# GOL-024: Symmetry Lines

Opposite living pairs sustain cells, while two living samples along a ray extend life. Compose symmetry and direction, with an optional additive Game of Life layer.

[Open simulation](https://100gol.com/experiments/024) · [Directory](https://100gol.com/experiments)

## What to explore

Expose the consequences of those literal local rules, without adjusting them to
force the predicted alternating grid. Make each source of life inspectable.

## Rules, update order and replay

Binary square lattice, 80/120/160 square. Toroidal by default; bounded edges read
as dead. Minimum engine dimensions 17 ensure distinct samples at maximum radius 8.
Directions are N, NE, E, SE, S, SW, W, NW. Symmetry tests four opposite axes at
one equal distance from the focal cell. Rays test two distinct distances in the
same direction; intermediate positions are ignored when distances are separated.
A match requires both samples alive. Extra neighbors never veto a match.
Each family counts matching enabled axes/directions and requires at least its
configured minimum. Birth and survival switches independently select whether
that family's match applies to a currently dead or living cell.

The geometry master switch gates both families. The Life switch independently
gates ordinary immediate eight-neighbor B/S masks. The next state is the OR of
all applicable enabled clauses. No veto, priority, movement or evolution RNG.
All sites read one frozen board and commit simultaneously; one Step is one generation.
Evidence records previous occupancy, matching-axis/direction masks, Moore count,
and all contributing sources. Evidence does not affect evolution. Replay includes
all arrays, generation, evidence-valid flag, dimensions, topology and configuration.
Reset rebuilds the selected composition with the same seed and clears generation
and evidence. Clear creates an empty field at Step zero. Painting, topology edits
and rule edits pause and preserve generation, clearing stale evidence. Rule edits
preserve occupancy. A disabled layer retains its settings.

## Reading the simulation

Canvas 2D: lime opening, cyan symmetry, violet rays, amber Life, cream multiple
sources. Dead results remain dark. Color off shows binary life. Inspection pauses
painting, marks symmetry samples cyan and ray samples dashed violet; Life inputs
are outlined amber when enabled. Gold marks the center. Written current matching
axes/directions, eligible pathways, ordinary count, next result and prior source
remain accessible without color. Arrow keys select, Enter paints outside inspection,
P toggles playback, S steps. Shared mobile randomize-and-play shortcut.

## Reproduce a starting configuration

[Download example JSON](https://100gol.com/api/experiments/024/configuration). Import it using Share & reproduce in the simulation controls. It starts paused at Step zero. Files contain rules and initial conditions, not evolved boards or manual edits. See [format, limitations and automated access](https://100gol.com/agents).