The collapse dialog
"Collapsing" a geometry means making a geometry use just as many facets as required and no more.
The usual way to get a geometry into Molflow is by importing a CAD file in STL format, which consists of triangles. That means that every vertex is created as many times as the number of facets that contain it.
Therefore, not only for speedup, but also for usability reasons, the first thing to do when opening an STL file is to collapse it.
The dialog below opens either when you open/insert an STL file or when you issue the Facet/Collapse command:
Collapsing consists of three steps:
- Finding vertices that are at the same coordinate and merging them
- Finding facets that are
- Coplanar (in the same 3D plane and normal vector pointing in the same direction)
- Adjacent to each other
- Have the same outgassing, temperature, etc. parameters and merging them.
- Finding consecutive edges that are collinear (i.e. if a straight line is divided to 6 different sections) and merging them.
Therefore you can toggle which of these steps you want to perform.
Vertices option
This is required to run at least one time, otherwise facet collapsing won't work.
It operates on all vertices of the geometry, regardless of the selection.
The tolerance value is the maximum distance in centimeters , within which two vertices are considered to be in the same coordinates.
Facets option
Each facet\'s plane can be defined by a Ax+By+Cz+D=0 equation. The tolerance value is the maximum coefficient difference within which two facets are considered coplanar.
To avoid facets with very large number of vertices (for example holed facets), you can limit the max. number of vertices that a collapsed facet contains.
Collinear edges option
You can leave it on all the time. The tolerance value is in degrees, the maximum degree of turn under which two consecutive edges are considered collinear.