Followme with the SketchUp API

medeek

I am trying to create (rebar) with the follow me tool in the API. I have a rectangle path with arcs at the corners. I've been fighting with this for hours now and I can't seem to get it to work. My chunk of code is below:


@Tbarbr = @Topbardia * 6.0
		@Topbarradius = @Topbardia/2.0

		arc1x = @Ftgx1 + @Ftgwidth/2.0 + @Tbarbr
		arc1y = @Ftgx1 + @Ftgwidth/2.0 + @Tbarbr
		arc1z = @Slaby1 - @Rebar_clr

		arc2x = @Ftgx1r - @Ftgwidth/2.0 - @Tbarbr
		arc2y = @Ftgx1 + @Ftgwidth/2.0 + @Tbarbr
		arc2z = @Slaby1 - @Rebar_clr
		
		arc3x = @Ftgx1r - @Ftgwidth/2.0 - @Tbarbr
		arc3y = @Ftgx1b - @Ftgwidth/2.0 - @Tbarbr
		arc3z = @Slaby1 - @Rebar_clr

		arc4x = @Ftgx1 + @Ftgwidth/2.0 + @Tbarbr
		arc4y = @Ftgx1b - @Ftgwidth/2.0 - @Tbarbr
		arc4z = @Slaby1 - @Rebar_clr

		center1 = Geom;;Point3d.new arc1x, arc1y, arc1z
		center2 = Geom;;Point3d.new arc2x, arc2y, arc2z
		center3 = Geom;;Point3d.new arc3x, arc3y, arc3z
		center4 = Geom;;Point3d.new arc4x, arc4y, arc4z
		# centercircle = Geom;;Point3d.new arc1x, (@Ftgx1 + @Ftgwidth/2.0), arc1z
		centercircle = Geom;;Point3d.new (@BuildingWidth/2.0), (@Ftgx1 + @Ftgwidth/2.0), arc1z

		lp1s = [arc1x, (@Ftgx1 + @Ftgwidth/2.0), arc1z]
		lp1m = [(@BuildingWidth/2.0), (@Ftgx1 + @Ftgwidth/2.0), arc1z]
		lp1e = [arc2x, (@Ftgx1 + @Ftgwidth/2.0), arc1z]
		
		lp2s = [(@Ftgx1r - @Ftgwidth/2.0), arc2y, arc1z]
		lp2e = [(@Ftgx1r - @Ftgwidth/2.0), arc3y, arc1z]

		lp3s = [arc1x, (@Ftgx1b - @Ftgwidth/2.0), arc1z]
		lp3e = [arc2x, (@Ftgx1b - @Ftgwidth/2.0), arc1z]
		
		lp4s = [(@Ftgx1 + @Ftgwidth/2.0), arc2y, arc1z]
		lp4e = [(@Ftgx1 + @Ftgwidth/2.0), arc3y, arc1z]

		normal = Geom;;Vector3d.new 0,0,1
		xaxis = Geom;;Vector3d.new 1,0,0

		start_a1 = 3.14159265358979
		end_a1 = 4.71238898038

		start_a2 = 4.71238898038
		end_a2 = 6.28318530718

		start_a3 = 0.0
		end_a3 = 1.5707963268

		start_a4 = 1.5707963268
		end_a4 = 3.14159265358979

		grouptb1 = Sketchup.active_model.active_entities.add_group
		entitiestb1 = grouptb1.entities
		grouptb1.description = "REBAR TOP 1"
		grouptb1.name = "REBAR TOP 1"

		edgearray = entitiestb1.add_arc center1, xaxis, normal, @Tbarbr, start_a1, end_a1
		edge1 = edgearray[0]
		arccurve1 = edge1.curve

		edgearray = entitiestb1.add_arc center2, xaxis, normal, @Tbarbr, start_a2, end_a2
		edge2 = edgearray[0]
		arccurve2 = edge2.curve

		edgearray = entitiestb1.add_arc center3, xaxis, normal, @Tbarbr, start_a3, end_a3
		edge3 = edgearray[0]
		arccurve3 = edge3.curve

		edgearray = entitiestb1.add_arc center4, xaxis, normal, @Tbarbr, start_a4, end_a4
		edge4 = edgearray[0]
		arccurve4 = edge4.curve

		line1a = entitiestb1.add_line lp1s, lp1m
		line1b = entitiestb1.add_line lp1m, lp1e
		line2 = entitiestb1.add_line lp2s, lp2e
		line3 = entitiestb1.add_line lp3s, lp3e
		line4 = entitiestb1.add_line lp4s, lp4e


		# topbaredges = [line1b, arccurve2, line2, arccurve3, line3, arccurve4, line4, arccurve1, line1a]
		topbaredges = [line1b, edge2, line2, edge3, line3, edge4, line4, edge1, line1a]
		
		# path_face = entitiestb1.add_face(topbaredges)
		# path_edges = path_face.all_connected

		topcircle = entitiestb1.add_circle centercircle, xaxis, @Topbarradius
		top_face = entitiestb1.add_face(topcircle)

		status_top_bar = top_face.followme(topbaredges)

medeek

Here is what the path and face to extrude looks like:

medeek

Manually, using the follow me tool, I can extrude it along the path just fine. My code though does not seem to work but yet it does not throw any error in the ruby console.

medeek

Replaced the 6th line from the bottom with this:

topbaredges = line1b.all_connected

and now it works.

Dan Rathbun

So, it was failing because you were setting edge1, edge2, edge3 and edge4, to reference only the first segment of their respective arccurve, ...

... which caused the edge array topbaredges to have a set of 4 disconnected edge paths.

There are two easy ways around this.

First assume you had set each arc edge array to a reference like arc1edges, arc2edges, etc., from the add_arc() method call.

(Scenario A) - You create a literal nested array for your followme() method call, but flatten it using the Array class' flatten() method.

Ie, your literal edge array topbaredges would be defined like:

topbaredges = [
  line1b, arc2edges, line2, arc3edges,
  line3,  arc4edges, line4, arc1edges, line1a
].flatten

This should result in a 1 level array of all edge objects. (It is always good to test collections just in case. For example: if topbaredges.any? {|o| !o.is_a?(Sketchup::Edge) } will return true if there is a non-edge object in the collection.)

(Scenario B) - You use Ruby's built-in "splat" operator. It's the * character. It can convert an array to a parameter list, or a parameter list to an array.

Example:
` ary1 = [2,3,4]
ary2 = [6,7,8]
ary3 = [10,11,12]

ary = [ 1, *ary1, 5, *ary2, 9, *ary3, 13, 14 ]`
sets [ruby:1bj806zx]ary[/ruby:1bj806zx] to:
[ruby:1bj806zx][1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14][/ruby:1bj806zx]

So, [ruby:1bj806zx]*ary1[/ruby:1bj806zx] expands the array into the parameter list [ruby:1bj806zx]2, 3, 4[/ruby:1bj806zx], etc. (You'll often see this syntax used for method definitions to collect arguments into a method-local array. So, not only can you use it in literal expressions, but also in method call parameter lists.)

So, you could use this syntax (instead of the [ruby:1bj806zx]Array#flatten()[/ruby:1bj806zx] method.)
Ie, your literal edge array topbaredges would be defined like:

topbaredges = [
  line1b, *arc2edges, line2, *arc3edges,
  line3,  *arc4edges, line4, *arc1edges, line1a
]

medeek

Thank-you for providing clarity on this problem. I can't believe I didn't figure it out the answer was right in front of me. I guess the problem was that I wasn't fully understanding the "arc" construct. Now I realize that it is simply an array of edges, and can be manipulated as such.

One final issue with this follow me application is that the surface generated is inside out (reversed), what would be the best way to prevent this or reverse it. The follow me call does not output the handle to surface so there is no easy way do this at least from a cursory inspection of the code.

Garry K

top_face.reverse!() if (top_face.normal.z < 0)

sdmitch

Or perhaps

top_face = entitiestb1.add_face(topcircle)
top_face.reverse! if top_face.normal.samedirection?(topbaredges[0].line[1]
status_top_bar = top_face.followme(topbaredges)