Add flash reaction effect

[slarticodefast]

About the PR

Adds the flash reaction effect from SS13 (see tg wiki).
1 aluminium
1 potassium
1 sulfur
The range scales with the reagent amount.

Why / Balance

Chemistry needs a few more fun reactions that are non-lethal.

Technical details

Adds a new entity effect that calls FlashArea.
It also spawns a disappearing pointlight prototype similar to that used by the flashbang for better visual feedback.
The pointlight is scaled in size according to the flash range.

Media

ss14.flash.reaction.mp4

(I accidentally had the dropper in draw mode, but you still see what happens)

Requirements

• I have read and am following the Pull Request and Changelog Guidelines.
• I have added media to this PR or it does not require an ingame showcase.

Breaking changes

none

Changelog
🆑

• add: Mix 1u aluminium, 1u potassium and 1u sulfur for a flash reaction effect. The radius scales with the reagent amount.

[Sadie-silly]

Make it use the flashbang sound effect, rather than the normal flash sound. It just fits better.

[Dutch-VanDerLinde]

chemical mix that requires you to flash it to mix...

[slarticodefast]

Make it use the flashbang sound effect, rather than the normal flash sound. It just fits better.

I was planning on also adding a sonic explosion reaction that makes you deaf for a while and add it to the flashbang. So I wanted to reserve the "bang" sound for that for consistency. But I agree the "click" sound in the flash is not perfect.

Edit: I gave the flashbang sound effect a try and it does not really fit. Way too loud and more bang than flash.

[thebadman4662]

Just want to say that that this reaction basically guarantees gibbing via some rather easy mixes, on one hand it would be nice to have such infernal recipe for antag, on another only counterplay is to have flash protection at all times cause as soon as its mixed, you are as good as dead and you won't be able to escape which is pretty powerful for 0TC.

[LittleNyanCat]

You should add a sound that better reflects the powdery, chemical reaction that this is, instead of sounding like a camera flash.

Here are some samples I quickly found on freesound, though there are more:

https://freesound.org/people/Kinoton/sounds/468076/
https://freesound.org/people/Kinoton/sounds/415155/

They sound exactly like you would expect from this reaction, just need a little cropping. Perhaps they could be used as a pool of several variations instead of always the same sound.

[nighoggDatatype]

Uh, how does this interact with head revs?

[thebadman4662]

Uh, how does this interact with head revs?

This is AOE and hrevs need direct attacks, splashing cryostasis mix applies touch effects rather than mixes, so nothing happens that way either. At best it just makes catching someone you want to convert easier.