Hard Effects

Tilted polar stripes with a fade to dark at the bottom

A picture built in steps: tilt, then polar coordinates, then draw stripes, then color it, then finish with a fade to dark at the bottom. Every step is listed below with its exact numbers.

The target picture for the shader challenge "Tilted polar stripes with a fade to dark at the bottom"
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 416 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

Space
p = (uv - 0.5) * float2(aspect, 1.0)
Step 1: Tilt
turn p by 0.4 radians: c = cos(0.4), s = sin(0.4), p = float2(c * p.x + s * p.y, -s * p.x + c * p.y)
Step 2: Polar coordinates
p = float2(atan2(p.y, p.x) / 3.1415927, length(p) * 2.0) (x = angle from -1 to 1, y = distance)
Step 3: Pattern
m = step(0.55, frac(dot(p, float2(0.0, 1.0)) * 6.0))
Step 4: Colors
lerp(float3(0.84, 0.85, 0.93), float3(0.28, 0.07, 0.89), m)
Step 5: Finish
col *= 0.7 + 0.3 * uv.y

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