EntitiesObserver and attributes

rvs1977

Hi,

Im working with EntitiesObserver, and having trouble understanding the method
def onElementModified(entities, entity).

For instance, if you add an EntitiesObserver to a group consisting of a face, the EntitiesObserver will fire when you doubleclick the group and alter the face.

(Eg. moving one of the edges so that the area of the face will increase.) In that case it will fire 3 times because 2 edges will get longer, and the face itself will increase in size.

If you have set an attribute to the face it is then possible to retrieve the value by saying
myFaceAttr = entity.get_attribute "rsdict", "face_attr", and you can set a new value with set_attribute "rsdict", "face_attr", "new value".

But now my question is: what if I have an attribute set to the group, and I want to alter that when the EntitiesObserver fires. Is it possible to see name of the parent of the entity? (The face is a child of the group)

Hope the question is understandable...

-Rasmus

Dan Rathbun

@rvs1977 said:

But now my question is: what if I have an attribute set to the group, and I want to alter that when the EntitiesObserver fires. Is it possible to see name of the parent of the entity? (The face is a child of the group)

model#active_path

Get the group instance's name from inside the observer callback:

editpath = entities.model.active_path
grp =( editpath.size > 0 ? editpath.last ; nil )
name =( grp ? grp.name ; "" )

Get the group definition's name from inside the observer callback:

entities.parent.name

A Group is a special flavour ComponentInstance, so it therefor has a ComponentDefinition, which is the real owner of the Entities collection.

rvs1977

Thank you Dan, but I try to explain it again:

My goal is to set an attribute to the group when a face has been modified. As you can see in the code below Im able to set an attribute to the face inside the group, but not the group containing the face. Do you have any ideas how to work around this problem?

If the group is called rsgroup:

yv_face_height = rsgroup.entities.add_face pts[0..3]
rsgroup.set_attribute "rsdict","area", yv_area
yv_face_height.set_attribute "rsdict", "yv_face_area", yv_area

class MyEntitiesObserver < Sketchup;;EntitiesObserver        
    def onElementModified(entities, entity)    
        
        attr_area = entity.get_attribute "rsdict", "yv_face_area"       
				
                if attr_area
                    yv_area_new = i.area.to_m.to_m                          
                    entity.set_attribute "rsdict", "yv_face_area", yv_area_new

                    #(HERE I WOULD LIKE TO SET THE ATTRIBUTE OF THE GROUP-something like;)
                    entity.parent.set_attribute "rsdict","area", yv_area_new
			
                end #attr_area       
        
    end #onElementModified_end   
end #class

Dan Rathbun

I showed you how to get a reference to the group (named grp in my example, above.)
Just ignore the calls to get the name ... BUT ...

... you have a vicious circle situation.

Changing attributes fires observers on Entities collections.

In SketchUp:
I made a box and grouped it. And left it selected.
I made a ref to the group:
grp = Sketchup.active_model.selection[0]

At the Ruby Console, I defined a quick checker class:

class Spy; attr_accessor(;name); def initialize(spy); @name = spy.to_s; end; alias_method(;has_method?,;respond_to?); # override respond_to? method; def respond_to?(meth); puts("\nSpy '#{self.name}' method '#{meth.to_s}' was called by Sketchup."); has_method?(meth); end; end

Then made two spy instances:
mspy = Spy.new("Model Entities Spy") gspy = Spy.new("Group Entities Spy")

And attached them:
Sketchup.active_model.entities.add_observer(mspy) grp.entities.add_observer(gspy)

Then added a dummy attribute:
grp.set_attribute "rsdict","area", (1.23).to_l.to_m.to_m

This was the output to the console:
[pre:gsyu95n9]Spy 'Model Entities Spy' method 'onElementAdded' was called by Sketchup.

Spy 'Model Entities Spy' method 'onElementRemoved' was called by Sketchup.

Spy 'Model Entities Spy' method 'onElementModified' was called by Sketchup.

Spy 'Group Entities Spy' method 'onElementAdded' was called by Sketchup.

Spy 'Group Entities Spy' method 'onElementRemoved' was called by Sketchup.

Spy 'Group Entities Spy' method 'onElementModified' was called by Sketchup.[/pre:gsyu95n9]

Problem is you are already within the EntitiesObserver instance attached to the Group's Entities collection !
You must be careful not to set up an infinite loop !

Changing the model from within observer callbacks can crash SketchUp !

rvs1977

@dan rathbun said:

Problem is you are already within the EntitiesObserver instance attached to the Group's Entities collection !
You must be careful not to set up an infinite loop !

Changing the model from within observer callbacks can crash SketchUp !

Ok, for now I will abandon this approach.

Please consider this example:


mod = Sketchup.active_model
ent = mod.entities 
      i = 0		
		h= {}
		ent.each do |o|
		attr = o.get_attribute "rsdict","area"		
    
			if attr 					
			   h[i] = {'structid' => 201, 'area' => attr}		
			   i += 1;			
			end
		end

Here it scans the entire model for groups with the attribute_dictionary "rsdict", "area".

Lets say it finds a group with the "rsdict" attribute. Inside the group there are a face
with an attribute attached to it.

Is it possible to scan that group for all its entities? Something like this:


mod = Sketchup.active_model 
ent = mod.entities 
      i = 0		
		h= {}
		ent.each do |o|
		attr = o.get_attribute "rsdict","area"		
    
			if attr
                           o.entites.each do |u|
                           yv_face_area = u.get_attribute "rsdict", "yv_face_area"

                           if yv_face_area
                               h[i] = {'structid' => 201, 'area' => yv_face_area}			                       i += 1;
                           end		  			
			end
		end

Dan Rathbun

Something more like:

mod = Sketchup.active_model
ent = mod.entities
h = {}
ent.each_with_index do |o,i|
  next unless o.is_a?(Sketchup;;Group)
  attr = o.get_attribute("rsdict","area")
  if attr
    o.entities.each do |u|
      next unless o.is_a?(Sketchup;;Face)
      yv_face_area = u.get_attribute("rsdict", "yv_face_area")
      if yv_face_area
        h[i] = {'structid' => 201, 'area' => yv_face_area}
      end             
    end                 
  end
end

I wonder why you are using ordinal integers as hash keys ??
You might as well just use an array:

mod = Sketchup.active_model
ent = mod.entities
h = []
ent.each do |o|
  next unless o.is_a?(Sketchup;;Group)
  attr = o.get_attribute("rsdict","area")
  if attr
    o.entities.each do |u|
      next unless o.is_a?(Sketchup;;Face)
      yv_face_area = u.get_attribute("rsdict", "yv_face_area")
      if yv_face_area
        h << {'structid' => 201, 'area' => yv_face_area}
      end
    end
  end
end

rvs1977

Great, this solved my problem! Thank you very much Dan!