Options to control the vignetting effect (darkening at screen edges).
Color of the vignette effect (alpha is currently ignored). Default: black.
Enable or disable the vignette effect. Default: false.
Softening amount of the vignette effect, between 0 and 1. Default: 0.5.
High values restrict the vignette closer to the corners, between 0 and 1. Default: 0.5.
Controls the shape of the vignette, from a rounded rectangle (0.0), to an oval (0.5), to a circle (1.0). Default: 0.5.