Face-me component transformations are not valid when an instance has more than one instance path

[noelwarren]

This affects all versions of SketchUp

In this model Sumelle is nested in a component that is instanced twice

There are two instance paths for sumelle
[instance_a, sumelle]
[instance_b, sumelle]

The ComponentInstance#transformation method cannot return a tranformation for sumelle that is correct for both instance paths. The InstancePath::transformation method could, since it has the necessary context. But it doesn't. This is the bug.

The following example gets instance path transforms for the two sumelles. The should be roughly pointing in the same direction as they both face the camera, but as you can see they are not.
Untitled.zip

# Using attached model
Sketchup.active_model.entities.map { |stand|
  Sketchup::InstancePath.new([stand, stand.definition.entities.to_a.first]).transformation.to_a
}
#[-0.9876782389772898, -0.15649823082297007, 0.0, 0.0, 0.15649823082297007, -0.9876782389772898, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0, -14.999999999999984, -25.0, 0.0, 1.0]
#[0.9876782389772898, 0.15649823082297018, 0.0, 0.0, -0.15649823082297018, 0.9876782389772898, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0, 19.249999999999986, -12.819118387212601, 0.0, 1.0]

Because of this we are unable to fully support face me components in our renderer

[thomthom]

Internal note: While not exactly the same, it's worth considering that we also have issue with providing correct transformations for instances outside the open context.

[sketchupbot]

Logged as: SKEXT-3266