How to give face a specific name

Developers Ruby API
#1

As we all know,when we draw a face,it has its entityID（number）and typename(“Face”), but these elements are fixed,whether the face can be named like a component, similar to the method “description” .

#2

You could add an attribute dictionary containing the name. But, so far as I know, there is no official attribute for “name” on edge or face.

1 Like
#3

This is not entirely true. Eg. In a current drawing context if you are drawing an edge or face “over” or “beside” a the face/edge will split/merge. But there will be ‘no such effect’ on group or componentinstance…

#4

Quick example:
(copy paste to Ruby console)

depth = 100
width = 100
model = Sketchup.active_model
entities = model.active_entities
pts = []
pts[0] = [0, 0, 0]
pts[1] = [width, 0, 0]
pts[2] = [width, depth, 0]
pts[3] = [0, depth, 0]
# Add the 'face' to the entities in the model
face = entities.add_face(pts)
edge = entities.add_edges(pts[1], pts[3])
# now the 'face' is 'just a half of the original one'
selection = model.selection.add face
#5

Sir, if I want to search for the entity through “each” function, how can I accurately find the face I want

#6

Something like (untested - off the top of my head)

ents.grep(Sketchup::Face).find {|face| face.attribute_dictionaries("yourDictName") != nil}

where ents is the Entities collection you want to search (model.entities or some ComponentDefinition.entities) and “yourDictName” is the AttributeDictionary name you use to name a Face. This should return the named Face or nil if it fails.

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#7

Correction … you need to use the singular #attribute_dictionary method to test for a specific dictionary. (The plural method does not take an argument.)

  # At the top of your extension submodule:
  DICT ||= "YourNamespace_YourExtensionName"

  # Elsewhere in the code ...

  # Find the first face with the extension's dictionary.
  def find_face(ents)
    ents.grep(Sketchup::Face).find {|f| f.attribute_dictionary(DICT) }
  end

  # Find all the faces with the extension's dictionary.
  def find_faces(ents)
    ents.grep(Sketchup::Face).select {|f| f.attribute_dictionary(DICT) }
  end
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#8

I’m a visual learner… and I would like to draw your attention:

def test_pid_id_attr
  depth = 100
  width = 100
  model = Sketchup.active_model
  entities = model.active_entities
  pts = []
  pts[0] = [0, 0, 0]
  pts[1] = [width, 0, 0]
  pts[2] = [width, depth, 0]
  pts[3] = [0, depth, 0]
  # Add the 'face' to the entities in the model
  face1 = entities.add_face(pts)
  #set attribute for face1
  face1.set_attribute( "testdictionary", "name", "face1" )
  pid_face1 = face1.persistent_id
  id_face1 = face1.entityID
  p "face1: #{face1} pid: #{pid_face1} id: #{id_face1} attr: #{face1.get_attribute( 'testdictionary', 'name' )}"
  # divide the original face1 to two faces
  edge = entities.add_edges(pts[1], pts[3])
  # Query  the two new face
  entities.grep(Sketchup::Face){|face|
    p "face : #{face} pid: #{face.persistent_id} id: #{face.entityID} attr: #{face.get_attribute( 'testdictionary', 'name' )} "
  }
  return
end
test_pid_id_attr

Result:

"face1: #<Sketchup::Face:0x0000018e95e02750> pid: 207 id: 465 attr: face1"
"face : #<Sketchup::Face:0x0000018e95e02750> pid: 207 id: 465 attr: face1 "
"face : #<Sketchup::Face:0x0000018e95e02110> pid: 209 id: 477 attr: face1 "

As you can see the original face1 is same as the first one after split. Moreover both of the split faces have a same attributes and entityID s…
Maybe Dan can explain it why?
EDIT:
Ups there was a typo…

#9

LOL … I was going to point out that error, and suddenly “poof” … you fixed it.

Yes … so we see that the new split off face has it’s own persistent_id and entityID, but gets a copy of the attribute dictionary. The code might need to rename the new half-face.

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#10

Yes sorry. :blush:
But still do not get how can be identical two faces if one is half of the original.
(The attributes could be inherited that seems to be understandable…)

#11

They are identical (mirror images of each other) because you divided a symmetrical rectangle using an edge drawn along it’s diagonal.

#12

I don’t think…
The original “big” face1 and one of the new ones are “identical” (The first two rows)

"face1: #<Sketchup::Face:0x0000018e95e02750> pid: 207 id: 465 attr: face1"
"face : #<Sketchup::Face:0x0000018e95e02750> pid: 207 id: 465 attr: face1 "

The two new face are not identical, Just the attributes (The last two row)

"face : #<Sketchup::Face:0x0000018e95e02750> pid: 207 id: 465 attr: face1 "
"face : #<Sketchup::Face:0x0000018e95e02110> pid: 209 id: 477 attr: face1 "

???

And how do we will know which one (from the new ones) will inherit the original ? The “left” or the “right” one? Is that depends of the split “edge direction” or what?

#13

No. Before the split, face1 is a rectangle. Afterward it is one of the triangles.
SketchUp reuses the reference and IDs.

I don’t know what the rule is. You might have to experiment. Or ask @tt_su.

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#14

Merging/splitting means the faces are rebuilt, the fact that a face reference remains is implementation detail.

How to handle that isn’t easy to dictate on a general basis. Entirely depends on the situation because there are too many permutations.

In this particular situation you could use the face’s bounds to determine “left”/“right”. That assumes this happens under controlled situations where orientation is consistent/predictable.