Architectural_Design_with_SketchUp

Architectural Design with SketchUp
mod = Sketchup.active_model # Open model
ent = mod.entities # All entities in model
sel = mod.selection # Current selection
# Get the one component’s definition
comp = nil
sel.each { |e|
if e.typename == “ComponentInstance”
comp = e.definition
end
}
# Iterate through all ungrouped faces
sel.each { |e|
if e.typename == “Face”
# Place a copy at the center of the bounding box
center = e.bounds.center
t = Geom::Transformation.new (center, e.normal)
new = ent.add_instance (comp, t)
# Now scale objects by south orientation
scale = 1-[(e.normal.angle_between [0,-1,0]),0.2].max
new.transform! Geom::Transformation.scaling center, scale, scale,
scale*2
# Explode it so that we can remove the face afterwards
new.explode
}
end
As you can see in Figure 6.26, this code places scaled circles (due to unequal scaling,
they actually become ellipses) onto each of the selected faces. If the face’s orientation points
south, the circles become enlarged, yet the farther the face deviates from this direction, the
smaller the circle becomes.
In the preceding code, you can see that we kept the first part as before: We loop through
the entities in the selection to find the one ComponentInstance. Next, we again iterate
through all the faces and place copies of the circle at their centers (oriented with the face
normal). Finally, we scale them based on orientation. To do this, we need to calculate the
angle between the face normal and the south orientation. This is conveniently done using
the angle_between method, which operates on the face normal and checks it against a unit
vector in the south direction ([0,-1,0]). This yields the angle in radians, but since this number
is between 0 and 1, it is perfect for us to use as a scale factor. To ensure that the circles don’t
get too small, we’ll pick as a scale factor the maximum value of either the angle or 0.2 using
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