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In this lecture, we're going to get our enemies shooting back at our player, and we're going to do

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this using the exact same shooter script that we used for our player.

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Before we go ahead and edit our script though, let's clean up our assets folder by dragging our shooter

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script into our scripts folder and then let's head into our prefabs, go into our enemy, and then add

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our Shooter component.

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In here.

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We want to give it the projectile prefab.

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So this time we're going to use our enemy projectile.

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And for now, we'll just leave all of the other things as default.

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We can edit those when we start testing.

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With that set, let's open up our shooter script and see what we need to change to get it to work for

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our enemies.

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Well, we want our enemies to fire automatically.

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So it's really just a case of overriding our is firing boolean.

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So this is no longer going to be getting set from a different script.

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Instead, what we're going to do is we're going to set this to true in our start method, but so this

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doesn't affect our player as well.

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Let's create a new variable so we can tell the system whether we're using the A control or the player

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control.

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This is as simple as creating a serialized field of type ball that we're going to call use a I.

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So if use IE is true, we're going to automatically set up our is firing ball and if it's false, we're

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going to accept input from the player.

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So in start, let's say that if we are using the AI then is firing is always going to be true.

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So let's save up our script as it is and jump into unity to test this inside of our enemy prefab, let's

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go down to our shooter script and check the use option.

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Now if we go ahead and hit play, we can now see that our enemies are shooting.

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But we've got some very weird behavior here.

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First of all, the shooting is very fast.

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And secondly, they're shooting in the wrong direction.

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So let's come out of play mode and fix both these problems.

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So over on our enemy prefab, let's first of all change our firing rate from 0.2 and make that a bit

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larger so maybe around one and see how that feels.

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And together, projectiles moving in the correct direction.

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Remember that in our shooter script we were telling it to use the op vector multiplied by the projectile

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speed.

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So our enemy is going to be following our up vector, which is still up the screen, even though our

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sprite makes it look like we're facing down.

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So first of all, let's rotate our sprite.

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So it follows more closely what the up direction should be.

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So we'll just jump into our enemy Sprite and on the Z component of our rotation, we'll just change

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that to 180 degrees.

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We'll see that the Green Arrow now points down.

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But remember, this is only for our sprite.

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So if we click on our enemy, we can see that the up arrow for this is still facing up with that set.

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The projectiles will now come out of the front of the ship, but we now need a way of rotating the entire

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ship so it faces down the screen.

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So to do this, we're going to have to rotate our objects when we instantiate them.

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And if we head over to our script folder, this was the job of the enemy spawn.

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So let's open up our enemy.

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Spawn a script, head down to where we're instantiating our enemies.

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And in here we're setting the rotation to cotangent identity.

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So no rotation, but we can very easily change this condition.

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So instead of using cotangent identity, we want to rotate our enemy 180 degrees when it's created.

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There are a few ways to do this, but the easiest way of doing this is to say Quaternions.

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Euler So you are.

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And if you're wondering about the weird spelling versus the pronunciation, it's because it's named

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after the mathematician Leonard Euler.

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Then inside the parentheses we need to specify the X, Y and Z rotation and we don't want to rotate

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on the X or Y, but we do want to rotate 180 degrees on the Z component.

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So if we save this and jump back into unity and then we can go ahead and hit play, we should now find

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that our enemies are the right way round and are shooting in the correct direction.

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So we now have a way of the enemies shooting back at the player.

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But the projectiles are all on a fixed firing schedule, so it's very predictable gameplay and this

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is the next thing that I'm going to want to change.

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So let's come out of play and head back over into our shooter script one more time.

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And then let's just recap on our firing CO routine.

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So while true, we're instantiating our object, giving it some velocity, destroying it after a set

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amount of time.

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And then the piece we're interested in is the weighting.

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So to make this more random, we're going to want to pass a random value into this wait 4 seconds.

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And because I think you're up to the task, this is going to be your challenge.

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I want you to go ahead and modify our routine to wait for a random amount of time between our projectiles.

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And as a hint, why not have a look at I'll get random spawn time method from our wave config.

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So because the logic here is going to be very, very similar.

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So once you've had a look at that method that we've written previously, think about what new variables

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we're going to need to add to our shoot script to make this work and potentially what we're going to

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need to change.

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So pause the video now and give that one a go.

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Okay.

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Welcome back.

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So hopefully you got on well with that challenge.

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And here we are in our wave config so we can see how we did it last time.

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Well, for our variables, we had a time between enemy spawns, a spawn time variance and a minimum

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spawn time.

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And if we head down to our get random spawn time method in here, we were getting a random spawn time

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between two values.

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And then to make sure that we weren't going into negative numbers, we were clamping our result.

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So let's essentially replicate this same sort of thing in our shooter script.

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We're currently waiting for our fire rate in our routine, but I think this should probably be renamed

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and used in a slightly different way.

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So I'm going to rename my firing rate to the base firing rate and then I'm going to create two more

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serialized fields.

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These are both going to be Float, and the first one is going to be called the firing rate variance.

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And by default, we're going to set this to zero.

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And then for our second variable, we're going to call this one the minimum firing rate.

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And we can maybe set that to around point one.

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With those set, let's head down to our routine and implement our logic.

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So in here we want a temporary variable of type float, which I'm going to call Time to next projectile.

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And this is going to be equal to a random range between our base firing rate minus our firing rate variance

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and our base firing rate plus our firing rate variance.

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Then to make sure that this value doesn't go below zero, because if it does, we're going to be waiting

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for negative seconds, which is going to cause us a lot of problems.

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So we're going to clamp this value by saying time to next projectile is equal to math.

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F Clamp the value we want to clamp is our time to next projectile.

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We want our minimum value to be the minimum firing rate and our maximum value is going to be our float

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max value.

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And then, rather than yielding for the amount of our base firing rate, we want to wait for the time

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to next projectile.

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So let's save this up and test out.

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Let's head into our prefabs and look at our enemy.

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We've already set our use AI to be true.

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We want our base firing rate to be around one, and we're going to add a variance of maybe around 0.5.

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So our projectiles will spawn anywhere between half a second and one half seconds between each other.

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Now, before we actually test, there's one more thing I do want to do in my shooting script, because

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we're getting a lot of variables in here and it's starting to get very cluttered.

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We've got this is firing flag that's public, but we don't ever really need to set it in the inspector.

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So it would make sense to hide that away.

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And we've also got a bit of a split between generic shooter functionality and other things specifically

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related to our air shooting.

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So let's jump back into our shooter script for one final time.

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And if we head up to our variables at the top, we're going to separate this up with some headers so

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we can use the header attribute.

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And I'm going to call the first one general and this will include our projectile prefab, its speed

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lifetime and maybe our base firing rate as well.

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And then we're going to have a second header attribute called I and this will have our use I flag and

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the variables that we're using to modify our firing rate.

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Finally, we're going to hide away this public variable, and we can do that with another new attribute.

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And this is called Hide in Inspector.

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And just like a serialized filled, this doesn't really affect the access level of our variable encode.

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It only affects the access in the inspector.

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So let's save this up and jump back into unity.

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And now we can see our shooter component is a lot more manageable if we're just dealing with general

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stuff, we can set up our first four variables and if we're interested in AI, then we can set these

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up and finally notice that our IS shooting variable is no longer present because we've hidden it in

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the inspector.

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So with that little bit of clean up a side, let's finally go and test our gain.

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We now have our enemies shooting at random intervals, which is a lot nicer and they're shooting a little

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bit slower and we can shoot back at them and destroy them.

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And with that, our core gameplay is pretty much finished.

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It still requires a little bit of tuning and we can add some more enemy waves and enemy types, but

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the fundamentals are all there.

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However, it is still a little bit boring, so over the next few lectures we're going to start adding

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some juice to our game.

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And the first piece of juice that I want to add is some particle effects to start selling the impact

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of the projectiles on the enemies.

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Well, we're starting that in the next lecture, so I'll see you there.