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Starfield        

Starfield

The starfield texture is found in system/starfield.dds(perhaps with different file format in future releases). It is referenced in the system/Sky.material file.

General Layout

 +---+---+---+---+
 | 1 | 2 | 3 | 4 |
 +---+---+---+---+
     | 5 |   | 6 |
     +---+   +---+

If the cell labeled 6 was to be slid upwards until it was above the 4, the shape could be cut out and folded, with the texture on the inside, into the box it represents:

             +---+
             | 6 |
 +---+---+---+---+
 | 1 | 2 | 3 | 4 |
 +---+---+---+---+
     | 5 |
     +---+

The axes of the box are aligned to the ecliptic plane and the location of the sun. If you imagine you are near the earth, the cells are aligned as follows:

  1. Away from the earth, parallel to the ecliptic plane. (model space: +x)
  2. Towards the sun. (model space: +z)
  3. Away from the earth, parallel to the ecliptic plane. (model space: -x)
  4. Away from the sun. (model space: -z)
  5. Away from the ecliptic plane, in the direction of the south pole. (model space: -y)
  6. Away from the ecliptic plane, in the direction of the north pole. (model space: +y)

For cells 1-4, the top of the texture is the part of the sky in the direction of the north pole. For cells 5-6, the top of the texture is closer to the sun than the bottom.

Milky Way and Landmarks

In particular, the 1 2 3 4 sequence of cells form a loop along which the milky way should be drawn.

Polaris should be found slightly above the middle of cell 6 with Ursa Minor coming off it to the lower right. Casseiopia is on the left and Ursa Major on the right. Orion should be in the centre of the lower half of cell 2.

Diagram

                   Axis  6     Into the page: 3
 ))                    \ ^     Out of the page: 1
 ))))                   \|
 SUN))  ---------  2<--- E --->4  ------------------------- Ecliptic plane --    
 ))))                    |
 ))                      v \ 
                         5


This image is accurate for summer in the northern hemisphere, so the earth should be tilting with the north pole near to the sun. In winter one should imagine the sun on the right hand side of the graphic with all other features the same.

Currently Grit does not support longitudes. However the time within Grit is always in local time, so the longitude does not matter. Simply configure the time for UTC + the correct amount for the longitude you want.

Latitude and seasons are supported. The default latitude is that of New York City and the date is the summer solstice (June 21).

Connections between cells

These are the places where the textures should be seamless (marked with *): (Quads should be slid and rotated into place, never mirrored)

 +---+---+---+---+
 | 1 * 2 * 3 * 4 |
 +---+-*-+---+---+
     | 5 |   | 6 |
     +---+   +---+  

 +---+---+---+---+
 * 1 | 2 | 3 | 4 *
 +---+---+---+---+
     | 5 |   | 6 |
     +---+   +---+

 +---+---+---+-*-+
 | 1 | 2 | 3 | 4 |
 +---+---+---+---+
     | 5 |   | 6 |
     +---+   +-*-+

 +---+---+---+---+
 | 1 | 2 | 3 | 4 |
 +---+---+---+-*-+
     | 5 |
     +-*-+

 +---+---+---+---+
 | 1 | 2 | 3 | 4 |
 +-*-+---+-*-+---+
     * 5 *   | 6 |
     +---+   +---+

 +---+---+-*-+---+
 | 1 | 2 | 3 | 4 |
 +---+---+---+---+
     | 5 |   * 6 |
     +---+   +---+

 +---+-*-+---+
 | 1 | 2 | 3 |
 +---+---+---+-*-+
     | 5 |   | 6 |
     +---+   +---+

 +-*-+---+---+---+
 | 1 | 2 | 3 | 4 |
 +---+---+---+---+
     | 5 |   | 6 *
     +---+   +---+

Category:Pipeline?