Physics
Two-Source Interference
A = sin(k r₁ - ωt) + sin(k r₂ - ωt)

Two coherent point sources produce a live ripple field of constructive and destructive fringes.
Computed & rendered in pure C# on the frozen OnlyCSharp 1.8 library — animation baked to GIF with the library's own
Gif encoder (no GPU, no ffmpeg, no external packages).