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CAD Forums => CAD General => Dynamic Blocks => Topic started by: Daniel J. Ellis on May 17, 2019, 02:41:01 AM

Title: Dynamic Gable-fronted Porch. Diagonal roof bracing
Post by: Daniel J. Ellis on May 17, 2019, 02:41:01 AM
I've been trying to create a dynamic block of a gable-fronted porch with diagonal roof bracing.  The dynamic bit comes from stretching the width to suit the opening beneath it.

The roof pitch is 45 degrees, which has kept things relatively simple.  I've managed to use constraints to get one side of the bracing to stretch properly, but I can't get the other side to work.  Oddly, I haven't been able to reproduce the working side (i.e. tried copying the block, exploding and re-making the block to try and reverse engineer it.

Can anyone suggest anything please?

dJE
Title: Re: Dynamic Gable-fronted Porch. Diagonal roof bracing
Post by: CAB on May 19, 2019, 01:15:18 PM
Might be easier to do a LISP to draw the line work.
Title: Re: Dynamic Gable-fronted Porch. Diagonal roof bracing
Post by: Daniel J. Ellis on May 21, 2019, 03:47:34 AM
OK, thanks, CAB.

That's way beyond my LISP knowledge, but it looks like I'll have to look into it!

dJE
Title: Re: Dynamic Gable-fronted Porch. Diagonal roof bracing
Post by: Dlanor on May 21, 2019, 05:07:30 AM
Can't open the drawing. I need AutoCAD 2010 version if possible.
Title: Re: Dynamic Gable-fronted Porch. Diagonal roof bracing
Post by: CAB on May 21, 2019, 12:22:25 PM
2010
Title: Re: Dynamic Gable-fronted Porch. Diagonal roof bracing
Post by: Dlanor on May 21, 2019, 12:33:32 PM
Thanks CAB
Title: Re: Dynamic Gable-fronted Porch. Diagonal roof bracing
Post by: Dlanor on May 21, 2019, 03:42:36 PM
Attached is drawing containing modified dynamic block as block. It works in Autocad 2010. I've constrained both the braces and added two new linear parameters, distance3 and distance4. They have their own stretches but no visible stretch parameters as they are chained to the left, right and top stretches. The distance multiplier for these actions has been set to 0.5 since the left brace will be affected by the left and top stretches and the right brace by the right and top stretches.

Title: Re: Dynamic Gable-fronted Porch. Diagonal roof bracing
Post by: Daniel J. Ellis on May 22, 2019, 03:35:46 AM
That's wonderful, thank you, Dlanor (and thank you CAD for saving it down for me).

One thing I've never understood about chained parameters is how you tell it WHICH other parameter it's chained to?

dJE
Title: Re: Dynamic Gable-fronted Porch. Diagonal roof bracing
Post by: Dlanor on May 22, 2019, 05:26:51 AM
To chain a parameter to another parameter you have to include it in one of that parameters action.

Sequence

Create two parameters. P1 is the control parameter, P2 the one that will be changed. Remove all action grips from P2

Create an action for parameter P1 and include P2 in the selection set of objects. In the case of your block I included the end of the paramjeter that will move, using a crossing as the action was a stretch.

Create an action for P2 selecting the gripless parameter end that will move and select the objects, then constrain the objects.

Right click on the parameter to be chained and select Properties. At the bottom under Misc the Chain Actions can now be set to Yes. Click on the action then right click and select properties.
Under Overrides you can set the Distance Multiplier. The Angle Offset is relative to the parameter direction.

You really need to play about with it to fully understand what does what. It took me months, on and off, whilst playing with an advanced dynamic door block to finally get some of this.