Fireflies

#Add them

import { Fireflies } from 'naturegl-grass';

const flies = await Fireflies.create({ scene, grass, count: 700 });

renderer.setAnimationLoop(() => {
  flies.intensity = nightFactor;                       // 0 hides them
  flies.update(dt, player.position, camera, renderer);
  renderer.render(scene, camera);
});

grass shares its baked terrain. Without a grass system, pass terrain (a description or a TerrainField). A description is baked at 256² for the fireflies.

#Options

#The update call

update(dt, focus, camera?, renderer?) advances the blink clock and moves the swarm centre to focus. Pass the camera and renderer to keep the point size right after a resize. The size is computed from the drawing-buffer height and the camera's field of view. The points object hides itself while intensity is below 0.01, so a daytime swarm costs nothing to draw.

#Where they fly

• Each point drifts slowly on its own loop and bobs up and down within heightRange.
• Points wrap around the focus square, so walking forward never leaves the swarm behind.
• The height comes from the baked terrain, so they follow hills.
• They blink in sharp pulses, and the glow is suppressed where the terrain mask is near 0. None hover over water or paths you masked out.

#Fade with your sky

Drive intensity from whatever says "night" in your scene. With NatureGL Sky, that is sky.night:

flies.intensity = sky.night;

The demo computes its own night factor from the sun elevation of its time-of-day slider.