Dynamic Block Behavior--Stretc

neophoible · 发表于 2022-7-6 23:55:02

I came across an item that looked like a good victim for some simple dynamic block surgery. (It's not important, but if you want to know, it is a bolt used as an axle.) After developing the block, I noticed that the behavior was not quite as predictable as I would have expected. I did not bother with any constraints, only a couple of linear stretches. They are in the same direction, but one is in the middle, the other at one end. The middle one seems to behave as I would expect.

When I enter a new value for the overall length, it updates by stretching the right end, and the left end stays put, as I would expect. However, if I drag the overall stretch, it does stretch the right end, but it also moves the object the same distance. Is there some principle of dynamic blocks that would predict this behavior? I'm doing this with vanilla AutoCAD 2012, but the DWG format is 2007, and the original drawing is from the early 90s.

I've attached a DWG file with the block already inserted.
Bolt Axle.dwg

Tuns · 发表于 2022-7-7 00:03:41

When you stretch, if you choose an entire object, it moves the entire object as if you had used the "move" command. Is that what you mean?

steven-g · 发表于 2022-7-7 00:05:49

It works as expected here. either the end stretches or the nut moves, but not the whole block.

Tuns · 发表于 2022-7-7 00:10:50

It works for me too. That's why I assumed he was using the stretch command or something similar (if there's something similar that is).

Dana W · 发表于 2022-7-7 00:16:36

The stretch behavior depends on what portion of the geometry you included in the "Stretch Area" as you are setting up the parameter/action combo. What are you referring to when you say "drag the overall stretch"?
When I drag either blue arrow, I see exactly what should happen. The end one stretches the right end of the bolt, and the middle one moves the nut along the bolt. In neither case does the left end move.

Dana W · 发表于 2022-7-7 00:20:42

Yeah, that is the only result I have ever gotten from using the stretch command. I never have figured out how to work it either.

neophoible · 发表于 2022-7-7 00:23:09

Thanks for all the tries and replies.  I'll address this one specifically:
I agree and was "sure" I was doing it correctly. And it sounds like I was right in this case.
Yes, that was a bit confusing. Sorry. I meant when I grab the rightmost linear stretch grip, the one on the end, and drag it.  It's supposed to change the overall length of the bolt, which it does, but in my case, it also moves the whole bolt that distance, like a combined stretch/move, except that the move does not have to be linear.  It does not exhibit this behavior when I simply type in the new value, and thus not the end of the world for me.
It sounds like the behavior on your system--and on everyone's but mine!--does it right, and the way I would expect.
I would do a video demo if I knew how and had the time.  Perhaps I haven't installed all of the SPs for 2012. But for now, I'd rather blame it on my system and see if I can get a new one. But, no, I know that's just wishful thinking. Still, I can dream, but the temptation is to curse...or to nap.

Dana W · 发表于 2022-7-7 00:30:19

Do you have Drag & Drop enabled? Do you have Grips enabled within blocks? Maybe the blue arrow is right smack on top of a grip and the whole block gets selected. I never activate the grips within blocks. They tend to be a bit of a bother at times, thus the option to toggle them exists.

neophoible · 发表于 2022-7-7 00:35:35

OK, Dana W, you expert, you! I had no idea that you could double up with a grip like that. I was indeed picking on the corner grip, which not only invoked the dragging but also activated the dynamic linear stretch. Turning the block grips off sounds like a good idea. I decided to use a simple toggle found here:http://www.ellenfinkelstein.com/acadblog/toggling-the-display-of-grips-within-blocks/. I'm sure one of the LT guys could write a macro in DIESEL

steven-g · 发表于 2022-7-7 00:39:31

Something like

copy

^C^C$M=$(if,$(=,$(getvar,gripblock),1),gripblock;0;;,gripblock;1;

[综合讨论] Dynamic Block Behavior--Stretc

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