perm filename PAGE14[00,BGB] blob
sn#046246 filedate 1973-06-05 generic text, type T, neo UTF8
~F83. POLYGON NODE FORMAT.
_____________________________________________
word | CW | CCW |
0 | polygon ring | 3
_____|___________________|___________________|
word | DAD | SON |
1 | level | 1st vector | 3
_____|___________________|___________________|
word | type | reloc |
2 | 10 | 33 3233 |
_____|___________________|___________________|
word | ENDO | EXO |
3 |1st polygon within |polygon surround me| 3
_____|___________________|___________________|
word | ALT | ncnt |
4 | shape {or 1st arc}| number of sides | 2
_____|___________________|___________________|
word | NGON | PGON |
5 | nest bro polygon | nest sis polygon | 3
_____|___________________|___________________|
word | | |
6 | NTIME time line PTIME | 3
_____|___________________|___________________|
Every polygon belongs to a level pointed at by the DAD link;
the ring of polygons of a level is formed in the CW and CCW links;
the son of a polygon is its first vector (or arc after the polygon
has been smoothed) and that first vector has the upper left most
locus of any vector of the polygon.
The ENDO, EXO, NGON, PGON are used to form the nested
polygon tree. Every polygon has non-NIL NGON and PGON links; the
trivial case being that the polygon points at itself twice. Every
polygon except one, the outer border polygon, has a non-NIL EXO
link. Every polygon that surrounds one or more other polygons has a
non-NIL ENDO link.
The ALT link position of a polygon temporarily points to the
first arc of a polygon during smoothing when a polygon has both
vectors and arcs. The final contents of the ALT link is a pointer to
the shape node of the polygon. The ncnt datum indicates the number
of sides of the polygon.
The time line of polygons runs thru the NTIME and PTIME
links which point either to a nearly exact match of a polygon; or to
a fusion polygon of a two for one match; or to one of the two
fission parts of a one for two match; (to find the other fission
part, the time links of the vectors must be scanned).
~I1973,800;F8- 14 -