topic Re: Min & Max constraints in Revit Architecture Forum

Min & Max constraints

Anonymous — Sat, 26 Dec 2020 17:02:56 GMT

Is there a way to set constraint dimension to be in between certain values? For example the min. dimension to be 50 and max 500?

Re: Min & Max constraints

constantin.stroescu — Sat, 26 Dec 2020 17:28:48 GMT

create a second parameter and use If formula twice as can be seen in my screenshot:

Re: Min & Max constraints

alan_eu — Sat, 26 Dec 2020 18:02:02 GMT

Nice, @constantin.stroescu ! I love formulas 🙂

Re: Min & Max constraints

Anonymous — Sun, 27 Dec 2020 11:28:35 GMT

Thank you very much, I love formulas - I will give this a try!

Re: Min & Max constraints

Anonymous — Sun, 27 Dec 2020 12:02:00 GMT

Re: Min & Max constraints

alan_eu — Sun, 27 Dec 2020 11:43:33 GMT

Do you have the "width" parameter in your family?

Re: Min & Max constraints

alan_eu — Sun, 27 Dec 2020 11:47:32 GMT

If you don't, you will have to create a parameter with this exactly name, including uppercase and by type (not by instance, in that @constantin.stroescu e.g.)

Re: Min & Max constraints

Anonymous — Sun, 27 Dec 2020 12:22:57 GMT

The formula does not give me an error, however it is not doing its job. What is missing? Why is it not restricting the minimal and maximal dimensions?

Re: Min & Max constraints

alan_eu — Sun, 27 Dec 2020 12:26:10 GMT

Load into your project and try it. Seems to be ok.

Send us the family, please.

Re: Min & Max constraints

Anonymous — Sun, 27 Dec 2020 12:30:17 GMT

Am I understanding this correctly? - I have to use the names of parameters in the parent family which are exactly the same as in child family? I think I must have misunderstood....

Also what is the reason I am going BY TYPE and not BY INSTANCE? - Could you please explain?

Re: Min & Max constraints

Anonymous — Sun, 27 Dec 2020 12:45:39 GMT

I have tested it in a project and the formula is not restricting anything. I have used BY TYPE for both the width and its constraint.

Re: Min & Max constraints

alan_eu — Sun, 27 Dec 2020 12:50:18 GMT

I found the erro in this image... You used the parameter width on your model. You would use the calculated value widht constraint.

You can use Type or Instance, you choose.

Re: Min & Max constraints

Anonymous — Sun, 27 Dec 2020 14:27:01 GMT

I am lost now. How do you make calculated value width constraint without having width as a parameter? Can you show me an example please?

Re: Min & Max constraints

alan_eu — Sun, 27 Dec 2020 14:58:24 GMT

You have to use your calculated value as the parameter. The Width is still necessary to change the Width Constraint value

Re: Min & Max constraints

constantin.stroescu — Sun, 27 Dec 2020 15:08:45 GMT

as you can see the real Length Parameters here are : W, D and H

Width , in my case, is an Input Parameter for W...

See , how it works when chainging Input Values ...

Formula in Parameter | Search | Autodesk Knowledge Network

Re: Min & Max constraints

Anonymous — Sun, 27 Dec 2020 16:55:41 GMT

Please advise where I have gone wrong...

I have done as you have suggested:

and when I loaded the family into project, I could not stretch the object by grip arrows:

EDIT: I realized I had it within a group (array). When I have ungrouped it and reloaded to the project (incl. parameters) and tested it, the formula was not working...

Re: Min & Max constraints

constantin.stroescu — Sun, 27 Dec 2020 19:07:37 GMT

I made a short screencast showing how a Family with Type Parameters and one with Instance Parameters work..

Family TypeParameters vs Family Instance Parameters | Search | Autodesk Knowledge Network

Re: Min & Max constraints

ToanDN — Mon, 28 Dec 2020 00:06:55 GMT

You cannot use a parameter in its own formula. You need an input parameter and an output parameter. Input is to type in value. Output is for the formula and constraining geometry if it is the intent.

Re: Min & Max constraints

Anonymous — Mon, 28 Dec 2020 08:43:20 GMT

Thank you very much for the link to the video! Very much appreciated

Is there any video that you could recommend me that I can study? - what I am trying to figure out is how to make a family that can do this:

The family needs to be stretchable left and right by arrows (the length dimensions will have odd site dimensions). The array of the panels which are in the middle needs to have a constraint (not to go below certain panel width) and also max constraint - once it reaches certain panel width it should make additional panel to fill up the length.

I have made the panels itself stretchable as desired, however I got stuck on everything else:

- array that will fill up certain length

- max & min constraints which will dictate array quantities

- overall width to be stretchable by arrows and not by dimensions listed on the properties panel

- making joint lines invisible

Re: Min & Max constraints

martijn_pater — Mon, 28 Dec 2020 09:32:57 GMT

@alan_eu wrote:
You used the parameter width on your model. You would use the calculated value widht constraint.

That one, select the dimension and associate the calculated parameter instead of the width parameter. Follow formula by @constantin.stroescu for the calculated parameter in the first post and it will work.