1 bsplinecurve b1 3 5 0 4 1 1 2 1 3 1 4 4 0 0 0 0.8 1 0.5 0 0.6 2 1 0 0.5 2 2 0 1 3 1.5 0 1 4 1.5 0 1 5 2 0 1
2 cvalue b1 2.0 x y z dx dy dz
8 cmovetangent b1 2.0 x y z dx $dyvalue $dzvalue 1
9 set dyvalue [expr $dyvalue + $delta ]
10 set dzvalue [expr $dzvalue + $delta ]
13 set length 7.0867664447042955