DrawNaiveLine

void DrawNaiveLine(const Point &p1, const Point &p2, unsigned char r, unsigned char g, unsigned char b)
{
  //test if the line is vertical
  if (Round(p1.x) == Round(p2.x)) DrawVerticalLine(p1, p2, r, g, b);
  //test if the line is horizontal
  else if (Round(p1.y) == Round(p2.y)) DrawHorizontalLine(p1, p2, r, g, b);
  //test if the line is diagonal
  else if (abs(Round(p1.x) - Round(p2.x)) == abs(Round(p1.y) - Round(p2.y)))
    DrawDiagonalLine(p1, p2, r, g, b);
  //otherwise the line is not simple
  else
  {
    if (DEBUG) printf("Drawing non-trivial line from p1(%3.3f, %3.3f) to p2(%3.3f, %3.3f)\n", p1.x, p1.y, p2.x, p2.y);
    //calculate slope
    //(no danger of divison by zero due to vertical line test)
    float m = (p2.y - p1.y) / (p2.x - p1.x);
    //calculate intercept
    float b_ = p1.y - (m*p1.x);

    //step through the y
    if (abs(m) > 1)
    {
      //starting with p1
      if (p1.y < p2.y)
      {
        if (DEBUG) printf("stepping along the y axis starting with p1\n");

        //calculate the distance
        float distance = p2.y - p1.y;

        //draw the line
        for (int i = 0; i < distance + 1; ++i)
        {
          //calculate the x value
          float x = m*(p1.y + i) + b_;

          //draw the pixel
          if (DEBUG) printf("drawing pixel at (%d, %d)\n",
            Round(x), Round(p1.y + i));
          FrameBuffer::SetPixel(Round(x), Round(p1.y + i), r, g, b);
        }
      }
      //starting with p2
      else
      {
        if (DEBUG) printf("stepping along the y axis starting with p2\n");
        //calculate the distance
        float distance = p1.y - p2.y;

        //draw the line
        for (int i = 0; i < distance + 1; ++i)
        {
          //calculate the x value
          float x = m*(p2.y + i) + b_;

          //draw the pixel
          if (DEBUG) printf("drawing pxel at (%d, %d)\n",
            Round(x), Round(p2.y + i));
          FrameBuffer::SetPixel(Round(x), Round(p2.y + i), r, g, b);
        }
      }
    }
    //step through the x
    else if (abs(m) < 1)
    {
      //starting with p1
      if (p1.x < p2.x)
      {
        if (DEBUG) printf("stepping along the x axis starting with p1\n");

        //calculate the distance
        float distance = p2.x - p1.x;

        //draw the line
        for (int i = 0; i < distance + 1; ++i)
        {
          //calculate the y value
          float y = m*(p1.x + i) + b_;

          //draw the pixel
          if (DEBUG) printf("drawing pixel at (%d, %d)\n",
            Round(p1.x+i), Round(y));
          FrameBuffer::SetPixel(Round(p1.x + i), Round(y), r, g, b);
        }
      }
      //starting with p2
      else
      {
        if (DEBUG) printf("stepping along the x axis starting with p2\n");
        //calculate the distance
        float distance = p1.x - p2.x;

        //draw the line
        for (int i = 0; i < distance + 1; ++i)
        {
          //calculate the x value
          float y = m*(p2.x + i) + b_;

          //draw the pixel
          if (DEBUG) printf("drawing pxel at (%d, %d)\n",
            Round(p2.x+i), Round(y));
          FrameBuffer::SetPixel(Round(p2.x + i), Round(y), r, g, b);
        }
      }
    }
  }
}