[Plugin] Center of Gravity

sketchartist023

@tig said:

The 'accuracy' setting affects the result... as you have found.
For simple forms the 'accuracy' of the results will not improve beyond a certain point, no matter what the settings are...
But otherwise the more 'iterations' the tool does the nearer the result is to being 'true'.
If you choose a 'more accurate' value, then the 'weight' might become more accurate, and the CofG might adjust very slightly.
If you have the time... then more iterations gives the most accurate results...
BUT sometimes the differences are so small it's not worth the delay...
It's up to you - your model - your time...

Thanks I found that using an accuracy of 5% works quite well with realtime weight on my end using the correct density I found on the internet for the material I use. Works a charm! Helps with configuring shipping information BEFORE having to go to Fedex etc and create real products beforehand so it reduces capital costs for me Thanks so much again. I have been within 5lbs accuracy with actual shipping items that I modeled. Just an update

pazzamnik

Hey Tig,

Thanks for the CofG plugin. It has been working quite well, but have one small easy, which I think is easy to overcome. I have drawn an aluminum extrusion and set the aluminum density. The size of the extrusion is 1m in length, so I can know my run length cost/per linear meter.

Whether I extend the extrusion 1m to 20m in length, CofG always comes back and gives me the same weight? Yet if I copy the meter long extrusion, put a couple bends on it, and run CofG, it gives me a new and hopefully correct weight.

Wondering if there might b an issue with my group that is causing an issue?

Thanks.

Dave R

What method are you using to extend the extrusion? If you are just scaling the group or component, you aren't updating its definition. If you open the group/component for editing and then modify its length, the definition gets changed and the plugin should give you the results you are looking for.

jojo9

Great plugin! its possible to add some toolbar buttons? i tried but had no luck.

#--------- menu -----------------------------
unless file_loaded?(File.basename(__FILE__))
   txt0="C of G..."
   txt1="Find C of G"
   txt2="Composite C of G"
   dir=File.dirname(__FILE__)+"/TIGtools"
   toolname="CofGravity"
   locale=Sketchup.get_locale.upcase
   path=dir+"/"+toolname+locale+".lingvo"
   if File.exist?(path)
     txt0=deBabelizer(txt0,path)
     txt1=deBabelizer(txt1,path)
     txt2=deBabelizer(txt2,path)
   end#if
   submenu=UI.menu("Plugins").add_submenu(txt0)
   submenu.add_item(txt1){CofGravity.new(1)}
   submenu.add_item(txt2){CofGravity.new(2)}
   
=begin   
  #plus
 	tb= UI.toolbar "Konstruktion"
 	
	cmd = UI;;Command.new(txt1) {CofGravity.calculate}
	cmd.small_icon = "../Images/Center_component_lg.png"
	cmd.tooltip = "Teilmassen Zentrum"
	tb.add_item(cmd)
	
	cmd1 = UI;;Command.new(txt2) {CofGravity.composite}
	cmd1.small_icon = "../Images/Center_component_lg_sum.png"
	cmd1.tooltip = "Hauptmassen Zentrum"
	tb.add_item(cmd1)   
=end  
end#if
file_loaded(File.basename(__FILE__))
#---------------------------------

sidenote. unable to format my text as code. I get a weird looking format table (please see attachment)

TIG

tb = UI.toolbar**.new**("Konstruktion")
Makes the new toolbar.
And use: cmd.small_icon = "Images/Center_component_lg.png"

assuming Images in in the same subfolder as the loading RB file ?
You cannot add a new button to a existing toolbar unless you have just made it, OR if the toolbar has been made during the same start-up session AND it has an enduring reference...
So in some earlier loading file [they load alphanumerically] use something like:

module MY_STUFF
  ###
  TOOLBAR = UI.toolbar.new("Konstruktion")
  ###
end

Then in your second file: tb = MY_STUFF::TOOLBAR Which is an enduring reference to the 'MY_STUFF' toolbar entitled 'Konstruktion'...
You can then add buttons to that toolbar as SketchUp starts - in any later loading script...

jojo9

TIG, thanks for helping! i got it running, with another loader script, as you said.
Furthermore, i corrected the call commands.

Pockocmoc

Hi all, I am doing a 3D model in Sketchup 2016 and when trying to use CoG, it gives to me "weight=0.0"... How is it possible?

Here is how I do :
I create my 3D object, I select it and press "G" to save it as a single component. Then I select it, and I run CoG, applying a density of 7850 Kg/m3 (c40 steel density). It calculates during 5-6 minutes and finally shows 0.0 ...

Any idea?

Thanks!

TIG

Is it a 'Solid' object in Entity Info ?

Without seeing the actual object and the settings you used I can't say what the issue might be.

Pockocmoc

Hi !

Well, it seems it is not recognized as a solid, because there is no "volume" entry in the Entity Info box.

Here is a picture :

Thank you.

Pock'

Pockocmoc

Oh, and even with a simple cube, (wich is solid) it does the same : no weight...

TIG

What version do you have ?
It should be v1.7 from the SketchUcation PluginStore ?
It's 3 years old but works on newer SketchUps anyway...

If you run it with the Ruby Console open are there any error messages ?

What settings are you using ?

What is getting reported exactly ?

Obviously the object's size versus the chosen density units can cause small objects to be reported as 0...
A small 'blade' probably needs to be in g/cm³ or similar...

Here's what I get with a component cube with protruding numerals [v2016].
It's a but over 1 m³ with a density of 2000 kg/m³ at the default 1% accuracy setting it returns a true volume in m³ and a weight in kg...
A much smaller [scaled] version reports '0' when the overly large units misapplied, but with g/cm³ it's fine...

Can you post a simple SKP that has issues so I can test it...

Box

It sounds like you may be creating component, but failing to tick the box that replaces the raw geometry with the component.
If there is no bounding box around your object it is just raw geometry, see if the component is in the component browser for you ready to use.

Pockocmoc

I am so stupid ... you are right TIG, it was because of the units, obviously! The blade weights 42 grams, so (0.0)42 Kg .

Thank you for all.

hute_zhaw

Hi Folks

I just installed this plugin into SketchUp 2017. It doesn't work as expected for me. The find CofG still works fine as far as I can tell but the Composit CofG returns a ruby error:

Error; #<TypeError; reference to deleted Group>
/Users/hute/Library/Application Support/SketchUp 2017/SketchUp/Plugins/CofGravity.rb;670;in `entities'
/Users/hute/Library/Application Support/SketchUp 2017/SketchUp/Plugins/CofGravity.rb;670;in `block in do_composite'
/Users/hute/Library/Application Support/SketchUp 2017/SketchUp/Plugins/CofGravity.rb;669;in `each'
/Users/hute/Library/Application Support/SketchUp 2017/SketchUp/Plugins/CofGravity.rb;669;in `do_composite'
/Users/hute/Library/Application Support/SketchUp 2017/SketchUp/Plugins/CofGravity.rb;117;in `initialize'
/Users/hute/Library/Application Support/SketchUp 2017/SketchUp/Plugins/CofGravity.rb;817;in `new'
/Users/hute/Library/Application Support/SketchUp 2017/SketchUp/Plugins/CofGravity.rb;817;in `block in <top (required)>'
SketchUp;1;in `call'

Has anybody got a clue how to fix this? It is really a pretty cool plugin and would be a shame if it became unusable.

TIG

Thanks for the bug-report.
I suspect that this is a glitch in the way v2017 handles exploded entities.
I'll investigate and fix it...

TIG

Here's v2.0 http://sketchucation.com/pluginstore?pln=CofG Its coding is now compatible with v2017 and it is also signed for use in v2016/v2017 in any loading-policy.

hute_zhaw

Outstanding work TIG, thanks that was quick, I can confirm it works after the upgrade of the plug-in.

Cheers

jbkbm

The plugin does not seem to be able to detect hollow spaces. Am I doing something wrong? I am trying to find the CoG of steel assemblies but when it calculates the weight, it includes the space between plates and gives me a number much higher than the actual weight.

TIG

Your image attachment isn't showing.
An object needs to be a sensibly formed 'solid' - as reported in Entity Info.
Otherwise results can be flaky...
'Hollows' are accounted for, if it's a proper solid...

If you attach your SKP we can look at it...

lsorrentino

Hello All, hello TIG,
I want to calculate the center of gravity of a small magnet, but the calculation always report volume = 0 and eventully weight = 0.

The plugin works perfectly on my pc with larger objects, the density is 7.6 g/cm3, I'm a newbie with sketchup in general, I'm probably doing something wrong

Luca

sketchup file

screenshot

result