Offset not working on all polylines !?

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0xdeadbeef
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Offset not working on all polylines !?

Post by 0xdeadbeef » Fri Feb 19, 2016 6:37 pm

I'm probably doing something wrong, but I'm puzzled why "Offset" ("Äquidistante) seems to work on one polyline but not on the other.
I attached an example with an outer and inner polyline. Created and tested with most recent QCad (Pro) 3.12.8.0 on Windows7.
If I select "Offset" and move the cursor over the inner polyline, the offset line is displayed as expected.
When I do the same on the outer polyline, I can see the polyline becoming selected, but no offset line appears.
It seems something is wrong with this polyline, but I don't know what or how I managed to do so.
Any idea what's going on there?
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offset issue.dxf
(100.83 KiB) Downloaded 162 times

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Clive
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Re: Offset not working on all polylines !?

Post by Clive » Fri Feb 19, 2016 8:55 pm

Hi

I’ve just tested this on Linux Mint, no problems there.

Haven't tested yet on Windows, unless anyone else has tested it.

Questions: What offset distance are you using?

Do you have separate layers for each polyline, if so is one of the layers locked?

Clive

0xdeadbeef
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Re: Offset not working on all polylines !?

Post by 0xdeadbeef » Fri Feb 19, 2016 9:51 pm

Offset is 3mm, number is 1, I try to get "Offset whole polyline" to work with the outer polyline (the rounded one). "Offset segment" works on it as well, just not the whole polyline which only works for the inner (edged) one.
And well, there is only one layer.

Hm, just tried to remove the outer polyline and recreate it using offset whole polyline on the inner one and rounding it. As soon as it's rounded, "offset whole polyline" doesn't work on it anymore.
I'm pretty sure this worked at some time in the past.
Side note: even for the inner polyline, the "offset whole polyline" doesn't always work correctly. At some locations, there is just one segment created - just like it had selected "offset segment" instead.

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Husky
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Re: Offset not working on all polylines !?

Post by Husky » Sat Feb 20, 2016 8:56 am

0xdeadbeef wrote:I attached an example with an outer and inner polyline.
First of all - I would recommend to delete the "Lines" underneath the inner polyline. It's easier for testing. :wink:
0xdeadbeef wrote:If I select "Offset" and move the cursor over the inner polyline, the offset line is displayed as expected.
When I do the same on the outer polyline, I can see the polyline becoming selected, but no offset line appears.
It seems something is wrong with this polyline, but I don't know what or how I managed to do so.
Any idea what's going on there?
I have the same experience also with a Windows OS - my best guess is that QCAD has a problem with doing a preview on Polylines with round joints. But if you click the mouse, regardless the preview, it will create an offset as expected.

0xdeadbeef wrote:I'm probably doing something wrong, but I'm puzzled why "Offset" ("Äquidistante) seems to work on one polyline but not on the other.
I assume it depends on the joint style - try it by yourself. Maybe I'm wrong ...
offset issue_test.dxf
(100.64 KiB) Downloaded 144 times
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0xdeadbeef
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Re: Offset not working on all polylines !?

Post by 0xdeadbeef » Sat Feb 20, 2016 12:36 pm

I'm not at home at the moment, so I can only try on my Notebook where I have currently an older version of QCad installed (3.6.3.0).
My own example works correctly there but without installing a newer version I can't say if this is a regression of QCad or an issue of the graphics card.
It's definitely not an issue of the joint style though. Tested all of them at home, I guess it must have something to do with the rounded edges.

As a a side enote; You're right about the underlying lines for the inner polyline. Must have happened when copying. From some version on, QCad started copying all unlocked layers instead of just the active one which I find mildly confusing.

[Edit]
I just installed the newest version on my Notebook and the erratic behavior is just the same as on my desktop PC. So IMHO it's a regression.
Maybe related to an update in the Qt lib?

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Husky
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Re: Offset not working on all polylines !?

Post by Husky » Sat Feb 20, 2016 7:57 pm

0xdeadbeef wrote:... I guess it must have something to do with the rounded edges.
That was what I was trying to say ...

Bevel joins, Miter Joins and the interpolated arcs with line segments will work perfectly - it fails only at the round join polylines which are build with arcs.
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0xdeadbeef
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Re: Offset not working on all polylines !?

Post by 0xdeadbeef » Sat Feb 20, 2016 9:18 pm

OK, sorry I thought you meant the joint style for the offset tool.
Anyway, I created a bug report.

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