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FS#2693Modify > Breakout: Fails with certain ellipses

Type
Bug
Status
Closed
Resolution
Fixed
Category
QCAD (main)
Severity
Low
Priority
Low
Reported version
3.32.4
Operating system
All
Reported
2025-09-11 by CVH
Closed
2025-11-07 by andrew
Votes
1

Follow up of FS#2685
Tested with 3.23.4 trial on Win 7 but probably not related to OS

With the example file attached to the related forum topic p48576
D2 fails for the lower left ellipse in magenta indicating the segment near (11.72, 2.58).

ShapeAlgorithms.getIntersectingShapes() locates 8 intersecting shapes ...
... That is not the issue here.
ShapeAlgorithms.autoSplit() for the given position returns 3 new segments:
(address may vary)

- [0] REllipse(RShape(address: "0x204229d0"), startPoint: "RVector(11.675918, 2.746654, 0.000000, 1)", endPoint: "RVector(11.977686, 2.428095, 0.000000, 1)", center: "RVector(11.852689, 2.644595, 0.000000, 1)", majorPoint: "RVector(-0.124996, 0.216500, 0.000000, 1)", majorRadius: 0.249993, minorRadius: 0.144334, ratio: 0.57735, startAngle: 45, endAngle: 180, full: false, clockwise: true)
- [1] Undefined
- [2] REllipse(RShape(address: "0x204239c0"), startPoint: "RVector(11.675918, 2.746654, 0.000000, 1)", endPoint: "RVector(11.977686, 2.428095, 0.000000, 1)", center: "RVector(11.852689, 2.644595, 0.000000, 1)", majorPoint: "RVector(-0.124996, 0.216500, 0.000000, 1)", majorRadius: 0.249993, minorRadius: 0.144334, ratio: 0.57735, startAngle: 45, endAngle: 180, full: false, clockwise: false)

The issue is that the new entities are only (re-)generated when longer than RS.PointTolerance (Good practice).

The approximated Simpson-length for the ellipse-arcs are:

- [0 CW] **NaN**   (instead about 0.683800238925154)
- [1] Not an RShape
- [2 CCW] 0.5773502691896258

Ellipse-arcs [0] starts at 45°, passes 0° in CW sense and ends at (-)180°.

The full ellipse is removed but not replaced by new segment [0] or [1].
Segment [2] is the segment that is broken out.

Similar new segment lengths for the segment near (12.02, 2.49):

- [0 CW] **NaN**    (instead about 1.12960650667804213)
- [1] Not an RShape
- [2 CCW] 0.13154400143673767

Regards,
CVH

Comments (2)

CVH 2025-09-13

Issue is related to FS#2565
"NaN length for arbitrary ellipse arc"

In the comment is explained why.

Regards,
CVH

CVH 2025-11-05

Please see my second comment on FS#2565 for the method to fix.

Closure requested.

Regards,
CVH