## Lines

Lines can be created:

• manually (choice of line type: segment, arcs, and entering extremity points)
• by propagation from existing lines with the aid of transformation
• by extrusion from existing points with the aid of transformation
• within the propagation or extrusion from other entities

## Circle arcs

The circle arc can be defined:

• in a coordinate system
• by three points
Arc defined in a coordinate system Arc defined by three points

An arc

• is included in a plane parallel to the XOY plane
• is anti-clockwise oriented around an axis parallel to the OZ axis

An arc

• is included in a plane defined by three points
• is oriented in the direction imposed by three points

There are some predefined coordinates systems (XYZ1, Z_ON_OX, Z_ON_OY) to simplify the circle arcs description in the different main planes.

## Line defined by propagation

A line can be created by propagation from an existing line with the aid of a transformation.

## Line defined by extrusion

A line can be created by extrusion from an existing point with the aid of a transformation.

## Nature of lines

Flux allows the user to modify the consideration of entities in building algorithms for faces, volumes and mesh.

A specific feature, called nature, is attached to the lines. There are some examples of nature attribute using in section Geometry building module of chapter Geometry: principles.