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‫So our objective is to be able to shoot projectiles and get an explosion effect when the projectile

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‫hits something, including when we hit the enemy tower and when the enemy tower projectiles hit us.

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‫Hello and welcome back.

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‫Now let's take a look at our section plan and see how far we've come.

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‫Now we know we've created a tank.

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‫It can move throughout the world.

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‫We made an enemy turret class.

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‫We added fire functionality and projectiles along with health damage and destruction in our game.

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‫Now we have winning and losing conditions and we're displaying those with widgets to our HUD.

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‫Now the last item is to add our special effects, which means we need some smoke trailing behind our

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‫projectile as well as some explosions and sounds.

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‫And there are going to be a couple other things that we add to spice up our game and make it look a

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‫bit more polished.

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‫Now, in this video, we're going to handle some hit particles.

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‫These are special effects for when the projectile hits something.

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‫This is going to involve something called a particle system.

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‫So let's go back into the editor and take a look at the particle systems we have in our project.

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‫So I'm here in the editor.

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‫I'm going to go into the assets folder and effects and here we have three effects.

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‫These are called particle systems.

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‫Now we have a hit effect, a death effect and a projectile trail.

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‫Now let's go ahead and double click on p hit effect and you'll see that here we have a particle system

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‫editor.

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‫And in this little viewport, we'll see this explosion happening over and over again.

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‫Now, luckily, this particle system has already been created for us and it looks like a nice little

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‫explosion.

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‫And we would like to see this explosion happen as soon as the projectile hits something.

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‫So that is our goal for this video.

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‫So here in V's code, I'd like to go back into our projectile class.

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‫So let's go into projectile H and I'm going to add a variable to this class and this is going to be

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‫a particle system.

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‫Now, this can be a private variable and the type is going to be U.

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‫Particle system and it's going to be a pointer and we can call this hit particles.

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‫Now I'm going to forward declare this and I'm also going to give this a new property.

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‫So let's say you property and I want to make this at it anywhere so we can set this from the blueprint

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‫for our projectile.

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‫And while I'm at it, I'm going to give this a category and I'll place this in the category combat,

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‫since it's sort of related to our other combat variables.

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‫Now this is edit anywhere because we plan on setting this from within the blueprint so we can go ahead

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‫and compile this.

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‫Now let's hop back in the editor and I'm going to close out of my other blueprints and go into our actors

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‫folder here in blueprints.

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‫Actors, here's our B.P. projectile.

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‫Let's open that up and open the full blueprint editor.

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‫Now, let's take a look in the details.

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‫Panel.

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‫Remember, BP projectile self must be selected to see these overall variables.

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‫And here's our combat section and we see hit particles.

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‫Now here we have a dropdown and we can select particle systems.

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‫Since this variable is of type you particle system, we're going to use the hit effect for our hit particles.

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‫So now we have a variable and its value is set here in the projectile blueprint.

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‫So let's compile and save this.

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‫Now, the next step is to actually spawn this particle system as soon as we've hit something, which

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‫means on hit is the perfect function to do this in now we need to know how to spawn particles and use

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‫gameplay.

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‫Statics has a handy function for that.

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‫It's called spawn emitter at location and it says plays the specified effect at the given location and

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‫rotation.

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‫Fire and forget.

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‫This is nice because we don't have to worry about removing it or deleting it.

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‫We just fire off this function.

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‫It spawns the particle system and takes care of cleaning it up for us, which is great.

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‫So let's take a look at the syntax now.

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‫There are a number of input parameters, but this function has a number of overloads.

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‫Now, since there are a number of versions of this function, let's go into V's code and take a look

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‫at those different versions.

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‫Now I'm going to open up projectile CP and take a look at the on hit function.

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‫Now just down here at the bottom I'm going to type you gameplay statics spawn emitter at location and

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‫as soon as I type the opening parentheses, it's pop up is showing me the input parameters I need to

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‫pass in.

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‫But we see one of three, which means there are three different versions of this function.

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‫Three Overloads.

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‫I'm going to click the down arrow twice to take a look at this particular overload.

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‫Now it takes a world context object, a particle system and a location, and the remaining input parameters

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‫have.

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‫Default values, so they're optional.

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‫Notice the rotation parameter is set to zero rotator.

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‫Now if we like, we could set the emitters rotation to the rotation of the actor by passing in get active

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‫rotation.

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‫It's not too important, but I would like to spawn the emitter with the same rotation as the actor.

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‫So I'd like to use get active rotation and pass that in.

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‫But the rest of these parameters are optional.

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‫So since we know we need to call spawn emitter at location to play a particle system, we can do this

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‫in the on hit function.

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‫We know the first parameter is a world context object and we already know how to handle that.

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‫We know that it takes a particle system and we have a particle system variable that we can pass in.

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‫We also know that we need a location and a rotation and we know how to get those for a given actor using

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‫get actor location and get actor rotation.

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‫So since you have all of this information, I'd like you to use the U gameplay statics function spawn

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‫emitter at location in the on hit function for the projectile class.

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‫So passing this for the world context object, passing the particle system itself, that new hit particles

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‫variable we created and use the projectiles location using get active location and use the projectiles

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‫rotation using get actor rotation.

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‫Pause the video and spawn the emitter in the on hit function now.

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‫Okay.

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‫So I'm going to remove this line that we used just to take a look at the function overloads for this

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‫function.

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‫And I'm going to place this just before we destroy the actor.

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‫So if you placed it, say, at the end of the function, that's okay.

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‫The challenge was left open ended for you.

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‫But we're going to place this just before we destroy the actor, because if we destroy the actor, then

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‫it doesn't make sense to spawn particles after that.

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‫So we're going to do this before we destroy the actor.

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‫So we're going to say you gameplay statics spawn emitter at location and first we need our world context

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‫object, which is going to be this.

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‫Next we need our hit particles followed by our actors location for which we're going to use get actor

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‫location.

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‫Next we're going to pass in the rotation for which we'll use get actor rotation and now we're spawning

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‫the emitter at the location.

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‫Now, one thing I'd like to point out is that if my owner is a null pointer and we return out of this

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‫function early, well, it might be a good idea to just destroy the projectile there.

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‫So I'd like to remove this return statement and give this if statement its own body will still return.

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‫But just before we return, we should be destroying the actor.

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‫So I'm going to call destroy here in this if check.

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‫And in fact, even if we fail all of the other checks here, checking the other actor, we don't want

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‫a projectile just lingering around in the world.

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‫So we should move this second call to destroy outside the if check.

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‫That way, we're destroying the projectile when it hits something, no matter what.

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‫That way, we don't have lingering projectiles for any reason.

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‫Okay?

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‫And while we're being safe, we should notice that we're using hit particles here, which means we should

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‫check to see if the hit particles are set before we attempt to use them.

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‫Otherwise, we might be using a hit particles variable that has not been set and we should not use null

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‫pointers.

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‫So we're going to place an if check here to see if hit particles is valid and if it is valid, then

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‫it's safe to call spawn emitter at location here.

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‫All right.

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‫Let's go ahead and compile this now.

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‫And with a successful compile, we'll hop back into the editor and here's BP projectile.

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‫We have our hit particles set, so make sure that that is set before we test this out.

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‫Otherwise, we won't see anything.

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‫And if we hit play, we can wait for our go widget and then boom, check that out.

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‫We have clouds of smoke.

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‫We have hit particles being spawned.

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‫I'm going to go ahead and shoot at our enemies and we'll see that they get spawned when we're hitting

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‫the enemies as well.

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‫Perfect.

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‫So in summary, we now have spawned some hit particles.

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‫We have explosions when our projectiles hit something in the world.

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‫And the next step is to have a smoke trail that follows behind the projectile as it's flying through

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‫the air.

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‫And we'll take care of that in the next video.

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‫I'll see you soon.