Re: Find balance point?



On Mar 22, 7:41 pm, "zulu" <noth...@xxxxxxxxxxxx> wrote:
I have a Visio page with several randomly placed different shapes, all of
different (in the real world) weights.

How can I move them around to make a certain point on the drawing the
balance point (the centre of gravity)

As I understand from this post and others, what you would like is to
have the application calculate the centre of gravity of a number of
masses, and mark it. The mark should move as the shapes are re-
arranged.

I'm not sure if there's any way to solve the problem generally, such
that you can easily add as many masses as you want, at least without
using scripting. But if you're patient and don't have too many masses
to deal with, you should be able to set this up in Visio. I did it for
four masses in a fairly short space of time. Try this:

1) Create an object to use as a mass. I just drew a circle with the
ellipse tool.
2) Give it a custom property, with label "Mass" and name "Mass", which
must be a number.
3) For convenience, I then edited the text of the object and used
"Insert->Field...". Under "Custom Properties" I found my property
"Mass" listed, and selected it. I also edited the shape's protection
and checked the box for text, so that I couldn't accidentally change
the text. The shape now displays its mass as a number.
4) Next, I edited the shapesheet for my shape. I could see an entry
for "Prop.Mass" under "Custom Properties".
5) I right-clicked and chose "Insert Section...", and selected "User-
defined cells". A new section appeared with an entry called
"User.Row_1"
6) I renamed the entry to "WeightedX" and gave it a formula of
"=PinX*Prop.Mass"
7) I right-clicked on that entry and chose "Insert Row".
8) I renamed the new entry to "WeightedY" and gave it a formulat of
"=PinY*Prop.Mass"
9) Next I closed the shapesheet and copied my shape a few times.
10) I opened up the "Drawing Explorer" window and found my shapes.
They were called "Sheet.1", "Sheet.2", etc. I renamed them to "Body.
1", "Body.2", etc. so that I could tell them apart from other things I
created.
11) I created a new object, another circle. I made it a different
colour and renamed it "Centre".
12) I turned on protection for the shape's position.
13) I opened up the new shape's shapesheet.
14) I gave it this formula for PinX:

=(Body.1!User.WeightedX+
Body.2!User.WeightedX+
Body.3!User.WeightedX+
Body.4!User.WeightedX)/
(Body.1!Prop.Mass+
Body.2!Prop.Mass+
Body.3!Prop.Mass+
Body.4!Prop.Mass)

and this formula for PinY:

=(Body.1!User.WeightedY+
Body.2!User.WeightedY+
Body.3!User.WeightedY+
Body.4!User.WeightedY)/
(Body.1!Prop.Mass+
Body.2!Prop.Mass+
Body.3!Prop.Mass+
Body.4!Prop.Mass)

If I had made more shapes, I'd have needed to expand the formulae to
include them all.

Now you can drag the weights around and the centre of gravity follows
them. You can edit a shape's properties and change its mass, and its
effect on the centre of gravity changes. If you make a mistake and the
centre of gravity ends up disappearing off your page, you can still
select it in the Drawing Explorer. I hope it's close enough to what
you need to help! I've made a lot of assumptions (e.g. that you're
happy to treat the objects as point-masses), so it's possible it's not
quite what you wanted.
.