0000482: Exporting to DXF causes zero vector length exception - FreeCAD Tracker

NOTICE: Migration to GitHub Issues

On Feb 7, 2022, the FreeCAD project migrated all issues from this site at tracker.freecad.org to our main GitHub repository. All new bugs must be submitted there.
This Mantis repository is in read-only mode and will be retained for reference as long as it is useful.

For details please see the announcement at the Forums: https://forum.freecadweb.org/viewtopic.php?p=555883#p555883

ID	Project	Category	View Status	Date Submitted	Last Update

0000482	FreeCAD	Bug	public	2011-11-11 15:36	2011-11-17 14:34

Reporter	cstrachan1	Assigned To	yorik
Priority	normal	Severity	trivial	Reproducibility	always
Status	closed	Resolution	fixed
Product Version	0.11
Fixed in Version	0.12

Summary	0000482: Exporting to DXF causes zero vector length exception
Description	To reproduce: Open attached file DXFTest Select Fusion object Select export from file menu enter a filename ending in .dxf exception occurs: colin@cs-sis-gcs-laptop:~/Downloads/free-cad$ bin/FreeCAD FreeCAD 0.12, Libs: 0.12R4851 © Juergen Riegel, Werner Mayer, Yorik van Havre 2001-2011 ##### #### ### #### # # # # # # # ## #### #### # # # # # #### # # # # # # # ##### # # # # #### #### # # # # # # # # # # # # # # ## ## ## # # #### #### ### # # #### ## ## ## processing Fusion Exception (Fri Nov 11 16:09:39 2011): Cannot normalize null vector Stack Trace: Traceback (most recent call last): File "<string>", line 4, in <module> File "/home/colin/Downloads/free-cad/Mod/Draft/importDXF.py", line 1135, in export block = getBlock(ob) File "/home/colin/Downloads/free-cad/Mod/Draft/importDXF.py", line 1037, in getBlock writeShape(obj,block) File "/home/colin/Downloads/free-cad/Mod/Draft/importDXF.py", line 1052, in writeShape dxfobject.append(dxfLibrary.PolyLine(getWire(wire,nospline), [0.0,0.0,0.0], File "/home/colin/Downloads/free-cad/Mod/Draft/importDXF.py", line 1002, in getWire mp = fcgeo.findMidpoint(edge) File "/home/colin/Downloads/free-cad/Mod/Draft/draftlibs/fcgeo.py", line 523, in findMidpoint perp.normalize()
Additional Information	Exporting a similar looking object from another file, DFXTest3 attached, does not create the exception. Both objects were created by cutting and pasting from other FreeCAD documents. Modifying the file Mod/Draft/importDXF.py to avoid the exception outputs a valid DXF file but with errors in the geometery. Both files display visually correct models in the modelling window. colin@cs-sis-gcs-laptop:~/Downloads/free-cad$ diff /home/colin/Downloads/free-cad/Mod/Draft/importDXF.py_orig /home/colin/Downloads/free-cad/Mod/Draft/importDXF.py_cs 1002,1015c1002,1016 < mp = fcgeo.findMidpoint(edge) < v2 = edge.Vertexes[-1].Point < c = edge.Curve.Center < angle = abs(fcvec.angle(v1.sub(c),v2.sub(c))) < # if (fcvec.angle(v2.sub(c)) < fcvec.angle(v1.sub(c))): < # angle = -angle < # polyline bulge -> negative makes the arc go clockwise < bul = math.tan(angle/4) < # the next bit of code is for finding the direction of the arc < # a negative cross product means the arc is clockwise < tang1 = edge.Curve.tangent(edge.ParameterRange[0]) < tang2 = edge.Curve.tangent(edge.ParameterRange[1]) < cross1 = Vector.cross(Vector(tang1[0][0],tang1[0][1],tang1[0][2]),Vector(tang2[0][0],tang2[0][1],tang2[0][2])) < if cross1[2] < 0: --- > if (edge.Vertexes[0].Point != edge.Vertexes[-1].Point) : > mp = fcgeo.findMidpoint(edge) > v2 = edge.Vertexes[-1].Point > c = edge.Curve.Center > angle = abs(fcvec.angle(v1.sub(c),v2.sub(c))) > # if (fcvec.angle(v2.sub(c)) < fcvec.angle(v1.sub(c))): > # angle = -angle > # polyline bulge -> negative makes the arc go clockwise > bul = math.tan(angle/4) > # the next bit of code is for finding the direction of the arc > # a negative cross product means the arc is clockwise > tang1 = edge.Curve.tangent(edge.ParameterRange[0]) > tang2 = edge.Curve.tangent(edge.ParameterRange[1]) > cross1 = Vector.cross(Vector(tang1[0][0],tang1[0][1],tang1[0][2]),Vector(tang2[0][0],tang2[0][1],tang2[0][2])) > if cross1[2] < 0: 1018c1019 < points.append((v1.x,v1.y,v1.z,None,None,bul)) --- > points.append((v1.x,v1.y,v1.z,None,None,bul))
Tags	No tags attached.

FreeCAD Information

2011-11-11 15:36	~~DXFTest.fcstd~~ (Attachment missing)

2011-11-11 15:37	~~DXFTest3.fcstd~~ (Attachment missing)

2011-11-11 15:37	~~dxftest.png~~ (Attachment missing)

2011-11-11 15:37	~~dxftest3.png~~ (Attachment missing)

2011-11-11 15:39	~~VisualComparison.png~~ (Attachment missing)

cstrachan1 2011-11-11 15:40 reporter ~0001278	Ubuntu 11.10 Linux, FreeCAD compiled from svn: updated and compiled 10th Nov 2011.

yorik 2011-11-17 14:34 administrator ~0001303	fixed in r5145

Date Modified	Username	Field	Change
2011-11-11 15:36	cstrachan1	New Issue
2011-11-11 15:36	cstrachan1	File Added: DXFTest.fcstd
2011-11-11 15:37	cstrachan1	File Added: DXFTest3.fcstd
2011-11-11 15:37	cstrachan1	File Added: dxftest.png
2011-11-11 15:37	cstrachan1	File Added: dxftest3.png
2011-11-11 15:39	cstrachan1	File Added: VisualComparison.png
2011-11-11 15:40	cstrachan1	Note Added: 0001278
2011-11-12 11:14	wmayer	Status	new => assigned
2011-11-12 11:14	wmayer	Assigned To	=> yorik
2011-11-17 14:34	yorik	Note Added: 0001303
2011-11-17 14:34	yorik	Status	assigned => closed
2011-11-17 14:34	yorik	Resolution	open => fixed
2011-11-17 14:34	yorik	Fixed in Version	=> 0.12