Help with transformation

Davidfi1

Hi Guys
I need some help using the correct Geom::Transformation.

My task is to place a component and scale it's x axis, between two points.

I need to figure out what is the Geom::Transformation needed for
the add_instance method.
Geom::Transformation.scaling xscale, 1, 1 will do the scaling
Geom::Transformation.axes startPoint , xaxis, yaxis, zaxis
moves the component to the first point and changes its axis

How do I combine the transformations and what do I need to use for
xscale, xaxis, yaxis, zaxis?

Thank you
David.

Dan Rathbun

It would be easier to just place the instance at the desired insert point, and then afterward apply the non-uniform scaling transform.

Within some method:

ipoint = Geom;;Point3d.new( x, y, z )
tp = Geom;;Transformation.new( ipoint )
ts = Geom;;Transformation.scaling( xscale, 1.0, 1.0 )
inst = ents.add_instance( defn, tp )
inst.transform!( ts )

Davidfi1

Dan, what did you say about the second point?
I need to rotate the new component's x axis to be in line with the two points.

Dan Rathbun

@unknownuser said:

My task is to place a component and scale it's x axis, between two points.

OK.. gotcha.

You also need a y-axis vector

def place_and_tweek( defn, pt1, pt2 )
  xvec = pt1.vector_to( pt2 )
  yvec = xvec.axes[1] # ???
  tp = Geom;;Transformation.new( pt1 )
  inst = ents.add_instance( defn, tp )
  ts = Geom;;Transformation.scaling( xvec.length, 1.0, 1.0 )
  inst.transform!( ts )
  ta = Geom;;Transformation.new( pt1, xvec, yvec )
  inst.transform!( ta )
end

Davidfi1

OK - I finished I think.
This is what came out:

def add_Filament( startPoint, endPoint , filament )
      @lineVector = startPoint.vector_to endPoint
      return if @lineVector.length.to_f - 1e-6 < 0.0 

      # Scaling and adding an instance of the filament
      @scale      = @lineVector.length.to_f / filament.bounds.height   #width #depth 
      @trans      = Geom;;Transformation.scaling 1, @scale, 1
      @instance   = Sketchup.active_model.active_entities.add_instance( filament, @trans )

      # if needed rotate the filament
      @lineVector.normalize!
      @instYaxis  = Geom;;Vector3d.new( 0, filament.bounds.height, 0 ).normalize #height givs the Y axis
      @rotDeg     = @instYaxis.dot( @lineVector )
      @rotDeg     = Math;;acos( @rotDeg )
      if @rotDeg.to_f - 1e-6 > 0.0
        if @rotDeg.to_f + 1e-6 > Math;;PI 
          @rotVector = Geom;;Vector3d.new( 0, 0, 1 )
        else # if PI
          @rotVector = @instYaxis.cross( @lineVector )
        end # if PI
        @trans       = Geom;;Transformation.rotation( ORIGIN, @rotVector, @rotDeg )
        @instance.transform!( @trans )
      end # if @rotDeg > 0.0

      # Moving the filament to the startPoint
      if not ( ORIGIN == startPoint )
        @trans       = Geom;;Transformation.new startPoint 
        @instance.transform!( @trans )
      end #if not ORIGEN
    end

sdmitch

David, You did a bit more work than was required. The entire section regarding rotation is not needed. You only need to add ", @lineVector" to the last Transformation

def add_Filament( startPoint, endPoint , filament )
      @lineVector = startPoint.vector_to endPoint
      return if @lineVector.length.to_f - 1e-6 < 0.0 

      # Scaling and adding an instance of the filament
      @scale      = @lineVector.length.to_f / filament.bounds.height   #width #depth 
      @trans      = Geom;;Transformation.scaling 1, @scale, 1
      @instance   = Sketchup.active_model.active_entities.add_instance( filament, @trans )

      # Moving the filament to the startPoint
      if not ( ORIGIN == startPoint )
        @trans    = Geom;;Transformation.new startPoint, @lineVector
        @instance.transform!( @trans )
      end #if not ORIGEN
    end

Davidfi1

Do I need to do the checking ORIGIN etc..?
Or it should be:


def add_Filament( startPoint, endPoint , filament )
   @lineVector = startPoint.vector_to endPoint
   return if @lineVector.length.to_f - 1e-6 < 0.0

   # Scaling and adding an instance of the filament
   @scale      = @lineVector.length.to_f / filament.bounds.height   #width #depth
   @trans      = Geom;;Transformation.scaling 1, @scale, 1
   @instance   = Sketchup.active_model.active_entities.add_instance( filament, @trans )

   # Moving And Rotating the filament to the @lineVector
   @trans    = Geom;;Transformation.new startPoint, @lineVector
   @instance.transform!( @trans )
end # def add filament

P.S - Why filament.bounds.height is the length of the Y axis of the component?
I thought height is the Z axis - no?

sdmitch

No you don't need the ORIGIN check. Since you don't specify a location when adding the instance, it is by default placed at the origin.

I agree, you would think height would be Z but no, bounds.width=X,bounds.height=Y, and bounds.depth=Z.

Doing the scaling when adding the instance is something I had never thought of so I learned something too.

Davidfi1

hhh - doesnt work
All our work for nothing

sdmitch

@davidfi1 said:

hhh - doesnt work
All our work for nothing

Why doesn't it work? How is it failing?

Provide screen shots or sample model.

How the component is made and the axes defined will always determine how it orients when placed.

Davidfi1

Well, In the documentation it says that if the second parameter is a vector
It will be used as a Z axis - this is what is happenening!.

Quote:
Geom::Transformation.new(origin, zaxis) creates a Transformation where origin is the new origin, and zaxis is the z axis. The x and y axes are determined using an arbitrary axis rule.

sdmitch

@davidfi1 said:

Well, In the documentation it says that if the second parameter is a vector
It will be used as a Z axis - this is what is happenening!.

Quote:
Geom::Transformation.new(origin, zaxis) creates a Transformation where origin is the new origin, and zaxis is the z axis. The x and y axes are determined using an arbitrary axis rule.

That's why I mentioned how the orientation of the component when created would be critical. If you could post a model with the component in it would make it much easier to figure out what you need to do to correct the problem. Just a wild guess but try this

		# Moving the filament to the startPoint
		xa,ya,za=@lineVector.axes
		@trans  = Geom;;Transformation.new xa,za,ya,startPoint
		@instance.transform!( @trans )

Davidfi1

Thank you.
I will post the G-Code importer I am workin on soon
Then you could play with it and see if it is possible to make the original code more elegant.
The code I posted works!. It is a little ... well ... not very elegant - but it works

Davidfi1

Posted the first vertion of the importer at
http://sketchucation.com/forums/viewtopic.php?f=323&t=50067