Trout

import { createAsset } from 'https://gaitkit.com/cdn/trout.mjs';

const trout = createAsset();
scene.add(trout);                      // rests on y = 0, front faces +Z

let dist = 0;
renderer.setAnimationLoop(() => {
  dist += speed * clock.getDelta();
  trout.position.set(0, groundY + trout.userData.altitude, dist);
  trout.userData.tick(dist);            // the body waves with the distance
  renderer.render(scene, camera);
});

import { useGLTF, useAnimations } from '@react-three/drei';
import { useEffect } from 'react';

// trout.glb from the Download button (it carries the knobs you set), saved in /public
export function Trout({ speed = 1 }) {
  const { scene, animations } = useGLTF('/trout.glb');
  const { actions } = useAnimations(animations, scene);
  useEffect(() => {
    const clip = actions['Loop'];
    clip?.play();
    if (clip) clip.timeScale = speed / 0.293;   // one Loop = 0.293 m of travel
  }, [actions, speed]);
  return <primitive object={scene} />;
}
// Live knobs or terrain-following feet: copy trout.mjs and runtime/ into your project and use the three.js tab.

# Import trout.glb (download below). It carries an in-place "Loop" animation.
@onready var anim: AnimationPlayer = $Trout/AnimationPlayer

func _physics_process(delta):
    velocity = transform.basis.z * speed
    move_and_slide()
    anim.play("Loop")
    anim.speed_scale = speed / 0.293   # one Loop = 0.293 m of travel

// Import trout.glb with glTFast (com.unity.cloud.gltfast).
animator.Play("Loop");
animator.speed = speed / 0.293   // one Loop = 0.293 m of travel