TITLE Plotter No. 2 — Landscapes in One Pen PROMPT A generative-art page in which a pen plotter draws an invented mountain landscape live, in a single blue pen, on a white sheet. The viewer watches the machine work: the gantry travels, the pen lifts and drops, the line appears exactly where the nib is. Each sheet is a new composition. Concept: the pleasure of watching a drawing being made by a patient machine. Palette: sheet white #FFFFFF on a pale grey cutting-mat surround #D9D9D9 with faint grid, a single ballpoint-blue ink #1F3FBF, machine parts in near-black #111111 and aluminium greys, a small red (#D93025) accent only on the pen clip and the emergency-stop style control. Light page, bright and technical. The drawing (generated per seed, then converted to an ordered list of polylines, i.e. a plot file): a stack of 5–8 receding ridgelines made from layered noise, each ridge hatched with a different technique so the tones separate: contour-following lines that wobble with the slope, vertical rain-like hatching, cross-hatching in shadow, stippled dashes for scree; occlusion handled by hidden-line removal (lines do not draw where a nearer ridge covers them: keep a running "horizon" height per x). Above: a sun as concentric circles or a spiral, or a crescent moon with a few stars, sometimes with horizontal cloud bands that break around it or a small flock of birds; below: a lake of horizontal dashes with the mirrored ridge broken into ripples, or a foreground of a few pine trees drawn as zigzag strokes. A thin border frame, registration crosses at corners, and a title block at the bottom edge lettered by the plotter itself in a single-stroke vector font defined in the page: "LANDSCAPE Nº 0417 · SEED 8F3A · 1 PEN · 2,318 STROKES". The machine: a drawn plotter around the sheet: two rails at the sides, a crossbar (gantry) that moves in Y, a pen carriage that moves in X with a cable loop, a pen that visibly lifts (shadow separates, carriage shows pen-up state) for travel moves and drops for draw moves. Motion follows the path at a constant feed rate with acceleration/deceleration at corners; travel moves are faster. Lines are rendered with slight ink variation: a tiny blob at pen-down, lighter ink at high speed, minute wobble. Paths are sorted to minimise travel, like a real plot. Signature moment: watching the pen race along a ridge then hatch a mountainside in hundreds of quick parallel strokes, the image building up tone. Entrance: the carriage homes to the corner with a small bump, draws the border and registration marks in the first two seconds, then starts the sky. Controls (styled as the plotter's physical control panel under the sheet: a knurled speed dial, a chunky lever toggle, two black keycaps, a red emergency-stop style mushroom button, a small monospace LCD): feed rate dial 1×–64× in seven detents (default 4×); pause/resume on the latching red HOLD button; "finish" (skip to finished) and "new sheet" keycaps (the finished sheet slides off to the right into a stack in the out tray and a blank feeds in from the left); the lever toggle switches the sound; pen colour is fixed. On wide screens the mat beside the machine carries a silk-screened "plot file" listing: every layer with its stroke count, ticked off as the machine completes it, plus pen-down and pen-up distances in metres. The LCD shows live status in mono: "PEN DOWN X 212.4 Y 88.0 37% ETA 01:12". Clicking anywhere on the sheet while it draws drops a "bird": the plotter will later add a tiny V-shaped bird stroke there. Optional sound (off by default): stepper-motor tones whose pitch follows axis speeds, via two oscillators, with a soft click on pen up/down. Typography: monospace technical (Menlo/Consolas/Courier), tiny, tracked; one small heading "Plotter No. 2". Responsive: on phones the sheet is portrait and the gantry simplified. Clicking the sheet after the plot is done wakes the machine to add the bird. Keyboard: Space hold, F finish, N new sheet, + and − feed. Reduced motion: the drawing appears finished, with a pair of layer-step keys on the panel to step through the layers. DESCRIPTION A bright, technical bench-top scene: a white A4 sheet lies on a pale grey gridded cutting mat inside a drawn pen plotter with two aluminium rails, a travelling gantry bar, a black carriage with a cable loop and a ballpoint whose red clip is the only warm colour besides the hold button. On load the carriage homes into the corner with a small bump, rules the border and registration crosses, then works through the sky, each ridge from far to near, the lake or pines, and finally letters its own title block. The landscape is a true plot file: every mark on the sheet is an ordered polyline that the pen actually travels, with travel moves, pen lifts, corner slow-downs and ink that is paler when the pen runs fast. The pleasure is in watching tone accumulate as the machine hatches a mountainside in hundreds of quick strokes, while a small LCD reports pen state, coordinates, percentage and time remaining, and a listing on the mat ticks off the layers. Every new sheet is a new seeded composition, and the finished ones pile up in the out tray. VISUAL TECHNIQUES - Seeded procedural landscape: 5–8 ridgelines from layered value noise and ridged noise with a peak envelope - Hidden-line removal with a running per-x horizon, walked front to back, also used to occlude the sun, clouds and the ridges behind the pines - Five hatching generators (slope-wobbling contours, vertical rain dashes, cast-shadow cross-hatching, scree stipple, downhill fall lines) with density falling off with distance - Lake of horizontal dashes whose density mirrors the skyline through a ripple displacement; pines as dense zigzag strokes - Single-stroke vector alphabet defined in the page, used for the plotted title block - Path simplification and greedy nearest-endpoint ordering of each layer to minimise pen-up travel - Motion planner: resampled paths, corner speed limits, forward/backward acceleration passes, trapezoidal travel moves - Incremental ink rendering on an offscreen canvas at capped device pixel ratio: pen-down blobs, speed-dependent opacity, width jitter and minute positional wobble - Canvas-drawn machine: brushed aluminium gradients, steppers, gantry trucks, a sprung cable loop, pen shadow that separates on lift, servo arm and state lamp - CSS-built control panel: brushed faceplate, conic-gradient knurled dial, lever toggle, keycaps, emergency-stop style hold button, reflective LCD with segment bar - Sheet feed animation with eased slide, slight rotation into a peeking stack of earlier plots - Optional stepper sound: two oscillators pitched from the X and Y axis speeds, filtered noise clicks for pen up and down INTERACTION MODEL The plot starts by itself. Turning the feed-rate dial (drag, mouse wheel, arrow keys, clicking a number, or + and −) changes the speed from 1× to 64×; the red hold button (or Space) latches the machine mid-stroke and releases it again; Finish (F) inks every remaining stroke at once and parks the gantry; New sheet (N) slides the finished drawing into the out tray, feeds a blank and begins a new seeded landscape with the next number. Clicking or tapping anywhere inside the frame leaves a small target mark, and the plotter later travels there and draws a tiny V-shaped bird, even waking up to do it if the sheet was already finished; with the sheet focused, Enter places a bird in the sky. The lever toggle turns the stepper sound on and off. The LCD continuously shows pen state, X and Y in millimetres, percentage, time remaining and the current layer. With reduced motion requested, the drawing is shown complete and two layer-step keys reveal or hide it one layer at a time.