bresenhams.js

/**
 * Bresenhams line algorithm for integers.
 * @see https://en.wikipedia.org/wiki/Bresenham%27s_line_algorithm#Algorithm_for_integer_arithmetic
 */
function plotLine(x0, y0, x1, y1) {
  /** Step direction on the x-axis */
  let sx = x0 < x1 ? 1 : -1
  /** Step direction on the y-axis */
  let sy = y0 < y1 ? 1 : -1

  let dx = Math.abs(x1 - x0)
  let dy = -Math.abs(y1 - y0)
  /** error value e_xy, which is balanced between x and y coords */
  let err = dx + dy
  
  while (true) {
    // Each coordinate
    console.log(x0, y0)
    if (x0 == x1 && y0 == y1) break
    let e2 = 2 * err
    if (e2 >= dy) {
      /* e_xy+e_x > 0 */
      err += dy
      x0 += sx
    }
    if (e2 <= dx) {
      /* e_xy+e_y < 0 */
      err += dx
      y0 += sy
    }
  }
}