Bresenham Line 2D

Bresenham.cs

        public static void DoLine(int startX, int startY, int endX, int endY, Action<int, int> callback)
        {
            int dx, dy;
            int sx, sy;
            int accum;//accumilator

            dx = endX - startX;//Start X subtracted from End X
            dy = endY - startY;

            sx = ((dx) < 0 ? -1 : ((dx) > 0 ? 1 : 0));//if dx is less than 0, sx = -1; otherwise if dx is greater than 0, sx = 1; otherwise sx = 0
            sy = ((dy) < 0 ? -1 : ((dy) > 0 ? 1 : 0));

            //dx = (dx < 0 ? -dx : dx);//if dx is less than 0, dx = -dx (becomes positive), otherwise nothing changes
            dx = Math.Abs(dx);//Absolute value
            //dy = (dy < 0 ? -dy : dy);
            dy = Math.Abs(dy);

            endX += sx;//Add sx to End X
            endY += sy;

            //x = 6
            //y = 5

            //accum = 3
            //accum - 5 = 1
            //startx + 1 = 1
            //accum - 5 = -4
            //accum + 6 = 2
            //startY + 1 = 1

            if (dx > dy)//if dx is greater than dy
            {
                accum = dx >> 1;//Accumilator = dx / 2
                do
                {
                    //Plot point
                    callback(startX, startY);

                    //Subtract dy from accumilator
                    accum -= dy;
                    //if accumilator is less than 0
                    if (accum < 0)
                    {
                        //Add dx to accumilator
                        accum += dx;
                        //Add sy to Start Y
                        startY += sy;
                    }
                    //Add sx to Start X
                    startX += sx;
                } while (startX != endX);
            }
            else
            {
                accum = dy >> 1;
                do
                {
                    callback(startX, startY);
                    accum -= dx;
                    if (accum < 0)
                    {
                        accum += dy;
                        startX += sx;
                    }
                    startY += sy;
                } while (startY != endY);
            }
        }