A color component used to define the gray level required.
A number betwen 0 and 1, or
nil
.
Return a color-spec in the
:GRAY
model with component
level
.
Note that short-floats are used for the component; this results in the most efficient color conversion process. However, any floating point number type can be used.
alpha
indicates the alpha value of the color. 0 means it is transparent, 1 means it is solid. If
alpha
is
nil
or not specified then the color does not have an alpha component and it is assumed to be solid.