Slow Light

The brief

Make an experimental WebGL experience that does something a browser is not expected to do.

The idea

Most graphics on the web are a fast approximation. Slow Light traces actual paths of light, one per pixel per frame, and averages them. Waiting is the point: a long exposure you can watch developing, which is also how photography began.

Decisions

• Scenes are pure signed distance functions, with no models or textures.
• Water is a true Fresnel interface with refraction, so reflections and depth are earned.
• The doorway in Door, Salt Flat toggles the sky as rays cross it, so the reflection agrees with the impossibility.
• Long shaders compile asynchronously so the page never freezes.

How it came together

1. Wrote a progressive accumulator with tiled rendering so long frames do not hit the GPU watchdog.
2. Added thin-lens depth of field, soft sun, volumetric fog and a dielectric water surface.
3. Found and replaced a blocky bloom kernel after inspecting the finals at full size.

How it works

A fragment shader marches each ray through a signed distance field, bounces it with a BRDF, and adds the sample to a floating-point buffer. Dividing by the sample count gives the image.