M2S (Mesh-to-Solid)
Creates an ACIS solid from an open 3d polygon mesh.

Written to create sculptable ACIS terrain models
for architectural site renderings. It could also be used
to create thin shells from meshes, by subtracting a moved
copy of the solid from the original solid.
- Updated 7/7/1998

- Works with REVSURF'd meshes that touch or cross axis of revolution.

- Works even if solid being constructed is not fully visible on screen.

- Works with all open meshes created with REVSURF, RULESURF,
EDGESURF, TABSURF, AI_MESH, and 3DMESH. Most of the stock 3D
surfaces will work if you use DDMODIFY to open them in the M
and N directions.

- Does not work with polyface entities.


The solid is created by projecting each mesh facet "down"
the current z-axis to a plane a user-specified distance below
the lowest vertex. To assure that all parts of the mesh are
generated as solids, this distance can not be zero, but the
solid can be SLICEd later if need be.

The solid will match the displayed mesh: if the mesh has
been smoothed and SPLFRAME is set to 0, the solid will be
smoothed. Otherwise, it will not be. The mesh itself is not
changed at all.