SOLVESPACE -- parametric 2d/3d CAD

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Arc Constraint Problems 02 (by Andrew McIntyre)
Jonathan - I thought at first your recommendation was working but now find the problem continues. I attach a simple drawing of a rectangle 700 x 400mm with 2mm dia. holes at either end of the top fold. Of course the fold lines are shorter than the outer lines to accommodate the holes so I applied the 'line difference' constraint to them.

Nevertheless if I change either of the two parameters in either direction to any great extent things get quite badly screwed up.

Of course the simplest solution is to omit the holes altogether which I will now do since they can be added to the dxf drawing at the next stage but I thought I would report back to you in case there is a gremlin at large that needs your attention!

I think an ellipse function might be extremely useful.It would also be useful to be able to turn off "REF" dimensions on-screen since it can be useful to insert them all over the place to check that a drawing is behaving itself, but they then add a lot of clutter when not needed!
Mon Jun 27 2016, 09:41:57, download attachment ARCF PROBLEM.slvs
(no subject) (by Jonathan Westhues)
Big changes in dimensions may sometimes cause convergence to undesired solutions. If you change the dimension with Analyze -> Step Dimension, then you may be able to avoid that. Or, the constraints would be much simpler if you sketched the un-drilled sheet, extruded it, and then added the drills as a Boolean difference.
Mon Jun 27 2016, 22:49:33
(no subject) (by EvilSpirit)
It will be step forward if we get rid of "Step Dimension". We just have to make dimension value become a parameter, then we can solve it natural way inside NewtonSolve, not trying to emulate this behaviour with additional steps around Newton method iterations. We can extend SolveBySubstitution to work with parameter->constant substitutions and get the same performance when we have case where parameter == value_constant, and we can throw the honest equations into Jacobian when we have parameter != value_constant (this happens just after value editing).
Tue Jun 28 2016, 05:08:44
Do not remove - step dimention (by ruevs)
It is useful for much more than avoiding "strange" solutions when resizing.
Mon Jul 4 2016, 09:03:53
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