Shapr3D randomly adding many control points


here is a way to reproduce the issue:

  • create a clean ellipse using the ellipse tool and lock it
  • extrude the ellipse with -5° negative draft angle
  • go back to the sketch with the created body visible
  • draw a line intersecting the ellipse

The clean ellipse, which was locked, seems to be replaced by a mess of control points.

Actually, a new curve has been created above the original ellipse. If you select the new curve and delete, then you get the original ellipse in place but the locked ellipse has been also modified: now, when extruding, there is an unwanted face added.

I understand that there is an automatic edge projection on the sketch, when we draw on a face of a body; this can be useful on certain occasions, this can be painful on other situations, but this cannot mask or modify a clean locked curve.

Looks like the solution could be not to project when the projected curve is very close to an existing curve (distance less than the internal tolerance), and no sketch modification at all when extruding a body [Edit] probably no cache modification or invalidate the cache entry, see below.


I made a few additional investigations.
For the “locked ellipse has been also modified”, here is what I think:

  • the original sketch is not actually modified: if you export it in DXF format, you get the same sketch before and after the issue occurs;
  • but Shapr3D is probably using a cached version of the sketch for performance optimisation, and this version is modified by the extrusion, so for the end users, it looks like the sketch has been modified;
  • as soon as you made a modification on the curve, it invalidates the cache entry for the curve and you revert to the correct curve definition, probably creating a new cache entry;
  • if you copy the curve, the copy is correct also, probably because the copy does not use the version in cache, which is a very good thing :grinning: