Surface tile

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Revision as of 08:48, 15 April 2009 by Arthur Dent (talk | contribs) (Alpha channel transparency added)
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Surface Tiles are a way to use high resolution ground textures for a small local region, usually around a base.

The earth is split into 2048 tiles in latitude and 4096 tiles in longitude.

The surface tiles in orbiter consist of two parts: The actual tile textures for the planet and the surface tile definition in the configuration file of a base.

Configuration file syntax

The syntax for a surface tile list is

BEGIN_SURFTILELIST
<texturelevel> <tilenumberfrommeridian_positive_for_east> <tilenumberfromequator_positive_north> <bitflag_for_transparency>
END_SURFTILELIST

The filenames for the textures follow a similar scheme:

<planet name>_<texture level>_<E/W><tile number in latitude>_<N/S><tile number in longitude>.dds

The function for getting the tilenumber in latitude is:

TN_lat = 1024.0 * latitude / 90.0

The function for getting the tilenumber in longitude is:

TN_long = 2048.0 * longitude / 180.0

Each surface tile is roughly 5 x 5 km large.

The transparency bitflag is usually 1. If the tile contains transparency in the alpha channel, the bitflag has to be changed to 3

Future developments

It is planned for future versions, to replace the surface tiles by a ultra high resolution planet texture (Level 15?).