|
Subtypes are frequently used in a save file in many of the entity records. Subtypes specify in more detail the characteristics of a geometry type. Interpolated curves (intcurve) and spline surfaces (spl_sur) are two of the major geometry types that make extensive use of subtypes.
|
|
|
Subtype definitions contain the bulk of the geometry information of a model and generally span numerous lines within a record of a SAT file. The subtype definition can be preceded and followed by other data pertinent to that record, and subtypes can be nested.
|
|
|
When a subtype definition is created as part of a record in the save file, it is numbered in an index table starting with 0. Because entity elements within a model often share geometry, the subtype index numbers can be referenced by other entity element records. When a particular record uses a subtype object which has been defined by another record, the latter record simply references the index number of the subtype rather than writing the entire set of data out again. These references are written out as "ref
n". The
ref indicates that this particular item has already been written out to the save file. The
n stands for the subtype reference number, counting from the beginning of the file.
|
|
|
All subtype and reference designations are enclosed between
subtype_start and
subtype_end designators, which are curly braces "{ }" in a SAT file and Tag 15 and Tag 16 in a SAB file.
|