All language subtitles for 9. System Target Handler

Welcome to the target handler.
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The target handler is another layer on top of the sensor manager.
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If you don't know about the sensor manager, I recommend you go check the other video about it.
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The target handler is a system that hooks up to the signals sent by the sensor manager, keeps track
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of the current target and informs other parts of the AI
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if the target was lost or acquired. Another functionality of the target handler is when a target that
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was previously acquired has become invisible.
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That means that maybe it has moved behind an obstacle like a building.
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In this case, a lose target sequence is started, and if the target is not found, it will be permanently
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lost.
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We need two signals and they will be called when the target has updates.
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So on_target_found and on_target_lost and they will both provide what target was found and what target
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was lost. In the initialize
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we have the usual suspects which are the parameters given by the key-pair value style of initializing and
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we hook to the sensor managers on target list update.
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This is the most important part of this one because this will parse the actual list that was received
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by the sensor manager.
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We'll also use a callback to the lose target timer.
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The main point of entry for this script is on_target_list_update when it actually receives the list
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of targets from the sensor manager.
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And here, what we need to do is, of course, we need to parse this list and get the target that is
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the closest to this particular enemy instance.
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So to do this, we actually put up a minimum distance and this should be quite huge and the target that
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has been found so far.
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Then we parse the new target list and for each target we calculate the distance.
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And if the distance is less than the minimum distance, then the new minimum distance will get this
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current distance and the target will be this one.
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And this assures that even if there is one target far away since the initial minimum distance is 9999,
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then then this means that it will be picked, but then once this gets updated, then it will go
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for closer and closer targets.
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If you don't have a target, then this means that the current target is null and the minimum distance
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target is not null.
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And this is the perfect case scenario because we initialize the current target with this one.
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We stop the lose target timer, which actually runs all the time while we don't have the target in our
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sensors.
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And lastly, we set was_target_acquired_internally to true. This will be used in another part of this
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script.
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And the other alternative is when the target gets acquired, not through the tank sensors, but if the
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tank gets informed by a signal or if the enemy gets hit from far away by the player. And if a target
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was found, then we emit the signal on target found with the current target.
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Once we have the target in place, we need to update its visibility at every frame.
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This happens in _process() and we have here update target visibility.
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How do we do this?
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Well, first, we need to make sure that the current target is still valid.
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This means that it was not destroyed it by some other AI instance.
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Then we have two variables is_in_range and is_visible.
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is_in_range is actually true or false.
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Based on the range sensor and the visible is the raycast from the enemy instance to the target. is_visible
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will be true in this case.
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But if we actually opt for the enemy to use the line of sight, then is_visible will query the sensors
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for the raycast and it would set to true or false.
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In some cases like the tactical tank AI,
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we don't need this as we just use the range sensor.
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But for the other two tanks this will be used.
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Next, we can use this functionality to check if it's in_range and is_visible and if it is in both,
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then the target_is_in_the_fire_range (= true).
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Otherwise it's false.
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Note that even if the tank doesn't use the raycast, we can still use visible because it would be set
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to true here.
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We don't have to worry about that.
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And if the target is in the fire range, then we no longer need the last known position.
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We just move it -500 meters below and we stop the lose target timer.
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If it's not in the range, then this means we have to do a lot of other stuff and if the lose target timer
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is stopped, then this means that we just lost the target.
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First we create the lose target time and this is where was_target_acquired_internally
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works because this time is what gets initialized in the timer lose target.
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And if the target was acquired internally, this means it might be nearby, in almost the sensors of the
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tank.
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And if it was externally (provided), it means that it might be further away.
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For example, from a communicator signal.
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This lose target externally is a little bigger.
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To give the opportunity of this tank to actually move to the target's position before it actually loses
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it.
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This final check is actually, in some cases, for the defensive tank.
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We disable this functionality.
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If it's not disabled, if it's true, then we start the lose target timer with the value that
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we just initialized.
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We also update the last known position to the target's last known position.
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And lastly, we set up the finite state machine's target_in_fire_range, either true or false based on
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all of this processing.
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When lose target finishes, it will emit the signal that the target was lost.
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Basically when lose target timer reaches zero
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this means that we failed to acquire back to the target and we can call the on target loss signal and remove
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the current target.
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Make it null and this will actually permanently forget about the target.
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Other functionalities here are disable lose target and enable lose target, which set up the should
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lose target to either true or false.
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These are for the defensive AI and they are called only when this AI goes into hiding because it will surely
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trigger this and we don't want to lose the target after its functionality happens.
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Basically, this is the target handler.
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Let me know in the comments what to think about this.