* `sky_parameters` is a table with the following optional fields:
* `base_color`: ColorSpec, changes fog in "skybox" and "plain".
(default: `#ffffff`)
+ * `body_orbit_tilt`: Float, angle of sun/moon orbit in degrees, relative to Y axis.
+ Valid range [-60.0,60.0] (default: 0.0)
* `type`: Available types:
* `"regular"`: Uses 0 textures, `base_color` ignored
* `"skybox"`: Uses 6 textures, `base_color` used as fog.