dxf show problem

Hi Guys,

i have a DXF file that include a spline, in qcad, it were shown as a circle, but in librecad, it shown as  a round rectangle.the dxf file is here:Graphic1.dxf

is there anybody?

Hey,

yo are absolutely right. The rendering on our end isn't correct.
I did test it in a other CAD app aswell and the DXF show's also as a circle, not as a round-rect.

I have been looking into the DXF code but I am not 100% sure yet the issue.

CAD DXF splines do consist of different degrees, a quadratic spline or a cubic spline and I think we render one or the other incorrectly.

We will for sure tackle this subject, however please be patient untill we found it the rootcauze and the correct solution.

I will troubleshoot this one.

R. van Twisk wrote

Hey,

yo are absolutely right. The rendering on our end isn't correct.
I did test it in a other CAD app aswell and the DXF show's also as a circle, not as a round-rect.

I have been looking into the DXF code but I am not 100% sure yet the issue.

CAD DXF splines do consist of different degrees, a quadratic spline or a cubic spline and I think we render one or the other incorrectly.

We will for sure tackle this subject, however please be patient untill we found it the rootcauze and the correct solution.

thank you, waiting for your good news

does this bug happen to all spline files, or only this particular one?

tryagain wrote

thank you, waiting for your good news

only particular file.

I encountered two dxf file show not quite right, this is a spline curve;

the other is a polyline, that is a bit strange, the low version of librecad have no problem to show it, the high version of librecad have problem to show. the arc in polyline shown error.

I don't see any issue with the Graphic1.dxf itself.

LibreCAD loads the spline as cubic, nothing unusual here.

I will try some unit tests of spline then.

  0
SECTION
  2
ENTITIES
  0
SPLINE
  5
2B
330
1F
100
AcDbEntity
  8
0
370
     5
100
AcDbSpline
210
0.0
220
0.0
230
1.0
 70
     8
 71
     3
 72
    20
 73
    16
 74
     0
 42
0.0000000001
 43
0.0000000001
 40
0.0
 40
0.0
 40
0.0
 40
0.0
 40
0.25
 40
0.25
 40
0.25
 40
0.25
 40
0.5
 40
0.5
 40
0.5
 40
0.5
 40
0.75
 40
0.75
 40
0.75
 40
0.75
 40
1.0
 40
1.0
 40
1.0
 40
1.0
 10
4.038665354330709
 20
0.6099685039370079
 30
0.0
 10
4.038665354330709
 20
2.784314960629922
 30
0.0
 10
2.276007874015748
 20
4.546972440944882
 30
0.0
 10
0.1016614173228347
 20
4.546972440944882
 30
0.0
 10
0.1016614173228347
 20
4.546972440944882
 30
0.0
 10
-2.072685039370079
 20
4.546976377952756
 30
0.0
 10
-3.83534251968504
 20
2.784322834645669
 30
0.0
 10
-3.835346456692914
 20
0.6099763779527559
 30
0.0
 10
-3.835346456692914
 20
0.6099763779527559
 30
0.0
 10
-3.835354330708662
 20
-1.564366141732284
 30
0.0
 10
-2.072708661417323
 20
-3.327027559055118
 30
0.0
 10
0.1016417322834646
 20
-3.327035433070866
 30
0.0
 10
0.1016417322834646
 20
-3.327035433070866
 30
0.0
 10
2.275988188976378
 20
-3.327047244094489
 30
0.0
 10
4.038653543307087
 20
-1.564397637795276
 30
0.0
 10
4.038661417322835
 20
0.6099448818897638
 30
0.0
  0
ENDSEC

tryagain wrote

only particular file.

I encountered two dxf file show not quite right, this is a spline curve;

the other is a polyline, that is a bit strange, the low version of librecad have no problem to show it, the high version of librecad have problem to show. the arc in polyline shown error.

Currently, the LC RS_Spline does not accept customized knot vectors from dxf.

1, need to add support of knot vector in dxfrw (DXF group code: 72, 40, 41);

2, need to support custom knot vectors in RS_Spline, currently; the knot vector is hard coded to uniform knots.

experimental knot vector support in master and 2.0 branch:

https://github.com/LibreCAD/LibreCAD/commit/765ee0e3cf8d6f690d8695a16bf2bbd6d521130d