c – 抗锯齿像素渲染

我正在尝试实现抗锯齿像素渲染.我的基本想法是渲染4个像素而不是1个像素,并根据其与“虚拟”像素的距离为每个“真实”像素赋予权重：

void put_aa_pixel(double x,double y)
{
    int x0 = int(X);
    int x1 = x0 + 1;
    int y0 = int(y);
    int y1 = y0 + 1;

    double weight_x1 = x - x0;
    double weight_x0 = 1 - weight_x1;
    double weight_y1 = y - y0;
    double weight_y0 = 1 - weight_x1;

    put_pixel(x0,y0,int((weight_x0 * weight_y0) * 255));
    put_pixel(x1,int((weight_x1 * weight_y0) * 255));
    put_pixel(x0,y1,int((weight_x0 * weight_y1) * 255));
    put_pixel(x1,int((weight_x1 * weight_y1) * 255));
}

乘以x和y权重给出了每个真实像素内的虚拟像素的重叠区域.我天真地认为这会给我一个完美的抗锯齿效果,但我测试程序中的移动像素只显示一个令人难以置信的闪烁.它看起来比没有任何抗锯齿的简单像素更糟糕.

但是,当我从乘法切换到加法时,它看起来好多了：

put_pixel(x0,int((weight_x0 + weight_y0) * 127.5));
    put_pixel(x1,int((weight_x1 + weight_y0) * 127.5));
    put_pixel(x0,int((weight_x0 + weight_y1) * 127.5));
    put_pixel(x1,int((weight_x1 + weight_y1) * 127.5));

添加权重似乎没有任何几何意义.那为什么这会更好呢？第一个版本出了什么问题？还有更好的方法吗？