★Why do we get unexpected results when drawing spline curves by selecting points in ZWCAD?

Issue:

When capturing endpoints of line segments to draw spline curves, why does the result differ from the expected?

Causes:

The captured points are not in the same plane, they have Z-axis coordinates.

Solution:

Click on the menu Express → Tools → Change Z Value of Coordinate to 0 (command ZVALTO0), select the graphical objects needed for drawing spline curves, and press Enter to set their Z-coordinates to 0. Then proceed with drawing the spline curves.