Light's direction (direction to the light source).
This is expected to be normalized.
Optional diskLight disk's angular diameter in radians.
For the sun, defaults to ~0.0095120444 (0.545 degrees)
For the moon, defaults to ~0.0099134702 (0.568 degrees)
Optional diskLight disk's luminance scale.
The light disk's luminance is computed from the given illuminance and the disk's diskAngularDiameter. This scale is applied to the computed luminance value to give users more control over the sun disk's appearance.
Defaults to 1.0.
Optional illuminanceLight's illuminance at the top of the atmosphere.
Defaults to [1.0, 1.0, 1.0]
Properties of a directional light influencing the atmosphere (e.g., sun or moon).