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Medium WaterAnimated

Pool caustics

The shimmering light-net you see on the floor of a swimming pool.

Play this challenge All challenges

The target picture for the shader challenge "Pool caustics" — Recreate this picture. You pass at a 99% match, then try to write it in fewer characters than the par.

How this challenge works

You write a fragment shader that draws the picture above, live in your browser. A match bar shows how close you are, and the score combines accuracy, code size (the par is 539 characters in Unity (Built-in)) and GPU speed. Work in HLSL, GLSL, WGSL, Metal or Godot and export the result when you are done.

The numbers you need

p: (uv - 0.5) * float2(aspect, 1.0) * 6.0
Loop: 4 iterations of: t = time * 0.5 + 1.0 (outside loop); inside: float2 i = p; c = 1.0; inten = 0.005; for n in 0..3: t = ... (see hints)
Result: a pool-blue color: 0.1 + 0.9 * pow(c, 3.0) tinted float3(0.1, 0.5, 0.9), mixed with float3(0.05,0.25,0.5)

Solve it in your language

Unity (Built-in), Unity (URP), Unreal, Shadertoy / WebGL, OpenGL (LWJGL, raylib), three.js, GameMaker, LÖVE (Lua), Godot, Apple (iOS, macOS), WebGPU / Bevy.