3D Four Seasons

Keep one recognizable place across all four seasons. Each season should change several mutually consistent visual cues while preserving camera state and interactions.

Author the seasonal identity

Inventory deciduous trees, evergreens, exposed surfaces, sheltered surfaces, lights, sky, and existing weather. Use species and climate appropriate to the project; the table is a temperate-scene starting point.

Season	Foliage and ground	Light and atmosphere	Motion
Spring	Fresh foliage; blossom on appropriate species	Soft warm daylight; gentle haze	Sparse petals or young leaves
Summer	Dense deep greens; full ground cover	Stronger daylight; readable shaded greens	Restrained leaf drift and breeze
Fall	Species-specific amber, red, and brown; litter	Lower warm sun; golden haze	More falling leaves
Winter	Bare deciduous branches; retained evergreens; exposed snow	Cool sky fill; pale sun; warm interiors	Optional sparse snow; little leaf drift

Choose particle effects only when they serve the scene. A seasonal selector does not require a storm or a full weather simulator.

Share one state

Use a four-component blend in the order [spring, summer, fall, winter]. Accept autumn as an alias for fall, then normalize to one internal key. The weights start nonnegative and sum to one.

const presets = {
  spring: [1, 0, 0, 0], summer: [0, 1, 0, 0],
  fall: [0, 0, 1, 0], winter: [0, 0, 0, 1],
};
const weights = [0, 1, 0, 0];
let target = presets.summer;
function setSeason(name) {
  const key = name === 'autumn' ? 'fall' : name;
  if (!Object.hasOwn(presets, key)) return false;
  target = presets[key];
  return true;
}
function stepSeason(dt, reducedMotion = false) {
  const a = reducedMotion ? 1 : 1 - Math.exp(-1.4 * Math.min(Math.max(dt, 0), 0.05));
  for (let i = 0; i < 4; i++) weights[i] += (target[i] - weights[i]) * a;
}