[osg-users] Advice on how to implement custom file format

[Chris Hanson]

Aaron, this sounds a lot like something I've worked with recently. If you
want to get in touch with me privately and share more details on the format
you are working with, I might be able to assist you more.

On Sun, Aug 16, 2015 at 3:11 PM, Aaron Andersen <aaron at fosslib.net> wrote:

> Hello,
>
> I'm planning to render a custom (preexisting) map file format using osg
> and was looking for some guidance. I haven't been using osg for that long
> so I figure it is worth asking if there is either a way to adapt some
> existing code in the library to fit this custom format, or if not, what
> people might suggest as a good way to go about implementing loading and
> rendering this map file format with osg.
>
> The map is composed of individual 3d mesh tiles of variable size that are
> "snapped" together side by side somewhat similar to toy Lego blocks. Most
> mesh tiles are relatively small so there are a large number of these mesh
> tiles required to draw the map. As for the file format itself, the map is
> broken up spatially into many separate files (known as "regions").
>
> I wish to write some code so that the map will be read into my application
> and populate the scene graph seamlessly so there won't need to be a loading
> screen every time the camera zooms to a new area of the map. The maps
> stored in this format are *way* too large to load into memory all at once,
> so I will need to stream data in as the camera approaches new areas and out
> as it leaves other areas, always keeping the scene graph up to date.
>
> I should mention that the map file format is a little peculiar in that
> none of the 3d mesh tiles have any absolute position information listed at
> all. Each and every mesh tile is placed relative to the an adjacent mesh
> tile. I can arbitrarily choose any mesh tile from a map file and place it
> at 0,0,0 and from there start placing adjacent tiles, and for each adjacent
> tile place the adjacent tiles, recursively over and over, to build up the
> map. I mention this placement peculiarity because it means that I can only
> ever know the absolute position of any mesh tile that is relatively close
> to the camera (ie. the area of the map I'm currently rendering).
>
> If any clarification is required please let me know and thank you kindly
> for any advice anyone can offer me.
>
> Aaron Andersen
>
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