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No.106 · Backgrounds

Isobar

A living weather map — contour lines traced over a drifting pressure field, with your cursor as a system of its own.

The prompt

Written for the variant you picked above: Frost

Create a background that looks like a surface-analysis weather chart come to life. On a near-black ground, sample a smooth pressure field on a 12px grid: three octaves of value noise, each drifting in a different direction at a slow rate, so the pattern evolves like weather rather than scrolling. Trace 16 evenly spaced contour levels between the field's current minimum and maximum with marching squares (linear-interpolated edge crossings, both saddle cases handled), drawing every segment of a level in one path. Minor isobars are hairlines at 16% opacity; every fifth line is a heavier "index" isobar at 42%, exactly as cartographers do. Mark the current global high and low with small mono "H" and "L" labels. Make the cursor a pressure system: add a soft Gaussian bump centred on the pointer whose strength eases in when the pointer enters and out when it leaves, so the isobars visibly bend and gather around it and the H often migrates to follow your hand. Redraw at ~20fps (weather doesn't need 60), pause when offscreen or the tab is hidden, cap DPR at 2, and draw one still frame under reduced motion. Take the line colour and ground colour as props so the chart can be re-inked. Selected variant — Frost: Frost: pale frost-blue isobars (#b9cce4) on near-black (#07080c); labels in the same frost at 60% opacity.

Notes

Interaction
The pointer adds a local high-pressure bump that bends nearby isobars; it fades in and out smoothly.
Motion
Field drifts continuously; canvas redraws at ~20fps; cursor influence eases at 8% per frame.
Accessibility
Canvas is aria-hidden. Reduced motion renders a single still chart with no cursor tracking.
Responsive
Grid scales with the container; cell size and level count are props for tuning density vs. cost.
On touch
No cursor bump on touch; the map still drifts.

Featured

01Glassbreak ButtonA solid plate that fractures from one impact point, cracks racing outward as the shards drift apart.04Liquid GlassA capsule of glass that bends what's behind it, carries a specular highlight around its rim toward your pointer, and squashes like a drop of liquid when pressed.07Phosphor Glass ButtonA liquid-glass pill that senses you coming: its rim light turns to face the cursor and the pill leans in to meet it.08Iris ShutterAn async button with a camera iris for a status light — blades close and turn while it works, then open onto the result.
81Atmosphere CardSmoked-glass link cards: colour pooled in the corners, slow contour currents underneath, a field that leans toward you.93Eclipse Event CardAn editorial event plate with an oversized date and an orbital eclipse bleeding in from the right, alive with slow drift.94Specimen CardAn object mounted under glass: hover lifts the pane with a sweep of reflection and swings out a paper catalogue tag.
95Silk FieldDomain-warped light that pours like liquid silk, with an optional glass lens that refracts the flow under your cursor.106IsobarA living weather map — contour lines traced over a drifting pressure field, with your cursor as a system of its own.
151Prompt ComposerA chat composer where attached files tuck into its top edge like tabs in a folder — they rise from behind it when added and sink back when removed. Send turns into stop while the reply streams.157Aura FieldA writing field where colour only exists while the AI is touching your text: the edge becomes a turning band of light and the words are rewritten in place, one by one, out of a soft blur.
205Halftone CTAA tall CTA banner where slow gold paint drifts beneath a fixed halftone grid, visible only through the dots.
212Nocturne Sign-inA single quiet column on near-black with a breathing seam of frost light behind it — email, password, magic link, nothing more.222Sigil Sign-inA split sign-in whose left half grows a geometric mark from your email — the same address always draws the same sigil.
275Voices CarouselA testimonial exhibition: one large quote at a time on frosted glass, crossfading between voices without ever resizing.
279Feral TitleA brutal condensed wordmark — heartbeat in the dark, letters slam in, a gash tears through and the word bleeds.
301 components