# The shader eye

> The second eye was a painting: one 850-line GLSL fragment shader that faked a whole eye in 2D on a full-screen quad. It found the idea of the page in the cornea, and then it hit its ceiling.

- URL: https://www.kiruk.in/making/glsl-eye
- Kind: Interface
- Made: Sep 2026
- Author: Arun Kumaar Sreenivasan
- Part of: How this was made (https://www.kiruk.in/making)
- Agent file: https://www.kiruk.in/making/glsl-eye/agent.md

![The shader eye in 1970, a flat green eye](https://www.kiruk.in/making/loader-eye/gen2-glsl-1970.webp)

**1970.** The same formula as on the right, in a different light.

![The shader eye in 2003, a flat eye with a mirrored page in the cornea](https://www.kiruk.in/making/loader-eye/gen2-glsl-2003.webp)

**2003.** The site's page, mirrored, sits in the cornea. That part was new.

## What it was

A fragment shader runs once for every pixel and answers one question: what colour is this point? This one answered it for a whole eye. Inside an almond the pixel is white. Inside a circle it is iris, with noise for fibres. A dome formula bends a painted page across the middle to stand in for a reflection.

There was no geometry. The lids, the lashes and the room were all the same flat plane.

## What it found

The era's screen lives in the cornea, and it is the only light. That sentence survived the rebuild unchanged, and became [a pattern of its own](https://www.kiruk.in/making/page-is-the-light).

## Where it stopped

- Every new detail cost every pixel, because the noise ran over the full screen each frame.
- Lashes and lids had no depth, so they could not go out of focus or cast a shadow.
- The iris could not slide under the cornea when the eye turned.

It stays in the site as the last fallback. If the 3D eye cannot start, this one still can.

## Lineage

### Came from

- [The SVG eye mark](https://www.kiruk.in/making/svg-eye-mark) (Interface, May 2026): The first eye was a logo: two rings, an arc and a pupil that follows the cursor, redrawn once for each era. It set the idea that one thing can be seen through many screens.

### Led to

- [The loader eye](https://www.kiruk.in/making/loader-eye) (Interface, May to Nov 2026): One human eye, drawn live in the browser and lit only by the screen it is looking at. It was built four times in six months, measured against a photograph of my own eye, and it changes era by blinking.
- [The page is the light](https://www.kiruk.in/making/page-is-the-light) (Pattern, Sep 2026): The eye has one key light, and it is the site itself. Each era's real home page is captured and stood in front of the eye at true size, where it lights the face and shows in the cornea.