automatic change of dimensions when you change area manually

Anonymous — Fri, 18 Jan 2019 20:55:08 GMT

for a circle, when i click on properties, i am able to change its area and the new circle with new radius is drawn automatically to satisfy that area that I wanted

but for a triangle i couldn't do it. is it because it didn't know what sides and angles to adjust, but for a circle it knew that all it needed to do was to adjust radius? in other words can it do it only for a regular shape? well, i tried a square too but it also doesn't allow manual entry for area for a square.

Re: automatic change of dimensions when you change area manually

Kent1Cooper — Fri, 18 Jan 2019 21:18:47 GMT

@Anonymous wrote:

for a circle, when i click on properties, i am able to change its area and the new circle with new radius is drawn automatically to satisfy that area that I wanted

but for a triangle i couldn't do it. is it because it didn't know what sides and angles to adjust, but for a circle it knew that all it needed to do was to adjust radius? in other words can it do it only for a regular shape? well, i tried a square too but it also doesn't allow manual entry for area for a square.

You're correct that it won't let you adjust the area number for something in which a change in area could be effected by way of multiple possible changes -- only when there's only one such possibility. So it can do a Circle, but it can't even do other regular shapes such as Polyline rectangles/squares/polygons, if their area could be adjusted by moving any vertex or any combination of vertices, because it can't know which one(s) to move. It doesn't inherently know whether a closed Polyline is "regular" in any way, though in some cases a routine would be able to determine that.

If you want to change the area of something without affecting its relative shape [i.e. make a geometrically "similar" version with a different area], a rather simple routine could certainly be written that would ask you to select something that has area, and what resulting area you want it to have, and it could Scale it using the Reference option for you. But even then, it wouldn't be able to just change it for you without at least one additional piece of information -- a base point about which to Scale it [it can reasonably assume the center for a Circle], unless you would always be willing to have it scaled about the same calculable location [e.g. middle of bounding box, geometric-center Osnap if it's a closed Polyline, some corner of its extents, etc.].

Re: automatic change of dimensions when you change area manually

pendean — Fri, 18 Jan 2019 21:24:54 GMT

AutoCAD doesn't work like that with polygons, they do not have that level of intelligence. Circles are the exception because there are no sides to a circle.

Are you new to the program, or are you looking to do more for a specialized need?

TIA

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automatic change of dimensions when you change area manually

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