Animating a gui node in helper function doesn't work

Questions
#1

I have some code I want to re-use between menus, which involves a simple animation. However, when I call this function from the lua module, the animation fails to work. I am passing self and dt to the helper function to set the timing animation. If I run the same code during initialization within the gui menu code itself, the animation plays fine. The node play_flipbook and text setting functions work fine in the helper code, but the animation seems to not work. If I set the animation timing using non-dt multiplied values then I can see some animation, but the positioning doesn’t work (the objects move much further than specified.)

#2

You need to elaborate on “the animation fails to work”. Does nothing happen? Do you get an error?

I’d also post the code you are using.

1 Like
#3

Here’s the code:

function M.refresh_items(self, dt, item_container, item, itemtext)
	self.offset = 1
	for i = 1, #item_container do
		if item_container[i] > 0 then
			local graphic_name = get_graphic_for_item(i)
			local node = gui.get_node(item .. self.offset)
			local pos = gui.get_position(node)
			gui.animate(node, "position.y", pos.y + 8, gui.EASING_INEXPO, dt * 64, (self.offset + 1) % 2 * 16 * dt, nil, gui.PLAYBACK_LOOP_PINGPONG)
			local textnode = gui.get_node(itemtext .. self.offset)
			gui.play_flipbook(node, graphic_name)
			gui.set_text(textnode, "x " .. item_container[i])
			self.offset = self.offset + 1
		end
		if self.offset > 20 then break end
	end
	for i = self.offset, 20 do
		local node = gui.get_node(item .. i)
		local textnode = gui.get_node(itemtext .. i)
		gui.play_flipbook(node, "item_placeholder")
		gui.set_text(textnode, "")
	end
end

Everything works when I use this helper function except the line:

gui.animate(node, "position.y", pos.y + 8, gui.EASING_INEXPO, dt * 64, (self.offset + 1) % 2 * 16 * dt, nil, gui.PLAYBACK_LOOP_PINGPONG)

However the items don’t animate at all from the helper function. If I use the same code from the game object (but I explicitly state the item_container and other arguments after) in the init section then the items bounce up and down. I made a function since I have multiple screens where I want to display the items so I didn’t want to copy+paste and slightly modify this section of code.

#4

Are you calling M.refresh_items() every frame? If so, it will initiate a new animation each frame. This will have the effect of overwriting the previous animation that you initiated. I think you’ll get one frame of animation out of it - but depending on the easing function you’ve picked it might be miniscule.

#5

No, only once when initializing the menu. Thanks though I have run into that before, but it’s not the case this time :smiley:

#6

I think I’m stumped then, unfortunately.

I thought perhaps you weren’t calling the module function from a gui script, but because the other gui functions work then you must be.

Do you get a sensible value for dt? You say you call it when initialising the menu but you must be calling it in update rather than init, so that you actually have a dt?

#7

I’m actually a bit confused by your use of dt in determing the times here. If you’re using a fixed dt then there aren’t any issues other than it being a bit weird (you could just specify an actual length in seconds rather than multiplying by your fixed dt). If you’re allowing a variable dt, then the duration and delay of your animation could potentially be lengthened significantly if for whatever reason the frame you begun the animation took a long time (which I suppose is most likely to happen in your circumstance - i.e. loading a lot of things at initialisation).