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Table of contents
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Table of contents

0:00
C# Observer/Delegate Basics
3:00
Generic Observer
6:25
Unity Event Tools
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unity game tutorial
unity
game development
game dev
game development unity
programming
c#
software development
learn to code
learn programming
unity tutorials
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Subtitles

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  • ruRussian
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00:00:00
to be honest I wasn't going to make a
00:00:02
video about The Observer pattern it
00:00:04
feels played out on YouTube dozens of
00:00:07
beginner videos about the same two
00:00:08
things updating UI and the new input
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system so today we'll quickly look at
00:00:13
the basics but the bulk of this video is
00:00:15
going to be about building a generic
00:00:17
Observer so that you can observe
00:00:19
property and field changes in play mode
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and then we're going to take it even
00:00:23
further so that you can observe values
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in edit mode and start building more
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complex tools using the unity tools
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class as always don't forget to hit the
00:00:32
like button when you learn something new
00:00:34
today let's get into
00:00:39
it let's review a basic use of the
00:00:42
Observer pattern a delegate type is a
00:00:44
bit like an interface it specifies the
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signature of a method all delegates are
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multicast in C which means it can hold
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references to more than one function and
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when it's invoked it calls each of the
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methods it references in turn one after
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the other the next line declares an
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event named on any collected using the
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previously defined notify delegate type
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the event keyword in C essentially adds
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safety features by restricting how the
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delegate can be used for example it can
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only be invoked from within the class or
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struct where it's declared and external
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code can subscribe or unsubscribe for an
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event using the plus equals or minus
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equal operators but cannot directly
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manipulate the list of subscribed
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delegates programmers still use
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delegates over shorthand action or Funk
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when they want to make code more
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understand able or self-documenting but
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in most cases people just use Funk when
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they want to return value and action
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when they do
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not so for this simple example when the
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player bumps into a collectible it's
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going to fire off the trigger the
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trigger will invoke our action any
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subscribers to the action will receive
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the points for this collectible and then
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we'll just disable the game object to
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make this work let's just make another
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class called score manager it'll have a
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text field it'll keep track of our
00:01:58
current score and and we're going to
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have it subscrib to our static event on
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our collectible class and we'll just
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have an add score method whenever the
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event is fired we're going to increase
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the score and update our text let's make
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sure that we unsubscribe for the event
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too I'm just going to move the
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subscription down into on enable because
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I prefer it that way and I'm going to
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move the updating of the text into its
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own method because I also want to call
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it on awake just so we make sure that
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the score text is going to be zero right
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at the start going to change these into
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expression body methods so it's a little
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bit
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shorter now back in unity I've already
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put the scripts onto the various game
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objects you can see here on this
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collectible I'm just going to change it
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to 50 points on this one but I'll leave
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the other box just at 10 and I've
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already put the script onto my HUD with
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the score text so just hit play and
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you'll see how it works everything will
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hook up and subscribe to the events
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right from the start you can see the
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score is zero if I come over here and
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grab this box suddenly we have 50 points
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and
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if we come over here to the other box it
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should go up by another 10 points there
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we go 60 points so that's as far as
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we're going to go with the simple
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Observer I'm just going to come out of
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play mode again here and I think what
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I'm going to do is actually just disable
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these two boxes because we're not going
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to work with Collectibles anymore for
00:03:18
the rest of this video what I want to
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talk about is using a generic Observer
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of type T we'll store our type t as a
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private field value but we can expose it
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to the editor so we can set it and then
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we're going to associate this with unity
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events let's expose t as a public
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property but we're going to have a
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special method set whenever we set the
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value we're going to notify observers
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that it's potentially been changed
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before we get to that let's set up a
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Constructor for this the Constructor
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needs to accept our value T and could
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potentially take in a first Unity action
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let's default it to null so we don't
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have to specify it if we don't want to
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we'll set the value if the call back
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wasn't null We'll add that as a listener
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to our Unity event and let's make sure
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that we initialize our Unity event
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whenever the Constructor fires in our
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set method let's say if the value coming
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into the set method is the same as the
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value we already have let's bail out now
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I want to keep invoke as a separate
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method because we might want to call it
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at other times and it can handle some
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other things for us such as debugging
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let's put a debug statement here that'll
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actually tell us how many events are we
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actually going to invoke here and then
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let's actually invoke them by passing in
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the value let's add some methods so that
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we can add and remove listeners I'll
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look co-pilot Phil in some of this but
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basically let's do some defensive null
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checking if everything's good let's add
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The Listener exactly the same thing for
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removing a listener let's also make a
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method so we can remove all listeners
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and finally just for the sake of
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completeness let's have a dispose method
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so that we actually remove all listeners
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and we just reset some values
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here come back up to the top and
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actually make these set and invoke
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methods public so that I can call them
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from whichever class is declaring an
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observable T let's come over to our
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empty hero class here and I'm going to
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declare a public Observer of type int
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that'll be for our health and we'll just
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start it with
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100 now in the start method I'm going to
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invoke that so any Unity events that are
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defined in the editor will fire off
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let's add an update method so that I can
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test this out so whenever I press the
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one key I want my health to go up by 10
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let's do a bit of cleanup here we
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actually don't need a serialized field
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here since this is public
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one more thing I've got a health display
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script already written it just has a
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reference to the text of my health and
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it has a public method that we can use
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to change that message let's recompile
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and go back to Unity so over here in the
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inspector you can now see I have this
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observable health value and it has room
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for some Unity events so we can drag in
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our health display reference here and
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call its public method which accepts an
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integer so I'll just come over here to
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my health display and I'm going to drag
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that in and then I can select its method
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it's a little bit off screen but it's
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there at the top because it matches the
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signature that's really it let's press
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play and try it
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out so in play mode here you can see it
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right away it invoked the event so it
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set it to 100 now I pressed one it went
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up to 110 let's press it again and so on
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it'll just keep going up by tens every
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time I press the button so at this point
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you might be thinking great how's this
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going to help me out first of all when
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you have Behavior associated with a
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value start thinking about using an
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object to encapsulate it you'll end up
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with something much more powerful and
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easier to debug than using just the
00:06:37
basic constructs of the language but
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beyond that I want to introduce you to
00:06:41
the unity events tools class which is
00:06:43
going to allow us to start adding Unity
00:06:45
events programmatically in edit
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mode up at the top of my class I'm going
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to add system reflection and using Unity
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editor. events now down in our public
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method add listener we can add the unity
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editor directive and do some special
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stuff when we're in edit mode so all
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we're going to do here is just use one
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of those methods from the unity event
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tools class to add a listener during
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edit mode and we can do the same thing
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in the public method remove
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listener now we're going to have to do
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something a little bit special when we
00:07:17
want to remove all listeners because
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there is no real method to do that so
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what we'll do is use some
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reflection first let's get the field
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info of a private field in the unity
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event Base Class which is named n
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persistent calls the field info object
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has a method named get value that
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retrieves the value of the field from an
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object in this case the onv value
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changed event object we can then use
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reflection again to get the method name
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clear we can then evoke the clear method
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on the value now this effectively will
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clear out the persistent calls list of
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the unity event for interest sake let's
00:07:50
go and have a look at the unity event
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Base Class which all Unity events
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inherit from the easiest way to do that
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I find is just to declare a variable of
00:07:59
that type and then command click into it
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it'll decompile in rer here and here we
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go so you can see right here at the top
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we've got our M persistent calls it's
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private persistent call group type so
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let's click into there and see if we
00:08:15
can't find this clear
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method and just a little bit down here
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you can see here is the clear method so
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it's not doing anything magical but the
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only way to get at it because up in the
00:08:28
unity Base Class it's marked as private
00:08:31
we need to use reflection okay let's
00:08:33
come out of here I'm just going to
00:08:34
remove that declaration that I made and
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clean up a little bit and what we can do
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now is think about how we can use this
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in an editor tool now I've already
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started a class here it doesn't do
00:08:45
anything special it's just overriding
00:08:48
the on inspector guey and calling the
00:08:50
Base Class you can see riters even
00:08:51
graded out because it does nothing so
00:08:53
just a few rules before we start adding
00:08:55
persistent events the referencing type
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must be Unity engine object object the
00:08:59
method that we call has to be public no
00:09:01
Anonymous or lambdas and the parameter
00:09:04
type has to match now the reason for
00:09:06
that is that everything that we put into
00:09:08
the unity event has to be
00:09:10
serializable so in our tool here let's
00:09:13
get a reference to our hero which is the
00:09:14
target of this inspector and let's start
00:09:17
adding some buttons we can have a button
00:09:18
to increase health one to decrease
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health and then what I want to do is
00:09:22
have two more buttons that will add or
00:09:24
remove a debugger now I've made a tiny
00:09:27
debugger Singleton which inherits from
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Unity object and has a method that will
00:09:31
match the signature that we can use just
00:09:33
for this example so we can have a button
00:09:35
that will add that method and one that
00:09:36
will remove it let's just take a quick
00:09:38
look at the debugger it's super simple
00:09:40
it's just inheriting from a boilerplate
00:09:42
Singleton and has a method that matches
00:09:44
the type of unity event we
00:09:48
want okay so back here in unity I'm
00:09:50
going to click add debugger and watch
00:09:52
what happens we serialize one of these
00:09:54
methods right into our Unity events that
00:09:57
also automatically added a single for me
00:10:00
now if I jump into play mode right away
00:10:02
we see that our start method invoked the
00:10:04
two listeners and we see the debug
00:10:06
message as well as showing the correct
00:10:08
Health amount now I can start moving the
00:10:10
health up and down no problem but what
00:10:13
happens if I remove the
00:10:14
debugger and then come out of play mode
00:10:17
well guess what that we already
00:10:19
serialized that onto the object so there
00:10:21
it is no problem that thing is going to
00:10:24
persist hence the name
00:10:26
persistent um what else can we try here
00:10:29
well how about if we just clear this up
00:10:31
again and I remove the debugger what's
00:10:34
going to happen let's go into play mode
00:10:36
and see what happens if I were to add a
00:10:38
debugger now if I click the button you
00:10:41
see it will add the debugger here but
00:10:44
it's not going to serialize it because
00:10:45
we did it in play mode so we come out of
00:10:47
play mode and it's gone so these editor
00:10:49
methods work just like dragging and
00:10:51
dropping so for example right now we
00:10:54
could just add another Unity event here
00:10:56
and technically we could just drag in
00:10:58
this s Singleton and reference the
00:11:00
method on it oops I missed there drag it
00:11:02
again and now we can just grab the debug
00:11:05
or debug method again and you'll see it
00:11:08
serialized it just as if we had done it
00:11:10
programmatically and that's the expected
00:11:16
Behavior just one more feature I want to
00:11:18
add to this today and that is the
00:11:20
implicit operator instead of having to
00:11:22
call health. Value every time you want
00:11:24
to get the value out of this public
00:11:26
property we can just use an implicit
00:11:28
operat to just convert whatever our
00:11:31
value T is right out into that type
00:11:34
automatically so that's just a shorthand
00:11:36
way of saying that when we request our
00:11:38
health property we don't have to tack on
00:11:41
the dot value it's just going to
00:11:43
implicitly convert our property into the
00:11:45
value integer that we want now as an
00:11:48
example of that let's just come back to
00:11:49
the hero class and add a bit of code to
00:11:51
our start method so we could say in
00:11:54
example one we'll get health dot value
00:11:56
so we'll grab the property but in
00:11:58
example example two will just get health
00:12:01
and you can see already in the code hint
00:12:03
here it's casting it as an integer but
00:12:05
let's see what happens when we debug
00:12:07
this out does it is example one equal to
00:12:10
example two and what if we just debug
00:12:13
the health object what is that going to
00:12:15
say let's recompile and hit
00:12:18
play so we can see that example one was
00:12:21
equal to example two but when we just
00:12:24
debug the object itself it's actually
00:12:26
telling us that it's an observer of the
00:12:29
system integer 32 type I will say one
00:12:32
thing about implicit operator and that
00:12:34
is it does have some overhead so don't
00:12:37
go throwing it everywhere but once in a
00:12:39
while it's very useful I was thinking a
00:12:42
cool editor tool that uses this might be
00:12:44
to observe a challenge rating on an
00:12:45
enemy in the editor and as your game
00:12:47
designers increase the challenge rating
00:12:50
your listeners can configure the enemy
00:12:52
with different strategies or gear the
00:12:54
only limitation really is your
00:12:56
imagination I think that'll have to be a
00:12:58
topic for a future video however if you
00:13:01
want to learn more about Advanced game
00:13:03
events check out the event Bus video and
00:13:05
I'll see you
00:13:07
there

Description:

Unity C# Architecture: Learn how to observe variables using a streamlined generic Observer class aided by the UnityEventTools class. This video covers play and edit modes, focusing on the serialization and persistence of UnityEvents programmatically in the Editor. 🔔 Subscribe for more Unity Tutorials https://www.youtube.com/@git-amend ▬ Contents of this video ▬▬▬▬▬▬▬▬▬▬ 0:00 C# Observer/Delegate Basics 3:00 Generic Observer 6:25 Unity Event Tools Generic Observer Source Code: https://gist.github.com/adammyhre/353195d4870e8fd0cc0028659e66f208 Resources Unity Event Tools Documentation https://docs.unity3d.com/2023.2/Documentation/ScriptReference/Events.UnityEventTools.html Creating Observable Variables with Delegates in Unity Using C# https://copyprogramming.com/howto/unity-c-creating-observable-variables-with-delegates Unity C# Creating Observable Variables with Delegates https://stackoverflow.com/questions/70445037/unity-c-sharp-creating-observable-variables-with-delegates Value Observer (FREE tool from Infinity Code) https://assetstore.unity.com/packages/tools/utilities/value-observer-266922?aid=1101lw3sv C# Implicit and Explicit Operators: A Comprehensive Guide https://medium.com/@gustavorestani/c-implicit-and-explicit-operators-a-comprehensive-guide-5e6972cc8671 Assets Shown In This Video (Affiliate Links) Dmitriy Dryzhak Models and Animations: https://assetstore.unity.com/publishers/10181?aid=1101lw3sv Odin: https://assetstore.unity.com/publishers/3727?aid=1101lw3sv Dungeon Mason Tiny Hero Duo: (FREE): https://assetstore.unity.com/packages/3d/characters/humanoids/rpg-tiny-hero-duo-pbr-polyart-225148?aid=1101lw3sv Chromisu: Handpainted Forest MEGA Pack https://assetstore.unity.com/packages/3d/vegetation/handpainted-forest-mega-pack-248421?aid=1101lw3sv SineVFX: Better Crystals https://assetstore.unity.com/packages/vfx/shaders/better-crystals-235002?aid=1101lw3sv VFX Trees: https://assetstore.unity.com/packages/vfx/particles/environment/stylized-vfx-trees-gpu-based-effect-238647?aid=1101lw3sv Kronnect Volumetric Fog & Mist 2: https://assetstore.unity.com/packages/vfx/shaders/fullscreen-camera-effects/volumetric-fog-mist-2-162694?aid=1101lw3sv Kronnect Cloud Shadows: https://assetstore.unity.com/packages/vfx/shaders/cloud-shadows-fx-267702?aid=1101lw3sv Kronnect Beautify: https://assetstore.unity.com/packages/vfx/shaders/fullscreen-camera-effects/beautify-3-advanced-post-processing-233073?aid=1101lw3sv Kyeoms Hyper Casual FX 2: https://assetstore.unity.com/packages/vfx/particles/hyper-casual-fx-pack-vol-2-245262?aid=1101lw3sv MalberS Animations: Forest Golems: https://assetstore.unity.com/packages/3d/characters/creatures/poly-art-forest-golems-164389?aid=1101lw3sv REXARD SpellBook Icons Megapack: https://assetstore.unity.com/packages/2d/gui/icons/spellbook-megapack-109615?aid=1101lw3sv ARCEY Vampire Skill Icons: https://assetstore.unity.com/packages/2d/gui/icons/vampire-skill-icons-250993?aid=1101lw3sv *Follow me!* https://linktr.ee/gitamend

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