Re: [openglean-devel]Font support.

[Richard R. <sf...@ol...>]

Varol:

I've been looking at your code a little more this morning.  It
looks like you only read characters in the range 0..255.

Have you given much thought yet to supporting large character sets?
I'm inclined towards the idea of reading font glyphs more or less
on-demand, rather than reading the entire font at once.  The
difficulties are in finding where as-yet-unread glyphs begin and
in rapidly finding glyphs in memory after loading.  (Allocating
pointers to all possible glyphs in a big array and filling unloaded
ones with NULL is probably not a very good solution; even for 16-bit
Unicode, on a 32-bit system, that's a quarter of a MB of pointers
for every font...)

I'm thinking of some kind of hash approach.  Take a sequence of
primes, where the Nth prime is approximately 2^N.  Take the glyph
number mod by the prime table size  That would be the primary
location for already-loaded glyphs.  As the table fills, reallocate
and re-hash.

For unloaded font glyphs, some kind of sparse array could be
used to locate known places in a font.  For example, after reading
the font glyph for 'a', you would know the location of 'b'.  (Well,
maybe not.  I am not sure if BDF files are necessarily presented
in the order of the glyph encoding.  But in most, if not all, cases
you will probably be better off to start searching for 'b' right
after 'a', I suspect.  (^&)

Additionally, perhaps loading up to 8 or 16 glyphs at a time
might be good.  If you need the Latin 'a', the chances are pretty
good that you'll need 'b' before too long.  (But for languages
like Chinese, I don't think the odds are so favorable.)


-- 
  "I probably don't know what I'm talking about."  http://www.olib.org/~rkr/