[Plugin] Center of Gravity

watkins

A few useful sites giving densities of building materials etc.

Mass, Weight, Density or Specific Gravity of Bulk Materials

Mass, or density, of over 80 different Bulk Materials from bauxite to zinc ore

(www.simetric.co.uk)

http://www.civl.port.ac.uk/britishsteel/media/BSCM%20HTML%20Docs/Loads%20of%20building%20materials.html

Density of Wood - The Physics Factbook

(hypertextbook.com)

Density of Common Building Materials per Cubic Foot

These values for density of some common building materials were collected from sites across the Internet

(www.rfcafe.com)

watkins

Forgot to say that TIG's volume calculator (+ density) and CofG calculator give you the complete story when reviewing loads.

pilou

Damned another very cool tool for ingeniery

DSG2k

Vista and SketchUp 7.1.6860 . . .

Unzip of CoG plugin zip in the plugins folder resulted in a lot of overwrite requests (I just got your Manifold, too). I overwrote the older deBabelizer with the newer one.

Now on load a "Load Errors" window pops up, saying:

Error Loading File CofGravity.rb
undefined method `deBabelizer' for main:Object

And the plugin does not appear in the Plugin menu.

I don't know Ruby so I didn't actually poke at anything in the code, nor did I see anything obvious to me.

Just FYI.

TIG

Have you got a file called deBabelizer.rb in the Plugins folder.
If not then please put a copy of it in there***.
You must extract all of the files and sub-folders in a zip file keeping their sub-folders etc.
A good unzip application will do that for you.
Moving files manually leads to problems as they end up in the wrong place.
Unzipping directly into Plugins can cause problems as files seemingly overwritten are not !***
With Vista you are probably best firstly extracting everything into a folder on your Desktop [e.g. 'CofG_1.1'] and then use copy/paste on all of that folder's contents [unchanged], en mass into the Plugins folder...

***You are on Vista so I suspect you have some access-right problems with your Plugins folder
The dreaded 'compatibility files' issue - it looks like you put the file into the folder but Vista 'protects you' by putting it into a parallel 'compatibility folder' so you don't actually get to find it, load it etc as it's not really there...
So I recommend you change the access-rights to the folder [properties] so you can write to it without problems...
The deBabelizer.rb file issued with all tools is the same file - you only need one copy in Plugins for any tool that uses it to load and to use it...

Gaieus

Hm. This is a very interesting piece of plugin, TIG; thanks!

It immediately brings teaching into my mind - as how you can (for instance) explain the different vectors arising in a Gothic structure for instance. It would be (also) interesting to see how these centers of gravity can interact with each other after a structure is assembled.

pilou

Why not put the Xray mode at the end of the process?
Because we can't see the CofG when this one is inside a volume
Pilou

TIG

Here's v1.2 http://forums.sketchucation.com/viewtopic.php?p=229401#p229401
with FR lingvo file by Pilou...

TIG

@unknownuser said:

Why not put the Xray mode at the end of the process?
Because we can't see the CofG when this one is inside a volume
Pilou

You can't set Xray mode on your own ?
Many want just the top SP for lifting, and the weight - so CofG is secondary...
If you want it then you can Xray it...

Sorry if I sound cranky... long week and tomorrow's Monday [aaargh!]

*Vous ne pouvez pas définir le mode Xray sur vos propres?
Beaucoup veulent juste le SP haut pour le levage, et le poids - donc CofG est secondaire ...
Si vous le souhaitez vous pouvez le Xray ...

Désolé si j'ai l'air grognon ... longue semaine et demain lundi [aaargh!];)*

TIG

@gaieus said:

Hm. This is a very interesting piece of plugin, TIG; thanks!
It immediately brings teaching into my mind - as how you can (for instance) explain the different vectors arising in a Gothic structure for instance. It would be (also) interesting to see how these centers of gravity can interact with each other after a structure is assembled.

It came from a PM request for a tool to find the perfect lifting point for a delicate piece of restoration stonework...
I added the composite tool to combine the CoG's and SP's of assembles of multiple or varying density units...
Any more ideas welcome...

TIG

'Composite C of G' is for use only on existing C of G elements - it's used to get a combined C of G for them.
If you have an assembly of parts that all have the same density then you can just make one group of all of them and find the C of G of that one group.
BUT if you have an assembly of parts of different densities you'll need to find the individual C of G's of each of them: then you select these C of G elements [only these, nothing else] and use the Composite C of G tool on them.
You only need to use the Composite C of G tool on the C of G's of parts with different densities that could unexpectedly relocate the assembly's C of G - 'off center' for example... Otherwise group and get the one C of G...

pilou

No problem i can make the Xray mode by hands

Another thing
Seems "Composite mode" don't works for me

object goup 1(without CoF), object goup 2(without CoF),
group 3 = Group1 + Group 2
Find Cof for group3 ok

object goup 1(with CoF), object goup 2(with CoF)
group 3 = Group1 + Group 2
Composite group 3 not Ok
What I miss?

pilou

@unknownuser said:

with different densities

haaaaaaaa
THX!

chrisjk

I can't seem to get it to do anything on a Mac..

TIG

@chrisjk said:

I can't seem to get it to do anything on a Mac..

Please explain a little more...
What can't you get to work ?
Open the Window > Ruby Console.
Select a group or component instance that has a volume - we are trying to find it's C of G !
Run the tool and answer the dialog's questions...
What happens / doesn't happen ?
What are the messages if any in the Ruby Console...
There is nothing different between a PC and a Mac for this tool [except 'PEBCAK' ]

driven

Error: #<NoMethodError: undefined method db' for CofGravity:Class> /Library/Application Support/Google SketchUp 7/SketchUp/Plugins/CofGravity.rb:153:in calculate'
/Library/Application Support/Google SketchUp 7/SketchUp/Plugins/CofGravity.rb:813

Dave R

I just installed it on my MacBook and tried running it. It worked fine for me. Thank you TIG.

TIG

@driven said:

Error: #<NoMethodError: undefined method db' for CofGravity:Class> /Library/Application Support/Google SketchUp 7/SketchUp/Plugins/CofGravity.rb:153:in calculate'
/Library/Application Support/Google SketchUp 7/SketchUp/Plugins/CofGravity.rb:813

Have you got deBabelizer.rb in the Plugins Folder ?
This file is for translation and is used by many of my tools and it ships with each of them - although it's always the same file...
It should come with the zip and is installed into the same folder as CofGravity.rb ?
The error is because 'db' which is the local def of deBableizer in the class is failing to get defined...

driven

@tig said:

Have you got deBabelizer.rb in the Plugins Folder ? :?

Hi Tig,

I only installed it to send you a report from another Mac, and am sure I used all of the correct instal procedures.

your other tools are still working (EEby.., Manifold, Vol..2) , after the CofG_1.2 instal (including deBalelizer.rb)

after the first (_1.2) Error, I replaced both files with the _1.1 files and had the same error.

I then tested all in the same drawing
EEby Rail--worked
Volume2 --worked
Manifold --worked
CofG --same error report (-1.2 re-installed from zip)

john

TIG

driven

A mystery...


def CofGravity;;calculate ### LINE 129 ==start of class/def that is reporting the error...

def db(string)
  dir=File.dirname(__FILE__)+"/TIGtools"
  toolname="CofGravity" 
  locale=Sketchup.get_locale.upcase
  path=dir+"/"+toolname+locale+".lingvo"
  if not File.exist?(path)
    return string
  else
    deBabelizer(string,path)
  end 
end#db

if (Sketchup.version.split(".")[0].to_i<5)
     UI.messagebox(db("C of G; Sorry, this is Version >= 6 Tool !"))
     return nil
end#if

model=Sketchup.active_model
entities=model.active_entities

############
if Sketchup.version[0,1].to_i > 6
  model.start_operation((db("C of G")),true)### LINE 153 GIVES ERROR !!!

Can you look at the script's contents and see if it looks like this ?
Works fine on a PC for me - can't see where a Mac might trip up ?