Texture color and settings:

These 4 buttons define how the texture will be mixed with the general color (zenith and horizon) parameters.

1/ General 'Blend' button and texture's 'Blend' button: The 'Zenith' and 'Horizon' colors are mixed with the texture. The 'Var' slider increases/decreases the area affected by the zenith (set to 0.287 right here) while the 'Dvar' slider increases/decreases the hardness of the texture over the base color (set to 1 on the picture). The 'Col' slider is set off.

2/ Same as 1, with the 'Hori' button set 'on': The texture's color replaces the horizon's color (pic on the left). The 'Col' slider interacts with colors the same way as usually. We can also set 'off' the 'Blend' button from the textures; the effect on the horizon will then be slightly more obvious (pic on the right). In the later case, 'Var' and 'Dvar' buttons are set 'off' and the sliders in the texture color dialog box will be useful only if 'Rgb to Int' is set 'on'. The 'Col' slider defines how much the general color (given by Zen and Hor sliders) has influence over the texture.

Note: Only the 'Hori' button lets you map a texture if the general 'Blend' button is set 'off'.

3/ The 'Zenup' and 'Zendo' buttons: Toggles the color values. 'Blend' (texture button) can be set 'on' or 'off' in order to ease the effect, but 'Hori' should always be set 'on' in this case, or it will be given priority over the other parameters.

Stars: It's very easy to get stars. You just have to set 'on' the 'Stars' button in the central pannel in order to get a result like the one shown on the left pic. An important note : the camera 'Clip End' (select the camera and F9 to get this parameter) is set to 100 by default. 'Clip End' stands for the distance to which you can see. Suppose that in this case you want to set 'Clip End' to 500, default parameters will result in the pic on the right. If you want to ease this somewhat noisy effect, you will have to play with some more parameters.

Star Dist: The maximum distance allowed between two stars. Increasing it from 15 to 25 will enlarge slightly the star field.

Min Dist: The minimal distance allowed between two stars. Increasing it to 5 prevents from having stars too close to each other.

Size: The maximum size a star can have. Reducing it to 1 will results in a finer star field.

Colnoise: Gives the stars some color if set to a greater value than 0. On the following picture, 'Colnoise' is set to 0.718.