FIXED AREA RECTANGLE

[jmartinarch]

I would like to draw a rectangle of a certain size (150 s.f.) then stretch it from a corner but have it automatically adjust to maintain the size desired.  So I would  start with a 10 x 15 shape, then have ability to stretch to 12.5' x ?  and as I stretch say the 10' width toward 12.5' the other end of rectangle (15) reduces to 12. 

Is it possible?

Thanks,

JM

ACAD 2011

[pendean]

I don't remember: does 2011 have Constraints? If yes, that's what you need to use/turn on.

[jmartinarch]

Yes, constraints are availale.  But not that easy to get a rectangle to maintain  an area.  Not  sure  if I can set the right  comb. of variables to get what  I want but thanks for the suggestion.

[dbroad · Accepted solution]

1. Select the rectangle and autoconstrain it.

2. Add a linear dimension constrain for the height and set it to the desired height (d1)

3. Add a linear dimension constraint for the width with the constraint text (<your target area>/d1)

4. Change dimension d1.  Dimension d2 changes to make the area constant.

[jmartinarch]

There it is.  Thanks much. 

[Tranatar]

I don't understand the (<your target area>/d1) part. Do i fill in the name of the area in the expression  And if so, how do you name the area..

I can't seem to let it show up in the parameter list. Can you please elaborate more?

[David_W_Koch]

I believe you will want to manually enter the target area, replacing the <your target area> with that number (in square drawing units).

Or, you could create a user parameter to hold the target area.  If you have multiple instances where you want to use the same target area, especially if you may want to change the target area for all instances, it may be better to set up a user parameter.

[Gangula2]

a little help here David, can I know how to make the user parameter editable & also it would be better if I can set the block to prompt to give the area required while inserting the block

[Gangula2]

Never Mind, Got it

[lathander]

And how do you do it ?  

I can create a new user parameter called AREA but I cant make it a field or connect it to the rectangle's area value. 
For a smooth workflow,
The function I need is to change AREA from outside the block editor for different rooms and then tweak dimensions while keeping the area constant. 

[Gangula2]

You can create a custom user parameter and use that parameter as a formula in one of the constraints.

Here's an example block for you. The user parameter that I've added in the block editor can be seen in the properties of the block for editing.

[David_W_Koch]

@lathander:  If you are using AutoCAD Architecture, you can get a similar effect using Space objects.  You set a Target area (and Target Length and Width, which should be set such that they result in the Target area) on the Design Rules tab for each Space Style.

If you place a non-associative Space, it will come in at the Target Length and Width (which, set properly, give you the Target area).  If you edit the Space with the grips, all bets are off - you can stretch and the Area will not be respected.  But if you use the Properties palette and, under the Actual Dimensions category, change either the Length or Width properties, the other will change to maintain the Area.  Perhaps not as on-screen interactive as a constrained rectangular polyline, but effective in its own way.

[lathander]

I got this,

I am wondering if there is a way to change the area parameter from outside the block editor, in model space. Since this is a tool/block to work with while tweaking the limited given areas, it is tedious to get in the block editor each time and change the area parameter's value and close and save block. 

It would be nice to change it on the fly, like a property value.

It is like you are tweaking the fixed area rectangle playing with 4m² and you see you have some more space so it can be raised to 5m²,  but you have to edit the block instead of just changing a value which is a drag.  

@Anonymous , I am on architectural but this is for a group project and many people just have autocad.   

Also they want me to create it stretchable on both axes. x and y. hmm. this has become a curious thing.

[Gangula2]

You don't have to edit the area parameter from inside the block editor. Once you place the block in the model space, you can edit the area parameter from the properties window if you select the block. 

The user parameter will be visible at the bottom of the properties window. (find screenshot below)

[lathander]

great. Thanks. 

I have attached what I could come up with so far, 
A friendly warning: you should turn off "display tickmarks for parameters with value sets" from block editor settings in options>user preferences if you want to preview my block. Otherwise, your graphics card may lag.

things I couldn't figure out:

- To put two grips on X and Y axis. so I can tweak the length of the rectangle, towards both directions.By entering values.   
- I can't constrain the area attribute at the geometrical center of the rectangle. (So I put a point parameter to move it freely. but this is not really a solution) 

If I accept both axes are undoable and add a rotation parameter to this mix,(so I can rotate it and stretch on Y-axis)  constraints go haywire.    

If I rotate (with the rotate command) my block 90 degrees when I click on the stretch grip and dial a value it behaves weirdly. 

I know I am pushing its limits, but a smart rectangle for early stages of brainstorming on the area layout should be doable. 

[lathander]

ok, an update. I figured out how to keep the area attribute at the center and make it work with the rotate parameter.
couldn't find a solution on making it XY stretchable. 
also, flips don't work with the rotation so I got rid of them.

A friendly warning: you should turn off "display tickmarks for parameters with value sets" from block editor settings in options>user preferences if you want to preview my block. Otherwise, your graphics card may lag.

[karan97RS]

Thank you very much.

Thats of great help.