Unexpected exception

[Jim Thurgood]

I generated a drawing with DoubleCAD XT and saved as a DXF (Various versions) but PyCam crashes loading these files.   I saved the same drawing as SVG and PyCam will then load it without error, however I get this message when generating the toolpath:
An unexpected exception occoured: please send the text below to the developers of PyCAM. Thanks a lot!
Traceback (most recent call last):
  File "pyinstaller\build\pyi.win32\pycam\outPYZ5.pyz/pycam.Gui.Project", line 4041, in generate_toolpath
  File "pyinstaller\build\pyi.win32\pycam\outPYZ5.pyz/pycam.Toolpath.Generator", line 62, in generate_toolpath_from_settings
  File "pyinstaller\build\pyi.win32\pycam\outPYZ5.pyz/pycam.Toolpath.Generator", line 226, in generate_toolpath
  File "pyinstaller\build\pyi.win32\pycam\outPYZ5.pyz/pycam.Geometry.Model", line 683, in get_offset_model
  File "pyinstaller\build\pyi.win32\pycam\outPYZ5.pyz/pycam.Geometry.Polygon", line 965, in get_offset_polygons
  File "pyinstaller\build\pyi.win32\pycam\outPYZ5.pyz/pycam.Geometry.Polygon", line 911, in simplify_polygon_intersections
IndexError: list index out of range

[Lars]

Hi Jim,

thanks for reporting this issue!

Please send me one of these DXF files, that caused PyCAM to crash - I am very insterested in improving the robustness of the file format importers. Just use my sourceforge mail address.

Regarding the exception:
please try to apply the following patch:

--- src/pycam/Geometry/Polygon.py   (Revision 1101)
+++ src/pycam/Geometry/Polygon.py   (Arbeitskopie)
@@ -904,8 +904,10 @@
                     groups = []
                     last_start = 0
                     for group_start in group_starts:
-                        groups.append(new_group[last_start:group_start])
-                        last_start = group_start
+                        if last_start != group_start:
+                            # avoid empty groups
+                            groups.append(new_group[last_start:group_start])
+                            last_start = group_start
                     # Add the remaining lines to the first group or as a new
                     # group.
                     if groups[0][0].p1 == new_group[-1].p2:

I think, this should fix the issue, but I could not test it here.
Please send me the offending SVG file and describe your task settings, if the above patch does not help!

cheers,
Lars