STL to ACIS SAT conversion

Convert an STL file into ACIS SAT, which can be more readily imported into various CAD packages.

STL to ACIS SAT converter
=========================

Adam H. Aitkenhead
31st March 2010

Convert an STL file into an ACIS v4.0 SAT file (Standard ACIS Text), which can be more readily imported into various CAD packages (including Solidworks) as a solid model.


USAGE:
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>> CONVERT_stl_to_sat(STLfilename)
or
>> CONVERT_stl_to_sat(STLfilename,STLformat)

converts the stl file <STLfilename> into an ACIS SAT file. The optional string <STLformat> defines the format of the STL file as one the following:
'auto' - (The default option) Automatic detection of the file format
'ascii' - ASCII format
'binary' - Binary format


EXAMPLE:
========
>> CONVERT_stl_to_sat('sample.stl')

converts the STL file 'sample.stl' into an ASIC SAT file called 'sample.sat'.


STL REQUIREMENTS:
=================
The STL data must meet the following criteria:

1. All facets are triangular.
2. No duplicate or overlapping facets exist.
3. The mesh is properly closed.
4. The facet normals are properly defined.
5. For each facet edge, there must exist an odd number of identical edges on adjacent facets.

Although uncommon, some STL meshes may not meet requirement 5 and cannot be converted to SAT using this code.


OTHER NOTES
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For a description of the ACIS format, refer to: http://local.wasp.uwa.edu.au/~pbourke/dataformats/sat/sat.pdf

Depending on the hardware, conversion is performed reasonably quickly for STL meshes of up to a few thousand facets. For larger meshes the conversion time increases roughly with the square of the number of facets.