Whether you’re making a platformer or a top-down game, you want your instances to flip, depending on where they’re facing on the X-axis: that is, either left or right.
That can simply be done by modifying the X-scale of a sprite/instance.
1 is the default scale. So, using
-1 as the X-scale would flip the sprite in the other direction.
In an instance, it can be done with the
if (hsp != 0) image_xscale = sign(hsp)
If the hsp (horizontal speed) is not zero, it sets the image_xscale to its sign (either 1 or -1).
The same effect can be applied on a sprite being drawn with
draw_sprite_ext or any form of it.
draw_sprite_ext(sArrow, 0, x, y, -1, 1 ... ) // Flip the arrow horizontally