... or rather, not finding cast members quickly.
The project I am working on has a map of the world at several levels of
detail with each level being twice as detailed as the level below it. The
first level has the earth cut up into two 2048x2048 images, the second level
has four 2048x2048 images, and so on. Once you get to level 7, the image set
is not complete (currently it only covers only BC, Canada).
If you are at level 7 and move to an area not covered by that level's image
set, it jumps to a lower level until it can find an image. The images are
named like: level_row_column, where row and column are dervied from the
camera's position (longitude and latitude). The code to check to see if an
image exists at the current position on the current level is as follows:
testmember = member(string(curlevel)&"_"&string(currow)&"_"&string(curcol))
if testmember <> void then
curimage = testmember.image
else
--jump to lower level and try again
end if
When the member being sought after exists, the above runs in under a
millisecond, when the member does not exist it takes 80 milliseconds to not
find it. While this is still fast (given that it has to search through
1000's of members), it unfortunately leads to a verry noticable slow down as
I need to check for several members per frame.
I have a couple of solutions, but each has its drawbacks.
1. For each level, compile a look-up table to determine which images exist
at that level. Drawback: due to the number of images involved, this look-up
table would be huge, and memory is very tight in this program already to the
number of large images being moved in and out of memory all the time.
2. Access the members, using the numerical version of member() i.e.
member(membernum,castnum). This has the added advantage of actually being
faster when the image exists as well. Drawback: The images are sorted by
level into different casts, but are not guarrenteed to be sorted correctly
within those casts. I think they are, but there are thouands of images to
check.
Ideally, I'd like a method of determining whether a castmember of a given
"name" exists and have failure returned a lot faster than it is using
member(name). I'm probably going to go ahead with option 2, but if any of
you out there have any other ideas, I'd love to hear them.
Thanks in advance,
Kevan Dettelbach
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