atlas/web/_js/atlas.js

/*
	========================================================================
	The 2022 /r/place Atlas

	An Atlas of Reddit's 2022 /r/place, with information to each
	artwork	of the canvas provided by the community.

	Copyright (c) 2017 Roland Rytz <roland@draemm.li>
	Copyright (c) 2022 r/placeAtlas2 contributors

	Licensed under the GNU Affero General Public License Version 3
	https://place-atlas.stefanocoding.me/license.txt
	========================================================================
*/

window.addEventListener("error", function (e) {
	console.error(e);
	let errorMessage = "<p class=\"error\">An error has occurred:</p>";
	errorMessage += "<p class=\"errorBody\">" + e.message + "</p>";
	errorMessage += "<p class=\"errorBody\">on line " + e.lineno + "</p>";
	errorMessage += "<p class=\"error\">If this keeps happening, feel free to tell us on <a href=\"https://discord.gg/pJkm23b2nA\">our Discord server</a>.</p>";
	document.getElementById("loadingContent").innerHTML = errorMessage;
});

function getPositionOfEntry(entry) {
	let startX = 2000, startY = 2000;
	for (const [x, y] of entry.path) {
		startX = Math.min(x, startX);
		startY = Math.min(y, startY)
	}
	if (startX === 2000 || startY === 2000) return null;
	return [parseInt(startX), parseInt(startY)];
}

const areaMap = new Map();

// Modified from https://stackoverflow.com/a/33670691 
function calcPolygonArea(vertices) {
	const hit = areaMap.get(vertices);
	if (hit != null) {
		return hit;
	}

	let total = 0;

	for (let i = 0, l = vertices.length; i < l; i++) {
		const addX = vertices[i][0];
		const addY = vertices[i == vertices.length - 1 ? 0 : i + 1][1];
		const subX = vertices[i == vertices.length - 1 ? 0 : i + 1][0];
		const subY = vertices[i][1];

		total += (addX * addY * 0.5);
		total -= (subX * subY * 0.5);
	}

	const area = Math.floor(Math.abs(total));
	areaMap.set(vertices, area);

	return area;
}