creatures/ -- the 2D creature factory

A small, reusable factory for procedural side-view animals, decomposed by concern (factories + a composer, not one huge file). It is consumed by the First Light gallery piece (../creatures.html) today and is meant to be included by the Natura world renderer next, so a world can draw its agents as articulated models instead of dots.

Layers (each its own file, one concern)

species.js    DATA      what animals exist -- proportion/colour tables (SPECIES quadrupeds, BIRDS bipeds).
                        Adding a creature = adding a row here. No drawing, no behaviour.
render.js     DRAWING   how a def is drawn -- drawCreature (quadruped) + drawBird (biped), with the
                        level-of-detail resolve (far silhouette -> full model). Math helpers internal.
behaviour.js  DECISION  what an animal does over time -- BEH loops of {posture, movement, gait} segments,
                        GALLOP, and targetOf() to pick the current segment. Never touches the canvas.
voice.js      SOUND     a reusable WebAudio VOICE per creature -- CreatureVoice.play(ctx,dest,name,t,opts).
                        Band-limited transient/textural only (no square/saw, no sustained drone); variants
                        for variety; SCENES (marshNight, dayGarden). Context-agnostic (a live AudioContext
                        AND an OfflineAudioContext), so voice-check.html VERIFIES it device-free.
creatures.js  COMPOSER  the facade -- wires the three together into one surface (draw / SPEC / isBird /
                        BEH / GALLOP / targetOf / mulberry / clamp). The only thing a consumer needs.
                        (voice.js self-attaches Creatures.voice when present; load it too if you want sound.)

The audio bench: voice-check.html. Renders any voice/scene through an OfflineAudioContext (no speakers, no desktop) and draws its FFT spectrogram + metrics -- the device-free, decisive check. ?voice=NAME / ?scene=NAME / ?variant=NAME. Use it before trusting a sound; it caught (and led to fixes for) the duck under-level, the cricket high-freq skirt, and the grain-onset click.

Data flows one way: species (data) -> render (draws it), and behaviour (decides) -> a pose -> render (draws that pose). Render depends on nothing; the composer depends on all three.

Contracts

• Creatures.draw(ctx, name, x, y, dir, phase, scale, pose) -- resolve name, dispatch to the right body plan. dir is +1/-1 facing; phase is the gait cycle [0,1); pose (optional) is the eased posture {neck, ear, stand, peck, gait, lod}.
• Creatures.targetOf(c, e) -- for a creature c with {beh, seed} at loop time e (seconds), the active behaviour segment. The consumer eases its live pose toward it (so heads raise and legs plant smoothly) -- easing is scene policy, not library policy.
• Determinism: all texture/scatter randomness comes from mulberry(seed) (no Date/Math.random), so a frame is reproducible.

Add a creature

1. Add a row to SPECIES (quadruped) or BIRDS (bird) in species.js.
2. If it needs a new feature (a horn, a sheen, stockings), add a flag there and a small gated block in render.js. Most creatures need no render change.
3. node creatures/creatures.test.js (data + wiring), then eyeball ?montage=<name> / ?zoom=<name> on ../creatures.html.

Consume it

Load the four scripts in order (they attach to window), then use the facade:

<script src="creatures/species.js"></script>
<script src="creatures/render.js"></script>
<script src="creatures/behaviour.js"></script>
<script src="creatures/creatures.js"></script>
<!-- then: Creatures.draw(ctx, 'deer', x, y, 1, phase, scale, pose) -->

Node: require('./creatures/creatures') (UMD) -- used by the test.

Deploy note

The gallery piece ships as art/first-light.html plus art/creatures/*.js (the four runtime modules, copied from here). The test and this doc stay here in the source and are not shipped.