Bug report #21282

[Expression] point_n function should be coherent with other vertex based functions and algorithms

Added by Harrissou Santanna over 5 years ago. Updated about 5 years ago.

Affected QGIS version:3.7(master) Regression?:No
Operating System: Easy fix?:No
Pull Request or Patch supplied:No Resolution:
Crashes QGIS or corrupts data:No Copied to github as #:29100


I don't know if I should report it as a bug or a feature request...

The point_n function returns a specific node on a geometry, based on the provided index. The first vertex index is 1.
But when using Processing to extract vertices from a feature, the vertex_index is 0-based. Some other expression that manipulates vertices (angle_at_vertex, distance_to_vertex) are also 0-based.
It could be nice to align the point_n function with the others.

Related issues

Related to QGIS Application - Feature request #21284: [Expression] Allow negative value for vertex index in ang... Closed 2019-02-15


#1 Updated by Harrissou Santanna over 5 years ago

  • Related to Feature request #21284: [Expression] Allow negative value for vertex index in angle_at_vertex/distance_at_vertex/point_n... functions added

#2 Updated by Mathieu Pellerin - nIRV about 5 years ago

  • Regression? set to No
  • Crashes QGIS or corrupts data set to No
  • Affected QGIS version set to 3.7(master)
  • Tracker changed from Feature request to Bug report

IMHO, it's an inconsistency which should be considered as a bug. Fixing this will have to wait until we cross the QGIS 4.0 bridge.

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