LinkShape[l, r1, r2, w] is a Graphics3D primitive that draws link shape with llength r1 and r2 radius and w width. |

LinkShape[l] is equivalent with LinkShape[l, , , ] |

LinkShape[l, r] is equivalent with LinkShape[l, r, r, ] |

LinkShape[l, r1, r2] is equivalent with LinkShape[l, r1, r2, ] |

LinkShape[] is equivalent with |

- The center point of the lower circle is {0,0,0}. The center point of the upper circle is {l,0,0}.

- The following options can be given:

PolygonNumber | 10 | number of polygons used for the half circle roundin |

- If the PolygonNumber→None, than the resulted graphics primitive is a line with two point at the two end.

- The PointSize of the points are r1/l and r2/l respectively. The thickness of the line is w/l.