straight before you even start :)
  • MonsenMonsen Administrator 🖼️ 81 images Cartographer
    I haven't experienced this myself, but I see how it can happen.
    As you may know, smoothed entities doesn't actually go through their nodes, rather their path is calculated based on the position of the node, and any point of the curve is mainly being affected by three nodes. While this is true for a straight path too, a straight path always goes through it's nodes, and you can move nodes closer to each other without changing their corners (bends) as long as you move the node along the actual path. Not so with smooth nodes, as this would affect the curvature of the bend. So, smooth paths aren't really trimmed, they just have the trimmed part visually removed, but it is still there, which is evident if you use list on them. But when Combine Paths comes along, it grabs the entire path, not just the visible part.
  • Aha! I see - so it's a quirk of how nodes and smooth paths work. So what I'm taking away from this is that the best thing to do is to use straight to smooth before even the TRIM, not just before the "combine paths". This makes sense now, so thanks!

    As for the river that was already in-progress (had been trimmed while smooth, then smooth to straight, then I try to combine paths which is when all hell breaks loose), based on all of your responses in this thread, I decided to try and solve this by... letting all hell break loose. I hit combine paths, the bit that had been trimmed returned, and I just accepted it. Undid the combine operation (since it attached to the wrong ends), but the undo still leaves the suddenly-back-from-the-dead trimmed portion visible. So I trimmed the same part away again, but this time, it was already straight when I trimmed it. And then when I went to combine them, everything worked fine!

    So that seems to be it. Now I can get back to working smoothly, without this getting in my way. I'm currently in the process of redoing probably 60-70% of the rivers I had in my map (which is of an island nation that is over 900,000 square km in land area, so there are A LOT of rivers!). Last year, I completely redesigned the whole place basically, moving all my provinces around like jigsaw puzzle pieces and changing the overall shape of the country. Naturally this broke many of the rivers. I've only recently gotten to the "fix the rivers" phase of this whole redesign, so as you can imagine, suddenly having this huge roadblock in the way of being able to trim a river then add a new sections to it was a major pain. Thanks again for the help!
  • LoopysueLoopysue ProFantasy 🖼️ 40 images Cartographer
    Umm... I think you might have meant 'smooth to straight' in the first line? :)
  • MonsenMonsen Administrator 🖼️ 81 images Cartographer
    Note that when trying to use combine paths on things like rivers, it may sometimes be easier to just trace them instead. Just use the trace feature of most drawing tools, and then just continue drawing when you get to the end to add a little extra bit (and in the end, delete the original entity)
  • @ Loopysue - yes I did! Damn it, I knew I'd get them backwards at least once, with how many times I wrote those two phrases during these last few posts lol

    @ Monsen - I've generally had mixed results when tracing smooth objects (whether paths or closed polys). Sometimes the new path is off from the original in a few spots. So I generally stopped bothering trying to trace, for example, rivers, a while ago, and prefer to modify existing ones instead.

    On the other hand, it never occurred to me to turn the original river straight, then trace a new river. I just tried that: the new river seems to precisely follow all the little bends and kinks of the original, but is smooth, and after changing the original, traced river back to smooth, they look perfectly identical as far as I can tell. Which was exactly my problem with tracing them: when I just traced a smooth path with a new smooth path, sometimes they wouldn't be identical. So it looks like that will work as well! So thanks again for giving me another way to do things.
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