b = argument0;
c = argument1;
a += 1;
for (i = room_height; i > 0; i -= 1)
{
    a += 1;
    draw_background_part_ext(background_index[0], 0, i, background_width[0], 1, x + (sin(a / b) * c), y + i, 1, 1, c_white, image_alpha);
}