Unreal Engine - Casting and Interfaces Explained 

lol so many comments about the cat

@@ReidsChannel Maybe they should be renamed "Catstings" :P

@@ReidsChannel Any chance you could do interfaces vs components? I can use them the same way for my status effect system, but not sure if there's some big advantage to either.

@@ReidsChannelThe cat was a nice touch to entire thing :D

Knowing why things work definitely helps me retain the info.

"Learning *why* something is good is so much better than just seeing how to do something." This x1000. This is why I like this channel, Ryan Laley, Matt Apsland, et al. They go into how and why things work so you can understand how to best utilize it, and troubleshoot/debug when needed.

fucking dead right! I am always left wondering why from other youtubers! lol I also agree that Ryan and Matt are awesome too. Maybe you guys can do a dev collab! :)

This right here is why 99% of RU-vid “tutorials” are absolute garbage

Nice detail, thank you!

aha! I was asking myself why he used the checking. Nice catch

btw, to avoid checking we could pass the projectile's reference as input and make the interface function destroy it I guess?

@@loremipsum3147 Yes, but you have to be careful because now the paintable object will destroy ANY actor that calls this interface and you might not want that. Also if you use the DestroyActor node, what happens if it wasn't an actor that called the interface? What if it was the PlayerController that called the interface? Honestly I think that the projectile destroying itself is the best choice here, because this decision to destroy itself should be made by the projectile and not the painted object. Another option would be to add an output variable to the interface function and use that to decide if the projectile should destroy itself (default "no").

@@t3hpwninat0r thank you for the explanation and yes, I agree with you destroying in the interface is generally a bad idea. Btw, about returning an output variable, if the actor did not implement the interface and we call the function, what will be the return value? (I guess it is the default no?)

That last point, especially. In many cases, you can get away with casting using the "make it a variable" method without hardly any performance penalty.

Can you please elaborate on your point about interfaces having a lower cost than casting? What exactly is the lower cost? Do you have any info on this from an engine standpoint, or better yet, from a C++ language standpoint? I'd be very interested to know.

@@GeorgePence I think there is a myth around "performance" improvements with Interface vs Cast where as from what I have read its basically the same outside of the main reason people tell you to use Interfaces in Blueprint specifically is because when you Cast in BP it creates a HARD link to every Class you Cast to (and ever Class it Casts to) which means they are all loaded into memory. So in his example where he says people do Multiple Casts to multiple Classes every one of those classes will be loaded into memory, now if they are Parent classes it might not be too bad but if you cast to Cat & Lounge & Final Boss & etc it means all those Classes (and any Classes they Cast to) and related items such as Meshes and Particles etc are loaded into memory as soon as you Call / Cast to FirstPersonProjectile

@@shannenmr Thanks for the reply. Yes, I agree also, people throw these phrases around and it's sort of like an urban legend. Very rarely does anyone ever have any legitimate info to back it up with, so I appreciate you providing some proper details.

Sounds like you need to find a new online course ;)

Thanks! No I don't but I do some tutoring sometimes haha

Doesn't this mean that you can always cast to the player in single player games to cause damage? Or is the dependency 2 way?

​@@thelawgameplaywithcommenta2654 You should always use interfaces to get the reference of a class, example: I get the playercharacter in my code so its a Character class even if it referes to a class that inherits from it, for example the FirstPersonCharacter that is given with the template, but I want to run something in that child class not in the parent given, infact as you know if I have in my FPSCharacter a function and I get a Character class I can't obviously call that function from that, but I can call an interface call, so usually you create an interface to get the reference of the player, in that interface you create a getPlayerRef function with an output that is the actual playercharacter class like the FPSCharacter, you implement that interface in that character class and override the function to return self as the output, so when you call that function as message from the character class that you obtained like with a getPlayerCharacter or whatelse you can get with that getPlayerRef the actual reference as the class you need. Sorry if it's hard to explain, Im not english so I tried to make the best explanation possible.

@@thelawgameplaywithcommenta2654 Anyway to deal damage I suggest to run the damage function given with unreal and then handle that damage with the event anydamage or the other ones, instead of making your ones, otherwise if need more complexity you can do as you need

Thanks for the tip!

ty :) I have made a couple but no one watches lol

@@ReidsChannel please link them

@@ReidsChannel also am looking through your playlists . unfortunately u just have a gaint playlist of tutorials . i would highly recomment u break it up atleast into series and have separete c++ playlist . thank you good day to you sir .

Yeah, its just explaining it clearly that is a struggle haha but glad u like it

I see what you did there

Cat -> Pawn -> Actor Furintue -> Actor Sure they both derive from actor so they are both actors but I think what Im trying to say in the video is that they are both not pawns