qcad won't hatch some selections

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qcad won't hatch some selections

Postby klavs » Wed Dec 01, 2010 9:24 am

Hi,

I'm rather new at qcad - and am having huge problems getting qcad to hatch.

You can see what I'm trying to hatch here:
http://vsen.dk/files/hus-forskudt-spaer-snit.png

and here's the DXF:
http://vsen.dk/files/hus-forskudt-spaer-snit.dxf

I've divided all lines that cross the area I want to hatch (to draw insulation) and have confirmed they are all divided at the intersection. Yet the hatch tool still doesn't succeed :(

As you can see I could get qcad to hatch some places.

Any hints would be very much appreciated.

p.s. I'm running 2.2.2.0 on Linux.
klavs
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Postby andrew » Wed Dec 01, 2010 4:38 pm

Try putting all entities of your hatch boundary on one separate layer (good practice). Then make sure that there are no duplicate, missing or not properly connected entities.

You definitely should work with layers a lot more. Put all dimensions on a separate layer, all text labels on one, all hatch boundaries on one layer, all hatches on another, etc.

Without using layers your drawing very quickly becomes unmanageable.
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Postby klavs » Wed Dec 01, 2010 5:12 pm

Can I still draw lines on layer1 - as a parallel - with a certain distance to a line on layer0 ? (that's what I need in this case).

Also - when I select all the entities that make up the hatch "block" - it looks correct - as all are divided where they should be, and together form a whole as they should.

Could you see any errors in the dxf file I linked to?

I'd definetely vote for a better hatch functionality - as it should be able to figure out what constitutes a "closed box" - by following the selected entities, until it reaches the next selected entity - etc. until it reachs the point where it started - then having the coordinates to draw the hatch in (this is how I figure it could be coded the easiest)
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Postby andrew » Wed Dec 01, 2010 5:21 pm

klavs wrote:Can I still draw lines on layer1 - as a parallel - with a certain distance to a line on layer0 ? (that's what I need in this case).


Yes, sure.

klavs wrote:Also - when I select all the entities that make up the hatch "block" - it looks correct - as all are divided where they should be, and together form a whole as they should.

Could you see any errors in the dxf file I linked to?


I would need a drawing with the complete hatch boundary isolated on one single, separate layer to check this.

klavs wrote:I'd definetely vote for a better hatch functionality - as it should be able to figure out what constitutes a "closed box" - by following the selected entities, until it reaches the next selected entity - etc. until it reachs the point where it started - then having the coordinates to draw the hatch in (this is how I figure it could be coded the easiest)


It is possible that future QCAD versions will offer a better selection for hatch areas. However, this would likely not solve the most common hatch problems (duplicate entities and small gaps between entities).
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Postby klavs » Wed Dec 01, 2010 6:06 pm

Perfect. I'll RTFM the manual on layers then :)

I'll put the hatch on a seperate layer and see if it works then :)

Small gaps should be easily solvable - if you simply add a setting for "bridge gap to closest endpoint/point on other selected entities" - and then you'd simply "look" for the nearest point from where the gap starts and out in "circles" :)

Also - some information when the hatch fails - and a highlight of the area where it fails would be very helpful in tracking down problems. I haven't seen how the hatch-code works - but I'm assuming that when it stops - it knows at what coordinates it gives up - and thus it could highlight that area (a red circle f.ex.) and write a complaint out


I don't understand the duplicate entities problem - so I can't comment on that.
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Postby klavs » Wed Dec 01, 2010 10:47 pm

Solved - putting the hatch lines on another layer helped tremendously.

One problem though. Often the hatch "border-lines" is also lines that is part of the construction - and thus should not be ONLY on the "hatch" layer - but also on the construction layer.

I figure I could put a "hatch-border-line" on top of the construction line - but I have found no way of selecting 1 item over another - when they are on the same exact spot.. (I don't even know if there can exist two lines on top of each other - with no divergence) ?
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Postby klavs » Thu Dec 02, 2010 8:59 am

I found it worked as I intuitively thought/hoped it would. I simply mark the "hatches" layer - and then draw new lines on top of the existing construction lines - hiding the construction/elements layer when I need to see if the hatch is complete.

Works great and makes it a lot easier.

IMHO these two tips (use layers - and then mark hatches layer and redraw/draw hatch borders on that layer) should be in the manual on hatches - would have saved me some grief :)
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Postby andrew » Thu Dec 02, 2010 9:50 am

klavs wrote:I simply mark the "hatches" layer - and then draw new lines on top of the existing construction lines - hiding the construction/elements layer when I need to see if the hatch is complete.


Yes, that sounds like a good idea. The QCAD book suggests a similar procedure. Note that the user reference manual only explains the various tools but not basic CAD concepts and procedures. The book on the other hand is a complete introduction to CAD and QCAD:

http://www.ribbonsoft.com/qcad_book.html
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Postby klavs » Thu Dec 02, 2010 9:53 am

I ordered the software+book edition - so I'm looking forward to receiving the book :)

IMHO the online manual still should contain good tips - or a comment option, so users could comment on it.

IMHO more happy Open Source Users = more users who want to economically support the software.

Perhaps you could sell support to companies? I have family in a LARGE danish company who have a dedicated CAD support staff (not for qcad - but for their microstation cad) - smaller companies would probably be happy to use qcad, if they could pay for a support option.
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