Fireflies 萤火虫
Points that drift slowly and pulse their brightness with an independent sine phase. 缓慢漂移的点，亮度按各自独立的相位做正弦脉动。
Runs live on this page. Move the pointer, click, or drag — whichever the effect listens for. 就在本页实时运行。移动鼠标、点击或拖拽——看它响应哪一种。
How it works原理拆解
Each firefly carries ph, its own phase in the sine wave, and opacity is 0.4 + abs(sin(ph))*0.6. Because ph advances at the same rate for all but starts random, the field twinkles asynchronously — the whole point of the effect. shadowBlur adds the halo without any extra particles. 每只萤火虫带一个自己的相位 ph，透明度是 0.4 + abs(sin(ph))*0.6。ph 的推进速度一致，但起点随机，所以整片是不同步地闪——这正是这个效果的意义。shadowBlur 负责光晕，不需要额外粒子。
What to change可以改的地方
- 1Give each firefly a slightly different ph increment so they never fall into rhythm.
- 2Slow the drift to a quarter speed and the scene becomes genuinely nocturnal.
- 1给每只不同的 ph 增量，它们就永远不会同步成一片。
- 2漂移速度降到四分之一，夜晚的氛围才真的出来。
Source code源码
Self-contained — paste it into any HTML file and it runs. No libraries. 完全独立——粘进任意 HTML 文件就能跑，不需要任何库。