OptionalcastInitial DirectionalLight.castShadow — §68's own example field,
driving §69's machinery. Defaults to false; see the property.
OptionalcolorInitial color, copied into the light's own array as linear-light RGB.
A CSS string is parsed as sRGB and decoded first (§60a). Defaults to
white [1, 1, 1], §68's own example value.
OptionalintensityInitial DirectionalLight.intensity. Defaults to 1, so an
unconfigured light contributes exactly its color (decision, 2026-08-04:
§68's example intensity: 3 is illustrative and Appendix A pins no light
defaults; 1 is the multiplicative identity).
OptionalshadowInitial DirectionalLight.shadow settings (§69). Omitted fields take DirectionalLightShadow's documented defaults, and the record is constructed whether or not the light casts — so configuring a light before switching it on is a plain assignment rather than an allocation.
Construction arguments of DirectionalLight (§68).