Group.volume

Dan Rathbun

](http://code.google.com/apis/sketchup/docs/ourdoc/group.html#volume)":3osf11lz]

Sketchup 8.0+

The volume method is used to compute the volume of this group if and only if this group is manifold.

... If the group represents a manifold volume, volume will be a positive value. If volume is negative, the group is not manifold.

See Also: Group.manifold?

Dan Rathbun

Mike, are you using Free or Pro edition ?

Can you provide an example of when it "doesn't work" ?

Didier Bur

Hi,

If you're in trouble with group.volume, try this: (assumed g parameter is a group entity)

def vol(g)
	v=0.0
	for face in g.entities
		next unless face.kind_of? Sketchup;;Face
		v +=(2*face.area*face.vertices[rand(2).to_i].position.to_a.dot(face.normal))/6
	end
	# if needed, convert cubic Inches to m3
	return (v * 0.000016387064)
end

morci429

Hi Didier, Great code thank u very much it did the job for me but its always worth to learn another way so Dan here's what i was trying to do with group.volume


pt = []
pt[0] = [0,0,0];pt[1] = [100,0,0];pt[2] = [100,100,0];pt[3] = [0,100,0]
face = Sketchup.active_model.entities.add_face pt
face.pushpull -100

then i had to find out how many entities i had in the model and which of them is faces so i can add them to the group using selection.clear and selection.add

and then i add all the faces to a group and i made a few copies of it.
and i tried to use the function but it never worked.
could you demonstrate a good practice of the function?
thanks you

TIG

Why not add the face directly into the group in the first place?

model=Sketchup.active_model
group=model.active_entities.add_group()
face=group.entities.add_face(pt)
face.pushpull(-100)
faces=[]
group.entities.each{|e|faces << e if e.class==Sketchup;;Face}

now faces is an array of all of the new faces inside group ?
You can use new_group=group.copy etc...
Then

new_faces=[]
new_group.entities.each{|e|new_faces << e if e.class==Sketchup;;Face}

etc etc...

morci429

that is certainly a better way thank you.
but still group.volume still not working.
did you use it before? what would be the way to use it?
thanks

TIG

The group.volume in v8 [ http://code.google.com/apis/sketchup/docs/ourdoc/group.html#volume ] and Didier's way otherwise should both work... for 'manifold' / 'solid' forms...
What is the output/error in the Ruby Console ?

thomthom

@morci429 said:

but still group.volume still not working.

Exactly what isn't working?
Unexpected result?
Errors?

morci429

Didier's way is working with no proplems.
and this is the error message when i try to use group.volume
group.volume
Error: #<NoMethodError: (eval):41: undefined method `volume' for #Sketchup::Group:0x4d28ba0>
(eval):41

morci429

i think i know where the problem is.. it only works in SketchUp 8. i just tried it
really sorry about that.
i was using 7 before that