Brightness multiplier (0 = off).
Density multiplier.
Effective limiting magnitude right now (after sky brightness).
Black-body colours for 3200, 4300, 5500, 7000, 10000 and 20000 K.
Tint saturation.
Seed folded into the cell hash.
Size in pixels.
Twinkle strength.
Twinkle speed.
Creates the star-field uniforms.