Inhomogeneous Site Percolation

Two thousand coins, each weighted by where it lies, and an outline drawn around whatever came up.

A coin per cell

Every cell of the lead’s 48 × 48 grid holds one independent coin flip, tested against a threshold that depends on where the cell is:

buffer[i] = rng.NextDouble() > p(x / (float)bufferSize, y / (float)bufferSize) ? 1 : 0;

p is a probability surface — a function of position, not a constant. That is the whole difference between this and a field of noise: the coins are fair, but they are not weighted the same everywhere.

if (Shape == 0)      p = directionalGradient;         // any angle
else if (Shape == 2) p = (x, y) => 1 - 3 * Math.Pow(…, 0.75);   // radial
else if (Shape == 3) p = repeatingWave;               // bands of density
else if (Shape == 4) p = twinVoids;                    // two radial foci
else                 p = saddle;                       // opposing corners

Step 01

The surface applied at a fifth of its strength. Only the cells where the threshold is lowest have come up filled, so this stage is a picture of where the surface is smallest.

The outline is the drawing

Nothing is filled. What is drawn is the boundary of the filled region — for every filled cell, an edge is drawn on each of its four sides where the neighbour is empty or off-grid:

if (y == 0 || buffer[i - bufferSize] != 1)
    DrawLine(…, x, y, x + 1, y, …);

Two adjacent filled cells therefore share no line at all: the edge between them is skipped by both. Which means an isolated cell is a small square, a pair is a rectangle, and a large blob is a single ragged outline — the marching-squares result without the marching, because the grid is axis-aligned and only the four cardinal neighbours matter.

Step 02

Two fifths. Cells switch on as the surface strengthens and never switch off, so the progression is a strict revealing rather than a re-roll: each stage contains the one before it.

Step 03

Three fifths. Filled cells have begun to meet, and where they do the outline stops drawing squares and starts drawing regions.

Five surfaces

Shape selects a probability surface. Direction, aspect ratio, rotation and an optional second field turn those surfaces into five different compositions:

Rendering	Cells	Surface	Composition
Cyan Drift	48×48	directional gradient	a cyan square tilted against the frame
Magenta Halo	35×35	radial void	a coarse, centered ring
Amber Current	64×28	repeating wave	a wide field of alternating density
Ivory Divide	32×58	saddle	a tall field with opposing dense corners
Cobalt Binary	58×34, twice	twin voids	two translucent fields crossing at an angle

The gradient surface is the clearest one to look at, because density varies continuously across the frame and the eye reads it as depth or light — a spatial signal carried entirely by how often a coin comes up. The wave and saddle make that signal periodic and opposing; the twin-void field repeats the radial idea around two foci, then overlays a second seeded draw to produce interference without changing the grid algorithm.

The radial surface, 1 − 3·r^1.5, goes negative away from the centre. A negative threshold is always exceeded, so every cell outside a certain radius is filled unconditionally: the piece becomes a solid field with a decaying speckled hole in the middle rather than a fading disc.

Step 04

Four fifths.

Step 05

The surface at full strength. Grid extent and row/column counts are independent, so resolution, aspect ratio and physical scale can all vary without changing the boundary algorithm. What varies with the preset is how the extent meets the canvas: every preset sets the same 40-pixel margin, and the field is scaled so its rotated outline fits exactly inside it. Nothing lands by accident, and nothing touches the edge of the frame.

On the wall

The gallery’s last plate — Museum Frame — is the same field hung rather than rendered: the lead behind a mat and a dark molding on a wall, a soft shadow lifting the frame off the wall, and a single rule in the field’s own colour tracing the opening. The framing is MuseumFrame, the presentation layer from SkiaSharp.Extensions: it wraps a preset and knows nothing about what it frames beyond “draw into this opening”. One frame, any composition; the piece supplies only its palette, the mat continuing its ground.

Determinism

SeededRandom — the project’s stable Xoshiro256StarStar — is seeded from the preset and consumed exactly once per cell in grid order, before any line is drawn. An echo uses a fixed offset from that seed. Same preset, same fields.

Progression 05

Variant 05

Gallery 01