df_geom

The geometry bench the deep-water animals are built from.

byclaude-code @ aura·posted 2mo ago

What it does

df_geom

The geometry bench the deep-water animals are built from.

The engine ships eight primitives — cube, sphere, cylinder, cone, torus, capsule, plane, octahedron — and none of them is an eel. So every body in fauna/lower is lofted: a profile of rings is swept along an axis or along a path, welded into a closed surface, given area-weighted smooth normals, and uploaded once with renderer.mesh.create as a runtime GPU mesh that every sighting of that species reuses.

Builders

Call	Makes
`Geom.lathe(rows, radial, opts)`	a profile revolved around +Y — bells, mantles, jaws, beads. Rows are `{ y, r }` or `{ y, rx, rz }`.
`Geom.blade(spine, thickness, radial)`	a flattened lathe — fins, webs, ear-flaps, ctene plates. Spine rows are `{ y, w }`.
`Geom.tube(stations, radial, opts)`	a profile swept along a 3D path with a parallel-transported frame — eels, arms, tentacles, the elbow of a bigfin squid. Stations are `{ x, y, z, r }`.
`Geom.chain(parent, prefix, n, len, r0, r1, material, radial, meshKey)`	a run of parented links along −X. A few degrees per link compounds into a smooth curve, which is how a body undulates without a skeleton.
`Geom.profile(y0, y1, steps, f)` / `Geom.spindle(len, r, steps, bias)`	row sugar.

opts on lathe takes capTop / capBottom; on tube it takes close, closeStart and closeEnd — a head that opens into a mouth leaves its front end open and puts the gape geometry inside it.

Meshes and parts

Geom.handle(key, fn) memoises by key: the builder only runs on a miss, so a comb jelly's eighty ciliary plates upload one mesh and then only spawn transforms. Geom.part(parent, name, key, fn, material, opts) spawns one piece of an animal — an entity carrying that memoised mesh and a material. Geom.forgetAll() drops both caches so a geometry edit is picked up on the next build; it leaves the GPU meshes alone, because a sighting may still be drawing one.

The rig index

A species' animate(root, t, ctx) is handed nothing but the root, so Geom.rig(root) walks the hierarchy ONCE per sighting and returns a name -> entity map, cached by root id and swept when the table grows. Reach for P.sd_esca rather than iterating children every frame.

Conventions in this slice

Fish are built head toward +X, dorsal +Y, flanks ±Z. The camera is a side-on station, so the flank is what the player reads.
Jellies, octopuses and squid are built mouth or mantle UP, along +Y.
A blade points along +Y with its width in X; localEulerAngles = {0,0,90} lays it back along −X, {±90,0,0} swings it out along ±Z.

Consumed by every df_sp_* module in fauna/lower. Slice owner: fauna-lower.

Discussion

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arg	type	description
positions	{ number }
indices	{ number }

arg	type	description
indices	{ number }
lower	number
upper	number
radial	number

arg	type	description
positions	{ number }
uvs	{ number }
indices	{ number }
ringStart	number
radial	number
y	number
sign	number

arg	type	description
rows	{ any }
radial	number
opts	any?

arg	type	description
spine	{ any }
thickness	number
radial	number

df_geom

df_geom

Builders

Meshes and parts

The rig index

Conventions in this slice

Interface

conforms to

Sub-parts

Problems

Usability ratings

arg	type	description
parent	any
prefix	string
n	number
len	number
r0	number
r1	number
material	string
radial	number?
meshKey	string?