gol_private_coderetreat_gpu.js

import { GPU } from 'gpu.js';
import expect from 'expect.js';

const gpu = new GPU();

const gameOfLifeFor = (n,m) => {
    const evolve = gpu.createKernel(function(board, n, m) {
        function countOfNeighbours(board, x, y, n, m) {
            let count = 0;
            for(let dy = -1; dy <= 1; dy ++) {
                for (let dx = -1; dx <= 1; dx++) {
                    if(x + dx >= 0 && x + dx < n && y + dy >= 0 && y + dy < m ) {
                        count += board[y + dy][x + dx];
                    }
                }
            }
            return count - board[y][x];
        }

        const x = this.thread.x;
        const y = this.thread.y;

        let count = countOfNeighbours(board, x, y, n, m);
        return ((count === 2 && board[y][x] === 1) || count === 3) ? 1 : 0;
    }).setOutput([n,m])

    return board => {
        return evolve(board, n, m).map(l => Array.from(l));
    };
}

const ALIVE = 1;
const DEAD = 0;

const _ = DEAD;
const X = ALIVE;

describe("Game of life", () => {
    describe("3x3 world", () => {
        const evolve = gameOfLifeFor(3,3);
        specify("that empty board evolves to empty", () => {
            const board = [
                [_, _, _],
                [_, _, _],
                [_, _, _],
            ]
            let result = evolve(board);
            expect(result).to.eql([
                [_, _, _],
                [_, _, _],
                [_, _, _],
            ]);
        });

        specify("that a board with 2 by 2 block is stable", () => {
            const board = [
                [_, X, X],
                [_, X, X],
                [_, _, _],
            ]
            let result = evolve(board);
            expect(result[1][1]).to.be(ALIVE);
        });

        specify("that single cell world evolves to empty board", () => {
            const board = [
                [_, _, _],
                [_, X, _],
                [_, _, _],
            ]
            let result = evolve(board);
            expect(result[1][1]).to.be(DEAD);
        });

        specify("that middle cell from a diagonal stays alive", () => {
            const board = [
                [X, _, _],
                [_, X, _],
                [_, _, X],
            ]
            let result = evolve(board);
            expect(result[1][1]).to.be(ALIVE);
        });

        specify("that cell with 3 neighbours spawns", () => {
            const board = [
                [_, X, _],
                [X, _, _],
                [_, _, X],
            ]
            let result = evolve(board);
            expect(result[1][1]).to.be(ALIVE);
        });

        specify("that cell with two neighbours does not spawn", () => {
            const board = [
                [X, _, _],
                [_, _, _],
                [_, _, X],
            ]
            let result = evolve(board);
            expect(result[1][1]).to.be(DEAD);
        });

        specify("that cell with four neighbours dies", () => {
            const board = [
                [X, _, X],
                [_, X, _],
                [X, _, X],
            ]
            let result = evolve(board);
            expect(result[1][1]).to.be(DEAD);
        });

        specify("that cell with four neighbours dies", () => {
            const board = [
                [X, X, _],
                [X, X, _],
                [X, X, _],
            ]
            let result = evolve(board);
            expect(result[1][2]).to.be(ALIVE);
        });

    });
    specify("that glide works in large world", () => {
        const evolve = gameOfLifeFor(7,5);
        const board = [
            [_,_,_,_,_,_,_],
            [_,_,X,_,_,_,_],
            [_,_,_,X,X,_,_],
            [_,_,X,X,_,_,_],
            [_,_,_,_,_,_,_],
        ];
        let result = evolve(board);
        let expectedResult = [
            [_,_,_,_,_,_,_],
            [_,_,_,X,_,_,_],
            [_,_,_,_,X,_,_],
            [_,_,X,X,X,_,_],
            [_,_,_,_,_,_,_],
        ];
        expect(result).to.eql(expectedResult);
    });
});