All language subtitles for 8. System Communication

Welcome to the communicator system.
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This system is responsible for propagating knowledge from one AI agent to another.
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In this particular case, if one tank acquires the target, it will then try to inform others about
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it.
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Let's find out how this all works.
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The communicator is made out of two parts.
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One of them is the main system that is attached to all AI agents.
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You can find this system on every AI instance, child to the main kinematic body because it uses the collision.
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The other is the signal, which is similar to a projectile, but it travels directly to another instance
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and when it arrives, it's meant to inform that AI instance that it has a new target.
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Let's start with the main communicator component.
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Here we can find the following parts.
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First, you have the area collision, which will keep track of all other AI agents that are in the vicinity
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of this one.
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To not be able to communicate faraway distances.
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Of course you can change this by changing the collision sphere shape to different sizes.
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So this particular instance would communicate farther away or on shorter ranges.
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The other two parts are two timers: the ClearSignalListTimer and the CommunicateTimer.
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The communicate timer is actually triggered so that the communication doesn't happen all the time,
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but with 2 seconds delay in between them.
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And of course we don't want to send to the same tank the signal twice.
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So we keep track of the signal list and at some point we clear it up because the tank that received a signal
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from us might have lost the target and is good to be able to communicate with it again, but at some
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point later in time.
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Now let's look at the communicator script and see how this works.
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First, I want to highlight the following variables.
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The signal prefab, which is actually you can see here, it's the signal that we use as the projectile.
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This will get instantiated when we need to communicate between different AI instances.
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We also have the maximum communication number.
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Basically, once we send the signal out to three different other AI instances, we stop this communicator
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from working.
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This is do not overpower the system and let the whole map come after us.
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Next, we have the nearby list, which will be updated by the area collision on_body_entered and
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on_body_left.
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This will get updated with more or less AIs that are in our nearby field.
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The signaled_list is a list of tanks that already have received communication from this one.
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We do not want to send the same thing twice.
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The current_communication is actually a counter that keeps track of how many AI agents have we signaled to,
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and this will be used to compare to the maximum communication to stop once we reach the limit.
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And of course you can change this to communicate to more or less AIs depending of your balancing
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of the game.
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In the initialize function we get the tank object that is the parent of this and we also will need the
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target handler. In the restart,
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we reset basically the communication so that we can communicate to three AIs in this case. And also
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we clear the signaled_list so that we can communicate with the same three AIs that we want.
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The main functionality is the throw_signal, but before
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we go into this
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I want to quickly point out how the nearby list gets updated.
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We have the area collision and in the node here we have body_entered and body_exited.
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Here these two are actually signals that are hooked up with these two functions.
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And here we get the type of the body that has entered or left and if it's enemy and it's not in the
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nearby list already, and of course it's not the same one.
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We want to prevent collision to itself because we don't want this tank to issue communications to itself.
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Then we append it to the nearby list.
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Alternatively, if this tank exited, then we actually remove it from the nearby list.
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Basically, this is how we get a nearby list
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working every frame. throw_signal() is not actually called by any other script, but by using this timer,
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which as I mentioned, is in the on_communicate_timer.
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This is also a signal that's hooked up through the Godot system.
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Once this reaches zero, first we need to make sure that we still have a valid target for this particular
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tank.
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So in this case, if the target exists and is the instance valid, and then if we have reached the maximum
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communication number, we need to stop the communicate timer and of course return and otherwise we haven't
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reached it yet and we can actually throw a new signal.
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Now let's look at the throw_signal functionality. And here we need to do the following:
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First, we need to check if the nearby list has some tanks around.
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If we don't have anyone around, then we cannot communicate with someone.
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We return.
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Basically, this just stops the execution of this function here.
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Then we have the other enemy which we will get from the nearby list, and this is actually generated through
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a random number.
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So we get the random index number.
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We also need to check if the other enemy still exists and the instance is still valid, and then if
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the other enemy doesn't have already the same target.
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Because if it does have the target.
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Then sending a signal to it would be useless.
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We don't want to have the same enemy signaled twice, so we check it in the signaled_list.
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But if the selected enemy passes all of these checks, then this means we can properly issue a new signal.
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We increase the current communication number.
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We append this other enemy to the signaled_list.
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Lastly, we create a new signal, and the first two steps are, of course, instantiate the signal and
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add it to the root scene node and then set up the position as well as the rotation of the signal.
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And lastly, trigger the start functionality which will receive the other enemy and what target the
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other enemy should receive.
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The last callback that we need to mention here is on_clear_signal_timeout
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.
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This just clears the signaled_list to be able to inform the enemies that already have been informed by
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this particular one.
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The other part of the communicator is the actual signal and we can check its code right now.
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And basically here it looks very, very similar to a projectile.
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Besides the start which actually receives the other enemy and the target we actually wait for is
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enabled because we don't want to start moving this while it's not at the correct position.
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We create the direction vector and then we normalize it and we move this particular object towards the
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position using the speed and delta.
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The other part of this is actually calculating the distance between this current signal and the enemy.
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And if it's below one, it means that it has reached the intended target, and if it has the function
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on signal hit, then it will call it.
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If it's not, then might be a mistake or might have hit something else.
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But this should not be the case.
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And then the signal will actually be removed.
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This happens with this function.
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There is also one particular case that the signal might handle.
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So if we send the signal to a particular enemy and that enemy gets destroyed before the signal reaches
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it.
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In this case, this won't work anymore.
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So we need to have also a lifespan that actually is 5 seconds and it will automatically start.
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So if the signal either reaches the enemy or has elapsed 5 seconds after each instantiation, then it
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will get destroyed. And for the signal hit on the enemy.
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If we go back to the enemy script, then this is the function we are looking at.
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This was also discussed in the main enemy video, but quickly, just a refresh.
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It gets to the target and if the target is still valid, then it will set the target externally to the
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target handler.
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So this new enemy will get informed about this target via the signal.
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This is it for the communicator.
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I hope you liked it.
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And leave a comment here and tell me.
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See you in the next one.