Suppose I have a cutout character made of a hierarchy of multiple sprites.
Now I want to turn it into a "ghost" for a while, by modulating its transparency.
The problem is, when I set the transparency of the top-level sprite (the parent of the entire hierarchy), it pretty much works by setting the transparency on all of its subnodes, which looks terrible, because the parts that weren't supposed to be visible (because they were previously obscured by other parts, like clothes, body etc.), now can be seen through other parts :P Here's a simple mockup example that demonstrates this problem:
What I rather expected is this:
(not made in Godot; I made it in a graphics editing software)
that is, I want the entire image of the sprite to become semi-transparent, not its particular consistuent parts.
If it makes any difference, there may be more than one such a "ghost" on screen, each with different transparency (since some of them will gradually disappear and appear again).
How can this be achieved in Godot?
I tried to save the hierarchy as a scene, then instantiate it and change its opacity instead, but the effect is the same.