if (argument0 == 0)
{
    if (instance_exists(obj_mainchara))
    {
        xdist = (obj_mainchara.x + (obj_mainchara.sprite_width / 2)) - (x + (sprite_width / 2));
        ydist = obj_mainchara.bbox_top - bbox_top;
        if (abs(xdist) >= abs(ydist))
        {
            if (xdist >= 0)
                sprite_index = rtsprite;
            else
                sprite_index = ltsprite;
        }
        else if (ydist >= 0)
        {
            sprite_index = dtsprite;
        }
        else
        {
            sprite_index = utsprite;
        }
    }
}
if (argument0 == 1)
{
    if (instance_exists(obj_mainchara))
    {
        xdist = (obj_mainchara.x + (obj_mainchara.sprite_width / 2)) - (x + (sprite_width / 2));
        ydist = obj_mainchara.bbox_top - bbox_top;
        if (abs(xdist) >= abs(ydist))
        {
            if (xdist >= 0)
                sprite_index = rsprite;
            else
                sprite_index = lsprite;
        }
        else if (ydist >= 0)
        {
            sprite_index = dsprite;
        }
        else
        {
            sprite_index = usprite;
        }
    }
}