Function snowBox

src/generators/snow.ts:89–274

({
  // min and max box extents of the snowBox
  box,
  // minimum y-coordinate to clamp particle position, which can be used to
  // fake hitting a ground plane and lingering there for a bit
  minY,
  // number of Gsplats to generate (default: calculated from box and density)
  numSplats,
  // density of Gsplats per unit volume (default: 100)
  density,
  // The xyz anisotropic scale of the Gsplat, which can be used for example
  // to elongate rain particles (default: (1, 1, 1))
  anisoScale,
  // Minimum Gsplat particle scale (default: 0.001)
  minScale,
  // Maximum Gsplat particle scale (default: 0.005)
  maxScale,
  // The average direction of fall (default: (0, -1, 0))
  fallDirection,
  // The average speed of the fall (multiplied with fallDirection) (default: 0.02)
  fallVelocity,
  // The world scale of wandering overlay motion (default: 0.01)
  wanderScale,
  // Controls how uniformly the particles wander in sync, more variance mean
  // more randomness in the motion (default: 2)
  wanderVariance,
  // Color 1 of the two colors interpolated between (default: (1, 1, 1))
  color1,
  // Color 2 of the two colors interpolated between (default: (0.5, 0.5, 1))
  color2,
  // The base opacity of the Gsplats (default: 1)
  opacity,
  // Optional callback function to call each frame.
  onFrame,
}: {
  box?: THREE.Box3;
  minY?: number;
  numSplats?: number;
  density?: number;
  anisoScale?: THREE.Vector3;
  minScale?: number;
  maxScale?: number;
  fallDirection?: THREE.Vector3;
  fallVelocity?: number;
  wanderScale?: number;
  wanderVariance?: number;
  color1?: THREE.Color;
  color2?: THREE.Color;
  opacity?: number;
  onFrame?: ({
    object,
    time,
    deltaTime,
  }: { object: SplatGenerator; time: number; deltaTime: number }) => void;
})

// - anisoScale: the vec3 uniform of the snowBox anisotropic scale

export function snowBox({
  // min and max box extents of the snowBox
  box,
  // minimum y-coordinate to clamp particle position, which can be used to
  // fake hitting a ground plane and lingering there for a bit
  minY,
  // number of Gsplats to generate (default: calculated from box and density)
  numSplats,
  // density of Gsplats per unit volume (default: 100)
  density,
  // The xyz anisotropic scale of the Gsplat, which can be used for example
  // to elongate rain particles (default: (1, 1, 1))
  anisoScale,
  // Minimum Gsplat particle scale (default: 0.001)
  minScale,
  // Maximum Gsplat particle scale (default: 0.005)
  maxScale,
  // The average direction of fall (default: (0, -1, 0))
  fallDirection,
  // The average speed of the fall (multiplied with fallDirection) (default: 0.02)
  fallVelocity,
  // The world scale of wandering overlay motion (default: 0.01)
  wanderScale,
  // Controls how uniformly the particles wander in sync, more variance mean
  // more randomness in the motion (default: 2)
  wanderVariance,
  // Color 1 of the two colors interpolated between (default: (1, 1, 1))
  color1,
  // Color 2 of the two colors interpolated between (default: (0.5, 0.5, 1))
  color2,
  // The base opacity of the Gsplats (default: 1)
  opacity,
  // Optional callback function to call each frame.
  onFrame,
}: {
  box?: THREE.Box3;
  minY?: number;
  numSplats?: number;
  density?: number;
  anisoScale?: THREE.Vector3;
  minScale?: number;
  maxScale?: number;
  fallDirection?: THREE.Vector3;
  fallVelocity?: number;
  wanderScale?: number;
  wanderVariance?: number;
  color1?: THREE.Color;
  color2?: THREE.Color;
  opacity?: number;
  onFrame?: ({
    object,
    time,
    deltaTime,
  }: { object: SplatGenerator; time: number; deltaTime: number }) => void;
}) {
  box =
    box ??
    new THREE.Box3(new THREE.Vector3(-1, -1, -1), new THREE.Vector3(1, 1, 1));