Has anyone had any success with using expressions/formulas in a dynamic block. I want to create a dynamic flat truss with webbing, where you can select the number of V webbs and as your stretch the length of the truss the vees stretch accordingly. With the array parameter, you seem to be limited to predefining a spacing and the number of instences increases as you stretch the object. I want to set the number of instences and let the spacing change. In particular I have tried using the Parameters Manager to create a user parameter that takes the lenght of the truss and divides it by a number. When I try this AutoCAD gives me "A dependent expression cannot be evaluated" It appears that all of the Action Parameters cannot be used in expressions which really limits things. Anyone have a suggestion?
Adding members thru a Stretch is usually the domain of an Array Action. The problem here is that the Arrayed item is static or can be manipulated as a group. I.e.: If you add a Stetch Action to the Array entity all the Array objects will Stretch the same. You could use the Array to get the number of objects needed and then a Stretch Action to lengthen or shorten the group of webs.
Angles can be very tricky to Stretch. You will find that Slopes and Radians will need to be the multipliers to get these to move where you want them to. (I do not have experience with Constriants so there may be options there to keep the web where it needs to be.)
A couple random thoughts on your issue.