RosettaCodeData/Task/Bitmap-Bresenhams-line-algorithm/C++/bitmap-bresenhams-line-algorithm.cpp

void Line( float x1, float y1, float x2, float y2, const Color& color )
{
        // Bresenham's line algorithm
  const bool steep = (fabs(y2 - y1) > fabs(x2 - x1));
  if(steep)
  {
    std::swap(x1, y1);
    std::swap(x2, y2);
  }

  if(x1 > x2)
  {
    std::swap(x1, x2);
    std::swap(y1, y2);
  }

  const float dx = x2 - x1;
  const float dy = fabs(y2 - y1);

  float error = dx / 2.0f;
  const int ystep = (y1 < y2) ? 1 : -1;
  int y = (int)y1;

  const int maxX = (int)x2;

  for(int x=(int)x1; x<=maxX; x++)
  {
    if(steep)
    {
        SetPixel(y,x, color);
    }
    else
    {
        SetPixel(x,y, color);
    }

    error -= dy;
    if(error < 0)
    {
        y += ystep;
        error += dx;
    }
  }
}