require 'sketchup.rb' 
def ang_betwen_lines
    ss = Sketchup.active_model.selection 
    e1v1, e1v2 = ss[0].vertices # These are assumed to both be edges 
    e2v1, e2v2 = ss[1].vertices 
    if ((e1v1 == e2v1) || (e1v1 == e2v2)) then pt = e1v1 # find the shared vertex 
    else pt = e1v2 
    end 

    p1, vec1 = ss[0].line 
    p2, vec2 = ss[1].line 
    angle1 = vec1.angle_between(vec2) 
    angle2 = vec2.angle_between(vec1) 

    puts "#{vec1} #{vec2}\n"
    data = "Angle=#{angle1.radians}#{176.chr}\nAngle=#{angle2.radians}#{176.chr}"
    puts "Vec1+, Vec2+:\n#{data}"


#    UI.messagebox("Enter") 

    p1, vec1 = ss[0].line 
    p2, vec2 = ss[1].line 

    vec1.reverse! 

    angle1 = vec1.angle_between(vec2) 
    angle2 = vec2.angle_between(vec1) 

    puts "#{vec1} #{vec2}\n"
    data = "Angle=#{angle1.radians}#{176.chr}\nAngle=#{angle2.radians}#{176.chr}"
    puts "Vec1-, Vec2+:\n#{data}"

#    UI.messagebox("Enter") 

    p1, vec1 = ss[0].line 
    p2, vec2 = ss[1].line 

    vec2.reverse! 
    
    angle1 = vec1.angle_between(vec2) 
    angle2 = vec2.angle_between(vec1) 

    puts "#{vec1} #{vec2}\n"
    data = "Angle=#{angle1.radians}#{176.chr}\nAngle=#{angle2.radians}#{176.chr}"
    puts "Vec1-, Vec2-:\n#{data}"

#    UI.messagebox("Enter") 

    p1, vec1 = ss[0].line 
    p2, vec2 = ss[1].line 

    vec1.reverse! 

    angle1 = vec1.angle_between(vec2) 
    angle2 = vec2.angle_between(vec1) 

    puts "#{vec1} #{vec2}\n"
    data = "Angle=#{angle1.radians}#{176.chr}\nAngle=#{angle2.radians}#{176.chr}"
    puts "Vec1+, Vec2-:\n#{data}"
end