function scr_plat_set_difference()
{
    switch (dif_type)
    {
        case 0:
        case 1:
            dif_x = sign(x - xprevious) * max(abs(hspeed), abs(x - xprevious));
            dif_y = sign(y - yprevious) * max(abs(vspeed), abs(y - yprevious));
            break;
    }
}