OptionaldefinesDoes this fill DEFINE the model's extent? Default true; see uploadFills (#3359).
Vertex indices marking the start of each hole. Empty = no holes.
OptionaloriginOpt-in f64 anchor. points/worldY are local to it; legacy inputs omit it.
Flat ring buffer: [x, z, x, z, …]. Y is taken from worldY.
Straight-alpha RGBA in [0..1]. The shader premultiplies.