Add a [pulse] built-in effect to RichTextLabel

[Calinou]

In games, blinking text is one of the more frequently used animations. It can be (sparingly) used to bring attention to important messages in a chat log or inventory tooltip, for instance.

This effect accepts the following options:

• freq: How fast text blinks (higher is faster).
• color: The target color multiplier for blinking. The default mostly fades out text, but not entirely (for better accessibility).
• ease: The easing function exponent to use. Negative values provide in-out easing, which is why -2.0 is the default.

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• This closes Add a [pulse] built-in effect to RichTextLabel godot-proposals#6516.

Testing project: test_richtexteffect_pulse.zip
Note: Opening the project will print this error about 100 times, but this occurs when using unmodified master branch too:

ERROR: Condition "p_ptr == nullptr" is true.
   at: free_static (core/os/memory.cpp:148)

Preview

C++-based version (this PR) on the left, script-based version on the right (included in the testing project):

test_richtexteffect_pulse.mp4

[mhilbrunner]

Seems useful! Thoughts:

1. Would it be possible to add a parameter for total number of pulses before it stops? With the default/-1 being infinite, but its pretty common to let an important keyword pulse once (or 2-3 times) only to avoid it being distracting. Only if this won't add a ton of complexity though.
2. At first glance, it feels a bit weird for the bobbing effect to be a pulse effect parameter instead of its own thing, but maybe thats just me.

[Riteo]

@mhilbrunner

At first glance, it feels a bit weird for the bobbing effect to be a pulse effect parameter instead of its own thing, but maybe thats just me.

Yeah I agree with your thoughts and especially this one.

[Calinou]

1. Would it be possible to add a parameter for total number of pulses before it stops? With the default/-1 being infinite, but its pretty common to let an important keyword pulse once (or 2-3 times) only to avoid it being distracting. Only if this won't add a ton of complexity though.

To do this, I need to check if it's possible to set a state variable when the RichTextLabel is last modified.

2. At first glance, it feels a bit weird for the bobbing effect to be a pulse effect parameter instead of its own thing, but maybe thats just me.

I'm not sure if a dedicated tag for bobbing is warranted, but I may as well remove the bobbing functionality entirely as I don't think it'll be used often.

[Calinou]

I've pushed a commit that removes the height option from the [pulse] effect, in case we decide to go with that route.

[mhilbrunner]

To do this, I need to check if it's possible to set a state variable when the RichTextLabel is last modified.

Don't spent too much time on it, can also be followup work. Would be useful though.

I've pushed a commit that removes the height option from the [pulse] effect, in case we decide to go with that route.

Makes sense IMO

[KoBeWi]

Would it be possible to add a parameter for total number of pulses before it stops?

This wouldn't work well with text gradually appearing with visible characters.

[KoBeWi]

The implementation looks ok and it works correctly.

[akien-mga]

CC @Eoin-ONeill-Yokai, you might be interested ;)

[akien-mga]

I think we're close to consensus so I'm putting this on the 4.2 milestone (too late for 4.1 as we entered feature freeze).

[mhilbrunner]

Feature looks good to me, same for the code. Will need to be documented.

[Eoin-ONeill-Yokai]

This looks great! I don't see any problems with the code.

I'm happy to see this integrated directly in the engine if others are; I admittedly only restricted it to a custom RichTextEffect implementation only as a proof of concept to make sure that the API was good enough as I had originally implemented it into the C++ directly. There's a discussion to be had on whether or not the custom RTEs could be less of a burden for users to use, but I don't think a decision should be made there until we really flesh out our asset library situation (as discussed in the sprint right now ;) )

Anyway, looks good and works as expected.

[djrain]

The "ghost" effect in the docs is very nice and quite similar - seems to me that its "span" variable could fit in nicely here, and make it a lot more flexible. Can we combine them?

[Calinou]

The "ghost" effect in the docs is very nice and quite similar - seems to me that its "span" variable could fit in nicely here, and make it a lot more flexible. Can we combine them?

This doesn't seem to be something commonly used in games. We have a custom effect system so you can still use it 🙂

Either way, I've squashed commits in this PR and rebased it against master (no other changes were made).

[YuriSizov]

Thanks!