code: public static boolean isColinear(Point3d ptA, Point3d ptB, Point3d ptC) {
          Vector3d vectorAB = new Vector3d();
          Vector3d vectorAC = new Vector3d();
          Vector3d normal = new Vector3d();
  
          StereoTool.getRawNormal(ptA, ptB, ptC, normal, vectorAB, vectorAC);
          return isColinear(normal);
      }
docs: Checks the three supplied points to see if they fall on the same line.
  It does this by finding the normal to an arbitrary pair of lines between
  the points (in fact, A-B and A-C) and checking that its length is 0.
  
  @param ptA
  @param ptB
  @param ptC
  @return true if the tree points are on a straight line