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import { pairs } from '../util.js';
function mod(k, n) {
return ((k % n) + n) % n;
}
function pos_wrap(lattice, x, y) {
const height = lattice.length;
const width = lattice[0].length;
return [mod(x, width), mod(y, height)];
}
function neighbors(lattice, x, y) {
const offsets = [-1, 0, 1];
const positions = pairs(offsets, offsets)
.filter(([dx, dy]) => dx !== 0 || dy !== 0)
.map(([dx, dy]) => pos_wrap(lattice, x+dx, y+dy));
const neighbors = positions
.map(([x, y]) => [x, y, lattice[y][x]]);
return neighbors;
}
export const lattice_rules = {
empty: (lattice, x, y) => {
const num_active_neighbors = neighbors(lattice, x, y)
.map(([x, y, cell]) => cell.type)
.filter(type => type === 'mutable' || type === 'active')
.length;
if (num_active_neighbors === 3) {
return { world_updates: [{ x, y, from: 'empty', to: 'active' }] };
}
},
active: (lattice, x, y) => {
const num_active_neighbors = neighbors(lattice, x, y)
.map(([x, y, cell]) => cell.type)
.filter(type => type === 'mutable' || type === 'active')
.length;
if (num_active_neighbors < 2) {
return { world_updates: [{ x, y, from: 'active', to: 'empty' }] };
} else if (num_active_neighbors > 3) {
return { world_updates: [{ x, y, from: 'active', to: 'empty' }] };
}
},
mutable: () => {},
immutable: () => {},
flag: () => {},
};
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