[sldev] [ogpx] Snowglobe on OpenSim grids

[Philippe (Merov) Bossut]

Hi,

On Sun, Dec 13, 2009 at 11:45 PM, Dahlia Trimble <dahliatrimble at gmail.com>wrote:

> I was under the (possibly false) impression that the SL viewer used
> JPEG2000 discard levels as a means of mipmapping, at least for textures. The
> current OpenSim map tiles used with the traditional map feature are standard
> image assets, which should be encoded using JPEG2000. Is the Snowglobe map
> using JPEG2000 images as well?
>

No, Snowglobe is using jpeg images, the same ones that are used by the SLURL
webapp. But that's a red herring anyway. The JPEG2000 multires property
would not help us a bit with the map of the entire VW unless we were to
create a single *huge* image of the entire universe which would be crazy
when zooming in. When zooming out, accessing each region to get one single
pixel for each region is very costly (even assuming JPEG2000 is helping
here) and the main reason for the slowness of the old map.

When I said "mipmapping" then I referred to the general "multires image
rendering" aspect of the technique, not its implementation as OpenGL
textures. The map in particular is a very "hollow" mipmap with vast area of
"ocean" and we optimize for that, avoiding allocating memory for those
tiles.


> Is there documentation available for the map tile protocol used with
> Snowglobe
>

We use the "HTTP Texture" way of fetching images. It is documented here:
   http://wiki.secondlife.com/wiki/HTTP_Texture

Reading through it tonight, I realize this doc needs to be cleaned up of old
dev stuff...

Cheers,
- Merov
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.secondlife.com/pipermail/sldev/attachments/20091214/3406867e/attachment.htm