About this reference

What’s documented

The runtime API of hydra-synth, pinned to the exact version in the footer. The function names, parameter names, types, and defaults are generated from that version’s source (glsl-functions.js, array-utils.js). If any of them change upstream, the build fails until the affected annotation is reviewed again. Each annotation also records a hash of the shader it was written against, so a changed shader body fails the build too.

How the descriptions were made

For each function:

1. Read the shader. Ranges, units, periodicity, and what values do nothing come from the GLSL itself. Every page links to the exact source lines.
2. Render it. Each sweep strip is a set of real hydra-synth frames, rendered headless with the same library version, sweeping one parameter while holding the others fixed. Anything stated about direction, wrapping, or edge behavior was compared against these renders.
3. Flag surprises. When the shader does something its parameter name doesn’t suggest, the page says so in a Quirk callout and points to the evidence.

“Useful range” is a judgment call: the span where turning the knob changes the picture in interesting ways. Hydra never clamps arguments, so any number is legal unless “Defined for” says otherwise.

Review status

The prose and parameter annotations were drafted by Claude (Anthropic), an AI model. A page marked unreviewed draft has not been checked line by line by a human yet. Treat its claims as checked against renders, not as authoritative. The strips are real output, but the sentences describing them may still be wrong.

Test cards

Geometry examples sample a procedural grid card (/cards/uv-grid.png) and color examples a procedural color chart (/cards/color-chart.png); both were generated for this site (scripts/make-cards.mjs) and are CC0. The photo (/cards/photo.jpg) is Colorful umbrellas over the Szinva Bridge by Szalax, CC0 1.0, via Wikimedia Commons (cropped). All cards are served with CORS headers, so examples work unchanged when opened in the hydra editor.

Licenses

• Site code: AGPL-3.0, matching hydra-synth.
• Prose and annotations: CC BY 4.0.
• hydra-synth (bundled, unmodified): AGPL-3.0, © hydra-synth contributors. Source at the pinned commit.

This is an independent project, not an official hydra resource. For the official docs see hydra.ojack.xyz/docs.