Bug introduced in 10.4 or earlier and persisting through 11.2
CASE:2326540
Solution: Wait and use N
meanwhile.
I've faced this problem writing an answer for Animate point go round a triangle.
For coordinates with exact values, instead of moving along a multi-line LineScaledCoordinate
is mooving along extrapolated first segment.
It is not always the case but always for exact values. N
is the fix.
Needs["GraphUtilities`"]
vertices = {{0, 0}, {1, 0}, {1, 2}, {2, 1}};
Slider[Dynamic@t]
Graphics[{
EdgeForm@Thick, FaceForm@None, Polygon@vertices
,
AbsolutePointSize@12, Red, Dynamic[Point[LineScaledCoordinate[vertices, t]]]
,
AbsolutePointSize@12, Blue, Dynamic[Point[LineScaledCoordinate[N@vertices, t]]]
},
PlotRange -> {{0, 4.5}, {0, 4.5}}, Frame -> True
]