Bresenham + 八分法 算法生成圆

  #define PutPixel putpixel
/* 八分法 */
void CirclePoints(int x, int y, int t, int s, color mycolor)
{
    PutPixel(t+x, s+y, mycolor);
   
   
    PutPixel(t-x, s+y, mycolor);
   
    PutPixel(t+x, s-y, mycolor);
    PutPixel(t-x, s-y, mycolor);
   
}

/* 画圆 */
void DrawCircle(int centreX, int centreY, int R, color mycolor)
{
    int x, y, delt, dHD, deltV, next;
    x = 0;
    y = R;
    delt = 2 * (1-R);
    while(y >= 0)
    {
        CirclePoints(x, y, centreX, centreY, mycolor);  
        if(delt < 0)
        {
            dHD = 2 * (delt + y) - 1;
            if(dHD <= 0)
            {
                next = 0;
            }
            else
            {
                next = 1;
            }
        }
        else if(delt > 0)
        {
            deltV = 2 * (delt - x) - 1;
            if(deltV <= 0)
            {
                next = 1;
            }
            else
            {
                next = 2;
            }
        }
        else
        {
            next = 1;
        }
        switch(next)
        {
            case 0: x++;
                    delt += 2 * x + 1;
                    break;
            case 1: x++;
                    y--;
                    delt += 2 * (x - y + 1);
                    break;
            case 2:y--;
                    delt += -2 * y + 1;
                    break;
        }
      } 
}