Unusable Helix Projections
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Unusable Helix Projections
Im am modelling cooling water lines with tubing coils. When I try to make a drawing out of it, the projections in the drawing page are unusable for a technical drawing. I have made a simple example to show this. The top projection is only a simple line instead of the expected ring. The lower projection has not all hidden lines correctly removed. The curves at the tube turns are disturbed.
Attached are the document and a script to create the part.
Ulrich
OS: Windows 7
Word size of OS: 32-bit
Word size of FreeCAD: 32-bit
Version: 0.15.4527 (Git)
Branch: master
Hash: 0da2e4c45a9a259c26abd54c2a35393e1c15696f
Python version: 2.7.8
Qt version: 4.8.6
Coin version: 4.0.0a
OCC version: 6.7.1
Is this a bug in FreeCAD, in OpenCascade or do I something wrong?Attached are the document and a script to create the part.
Ulrich
OS: Windows 7
Word size of OS: 32-bit
Word size of FreeCAD: 32-bit
Version: 0.15.4527 (Git)
Branch: master
Hash: 0da2e4c45a9a259c26abd54c2a35393e1c15696f
Python version: 2.7.8
Qt version: 4.8.6
Coin version: 4.0.0a
OCC version: 6.7.1
- Attachments
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- spring.zip
- (533 Bytes) Downloaded 42 times
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- helix_projection.FCStd
- (32.76 KiB) Downloaded 49 times
Re: Unusable Helix Projections
Noulrich1a wrote:do I something wrong?
unlikelyulrich1a wrote:Is this a bug in FreeCAD
Yes, but it's so severly that i would rather call it a limitation.ulrich1a wrote:in OpenCascade
In fact we are using the hidden line removal, for a purpose that might extend way further then their originally intended usage.
As this won't be resolved shortly, please open a ticket in our bug tracker.
Re: Unusable Helix Projections
This much is OCCT's fault. The deformed arcs in the drawing are probably caused by FreeCAD.
Re: Unusable Helix Projections
I have issued a bug report: http://www.freecadweb.org/tracker/view.php?id=1937
I OpenCascade 6.8 were reported, that there a tolerance problem with the hidden line removal was improved. But it did not help either.
Ulrich
I OpenCascade 6.8 were reported, that there a tolerance problem with the hidden line removal was improved. But it did not help either.
Ulrich
Re: Unusable Helix Projections
I made a test with an older FreeCAD-release under wine. For me it looks more like a regression.
The Draft-projection still is the same with a lot of not hidden lines: Whereas the Drawing-Workbench produced a nice projection: The projection from top of the helix produced also only a straight line.
Are there only subtle differences in the call of the projection function?
Ulrich
OS: Windows XP
Platform: 32-bit
Version: 0.14.2512 (Git)
Branch: master
Hash: e157152c962fe1fe5340dbe825f31f1e21f9a09a
Python version: 2.6.2
Qt version: 4.5.2
Coin version: 3.1.0
SoQt version: 1.4.1
OCC version: 6.5.1
The Draft-projection still is the same with a lot of not hidden lines: Whereas the Drawing-Workbench produced a nice projection: The projection from top of the helix produced also only a straight line.
Are there only subtle differences in the call of the projection function?
Ulrich
OS: Windows XP
Platform: 32-bit
Version: 0.14.2512 (Git)
Branch: master
Hash: e157152c962fe1fe5340dbe825f31f1e21f9a09a
Python version: 2.6.2
Qt version: 4.5.2
Coin version: 3.1.0
SoQt version: 1.4.1
OCC version: 6.5.1
Re: Unusable Helix Projections
I had still some older Versions on this computer. The disturbed curves were introduced between
OS: Windows 7
Platform: 32-bit
Version: 0.14.3044 (Git)
Branch: master
Hash: 843838ec194010197dcaf9e5d83d55f253d2ac03
Python version: 2.6.2
Qt version: 4.5.2
Coin version: 3.1.0
SoQt version: 1.4.1
OCC version: 6.5.1
and
OS: Windows 7
Platform: 32-bit
Version: 0.14.3071 (Git)
Branch: master
Hash: 15406d1498e284739fd921d6fdc071905601b34b
Python version: 2.6.2
Qt version: 4.5.2
Coin version: 3.1.0
SoQt version: 1.4.1
OCC version: 6.5.1
Ulrich
OS: Windows 7
Platform: 32-bit
Version: 0.14.3044 (Git)
Branch: master
Hash: 843838ec194010197dcaf9e5d83d55f253d2ac03
Python version: 2.6.2
Qt version: 4.5.2
Coin version: 3.1.0
SoQt version: 1.4.1
OCC version: 6.5.1
and
OS: Windows 7
Platform: 32-bit
Version: 0.14.3071 (Git)
Branch: master
Hash: 15406d1498e284739fd921d6fdc071905601b34b
Python version: 2.6.2
Qt version: 4.5.2
Coin version: 3.1.0
SoQt version: 1.4.1
OCC version: 6.5.1
Ulrich
Re: Unusable Helix Projections
There is only one commit in between git commit 9c5f1c216d2428cdbfb6ddab5752569fbd26768e
Looks like I'm to blame
But I'm still convinced that the approximation paramerers (number of segments and allowed tolerance) are unsuitable.
Looks like I'm to blame
But I'm still convinced that the approximation paramerers (number of segments and allowed tolerance) are unsuitable.
Re: Unusable Helix Projections
With maxsegs=50 and OCC version: 6.8.1.dev-27a6612 i get
Re: Unusable Helix Projections
What makes me wondering was, that with OCCT 6.5.1 the Draft-Projection had a lot of visible lines that should have been hidden, whereas with the same FreeCAD-version and the same OCCT-version the Drawing-Projection was not perfect, but a lot better. So there seems to be something different in the projection-call from the Draft-workbench compared to the projection-call from the Drawing-workbench.
Unfortunately I have no actual build with OCCT 6.5.1 in order to check, if all the hidden lines in the Drawing-projection are caused by a different OCCT.
Your picture from the last post is a Draft-Projection or a Drawing-Projection?
Ulrich
Unfortunately I have no actual build with OCCT 6.5.1 in order to check, if all the hidden lines in the Drawing-projection are caused by a different OCCT.
Your picture from the last post is a Draft-Projection or a Drawing-Projection?
Ulrich
Re: Unusable Helix Projections
Drawingulrich1a wrote:Your picture from the last post is a Draft-Projection or a Drawing-Projection?
One problem is that OCCT returns 8 groups of edges.
VCompound // hard edge visibly
Rg1LineVCompound // Smoth edges visibly
RgNLineVCompound // contour edges visibly
OutLineVCompound // contours apparents visibly
IsoLineVCompound // isoparamtriques visibly
HCompound // hard edge invisibly
Rg1LineHCompound // Smoth edges invisibly
RgNLineHCompound // contour edges invisibly