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|ID||Project||Category||View Status||Date Submitted||Last Update|
|0027656||Community||[OCCT] OCCT:Modeling Algorithms||public||2016-06-30 09:44||2016-07-20 17:08|
|Platform||Win64||OS||Win7||OS Version||64 bit|
|Product Version||[OCCT] 7.0.0|
|Target Version||[OCCT] Unscheduled||Fixed in Version|
|Summary||0027656: BRepFill_OffsetWire does not build offset of b-spline curves|
|Description||I have found that no wire has been created using the GeoMaps Intersection option. I believe it is because the curves are deiniert as Spline.|
|Steps To Reproduce||Draw> brestore c:/aWire.brep s1|
Draw> mkoffset mk1 s1 1 1 i
|Tags||No tags attached.|
|Test case number|
|Attached Files|| aWire.brep (703 bytes) 2016-06-30 09:44|
wire.brep (33,351 bytes) 2016-06-30 12:21
Indeed, if we create the same form wire from line segments the operation works:
polyline w 0 0 0 10 0 0 20 10 0 0 0 0
mkoffset r w 1 1 i
The attached aWire.brep is based on b-spline curves of degree 1.
|Yes you are right but algorithm has general problems as soon as it contains Spline (see new attached wire.brep).|
The offset algorithm with the option GeomAbs_Intersection has a limitation that it works only with analytical geometries. If there is a join of b-spline or bezier curves this case does not work by intention. It is because during making intersection join we need to extent the curve till the point of intersection. And though b-spline can be extended, nevertheless we cannot rely on such extension in general case as it can give unexpected oscillations.
There should be another solution for this problem. There is GeomAbs_Tangent join type. With this join type, it is intended that a tangent lines a created as continuation of joined curves, and intersection point of these tangent lines will be used as a join point on offset contour.
However, in the current implementation GeomAbs_Tangent join type is not considered and the algorithm will fail. So, this problem is open and needs to be solved.
We have no plans to schedule this task in the nearest future, unless it is paid by some third party.
|2016-06-30 09:44||anpoit00||New Issue|
|2016-06-30 09:44||anpoit00||Assigned To||=> msv|
|2016-06-30 09:44||anpoit00||File Added: aWire.brep|
|2016-06-30 11:34||msv||Note Added: 0055602|
|2016-06-30 12:21||anpoit00||File Added: wire.brep|
|2016-06-30 12:23||anpoit00||Note Added: 0055603|
|2016-07-18 15:10||msv||Summary||BRepFill_OffsetWire should not create offset wire => BRepFill_OffsetWire does not build offset of b-spline curves|
|2016-07-18 15:10||msv||Assigned To||msv => ema|
|2016-07-18 15:10||msv||Status||new => assigned|
|2016-07-20 17:08||msv||Note Added: 0056062|
|2016-07-20 17:08||msv||Assigned To||ema => msv|
|2016-07-20 17:08||msv||Priority||normal => low|
|2016-07-20 17:08||msv||Target Version||=> Unscheduled|
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