Can't seem to interpolate alpha

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Owl

Hey all! I'm trying to interpolate the 'modulate' property (specifically the alpha) of the tween's parent node (of type Sprite), but it seems to never do anything?

My first attempt was to write it like so:

tween = Tween.new()
add_child(tween)
tween.interpolate_property(self, "modulate", Color(1, 1, 1, 0), Color(1, 1, 1, 1), 1.0, Tween.TRANS_LINEAR, Tween.EASE_OUT_IN)
tween.start()

That didn't do anything. Then I figured, maybe 'self' is the wrong keyword to use, so I swapped it with a variable that refers to the parent's node (the Sprite one). No go.

I've tried addressing the "modulate:a" directly (writing it as both "modulate:a" and "modulate.a" instead of "modulate" while changing Color(1, 1, 1, 0) and Color(1, 1, 1, 1) to 0 and 1 respectively - still no go).

I'm running Godot 3.4.4.

What am I doing wrong? ^_^

Thanks!

cybereality

The tween code looks correct. What node is the script attached to (is it the self you want to change the alpha of)? Also where or when are you calling that code?

Owl

cybereality Hey! I'm not sure if the 'self' in the interpolation line refers to the tween itself or to the node running the script (so basically its parent node, the Sprite whose alpha I want to modify) - but either way, I've tried both 'self' and a variable that refers to the Sprite, but the alpha doesn't seem to change.

The script (called flash.gd) is not attached to any node by default. It starts with "extends Sprite". Then somewhere in another script, I have:

var _flash = load("res://flash.gd")
var _flash_instance = _flash.new() 
_flash_instance.flash(Color.white, 1, 0) # flash() is the function that creates the tween and starts it
add_child(_flash_instance)

I can see in 'Remote' that both '_flash_instance' and its Tween child are in the tree.

I can also confirm that the z_index is correct, if I manipulate the alpha directly (outside the tween), I can see the effect.

cybereality

I believe you have to add the node (flash instance) before you add the tween.

Owl

cybereality That worked! Though not sure why?? Still many thanks!!

cybereality

Godot operators on Nodes, but only those that are in the tree. They become in the tree when you do add_child on a node already in the tree. Otherwise they basically don't exist. Pure code can work in terms of functions (like if you have a function that does simple math) but not that affects the graphics.