Area lights in shaders — Zsolt Ero (hyperknot)

The five .glsl.txt files contain the complete recovered fragment-demo code,
including its original mathematical functions, animation and display transforms.
Only whitespace has been normalized; the shader logic is unchanged.
They are also the exact source files fetched by the interactive widgets.

The renderer uses locally bundled Three.js, WebGLRenderer and ShaderMaterial,
a 2 x 2 fullscreen plane, and an orthographic camera. It supplies:

  uniform vec3 iResolution; // physical drawing-buffer width, height, 1
  uniform float iTime;      // simulation time in seconds

Its vertex shader is:

  void main() { gl_Position = vec4(position, 1.0); }

It appends this fragment entry point to the reference source:

  void main() {
    mainImage(gl_FragColor, gl_FragCoord.xy);
    gl_FragColor.a = 1.0;
  }

The explicit alpha makes the display opaque: the original vec4(v) output's
alpha is not used for compositing these demos. The RGB computation is unchanged.
Three.js supplies built-in declarations and highp precision. No textures,
channels, mouse input, additional passes or built-in lights are required.

The shaders already encode display colors: inverse-square uses gamma 2.2;
the other four use their own piecewise linear-to-sRGB function. The renderer
uses SRGBColorSpace and NoToneMapping and adds no color-conversion shader chunk.

Initial times: inverse-square 0 (static), point-light 1, tiny-disc 0.5,
rod-light 6, rectangle-area-light 6 seconds. All demos start paused. Time only
advances during explicit playback while visible in the active tab. Reset pauses
and restores the initial time. No pointer-dependent behavior is omitted.

Resolution follows the square display size, with device pixel ratio capped at
2 and each drawing-buffer dimension capped at 1024. Dimensions are rounded to
an even number so no pixel lands exactly on the analytical center singularity.
The 512 x 512 PNG posters
were captured from these shaders at the initial times. They remain available
without JavaScript, on unsupported browsers and after a graphics context loss.

The complete code can be expanded beside each widget or read at its plain-text
link. Unmodified archival inputs and provenance are retained separately from
this published article. Current remote execution was not available for an
independent live comparison; these demos reproduce recovered historical code.