Gongoizer is a free WebGL2 animated background that recreates analog video feedback: the flowing stripes and spirals you get when a video mixer's output loops back into itself. It renders live in your browser, with no video file.
Pick one of 60 presets in the control panel, or start on one from the address bar:
Script tag (fills whatever box you give it):
<script src="https://greatsphynx.neocities.org/gongoizer-background/gongoizer.js"></script>
<feedback-background preset="06" panel-key="off"
style="position:fixed;inset:0;z-index:-1"></feedback-background>Or an iframe, with no script on your page:
<iframe src="https://greatsphynx.neocities.org/gongoizer-background/?preset=06&embed"
style="position:fixed;inset:0;width:100%;height:100%;border:0;z-index:-1;pointer-events:none"></iframe>Attributes: preset (01–60), params (JSON overrides), fallback (image if WebGL2 is missing), panel-key (word that opens the controls; off disables). All presets and palette names are listed in preset-list.json.
Useful params, layered on top of the preset:
timeScale: overall speed (1 normal, 0.5 half).hueSpeed: colour cycling (0 holds the colours still).palette: colour scheme, e.g. "neon", "ice", "sunset" (72 in all).mirror: 0 off, 1 left/right, 2 four-way, 3 kaleidoscope.cutout: shape the flow wraps around: 0 none, 1 diamond, 2 circle, 6 hexagon, 7 star.<feedback-background preset="04" panel-key="off"
params='{"timeScale":0.5,"hueSpeed":0,"palette":"ice"}'></feedback-background>To self-host, download gongoizer.js and serve it from your own site. It is one file with no dependencies.
fallback image.