The pattern describes a mesh to generate: positions of nodes within a geometrical domain and nodal connectivity of elements. As well, a pattern specifies the so-called key-points, i.e. nodes that will be located at geometrical vertices. Pattern description is stored in <pattern_name>.smp file.
The smp file contains 4 sections:
The first line holds the number of nodes (N).
The next N lines describe nodes coordinates. Each line holds 2 coordinates of a node.
A key-points line: indices of nodes to be mapped on geometrical vertices. An index n refers to a node described on an n-th line of section 2. The first node index is zero.
The 2D pattern must contain at least one element and at least one key-point. All key-points must lay on boundaries.
An example of a simple smp file and a preview of a pattern described in this file:
To apply pattern mapping to a geometrical object:
From the Modification menu choose the Pattern Mapping item or click "Pattern mapping" button in the toolbar.
The following dialog box shall appear:
To apply a pattern to a geometrical object, you should specify:
Then you either load a .smp pattern file previously created manually by clicking on the "Load pattern" button, or click on the New button for automatic generation.
For an automatic generation you just specify a geometrical face having a mesh built on it. Mesh nodes lying on face vertices become key-points. Additionally, you may choose the way of getting nodes coordinates by projecting nodes on the face instead of using "positions on face" generated by mesher (if there is any). Faces having a seam edge can?t be used for automatic pattern creation.
When creating a pattern from an existing mesh, there are two possible cases:
The mapping algorithm is as follows:
Key-points are set in the order that they are encountered when walking along a pattern boundary so that elements are on the left. The first key-point is preserved.
Find geometrical vertices corresponding to key-points by vertices order in a face boundary; here, "Reverse order of key-points" flag is taken into account.
Boundary nodes of a pattern are mapped onto edges of a face: a node located between certain key-points on a pattern boundary is mapped on a geometrical edge limited by corresponding geometrical vertices. Node position on an edge reflects its distance from two key-points.
Coordinates of a non-boundary node in a parametric space of a face are defined as following. In a parametric space of a pattern, a node lays at the intersection of two iso-lines, each of which intersects a pattern boundary at least at two points. Knowing mapped positions of boundary nodes, we find where isoline-boundary intersection points are mapped to, and hence we can find mapped isolines direction and then, two node positions on two mapped isolines. The eventual mapped position of a node is found as an average of positions on mapped isolines.
See Also a sample TUI Script of a Pattern Mapping operation.