Hi, and welcome to the QCAD forum.
A circle with radius 1 has an enclosed area of
Pi*r² =
3.14159265...
Then 3/4 of a circle or an arc sector has an enclosed area of
2.35619449... Not at all
2.35227962
Adding a square with sides of 1, with an area of 1 results in
3.35619449...
I can not replicate the Hatched area =
3.35227962 for both rightmost cases.
Both are reported to have an area of
3.35619449 (Rounded to 8 digits) on my system.
Only correct for the top example as Hatch!
Luckily the
2D Area Centroid (Misc .. Information .. 2D Centroids) methods reports the correct answer.
I wouldn't have expected otherwise.
Select the Centroid marker and see its custom properties for values in full floating point notation.
Not utterly
3/4Pi and
3/4Pi+1 because your 3/4 circle sectors are slightly malformed.
Top middle we expect angles between segments: 90, 180,
180
Top bottom: 90,
90, 270
The difference is 4e-8 in both cases.
Negligible but it has a minute impact on the results in full floating point.
- - - - - - - - -
Before, areas of polylines including bulging segments were calculated as the area of the polygon based on the nodes.
Bulging out or inwards was not accounted for. (3.15.2.2 - v3.20.1.6)
Prior (>3.13.0) and afterwards is was by segmentation.
After I released
Centroids I also
explained in detail how my tools did the trick correctly.
-> As polygon, adding
OR subtracting each arc segment area based on the bulge factor and chord length.
Perhaps it was not implemented with the same great care for details by Andrew.
Initially for Polylines (No exact details) and later for Hatches (>3.27.7).
Remark that the Polyline swaps orientation (CW<>CCW) with bulge +/-2.41421356 or without (=0 -> triangle)
Both are QCAD Pro resources,
proprietary code that can not be verified by us simple users.
Some minute error can be expected because of the naive summation algorithm.
Centroids exploit a second-order compensation for summing (long) chains of values.
Your best option is to file a bug report on
QCAD Bugtracker.
Regards,
CVH
