// 3to4points.ls   by Felipe Esquivel <felipe@garagepost.tv>
//
// This simple script creates a point based in the position of other 3 points,
// the 4 points are co-planar (all are in the same plane).
// 
// Use: Select 3 points and run the script. The first point is the tail 
// of the vectors, the 4th vector is the result of the sum of both vectors
// (trust me, it works). 

@version 2.4
@warnings
@script modeler
main
{

loc1 = <0,0,0>;
loc2 = <0,0,0>;
loc3 = <0,0,0>;
loc4 = <0,0,0>;

selmode(USER);

editbegin();

// check if 3 and only 3 points are selected
numPts = pointcount();
if(numPts != 3)
{
   error("You must have 3 points selected to perform this operation");
   return;
}
if(numPts == 3)
{
  loc1 = pointinfo(points[1]);
  loc2 = pointinfo(points[2]);
  loc3 = pointinfo(points[3]);


  // calculate the fourth point with vectors
  loc4 = loc2 - loc1 + loc3;


  addpoint(loc4);
}

editend();
}