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IDProjectCategoryView StatusLast Update
0033043CommunityOCCT:Modeling Algorithmspublic2022-10-19 12:17
Reportereryar Assigned Tomsv  
PrioritynormalSeverityminor 
Status newResolutionopen 
PlatformWindowsOSVC++ 2015 
Product Version7.6.0 
Target Version7.8.0 
Summary0033043: Cannot display the result edge in 3d viewer when project circle on plane
DescriptionWhen use the following Tcl in Draw:
circle c 0 0 10 1 0 0 3
plane p 0 0 0 0 0 1
projonplane r c p

In Draw mu4 views can display the project curcle correctly, but can display nothing when to display the edge built from the project result curve:
mkedge e r
vdisplay e
Steps To Reproducecircle c 0 0 10 1 0 0 3
plane p 0 0 0 0 0 1
projonplane r c p
mkedge e r
vdisplay e

# parameters should be approptriate.
# current values are used just for the demonstration of an issue despite of numbers used.
crvtpoints r c 0.00001 0.1
TagsNo tags attached.
Test case number

Attached Files

  • draw.png (38,656 bytes)

Activities

eryar

2022-06-28 06:53

developer  

draw.png (38,656 bytes)

azv

2022-06-28 08:45

administrator   ~0109318

The problem is that the polygon representation of the edge has only 2 coincident nodes.
 -------
Dump of 1 Polygon3Ds
 -------
  1 : Polygon3D with 2 Nodes
with parameters
Deflection : 0.001

Nodes :
         1 :                 0                 0                 0
         2 :                 0                 0                 0

eryar

2022-06-29 11:12

developer   ~0109364

Yes, the project result is BSpline curve:
Draw[2]> dump r

*********** Dump of r *************
BSplineCurve
  Degree 8, 17 Poles, 3 Knots
Poles :

   1 : 0, 0, 0
   2 : 0, -1.17809724509617, 0
   3 : 0, -2.35620388376992, 0
   4 : 0, -3.25736798067373, 0
   5 : 0, -3.60539563891143, 0
   6 : 0, -3.25736798067192, 0
   7 : 0, -2.35620388376992, 0
   8 : 0, -1.17809724509617, 0
   9 : 0, -3.67394039744206e-16, 0
  10 : 0, 1.17809724509617, 0
  11 : 0, 2.35620388376947, 0
  12 : 0, 3.25736798067192, 0
  13 : 0, 3.60539563891507, 0
  14 : 0, 3.25736798066646, 0
  15 : 0, 2.35620388376947, 0
  16 : 0, 1.17809724509617, 0
  17 : 0, 7.34788079488412e-16, 0
Knots :

   1 : 0 9
   2 : 3.14159265358979 8
   3 : 6.28318530717959 9

But I think for this particular case, its better to use a Line.

oan

2022-10-19 11:47

developer   ~0111655

The reported problem is a side effect of an issue in GCPnts_TangentialDeflection which is used to discretize edges inside BRepMesh.
The tool is unable to produce more than two points for the target curve despite of the fine parameters.

The following script shows the problem of GCPnts_TangentialDeflection and will be put to the Steps To Reproduction:

circle c 0 0 10 1 0 0 3
plane p 0 0 0 0 0 1
projonplane r c p
mkedge e r
vdisplay e
crvtpoints r c 0.00001 0.1

msv

2022-10-19 12:17

developer   ~0111657

To require GCPnts_TangentialDeflection to produce good distribution of points for such degenerated bspline curve is to require almost impossible.
I agree with the author of this bug eryar that in this particular case it is better to produce a trimmed line instead of bspline curve as a result of projection.
However, I am afraid of appearing other bugs that can appear due to another parameterization of line compared to the circle, when the projection algorithm will take part in projecting of some complex shape to a plane.
So, I propose to make a line as a projection result, and to check how this fix will impact a projection of some shape having the similar circle.

Issue History

Date Modified Username Field Change
2022-06-28 06:53 eryar New Issue
2022-06-28 06:53 eryar Assigned To => msv
2022-06-28 06:53 eryar File Added: draw.png
2022-06-28 08:45 azv Assigned To msv => oan
2022-06-28 08:45 azv Category OCCT:Modeling Algorithms => OCCT:Mesh
2022-06-28 08:45 azv Note Added: 0109318
2022-06-29 11:12 eryar Note Added: 0109364
2022-07-06 07:19 azv Target Version 7.6.3 => 7.7.0
2022-10-19 11:47 oan Assigned To oan => msv
2022-10-19 11:47 oan Category OCCT:Mesh => OCCT:Modeling Algorithms
2022-10-19 11:47 oan Steps to Reproduce Updated
2022-10-19 11:47 oan Note Added: 0111655
2022-10-19 12:17 msv Note Added: 0111657
2022-10-19 12:17 msv Target Version 7.7.0 => 7.8.0