Bug report #20888

vertex tool + topological editing

Added by Thomas Nogatz over 4 years ago.

Affected QGIS version:3.4.3 Regression?:No
Operating System:Windows 10 Easy fix?:No
Pull Request or Patch supplied:No Resolution:
Crashes QGIS or corrupts data:No Copied to github as #:28707


There seems to exist a bug with the node tool when using topological editing. Some screenshots are attached.

Please follow these steps:
  • create a new shapefile polygon layer
  • activate following snapping options via Advanced Configuration:
    Avoid intersection
    Topological Editing
  • Add polygon feature: triangle, beginning with lower left corner (A1), then lower right corner (A2), finally upper corner (A3)
  • Add polygon feature: square overlapping with the triangle (overlap will be deleted due to snapping options, so a second triangle will remain): set a node in A1, then make a node inside the triangle, then a node in A2, then the last node somewhere down outside the triangle (see screen_01.png, the first polygon is the upper one)
  • vertex tool (current layer): try to set a node on every available edge
  • vertices at lower left and upper right edge are set correctly (see screen_02.png)
  • setting a vertex at the common edge: a green cross appears at the vertex, but no topological error is reported (see screen_03.png)
  • setting vertices at lower right and upper left edge causes topological errors (invalid geometry, see screen_04.png)

This errors do not appear when working without topological editing. When you draw the polygons without overlapping, the error appears at the common (screen_05.png) and at the upper left edge (screen_06.png).

screenshots.zip (23.1 KB) Thomas Nogatz, 2018-12-28 09:46 AM

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