Thursday, November 08, 2012

Two Minutes with Constraint Quirkiness

Okay it's a little more than two minutes but less than three. I've been running into a few things lately that I don't recall being an issue in the past. Then again maybe my memory isn't what I thought it was? Take a look at this image. Seems pretty straightforward.

I've got a pair of Reference Planes that I want to keep positioned on either side of a rail (as in stiles and rails for a door). In the past I could do what you see and then use the dimensions on the right to shift the collection of reference planes up or down a bit. Now I find that I can't unless I select all three together. In the past I just grab the one in the middle and use the referencing dimension to shift it up/down. Doing that now gives me some weird results. It's probably better and easier to explain it with a video so here's one at You Tube.


Chad said...

I've seen similar items and changing the order I place constraints seems to have an affect on how it all moves. No idea why though.

Alfredo Medina said...

Interesting. I made a test using 2012, and it behaved in the same way as in your video. I wonder if it was ever different in previous versions?

Steve said...


I am an old timer so when I write remember I am remembering waaay baaack. Release 2012 is still new for many people!

Alfredo Medina said...

Yes, but that means that it is possible that it has been like this all the time; this might has been the 'normal' behaviour, even from waaay baaack, ... :)

Teun said...

Thank you for your Post. I enjoy reading your Blog.
I checked this strange behaviour. And it seems happen with Ref. Planes and not with Ref. Lines or Lines (Strong Weak or Not a Reference). And the Anchor only seems to appear when this happens. The Anchor shows the Ref. Plane that sticks to his place while the others change. You can change the position of this Anchor.
The Post of Luke Johnson suggest that most of the time the family will be stable in a project environment. But when it isn't you can try using Ref. Lines or replace the Eq. constrains with a Formula based Parameter.
But it's a bit scary and unpredictable behaviour.