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我用抗锯齿实现了 dda，它不适用于八分圆线。我不知道为什么要计算两个方向的误差我该如何使用它们？如果有可以帮助的教程或幻灯片的链接，我真的很感激。在这个实现中，我首先计算直线的斜率，然后计算误差，并通过最大误差绘制主要点，对于舍入的 x 或 y，我绘制带有误差的点。

void Application::dda_aa(Point2D start, Point2D end, Raster& raster, Color color) 
{
int slope;
int xs,ys,xe,ye;
float m,step,dx,dy,xn,yn,e,ex,ey;
//____________Initial______________
xs=start.get_x();
ys=start.get_y();

xe=end.get_x();
ye=end.get_y();

if(xs <= xe)
{
    if(ys <= ye)
    {
        slope=1;
    }
    else
    {
        slope = 4;
    }
}
else
{
    if(ys <= ye)
    {
        slope=2;
    }
    else
    {
        slope = 3;
    }
}
//____________Compute m ______________
dx = abs(xe - xs);
dy = abs(ye - ys);
m  = dy / dx;



if(dx >= dy)
    step=dx;
else
    step=dy;

dx=dx/step;
dy=dy/step;
xn=xs;
yn=ys;
int i=1;

//____________drawing ________________
while (i <= step)
{
        ey=yn-round(yn);
        ex= xn-round(xn);
        e = glm::max(ey,ex);
        raster.set_pixel_color_grayscale(xn,yn,e);
        raster.set_pixel_color_grayscale(xn,round(yn),1-(ey));
        raster.set_pixel_color_grayscale(round(xn),yn,1-(ex));
        switch (slope)
        {
            case 1:
                xn=xn+dx;
                yn=yn+dy;
            break;
            case 2:
                xn=xn-dx;
                yn=yn+dy;
            break;
            case 3:
                xn=xn-dx;
                yn=yn-dy;
            break;
            case 4:
                xn=xn+dx;
                yn=yn-dy;
            break;

        }
    }
    i++;
}
raster.set_pixel_color(xs,ys,color); 
raster.set_pixel_color(xe,ye,color); 
}
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