Scanline Displacer

A generator that draws raster lines displaced by a depth picture and coloured by a source picture, in motion — the look of a scanned image lifted into relief.

The lines are a queue. They enter at an edge set by Direction (Down, Up, Left, Right, Center Out, or any Angle), settle into a Spacing, and travel at Speed — either as a steady stream, or one line every Drop Every seconds with the whole stack shifting a slot. Lines is how many are alive and Samples how many points each one is made of.

Every sample is a spring. Where the Depth picture is bright, the line lifts by Amplitude; Follow and Drag are that spring's stiffness and damping, so a rigid raster (Follow 1) and a line that flows into the relief and settles are one dial apart. Near, Far, Invert and Gamma map the picture's values into that range first — a depth map is relative, not metric, and these are what make it stable.

Hidden Lines is what turns a stack of curves into a surface: a front line hides what is behind it under its bumps, done with the real depth buffer, so it works over a live background. Ground paints under the lines when you want the classic black instead.

The two pictures keep their own proportions. A sample reads the Image and the Depth at its own place in the view, against each picture's own area — so lines fall across the whole scene and bend and colour only where the picture actually is; outside it they are flat and Tint-coloured.

Every sample is a spring on the GPU, the queue of lines is a small CPU model, and the whole picture is one instanced draw.

Mode (int, default Lines) — Lines draws each line as one continuous mitred stroke, Points draws its samples as dots, Rectangles draws a rectangle per sample lying along the line, Rect Width × Rect Height with Rect Random giving every sample its own size from the seed.

Motion (int, default Stream) — Stream is the steady raster of slots. Fall makes every line a drop: it appears at the edge and accelerates under Gravity up to Fall Speed through empty space, then brakes hard (Brake, in seconds) to Speed where the picture is, creeps through it, and falls away again on the other side — a magnet dropped through a copper tube. Medium says what counts as "the picture": the Image's alpha, or the Depth's height. Fast drops are sparse and slow ones bunch, so the spacing of the raster becomes the picture's own. Space Stretch makes the empty space virtually longer so the acceleration and the brake are visible.

Colour. Color From takes the pixel under the lifted line or the one the sample came from. Tint multiplies. Space Color decides what colours an element outside the picture or over its transparent pixels: the Tint, a Gradient node along the travel, or Trace — the colour the sample last touched in the picture, carried out with it, per sample and per direction, and before the first touch the colour of the edge it is heading for.

Look. Beam dims a line where it moves fast, the way a tube's beam does; Glow adds the halo; Persistence keeps a fading picture of the last frames — the phosphor — in a private accumulation that still hides lines behind lines. Jitter and Jitter Rate twitch; Thickness / Length and their Random partners with a Seed make it organic and repeatable. Symmetry mirrors the picture the lines read.

Flow takes a Flow Map node's Image: its field drifts every sample along its line and pushes into the relief, scaled by Flow Strength, so the raster breathes with the flow. Max Slope breaks a segment steeper than the value, so where the depth jumps the vertical curtain disappears and the silhouette reads clean; 0 keeps the classic walls.

Cable a Camera node into Camera and the raster becomes a real relief seen through that camera: the lines lie on the picture plane, the displacement stands off it along z, the depth buffer hides what is behind, and an orbit looks around the surface. Through a camera the lines always take the colour of their own place on the picture rather than of the pixel that happens to be under them on screen, so the relief does not read the picture like a lens as the camera moves. Line thickness becomes a world size: it shrinks with distance, and each line stays one continuous mitred stroke rather than a chain of overlapping segments, so the relief never breaks into scales.

Backdrop draws the Image itself as the picture plane under the lines, at that opacity — with a Camera the picture turns with the relief and the two stay one object; flat, it is simply the picture under the lines.

Set Tube above zero and the lines also leave through the Geometry output: every live line swept into a tube of that radius, as one mesh. A 3D Scene's Mesh then gives them a material, a Light and real shadows — and because the tubes' UVs are the picture's, a Material whose Texture is the same Image paints them with it.

Front Line and Lines hand the raster to the rest of the graph as point clouds — z is the displacement, with a pen-lift between lines — for a Sonify, a Plexus or a Scope Voice.

• Scanline portrait: Video Player → Depth Estimation → Scanline Displacer (Depth) → Canvas, with the video's Image also cabled into the node's Image for colour. This is the built-in recipe of the same name.
• Turn the relief: add a Camera node into Camera and give it an orbit — a relief is invisible from straight ahead, so the orbit (or a side light) is what makes it read.
• Real shadows: Tube above zero → Geometry → 3D Scene Mesh, with a Material whose Texture is the same Image and a Light off to one side.
• Falling raster: Motion Fall, Medium Image Alpha, Space Color Trace — lines drop through empty space, slow through the figure and carry its colour out with them.
• Hear the picture: Front Line → Sonify, or Lines → Scope Voice for oscilloscope music drawn by the image itself.
• Breathing raster: Flow Map → Flow, Flow Strength around 0.5, over a still image.