图形学-直线算法

void lineDDA(int x0, int y0, int xEnd, int yEnd)
{
    float dx = xEnd - x0, dy = yEnd - y0, steps, k;
    float xInerement, yInerement, x = x0, y = y0;

    if (fabs(dx) > fabs(dy))
    {
        steps = fabs(dx);
    }
    else
    {
        steps = fabs(dy);
    }

    xInerement = float(dx) / float(steps);
    yInerement = float(dy) / float(steps);

    setPixel(round(x), round(y));

    for (k = 0; k < steps; k++)
    {
        x += xInerement;
        y += yInerement;
        setPixel(round(x), round(y));
    }
}

void lineBres(int x0, int y0, int xEnd, int yEnd)
{
    int dx = abs(xEnd - x0), dy = abs(yEnd - y0);
    int p = 2 * dy - dx;
    int twoDy = 2 * dy, twoDyMinusDx = 2 * (dy - dx);
    int x, y;

    if (x0 > xEnd)
    {
        x = xEnd; 
        y = yEnd;
        xEnd = x0;
    }
    else
    {
        x = x0;
        y = y0;
    }

    setPixel(x, y);
    
    while (x < xEnd)
    {
        x++;
        if (p < 0)
            p += twoDy;
        else
        {
            y++;
            p += twoDyMinusDx;
        }

        setPixel(x, y);
    }
}