@tig said:

point=Geom;;Point3d.new(1,2,3
> )### or whatever 'point' you are testing for
> exists=false
> compo=Sketchup.active_model.definitions['Cube']
> compo.instances.each{|ins|
>   if ins.transformation.origin==point
>     exists=true
>     break
>   end
> }
> if exists
>   puts 'That Cube exists already!'
> else
>   ### do your stuff to add a new instance of compo at point
>   Sketchup.active_model.active_entities.add_instance(cCube, Geom;;Transformation.new( [1, 2, 3] )
> end

How will this effect performance if I had hundreds of them? I figured something like this must be possible, but as the number of cubes grows, this would become less efficient. I'm talking on the scale of ~2000 cubes. Is this method efficient enough for the speed to be negligible?

@tig said:

name="Cube" name=Sketchup.active_model.definitions.unique_name(name)

if 'Cube' is already taken it becomes 'Cube#1'

if 'Cube#1' is already taken it becomes 'Cube#2' etc...

Sketchup.active_model.definitions.add(name)

That solves a different question I had (lol) but not the one I'm asking here.
Let's take point [1, 2, 3]. I want to add an instance of cCube at that point
Sketchup.active_model.active_entities.add_instance(cCube, Geom::Transformation.new( [1, 2, 3] ))
What I want to know, is how do I check that that instance of cCube does not already exist?
How do I prevent creating duplicate instances of a component?
If there is not a cCube at [1, 2, 3] then{ Sketchup.active_model.active_entities.add_instance(cCube, Geom::Transformation.new( [1, 2, 3] )) }

I have a script that rasterizes a line into cubes. My problem is, I want to make sure it doesn't generate duplicate cubes. How do I do that?

require 'sketchup.rb'
require 'extensions.rb'

cCube = Sketchup.active_model.definitions.add("Cube") ;

newface = cCube.entities.add_face( [ [0.5, -0.5, 0.5], [0.5, -0.5, -0.5], [-0.5, -0.5, -0.5], [-0.5, -0.5, 0.5] ] ) ;
newface.reverse! if newface.normal.z < 0 ;
newface.pushpull(1) ; # extrude it up to make a cube

Sketchup.active_model.selection.each { |entity|
	x = entity.start.position.x
	y = entity.start.position.y
	z = entity.start.position.z
	l = entity.length
	dx = (x-entity.end.position.x)/l
	dy = (y-entity.end.position.y)/l
	dz = (z-entity.end.position.z)/l
	for i in 0..l.to_int
		cx = (x - (dx*i)).round
		cy = (y - (dy*i)).round
		cz = (z - (dz*i)).round
		# a bit of code to make sure a cCube doesnt exist here already
		Sketchup.active_model.active_entities.add_instance(cCube, Geom;;Transformation.new([cx,cy,cz]))
	end
}