portfolio/assets/js/pathfinder.js

const timer = ms => new Promise(res => setTimeout(res, ms))

var cols = 8
var rows = 8

let grid = new Array(cols); 

let openSet = []; 
let closedSet = []; 

let start; 
let end; 
let path = [];

function heuristic(position0, position1) {
	let d1 = Math.abs(position1.x - position0.x);
	let d2 = Math.abs(position1.y - position0.y);

	return d1 + d2;
}


function GridPoint(x, y) {
	this.x = x; 
	this.y = y; 
	this.f = 0; 
	this.g = 0; 
	this.h = 0; 
	this.neighbors = []; 
	this.parent = undefined; 

	
	this.updateNeighbors = function(grid) {
		let i = this.x;
		let j = this.y;
		var tmpNeighbor;
		if (i < cols - 1) {
			tmpNeighbor = grid[i + 1][j]
			if (!player.isBoundary([tmpNeighbor.x, tmpNeighbor.y])) {
				this.neighbors.push(tmpNeighbor);
			}
		}
		if (i > 0) {
			tmpNeighbor = grid[i - 1][j]
			if (!player.isBoundary([tmpNeighbor.x, tmpNeighbor.y])) {
				this.neighbors.push(tmpNeighbor);
			}
		}
		if (j < rows - 1) {
			tmpNeighbor = grid[i][j + 1]
			if (!player.isBoundary([tmpNeighbor.x, tmpNeighbor.y])) {
				this.neighbors.push(tmpNeighbor);
			}
		}
		if (j > 0) {
			tmpNeighbor = grid[i][j - 1]
			if (!player.isBoundary([tmpNeighbor.x, tmpNeighbor.y])) {
				this.neighbors.push(tmpNeighbor);
			}
		}
	};
}


function init(destX, destY) {
	
	for (let i = 0; i < cols; i++) {
		grid[i] = new Array(rows);
	}

	for (let i = 0; i < cols; i++) {
		for (let j = 0; j < rows; j++) {
			grid[i][j] = new GridPoint(i, j);
		}
	}

	for (let i = 0; i < cols; i++) {
		for (let j = 0; j < rows; j++) {
			grid[i][j].updateNeighbors(grid);
		}
	}

	start = grid[player.canvasX][player.canvasY];
	end = grid[destX][destY]

	openSet.push(start);

	console.log(grid);
}


function search(destX, destY) {
	path = [];
	init(destX, destY);
	while (openSet.length > 0) {
		
		let lowestIndex = 0;
		for (let i = 0; i < openSet.length; i++) {
			if (openSet[i].f < openSet[lowestIndex].f) {
				lowestIndex = i;
			}
		}
		let current = openSet[lowestIndex];

		if (current === end) {
			let temp = current;
			path.push(temp);
			while (temp.parent) {
				path.push(temp.parent);
				temp = temp.parent;
			}

			return path.reverse()
		}

		
		openSet.splice(lowestIndex, 1);
		
		closedSet.push(current);

		let neighbors = current.neighbors;

		for (let i = 0; i < neighbors.length; i++) {
			let neighbor = neighbors[i];

			if (!closedSet.includes(neighbor)) {
				let possibleG = current.g + 1;

				if (!openSet.includes(neighbor)) {
					openSet.push(neighbor);
				} else if (possibleG >= neighbor.g) {
					continue;
				}

				neighbor.g = possibleG;
				neighbor.h = heuristic(neighbor, end);
				neighbor.f = neighbor.g + neighbor.h;
				neighbor.parent = current;
			}
		}
	}

	return [];
}

async function pathfind(destX, destY) {
	var newPath = search(destX, destY)
	for (let i = 0; i < newPath.length; i++) {
		if (newPath[i].x > player.canvasX) {
			player.direction = 'right'
		} else if (newPath[i].x < player.canvasX) {
			player.direction = 'left'
		}

		if (newPath[i].y > player.canvasY) {
			player.direction = 'down'
		} else if (newPath[i].y < player.canvasY) {
			player.direction = 'up'
		}
		player.canvasX = newPath[i].x
		player.canvasY = newPath[i].y
		await timer(100)
	}
}