A TIEPolylineLayer with EnableComplexPath = True whose path contains an iepaArcTo segment draws that arc correctly while the layer's Rotate is a multiple of 90 degrees, and draws a different curve as soon as the layer is freely rotated. The end points stay correct, the curvature between them does not.
The cause is in the free-rotation branch of IEDrawPolylineEx: the arc's radii are scaled by the anisotropic factors that fit the rotated point cloud back into the layer rectangle. Scaling the two radii of an ellipse by different factors is not a valid transformation of that ellipse (it also changes the ellipse's rotation angle, which is left untouched) and when the shrunken radii can no longer span the chord, the SVG arc algorithm inflates them and the arc collapses into a half-ellipse.
Unfortunately that is due to a limitation (not a bug, because it was a design choice) in our arc support. If you post sample layers file, I'll try it here and see if there is something we can do.
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Bug: Elliptical arc in a complex path is drawn wrongly when the layer is rotated
Posted - Sep 06 2026 : 10:20:57
