Block

A block is a 2D object in an extrusion set consisting of a closed boundary and a mesh within it. Each boundary of a block (external or internal) must contain at least 3 connected edges (where any edge is defined by two end points and a curvature type).

Blocks of two types can be created in the Extruder: regular and irregular. Regular blocks are simply-connected 3- or 4-sided polygons (triangles or quadrilaters) with structured mesh. All other types of blocks are considered to be irregular and they are meshed with unstructured mesh. Examples of irregular blocks are: blocks containing 5 or more edges on the external boundary (which may be convex or concave), blocks with multiply-connected or multiple boundaries (e.g. a block containing nested blocks), blocks with edges protruding inside.

Both structured and unstructured meshes consist of triangular and/or quadrilateral elements. Upon extrusion, a single zone (brick or wedge) is created from each element of the mesh. An extrusion set must contain valid blocks in order to produce zones when the zone generate from-extruder command is used.