Interface StarsFeatureOptions

Unit vector pointing TOWARD the sun. The stars pass hides stars when the sun is above the horizon (sunDir.y > ~0), so for a space scene the default (0, -1, 0) forces perpetual night and the stars are always visible. For a ground/atmosphere scene, feed the real toward-sun vector (-light.direction) so stars fade in at dusk.

0 clamps stars to the upper hemisphere (ground scenes); 1 wraps them over the full sphere (out in space, looking in any direction). Default 1.

Attenuate stars by the luminance of the sky already behind them (handy in an atmosphere). 0 (default) adds them at full strength everywhere.

Fade sky pixels below the horizon to black. Default false.

Bake the real Yale Bright Star Catalog (BSC5, ~9k stars) into an equirect and render those instead of the procedural field. true bakes with defaults; pass options to tune resolution/brightness. The bake is async, so stars are procedural for a frame or two until it completes. Toggle live via catalogMode. Omit to keep the (cheaper, no-asset) procedural field.

Start in catalog mode (vs procedural) once the bake is ready. Default true when catalog is set. Flip StarsFeature.catalogMode at runtime.

Place the catalog sky geographically: observer latitudeDeg (+N) puts the north celestial pole at that altitude, and siderealTime (radians, animatable — advances ~2π per sidereal day) spins the sky about the pole. Omit for identity orientation (equatorial frame == world). Catalog mode only.

Add a procedural Milky Way band, fixed in galactic coordinates (default-off). true enables it with default brightness/width; pass an object to tune. Shares the night/horizon fade with the rest of the starfield, so it only shows at night and respects the horizon. Toggle live via StarsFeature.pass's milkyWay.

Add a procedural aurora borealis (default-off): rippling vertical curtains in an arc above the horizon with a green→magenta gradient, animated from frame.time. true enables it with defaults; pass an object to tune. Shares the night/horizon fade with the rest of the starfield, so it only glows at night and respects the horizon. Toggle live via StarsFeature.pass's aurora.