All language subtitles for 5. Implementing Hit Detection

Welcome to hit detection.
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Basically, hit detection means that the enemy, when it gets hit by a projectile, it needs to be notified.
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Hey, wait a second.
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I have been hit.
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Let's find out how this works.
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So if I run the scene and we think this is a projectile and this is the enemy, if we move the projectile
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through the enemy, then a hit was detected in the output.
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Of course, multiple projectiles will yield multiple hit detected results.
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This is important because if the enemy does not directly detect the player, but the player hits the
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enemy, then the enemy should retaliate.
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Let's see how this is done. First,
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as you can see, there is no player, actually just the bullet.
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And the bullet has a mesh instance which is not so relevant just for visual purposes, but it has an
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area.
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And this is important because this is how the collision will happen.
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It has monitoring turned on and there is a collision shape which is a capsule shape.
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Please note that the collision shape is a little bigger than the projectile.
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This is just for the demo purposes to make it easier to use.
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Now let's see about the bullet.
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By the way, please note that the area
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has on body_entered and this signal is getting triggered in the bullet.
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So basically the bullet script is quite simple.
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It just detects if a body entered the area, it gets the parent of that object and then if the object
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has the method called register hit.
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In this case, for example, the AI would have implemented this method, then it calls it.
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If not, nothing happens.
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Now let's look at the AI.
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So here the actual collision happens in the kinematic body by just having the body in the bullet.
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We will not get the register hit, which is a level above it.
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So of course this get parent needs to be used.
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By the way, pro tip, make sure you have the same structure for the enemies as for the players because
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you have a generic projectile.
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Then,
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in some cases this might be at the body level, in some other cases it might be at the parent level.
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And then you have to implement either checks for just the body if it has this register hit or the parent
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and the body and it will get messy.
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So make sure you have the same structure for every object that needs to receive a projectile.
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But in this case is the higher level.
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So here is just a register hit and of course it will print hit detected.
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Then this can be later included in the AI's decision system and tell: Hey, please attack the player now
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or retreat or whatever.
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So basically this is the hit detection. Now that we have covered how to deal if sensors, state machines.
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Let's head over to the last part of the course, which is the actual project. I'll see you in there!