- Status Closed
- Percent Complete
- Task Type Bug Report
- Category QCAD (main)
-
Assigned To
Andrew - Operating System Linux (All / Other)
- Severity Low
- Priority Very Low
- Reported Version 3.12.3
- Due in Version Undecided
-
Due Date
Undecided
- Votes
- Private
Attached to Project: QCAD Bugtracker
Opened by Filip Zaludek - 07.12.2015
Last edited by Andrew - 08.12.2015
Opened by Filip Zaludek - 07.12.2015
Last edited by Andrew - 08.12.2015
FS#1319 - Ellipse precision
It is not possible to draw ellipse aligned to bounding box.
Please see constructed red “EP” and green “El” compared to white circle,
bounding box [-100,+100][-100,+100].
ellipse.dwg
(16.1 KiB)
This is an accuracy problem of the display only (arcs and ellipses are interpolated with small line segments to be displayed for performance reasons). The constructed ellipses are precise (see property editor). Calculations with ellipses are precise as well.
Ah, I can see it from circumference/length, but it gives really unpleasant result. For example, red ellipse crosses axes in
[-100,0], [0,99.97], [99.98, 0], [0, -99.96].
Is there any way to increase number of line segments displayed?
Regardless precision, I am not happy about construction. EP hor ver produces different appearance from EP ver hor.
Thanks!
No.
This is because the interpolation starts at different angles. The situation can be improved for ellipses with the same start angle and full ellipses by applying this minor patch:
https://github.com/qcad/qcad/commit/f2643aff45c018a952efbd4948e911a97145e077
This is answer I am looking for, as it will improve ellipses visual appearance.
/**
* Exports an ellipse with the current attributes.
* \todo switch from line based interpolation to arcs.
*/
Regards!