spatial.js

class Grid {
  
  constructor(w,h,cellSize) {
    this.grid = [];
    this.cellSize = cellSize;
    //
    this.createGrid(w,h);
  }
  
  createGrid(w,h) {
    for (let row = 0; row < w/this.cellSize; row++) {
      this.grid.push([]);
      for (let col = 0; col < h/this.cellSize; col++) {
        this.grid[row].push(null);
      }
    }
  }
  
  getCell(n) {
    return Math.ceil(n/this.cellSize);
  }
  
  handleSomething(unit) {
    
  }
  
  add(unit) {
    let pos = {
      x: this.getCell(unit.pos.x),
      y: this.getCell(unit.pos.y)
    };
    
    if (!this.grid[pos.x][pos.y]) {
      return this.grid[pos.x][pos.y] = unit;
    }
    
    let current = this.grid[pos.x][pos.y];
    while (current.next) {
      current = current.next;
    }
    current.next = unit;
    unit.prev = current;
  }
}

class Unit {
  
  constructor(grid,x,y) {
    this.grid = grid;
    this.pos = {x,y};
    this.grid.add(this);
  }
  
  update() {}
  
  draw() {}

}