Why is this sketch point contrained?

[Anonymous]

I sketched a trapezoid using the Line tool. I dimensioned 2 of the lengths. I see the parallel constraint and also the perpendicular constraint. I right clicked on one of the points to "fix" it. Now I want to drag the other point that doesn't have any constraints other than the parallel constraint but can not drag it anywhere. Why?

[TrippyLighting]

Post a screencast, or share your model/design by exporting it as a .f3d file and attaching it to your next post. Or both 😉

[Anonymous]

Forgot to include the screencast, thanks.

[TrippyLighting]

That looks like a very obscure bug, maybe Windows related (I am on a Mac), aside from the fact of course that it does not make any sense to actually apply a fixed constraint to that point because it's already full constrained.

When I try this by first selecting the point I cannot even get the marking menu to have the menu entry allowing me to fix/unfix the point  and first selecting the fix/unfix constraint from the sketch palette it does not let me select that point.

[jeff_strater · Accepted solution]

Yep, this is a bug.  I was able to reproduce it only by turning off the "Color sketch geometry by constraint status" preview option:

If this option is on, you cannot add the fixed constraint, which is the source of the problem.  If you remove the fixed flag, the point can be dragged.  As @TrippyLighting points out, the fixed on that point is not necessary - the point is already fixed.  I think the constraint coloring is blocking you from setting this as fixed, which is why you don't see the problem

Jeff

[TrippyLighting]

Yes, same on the mac!

[Anonymous]

OK, good to know. As a beginner I think there is always a reason for something and I must be slow or something. Now in this case since it's not even needed I realize I am a bit slow at picking things up, but it's funny how I run into bugs not knowing what I'm doing. Thanks.

[TrippyLighting]

Not knowing what you are doing is actually how many bugs are discovered, because you re following a workflow that experienced user would not try.

That's not a bad thing, and not only because it uncovers bugs.

Here's a mini tutorial on Sketching and constraints that I made just today to help two other new users that also had questions revolving around constraints. Maybe that helps avoiding some traps:

[Anonymous]

That's good thanks. What do I do if I have a fixed sketch point that is green? I'm finding it impossible to unfix in order to move objects. I click unfix but it remains green.