Bresenham's Line Algorithm

Bresenham developed an algorithm for drawing straight lines on a raster device. This algorithm uses integer arithmetic only and is faster and more accurate than the more obvious algorithms that use floating-point arithmetic. Most raster devices contain embedded variants of Bresenham's algorithm.

To connect P₁ = (x₁,y₁) with P₂ = (x₂,y₂) on a raster device:

The Algorithm:

    var dy = y2-y1
    var dx = x2-x1
    var d = 2*dy - dx
    var x = x1
    var y = y1
    while (x <= x2)
    {
      Draw pixel at (x,y)
      x++
      if( d<0 )
        d += dy + dy
      else
      {
        d += 2*(dy-dx)
        y++
      }
    }