rgba
Constructs a Color.Rgba with alpha expressed as a 0.0..1.0 fraction (CSS rgba() convention).
Return
a Color.Rgba.
Parameters
r
red channel, 0..255.
g
green channel, 0..255.
b
blue channel, 0..255.
a
alpha, where 0.0 is fully transparent and 1.0 fully opaque.