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Axis[point, vector] is a Mech data object that specifies an axis by origin and direction. The axis originates at point and points in the direction of vector. point must be a Mech Point object and vector must be a Mech Vector or Line object.
Axis[bnum, lpnt1, lpnt2] is interpreted as Axis[Point[bnum, lpnt1], Vector[bnum, lpnt2]]. The lpnti can be vectors, {x, y} or {x, y, z}, in the local coordinate system of body bnum or point numbers (positive integers) referencing coordinates that were defined with SetBodies.

• Any function that takes an axis argument can accept an Axis object, a Line object, or a Plane object (3D) in its place.
• In Modeler3D, vector may also be a Plane object, in which case the direction of the plane's normal is used.
• In Modeler3D, Axis[point, vector1, vector2] uses vector2 to explicitly specify the rotational reference vector of the axis (vector2 must be nonparallel to vector1).
• In Modeler3D, Axis[bnum, lpnt1, lpnt2, lpnt3] is interpreted as Axis[Point[bnum, lpnt1], Vector[bnum, lpnt2], Vector[bnum, lpnt3]].
• In Modeler2D, Axis[bnum1, lpnt1, bnum2, lpnt2] is interpreted as Axis[Point[bnum1, lpnt1], Vector[bnum2, lpnt2]].
• In Modeler3D, Axis[bnum1, lpnt1, bnum2, lpnt2, bnum3, lpnt3] is interpreted as Axis[Point[bnum1, lpnt1], Vector[bnum2, lpnt2], Vector[bnum3, lpnt3]].
• See also: ReferenceDirection.

Further Examples

Load the Modeler2D package.

The following are all valid axis specifications. The use of Location and Direction serve to show how the axes are interpreted by MechanicalSystems. First we show axes in the reference frame of body 1, the global reference frame.

Here are axes on body 2. Local point number zero is always defined as {0, 0}.

Axes can span multiple bodies.

After using SetBodies to define some local points, they can be referenced by index in a Plane object.

A 3D axis has an orthogonal reference direction that can be chosen by Modeler3D or specified explicitly.