Hello Bill H and the VisAD mailing list,
i have a question about the int[] Pol_f_Vert array in the
Gridded3DSet.isosurf() method (actually, the 2nd-to-last parameter in the
isosurf() method, i'm referring to it as Pol_f_Vert). As Bill said
before, Pol_f_Vert, "is an array that specifies the set of indices of
polygons adjacent to each vertex".
My question is (a detail oriented one) how is this array populated? If i
am correct the array is a mapping from vertices to polygons. So the array
stores vertex indices that indicate which polygon(s) the vertices belong
to. Is this correct?
But i do not understand how this array is populated. It looks as if the
method starts off by allocating 9 index entries per polygon, meaning that
a vertex could belong to up to 8 polygons and (i'm guessing) the 9th entry
is a number indicating how many polygons the vertex belongs to. Is this
correct?
Also, it is not clear how each vertex number is assigned to 1 of the 8
possible reserved slots for each polygon. For example, let's say we
discover that vertex 1 belongs to polygons 1, 2, and 3. How does the
method decide which of the possible 8 reserved slots to put a 1 into (for
polygons 1, 2 & 3, assuming that is how it works)? Although from looking
at printouts of the array, it looks as if it's doing more computations
than i am querying about here. There are in some cases quite a few more
slots of 9 entries than there are polygons, implying that the array is not
set up for 9 indices/polygon.
This array implementation is really baffling me. :(
-cheers, bob
PS Thanks to Bill H. for answering my last (1,000) question(s). :>
Robert S Laramee tel: (603) 868-1361 (new as of 19 Jan '00)
9 Woodman Ave, #316 office: (603) 862-0350
Durham, NH 03828 URL: http://www.cs.unh.edu/~rlaramee
