//  Coordinate axes for MP logo
//  Last edited on 2010-03-29 11:14:55 by stolfi

#macro arrow(p, q, rad, cor)
  #local udir = vnormalize(q - p);
  #local tlen = 8*rad;
  #local q0 = q - tlen*udir;
  #local p1 = q - 0.99*tlen*udir;
  union{ 
    cylinder{ p, p1, rad }
    cone{ q0, 3*rad, q, 0.2*rad }
    texture{
      pigment{ color rgb cor }
      finish{ ambient 0.75 diffuse 0.25 }
    }
  }
#end

#macro arrow_ball(p, rad, cor)
  sphere{ p, 1.01*rad 
    texture{
      pigment{ color rgb cor }
      finish{ ambient 0.75 diffuse 0.25 }
    }
  }
#end

#macro axes(len)
  #local o = <0,0,0>;
  #local rad = 0.02*len;
  union{ 
    object{ arrow(o, len*x, rad, <1.000, 0.000, 0.000>) }
    object{ arrow(o, len*y, rad, <0.000, 0.500, 0.000>) }
    object{ arrow(o, len*z, rad, <0.000, 0.333, 1.000>) }
    object{ arrow_ball(o, rad, <0.000, 0.000, 0.000>) }
  }
#end