sparse bitset compression

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The web is full of different solutions for compressing things, but some of
you have probably already done this and found a really good ratio
compression scheme that fits what I'm asking about.

I've got a load of entites, (4-7k) that live on a grid (1024x1024), and I
need to persist them to a savegame which gets sent across the network to
keep the save safe. I need to compress it. I'm compressing the entities in
the world already, ones that have been affected cost a few bytes, but the
but for the ones that don't have any changes, all I'm left with is the
coords. There are only a few that need the fatter compression, but at the
numbers I'm looking at, those "unchanged entity" coords add up to a lot of
data when storing as 20 bit structs. This is too much for sending over the
network regularly as part of a save.

I've had some ideas on how to compress the data, but they might be crap. I
don't know.

I can't easily regenerate the set so thought someone who wanted to compress
consumables might know the name of a good solution for sparse bitset
compression. The bits are clumped around different areas of the grid, so I
feel that something that leverages spatial coherence might do well.

Any leads would be highly appreciated.

-- 
fabs();
"The fact that an opinion has been widely held is no evidence whatever that
it is not utterly absurd." - Bertrand Russell

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<div dir=3D"ltr">The web is full of different solutions for compressing thi=
ngs, but some of you have probably already done this and found a really goo=
d ratio compression scheme that fits what I&#39;m asking about.<div><br></d=
iv>



<div>I&#39;ve got a load of entites, (4-7k) that live on a grid (1024x1024)=
, and I need to persist them to a savegame which gets sent across the netwo=
rk to keep the save safe. I need to compress it. I&#39;m compressing the en=
tities in the world already, ones that have been affected cost a few bytes,=
 but the but for the ones that don&#39;t have any changes, all I&#39;m left=
 with is the coords. There are only a few that need the fatter compression,=
 but at the numbers I&#39;m looking at, those &quot;unchanged entity&quot; =
coords add up to a lot of data when storing as 20 bit structs. This is too =
much for sending over the network regularly as part of a save.</div>


<div><br></div><div>I&#39;ve had some ideas on how to compress the data, bu=
t they might be crap. I don&#39;t know.</div>
<div><br></div><div>I can&#39;t easily regenerate the set so thought someon=
e who wanted to compress consumables might know the name of a good solution=
 for sparse bitset compression. The bits are clumped around different areas=
 of the grid, so I feel that something that leverages spatial coherence mig=
ht do well.</div>

<div><br></div><div>Any leads would be highly appreciated.<br clear=3D"all"=
><div><br></div>-- <br><div dir=3D"ltr">fabs();<div>
<span style=3D"line-height:20px;font-size:14px;font-family:&#39;Helvetica N=
eue&#39;,Helvetica,Arial,sans-serif">&quot;The fact that an opinion has bee=
n widely held is no evidence whatever that it is not utterly absurd.&quot; =
- Bertrand Russell</span><br>



</div></div>
</div></div>

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