Here's a link to a Google Sketchup plugin I just wrote. It draws outs roof framing tetrahedrons and roof framing kernels.
The tetrahedrons can be folded or unfolded. It also draws the dihedral angle... hip rafter backing angle.


http://www.sbebuilders.com/pdf/RoofFraming.zip

Just unzip it in the Google SketchUp \Plugins directory.
The file structure should look something like this.

C:\Program Files\Google\Google SketchUp 8\Plugins\RoofFraming.rb
C:\Program Files\Google\Google SketchUp 8\Plugins\RoofFraming\plan_angle.rb
C:\Program Files\Google\Google SketchUp 8\Plugins\RoofFraming\draw_angle_dim.rb
C:\Program Files\Google\Google SketchUp 8\Plugins\RoofFraming\interior.png
C:\Program Files\Google\Google SketchUp 8\Plugins\RoofFraming\exterior.png

Sim