wasm_game_of_life/www/index.js

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JavaScript
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// Import the WebAssembly memory at the top of the file.
import { memory } from "wasm-game-of-life/wasm_game_of_life_bg";
import { Universe, Cell } from "wasm-game-of-life";
let req_id;
let stop = false;
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const CELL_SIZE = 40; // px
const GRID_COLOR = "#CCCCCC";
const DEAD_COLOR = "#FFFFFF";
const ALIVE_COLOR = "#3399FF";
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const universe = Universe.new(10,10);
const width = universe.width();
const height = universe.height();
const canvas = document.getElementById("game-of-life-canvas");
canvas.height = (CELL_SIZE + 1) * height + 1;
canvas.width = (CELL_SIZE + 1) * width + 1;
const ctx = canvas.getContext('2d');
// The JavaScript runs in a requestAnimationFrame loop.
const renderLoop = async () => {
await new Promise(r => setTimeout(r, 200));
universe.tick();
drawCells();
if (stop == false)
req_id = requestAnimationFrame(renderLoop);
};
// Return Cell position
function getCursorPos(canvas, evt) {
const rect = canvas.getBoundingClientRect();
// Bound check: It seems that the last case can overlap
let x = Math.trunc((evt.clientX - rect.left) / CELL_SIZE);
if (x >= (width))
x = x - 1;
let y = Math.trunc((evt.clientY - rect.top) / CELL_SIZE);
if (y >= (height))
y = y - 1;
return { x,
y,
};
}
canvas.addEventListener('mouseover',
function(evt) {
console.log("Stopping Animation Frame");
stop = true;
});
canvas.addEventListener('mouseout',
function(evt) {
console.log("Starting Animation Frame");
stop = false;
start();
});
// Get Mouse position
canvas.addEventListener('click',
function(evt) {
var mousePos = getCursorPos(canvas, evt);
let cellsPtr = universe.cells();
let cells = new Uint8Array(memory.buffer, cellsPtr, width * height);
console.log("Click position : X = " + (mousePos.x) + ", Y = " + (mousePos.y));
const idx = universe.get_index(mousePos.y, mousePos.x);
if (cells[idx] === Cell.Dead)
console.log("Cell[" + idx + "] is : " + "Dead !");
else
console.log("Cell[" + idx + "] is : " + "Alive !");
// Change to inverse !
cells[idx] = (cells[idx] === Cell.Dead) ? Cell.Alive : Cell.Dead;
drawCells();
});
const drawGrid = () => {
ctx.beginPath();
ctx.strokeStyle = GRID_COLOR;
// Vertical lines.
for (let i = 0; i <= width; i++) {
ctx.moveTo(i * (CELL_SIZE + 1) + 1, 0);
ctx.lineTo(i * (CELL_SIZE + 1) + 1, (CELL_SIZE + 1) * height + 1);
}
// Horizontal lines.
for (let j = 0; j <= height; j++) {
ctx.moveTo(0, j * (CELL_SIZE + 1) + 1);
ctx.lineTo((CELL_SIZE + 1) * width + 1, j * (CELL_SIZE + 1) + 1);
}
ctx.stroke();
};
// We can directly access WebAssembly's linear memory via memory, which is defined in the raw wasm module wasm_game_of_life_bg.
// To draw the cells, we get a pointer to the universe's cells, construct a Uint8Array overlaying the cells buffer, iterate over each cell, and draw a white or black rectangle depending on whether the cell is dead or alive, respectively.
// By working with pointers and overlays, we avoid copying the cells across the boundary on every tick.
const drawCells = () => {
// Modify Plus const
const cellsPtr = universe.cells();
const cells = new Uint8Array(memory.buffer, cellsPtr, width * height);
ctx.beginPath();
for (let row = 0; row < height; row++) {
for (let col = 0; col < width; col++) {
const idx = universe.get_index(row, col);
ctx.fillStyle = (cells[idx] === Cell.Dead) ? DEAD_COLOR : ALIVE_COLOR;
ctx.fillRect(
col * (CELL_SIZE + 1) + 1, // x
row * (CELL_SIZE + 1) + 1, // y
CELL_SIZE, // Width
CELL_SIZE // Height
);
}
}
ctx.stroke();
};
function start() {
drawGrid();
drawCells();
req_id = requestAnimationFrame(renderLoop);
}
start();