Constrained area block wont move other parameters

[Anonymous]

Attached is a simple block for a storage unit which is constrained to 0.5 sq m.  It has a grip for dragging the length of the unit and the depth automatically alters to maintain the constant 0.5 sq m area.  It has a piece of text in the centre which remains central, and a small access zone dotted in front with a depth that is always constant.  The block also contains some point parameters (with associated move actions), a basepoint parameter, an alignment parameter and a linear parameter (with associated scale action) for scaling the text size.

It works pretty well but when dragging the length (constraint) parameter I would like to move the basepoint, point and linear parameters as well. How can I associate these parameters to the (constraint) length parameter?

I can easily do this via other linear parameters and associating move/stretch etc actions to them, but this length parameter is not an ordinary linear parameter, it's a constrained parameter. Without the constraint parameter and just using ordinary length parameters the constrained area won't be possible.

Can this even be done?

[Libbya]

You cannot constrain parameters.  Also, in my experience, dynamic parameters will not correctly alter dimensional constraints.  Oddly enough you can add dimensional constraints to the selection set of stretch actions and properties will show that the dimensional constraint value is changed correctly, but the constrained linework does not move.  If you try to stretch the constrained linework also, it will also fail.

With all of this in mind, I would make the following changes to your block.  Change the dimensional constraint so that it only has one grip.  Move the base point parameter to the base point of the dimensional constraint.  Move the point/move to the same point.  Move the whole block so that point is at 0,0.  Move the align grip to the same line as the dimensional constraint (or get rid of it) and ignore the fact that it cannot stay centered.  See attached.  

[Anonymous]

Libbya,

Thanks for this.

I found the same thing - you can't move/alter dimensional constraints. Like you point out, you can stretch them and despite their property changing accordingly they don't alter their associated entities.  If you add the entities to the stretch action or even add a second action stretching the entities it doesn't work. Pity really. Would be so nice to be able to also move grips when a constrained object is altered.

For me the alignment parameter at 0,0 is extremely important. It allows the user to drag the block from a palette and it will auto align to the wall or whatever they're inserting the block against.  The other really important thing for me is the ability to be able to move and re-size the text.  This block is only one of a whole suite of blocks for the same discipline. They all share a common parameter - "Text Height".  This allows the user to grab all blocks in the series and alter the text size globally as required.  If the text is larger than the object itself it's important to be able to move it somewhere legible.

To this end I came up with the attached alternative.  It allows auto rotation upon insertion, and allows the text to be moved and re-sized.  I've added a small dot in a colour that doesn't print (using our company standard ctb) that moves as the block is re-sized. This dot is for text alignment centrally if desired. I've also added additional visibility states for different sized units - which was always the intention.

Thanks again Libbya. I appreciate it. 

[Anonymous]

Hello Mr. @Anonymous 

(This might be irrelevant to the topic, I hope you are courteous to reply. )

I am Saram a Student of B.Arch and still learning AutoCAD. I wanted to Draw a few Parametric Shapes (Rectangle or a Polygon) with an Area Constrain. Like a Rectangle or a Polygon with An Area of 20000sqft but I am unable to do it can you kindly help me understand how to do it? any reference material would be a great help.

Currently Im just using the FIELD Command to manually approximate the Area of an Object but that's not very efficient. If I could create a block just like yours and change the area and move to adjust the height or width of rectangle it would be great. 

Looking forward for a reply. 

Thanks