Hard Filters
Kuwahara painting filter
The famous oil-paint look: for each pixel, average the calmest of 4 quadrants.
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 1264 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
- Radius
3 samples, spacing 0.004 in uv- Quadrants
top-left (x -3..0, y 0..3), top-right (0..3, 0..3), bottom-left, bottom-right (they overlap on the axes)- Per quadrant
mean color and variance of luminance (mean of squares minus square of mean)- Pick
the quadrant with the smallest variance; output its mean color
Helper functions provided
The toolbox has: scene(). Add them above your frag function with one click.
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.
Start coding