Matrix Rain 矩阵数字雨
One rain column every 14px, each with its own falling head position — the tail is just an unfinished clearing. 每 14px 一列数字雨，每列有自己的下落头位置——尾巴其实是「没清干净的上一帧」。
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
Instead of clearRect, every frame paints rgba(0,0,0,0.08) over the canvas. That leaves 8% of the previous frame, which is what creates the fading tail. A column resets to 0 only when it is past the bottom AND Math.random() beats 0.975, so the columns desynchronise almost immediately. 它不用 clearRect，而是每帧盖一层 rgba(0,0,0,0.08)。上一帧留下 8%，就形成了拖尾。一列只有在下落到画布外、且 Math.random() 大于 0.975 时才归零，所以各列几乎立刻就不齐了。
What to change可以改的地方
- 1Raise the clear alpha to 0.2 for short stubs, lower it to 0.03 for very long tails.
- 2Widen the character set with katakana or binary and the code looks different at a glance.
- 1清屏透明度改成 0.2 是短促的雨点，改成 0.03 是拖很长的尾巴。
- 2换一套字符（片假名或纯 01），一眼看过去的风格就完全不同。
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。