TITLE Zoetrope PROMPT A virtual zoetrope: the Victorian slotted drum that turns a strip of drawings into a moving picture. The viewer spins the drum by dragging; at low speed they see only a blur of slots and drawings sliding past; at the right speed the stroboscopic effect locks and a little figure suddenly comes alive, viewed through the passing slits. The physics of the illusion is simulated honestly: the image seen is the drum's strip sampled through moving slits, so the animation appears, quickens, dissolves, stands still or runs backwards depending on the rate and direction of spin, exactly as in a real one. Concept: recreate the moment of surprise that began cinema. Mood: candlelit parlour, wonder, mahogany and brass. Palette: dark room brown-black #17100B, mahogany drum and stand #6B3F1D (with highlights #8E5A2C), cream paper strip #E9D8B4, vermilion ink #C1272D for the figures' accents and the title, lamp-warm highlight tones derived from the cream. Dark page (a darkened parlour is the concept), lit by a single oil lamp from the upper left that casts a warm pool on the table and gleams on the drum. The apparatus (Canvas 2D): a cylindrical drum seen from slightly above and in front: a wide open-topped cylinder on a turned wooden pedestal with a brass spindle. The outer wall, in front, has 12 evenly spaced vertical slits; through the slits and over the near rim the viewer sees the inside of the far wall, where the paper strip with 12 frames sits. Render the cylinder geometry properly: the near wall as a dark curved band with bright slits moving across it (their spacing compressing toward the edges by cosine projection), the far inner wall visible through them carrying the frames (also projected on the cylinder so frames foreshorten toward the sides), top rim ellipses, the base shadow, and motion blur proportional to angular speed when not strobing. The illusion: compute what is visible per frame of rendering from the true drum angle. Add a "viewing aperture" model: the viewer sees the far wall only through the slits; because slits and pictures move in opposite directions across the line of sight, each slit sweeps a narrow glimpse of one drawing; persistence of vision is simulated by accumulating several sub-frame samples per display frame with decay (or by rendering each glimpsed frame sharp but horizontally compressed, as in a real zoetrope) so that at sufficient speed the sharp, steady, animated figure appears in place, slightly dimmer and thinner than the drawings really are. Below a threshold speed, show blurred streaks. Strips (interchangeable paper bands, each 12 frames, drawn procedurally in the page as simple, elegant silhouettes/line drawings in black and vermilion on cream, with frame numbers and tiny registration marks): 1) a galloping horse built from articulated shapes (body, neck, head, four two-segment legs in a keyframed gait cycle, tail streaming); 2) a juggler keeping three vermilion balls in the air; 3) a leaping frog/acrobat somersaulting over a hoop; 4) a bird in flight (wing cycle); 5) a couple waltzing (two figures rotating); 6) abstract: a bouncing ball that squashes, and a growing-shrinking star: the classic phenakistiscope motifs. The unrolled strip is also shown flat beneath the apparatus as a long paper band with all twelve drawings, so the viewer can compare the static frames with the living figure; the frame currently behind the nearest slit is underlined. Interaction: drag horizontally across the drum (mouse or finger) to flick it: it spins with angular momentum and slows gradually with friction, so the animation speeds, locks, slows and dissolves back into separate pictures: the signature moment is that lock-in, the instant the blur resolves into a galloping horse; a brass crank handle beside the stand can be turned for steady speed (on release a governor holds the speed reached until the drum is braked or grabbed; Enter on the focused crank sets or releases the governor), with a small rpm dial in the table apron that marks the "sweet band" in vermilion; reversing the spin runs the animation backwards; keys: left/right arrows add spin, Space brakes with a felt pad. A toggle "lift the lid" raises the slotted upper ring off the drum on two fine wires: now the viewer sees the strip directly and only smear, proving the slits make the picture. On wide screens a brass reading glass on a stand beside the drum magnifies the central view through the slits, so the lock-in can be seen large. A "draw your own" drawer: a strip of 12 small canvases where the viewer can scribble simple frames with the pointer (with onion-skin of the previous frame), then drops the strip into the drum. Typography: Victorian show-card style, used sparingly: the title "ZOETROPE" in wide-tracked Tuscan-flavoured serif capitals (a stack like "Playbill", "Bodoni MT", Didot, Georgia with heavy weight and generous letterspacing) in vermilion with a thin cream outline, subtitle in italic: "or, the Wheel of Life: turn briskly and look through the slits"; strip names on small paper labels in a handwriting-like italic; a short three-sentence note explaining why it works (the slits act as shutters; each glimpse is too brief to smear; the eye joins them). Optional sound toggle (off by default): the soft whirr and tick of the spindle rising with speed. Entrance: the lamp flares up, the drum is given one automatic flick and the horse gallops within the first three seconds, then coasts down. Reduced motion: the drum does not spin by itself and motion blur is off; a stepper lifts the lid and advances the drum one frame at a time at a slow rate on request. Layout: the scene fills the first screen; the controls sit on the table's front apron beneath it, with the drawing drawer sliding out below. DESCRIPTION A darkened Victorian parlour: a brass wall lamp flares up at the upper left, throwing a warm pool over patterned wallpaper and a mahogany table on which stands a slotted drum on a turned pedestal. One automatic flick sets it spinning, and within three seconds the bright slits sliding across the near wall fuse into a cream band in which a row of small black-and-vermilion horses gallops on the spot, dimmer and narrower than the drawings on the paper band lying unrolled on the table in front. As the drum coasts down the figure flickers, breaks into sweeping bars with comet tails of drawing, and finally stands as twelve separate slivers. Nothing is faked: the picture is built each frame by sampling the far-wall strip through the moving slits into a persistence buffer that fades like the eye, so the speed, direction and failure of the illusion all follow from how the viewer spins the drum. A reading glass on a stand shows the central figure enlarged; lifting the slotted lid turns the same drawings into a grey smear; and a drawer in the table holds twelve blank frames for a strip of the viewer's own. VISUAL TECHNIQUES - Canvas 2D cylinder rendering: near wall, far inner wall, rim ellipses and brass hoops with cosine-projected slits, staves and frames - Honest slit-scan simulation: each slit's trailing edge paints the opposite strip at twice the angular rate into an offscreen persistence canvas, sub-sampled within every display frame - Persistence of vision as exponential alpha decay (destination-out) tied to real elapsed time, giving natural flicker, lock-in and dissolve - Vertical parallax through the slits (the far wall is seen lower at the centre than at the edges) from the tilted viewpoint - Motion blur proportional to angular speed on far slits and stave seams; multi-sample smear and column-averaged strip when the lid is off - Six procedural twelve-frame strips drawn from articulated shapes and keyframed cycles (gallop, three-ball cascade, somersault, wing beat, waltz turn, squash-and-stretch ball with pulsing star), drawn wide to survive the slit squeeze - Paper texture with grain, frame numbers and registration marks; unrolled band of twelve cells with a travelling vermilion underline - Lathe-turned pedestal and spindle built from stacked gradient slices; brass crank wheel, felt brake pad, reading glass that magnifies the live canvas - Pre-rendered parlour: lamp glow, wallpaper revealed only inside the light, table grain, light pool and cast shadows; flickering flame with additive glow - Entrance choreography: lamp flare, letter-by-letter lighting of the show-card title, band unrolling, automatic flick - Show-card typography: wide-tracked heavy serif capitals in vermilion with a cream outline, italic subtitle, handwritten paper tags, engraved brass plates, SVG speed dial with the sweet band in vermilion - Web Audio whirr and spindle tick that rise with speed (off until switched on) INTERACTION MODEL Drag sideways across the drum with mouse or finger to turn it by hand and release to flick it; it keeps its momentum and slows with friction, so the figure locks in, slows and dissolves. Drag the brass crank round its wheel to drive the drum; on release a governor holds that speed until the drum is braked or grabbed. Left and right arrow keys add spin in either direction (spinning the other way runs the figure backwards), and Space or the red Felt brake plate presses a felt pad on the spindle while held. The dial in the table apron shows turns a minute, with the band in which the figure lives marked in vermilion, and a line of text names the state. Paper tags swap between six strips; the unrolled band on the table shows all twelve drawings and underlines the one behind the nearest slit. Lift the lid raises the slotted ring so that only smear remains. Sound switches the whirr and tick on or off. Draw your own strip opens a drawer of twelve frames to scribble in with black or vermilion ink, each showing a ghost of the frame before; Drop it into the drum loads the strip and sets it turning. With reduced motion the drum never spins by itself, blur and flicker of the lamp are off, and a Step the frames plate lifts the lid and advances one frame at a time.