WEBVTT 00:01.330 --> 00:06.640 Okay, so you're sitting at your desk and the project manager for your video game walks up and says, 00:06.640 --> 00:10.390 hey, lovely developer, I need knockback. 00:10.480 --> 00:15.190 And you look at your project manager and say, uh, what's knockback? 00:15.280 --> 00:17.050 And the PM says knockback. 00:17.080 --> 00:22.230 You know, when an enemy gets hit, it flies in the air, kind of like the death impulse. 00:22.240 --> 00:24.820 And you say, oh, knockback. 00:24.820 --> 00:25.620 Right. 00:25.630 --> 00:28.410 And your PM says, that's right, knockback. 00:28.420 --> 00:33.700 I need knockback and I know that you are capable of implementing that. 00:33.760 --> 00:39.970 The project manager then proceeds to tell you more details that you don't really know, such as well, 00:39.970 --> 00:47.140 damage abilities should have a knockback magnitude and when taking damage if it's not fatal knockback. 00:47.140 --> 00:53.800 And just so we have knockback well defined, it's when you launch the character into the air when they 00:53.800 --> 00:54.610 get hit. 00:54.610 --> 00:59.590 So for when an enemy takes fatal damage we have the death impulse, right? 00:59.590 --> 01:04.270 But when damage is not fatal, we are going to have a knockback. 01:04.270 --> 01:12.280 Now there should be a knockback chance that could be a parameter, and we can use that knockback chance 01:12.280 --> 01:17.710 to see if there was a successful knockback and then some damage abilities will not have knockback, 01:17.740 --> 01:20.590 their knockback chance will be zero, and so on. 01:20.620 --> 01:24.160 Now before your turns and walks away they say. 01:24.160 --> 01:29.530 Oh, and by the way, here's a hint use launch character and not add impulse. 01:29.530 --> 01:36.370 And then they turn and walk away, at which point you turn to your coworker and say, hey, why should 01:36.370 --> 01:39.000 we use launch character instead of add impulse? 01:39.010 --> 01:45.550 And your coworker turns to you and says, well, I think it's because you can use launch character without 01:45.550 --> 01:51.760 having to simulate physics and ragdoll the character and you say, oh, okay, that makes sense. 01:51.880 --> 01:55.780 So for this quest, you're going to implement knockback. 01:55.810 --> 02:00.730 There are a lot of steps to this, and you may find yourself needing to make some of the decisions, 02:00.730 --> 02:02.320 but I think you're capable of it. 02:02.320 --> 02:06.220 So pause the video and conquer knockback now. 02:09.440 --> 02:11.750 Okay so we need knockback. 02:11.780 --> 02:14.480 I'm going to start in the ability. 02:14.480 --> 02:20.150 So I'm going to close all tabs and go to my aura damage gameplay ability. 02:20.360 --> 02:23.720 So I'll go ahead and get the header file open. 02:24.140 --> 02:28.790 And I'm going to add a couple of parameters for knockback. 02:28.820 --> 02:34.670 Now we have a death impulse magnitude I'm going to have a knockback force magnitude. 02:34.670 --> 02:40.790 So whereas death impulse is an impulse are knockback is going to be a force. 02:40.790 --> 02:44.600 So I'm going to say knockback force magnitude. 02:46.020 --> 02:51.060 And it turned out that 60 was too low for death impulse. 02:51.060 --> 02:54.750 So I'm going to set those both to a thousand. 02:56.100 --> 02:59.400 But we'll almost certainly need to tweak this. 02:59.430 --> 03:02.220 Now we can also have a knock back chance. 03:02.220 --> 03:07.980 So if we want to do that we can say float, knock back chance. 03:08.790 --> 03:12.270 And I'm going to set it to zero by default. 03:12.270 --> 03:17.790 So it's more like something you enable rather than something that's enabled by default. 03:18.580 --> 03:22.060 If it's zero, then there's no need for knockback. 03:22.540 --> 03:26.170 Okay, so now we have a knockback magnitude. 03:26.170 --> 03:33.610 And just like death impulse, we're going to have a couple of parameters in our damage effect params. 03:33.700 --> 03:37.610 And that's going to be in our aura ability types. 03:37.630 --> 03:39.280 So let's open that. 03:40.990 --> 03:48.520 And right here in damage effect params, we're going to go ahead and add not only a knockback force 03:48.520 --> 03:52.090 magnitude, but a knockback force vector. 03:52.090 --> 03:56.470 So I'm just going to copy both the death impulse magnitude and death impulse. 03:56.470 --> 04:00.250 And this will be knockback force magnitude. 04:01.930 --> 04:04.820 By the way, it's okay if you didn't call yours the same. 04:04.840 --> 04:06.910 You could have just said knock back magnitude. 04:06.910 --> 04:07.990 That's totally fine. 04:07.990 --> 04:11.880 And instead of death impulse, we're going to have knock back force. 04:11.890 --> 04:13.420 A force is a vector. 04:13.900 --> 04:14.290 Okay. 04:14.290 --> 04:16.120 So we have those properties. 04:16.150 --> 04:20.740 Now we know that we're going to need something in the effect context right. 04:20.740 --> 04:22.600 For the knock back force. 04:22.690 --> 04:29.290 So really what we're going to do is just copy the knock back force here and paste it down in our effect 04:29.290 --> 04:32.070 context, just under death impulse. 04:32.080 --> 04:39.250 And once we have this set in the in the effect context, we know that it's going to have the correct 04:39.250 --> 04:41.100 magnitude by this time. 04:41.140 --> 04:46.210 Now because we have knock back force, we're going to have to handle it in. 04:46.210 --> 04:47.380 Net serialize. 04:47.380 --> 04:51.510 And by this point this is a pretty well known process. 04:51.520 --> 04:55.840 We're going to take the next bit in our rep bits. 04:55.840 --> 04:57.010 That's going to be 15. 04:57.010 --> 05:00.040 We're going to flip that bit and we're checking knock back force. 05:00.040 --> 05:02.380 Now to see if it's zero. 05:02.380 --> 05:06.400 And then we come down and check if that bit was flipped. 05:07.260 --> 05:09.660 Just like we did with Death Impulse. 05:10.200 --> 05:12.450 So we're checking the 15th bit. 05:13.460 --> 05:19.010 And then we're taking knockback force and calling net serialize on it. 05:19.040 --> 05:20.150 Piece of cake. 05:20.900 --> 05:26.830 And we have to make sure that we don't forget to scroll back up to serialized bits. 05:26.840 --> 05:33.380 And now that we're flipping 15 bits, we have to serialize all 15 of those bits. 05:33.380 --> 05:39.170 So this is something that we'll have to come back to each time we add to the effect context and update 05:39.170 --> 05:40.070 that as well. 05:40.430 --> 05:41.120 Okay. 05:41.390 --> 05:45.680 Now our effect context is going to need a getter and setter for this. 05:45.680 --> 05:52.940 So we're going to make a getter that returns an f vector called get knockback force. 05:53.660 --> 05:56.630 And it's going to return knockback force. 05:57.260 --> 06:02.090 And we'll have a setter void set knockback force. 06:04.130 --> 06:09.050 Which takes a const f vector reference called enforce. 06:11.640 --> 06:15.450 And we'll set knockback force equal to n force. 06:17.150 --> 06:18.890 And we have those now. 06:18.920 --> 06:24.330 Now we also are going to want a couple functions on our ability system library. 06:24.350 --> 06:27.020 So we'll go up to get death impulse. 06:27.230 --> 06:28.580 We'll copy it. 06:29.350 --> 06:32.920 We'll paste it and we'll have get knockback force. 06:35.170 --> 06:41.680 And we can go ahead and define this and we'll define it just like get death impulse. 06:42.280 --> 06:47.170 The only difference is we're going to call get knockback force on the effect context. 06:47.170 --> 06:51.370 And then we can scroll down to get set death impulse. 06:51.370 --> 06:55.900 And we can make one for set knockback force. 06:55.900 --> 06:58.990 So we'll call it set knockback force. 06:58.990 --> 07:02.290 And we'll call the input parameter in force. 07:02.440 --> 07:06.160 And we'll go ahead and generate the definition. 07:06.160 --> 07:08.770 Looks like Ryder gave me an inline one. 07:08.770 --> 07:12.460 So I'm going to cut it and put it into the cpp file. 07:12.550 --> 07:14.590 We're going to find set death impulse. 07:14.620 --> 07:18.430 We'll copy set knockback force just underneath it. 07:18.790 --> 07:23.830 Copy the contents from Set Death Impulse and change this to. 07:24.860 --> 07:25.310 Set. 07:25.340 --> 07:27.910 Knockback force passing in. 07:27.920 --> 07:29.510 In force. 07:30.540 --> 07:33.720 Now we have those functions on the ability system library. 07:34.200 --> 07:35.430 Okay, great. 07:35.460 --> 07:41.760 Next we need to make sure that our effect params carries that knockback force magnitude. 07:41.760 --> 07:46.130 And then also that we set the knockback force in it when we should set it. 07:46.140 --> 07:49.370 So back to aura damage gameplay ability. 07:49.380 --> 07:54.960 We're going to go into the cpp file to make damage effect params from class defaults, and we'll set 07:54.960 --> 07:56.420 that knockback force. 07:56.430 --> 07:59.460 We'll get it from the ability. 07:59.460 --> 08:07.530 So we're going to say params dot knockback force equals knockback force magnitude. 08:07.770 --> 08:10.320 And in fact we have to set the magnitude. 08:10.320 --> 08:15.060 Actually knockback force magnitude equals knockback force magnitude. 08:15.060 --> 08:18.690 Now we also have the knockback force chance right. 08:18.690 --> 08:21.480 We also made a knockback chance actually. 08:21.480 --> 08:25.560 So we could add that as well in aura ability types. 08:25.560 --> 08:33.000 In damage effect params we can just add another float for the knockback chance also. 08:33.000 --> 08:40.380 So I'm going to go ahead and make that two knockback chance equals zero. 08:41.930 --> 08:47.330 And we'll set that here in make damage effect params from class defaults. 08:47.330 --> 08:50.780 So we'll say params dot knockback chance. 08:52.430 --> 08:54.230 Equals knockback chance. 08:56.560 --> 08:57.460 There we go. 08:58.400 --> 09:05.780 So now we can start the whole thing rolling by setting the knockback force in the effect context. 09:05.780 --> 09:09.130 And I'm going to do this in the aura projectile. 09:09.140 --> 09:11.840 So I'm going to go ahead and get that open. 09:12.350 --> 09:17.390 I'll get the CP file open for it or a projectile. 09:17.840 --> 09:19.550 And we'll see that right here. 09:19.550 --> 09:21.320 We're setting death impulse. 09:21.470 --> 09:24.020 We can also set the knockback force. 09:24.140 --> 09:30.230 Let's calculate that though we're going to say const f vector knockback force. 09:30.910 --> 09:34.000 Equals get actor forward vector. 09:36.280 --> 09:37.270 Times. 09:37.270 --> 09:37.990 Damage effect. 09:37.990 --> 09:38.560 Params. 09:38.770 --> 09:39.340 Knockback. 09:39.340 --> 09:40.180 Force. 09:40.300 --> 09:41.680 But here's the thing. 09:41.680 --> 09:43.570 We have a knockback chance, don't we? 09:43.600 --> 09:46.090 So what we should do is roll the dice. 09:46.090 --> 09:48.970 We should see if we should get a knockback. 09:48.970 --> 09:56.650 So we're going to say const bool be knockback equals f math rand range. 09:58.940 --> 10:00.680 From 1 to 100. 10:01.640 --> 10:04.520 We'll see if that's less than damage effect params. 10:04.730 --> 10:05.330 Knockback. 10:05.330 --> 10:06.350 Chance. 10:06.650 --> 10:10.310 And we'll only do this if b knockback is true. 10:10.340 --> 10:17.750 So if B knockback is true, then we should calculate knockback force and we can take our damage effect 10:17.750 --> 10:20.570 params dot knockback force. 10:20.570 --> 10:24.020 And we can set that here equal to knockback force. 10:24.050 --> 10:30.590 Then when we call apply damage effect we'll be passing in the knockback force along with that. 10:30.590 --> 10:37.490 So that's only if we got a successful knockback and then apply damage effect can handle what happens. 10:37.490 --> 10:47.200 So an aura ability system library we can go into apply damage effect and we can set that knockback force. 10:47.210 --> 10:49.430 We'll do it right after setting the death impulse. 10:49.430 --> 10:51.170 So set knockback force. 10:51.350 --> 10:58.700 We'll get the effect context handle and we'll get damage effect params dot knockback force. 10:58.700 --> 11:01.580 So now that's set on the context handle. 11:01.700 --> 11:06.770 At that point we'll be applying the damage effect with a knockback force. 11:06.770 --> 11:13.220 And the last piece of this puzzle is to use that knockback force in the attribute set. 11:13.250 --> 11:20.570 Of course we need to add the capability there of using it, but we can go to the attribute set and at 11:20.570 --> 11:24.050 least find out where we should be reacting here. 11:24.050 --> 11:30.170 So I'm going to go into aura attribute set dot cp find handle incoming damage. 11:30.170 --> 11:31.130 Here it is. 11:31.130 --> 11:33.800 And find where we have be fatal. 11:33.800 --> 11:37.970 And right here is where we do the death impulse stuff. 11:37.970 --> 11:41.780 And in the else case is where we can do the knockback force. 11:41.780 --> 11:47.870 So we're doing the effects dot hit react while there hit reacting. 11:47.900 --> 11:50.360 They might be knocking back right. 11:50.360 --> 11:52.850 But we could also take over. 11:52.850 --> 11:56.330 Make sure they don't hit react if there's a knockback force. 11:56.330 --> 11:57.410 But that's up to us. 11:57.410 --> 11:58.780 It doesn't really matter. 11:58.790 --> 12:03.050 The the animations being played while in knockback while in the air. 12:03.050 --> 12:05.900 That just depends on what we want to be played. 12:05.900 --> 12:13.220 But either way, we're going to handle knockback here, and what we need to do is see if that knockback 12:13.220 --> 12:16.130 force is greater than zero. 12:16.130 --> 12:22.070 So we're going to check if and we're going to get that effect context. 12:22.070 --> 12:25.310 So from props we'll get the effect context handle. 12:25.310 --> 12:28.100 And how do we get that knockback force. 12:28.130 --> 12:30.530 Actually we have a function for that. 12:30.530 --> 12:35.900 So I'm going to cut what I just wrote and use your aura ability system library. 12:35.900 --> 12:41.240 Get knockback force passing in the effect context handle. 12:42.410 --> 12:47.690 Now this returns actually a knockback force which is a vector. 12:47.690 --> 12:53.630 So I'm just going to make a const f vector reference called knockback force. 12:54.380 --> 12:56.600 And I'll just set that equal to this. 12:56.600 --> 13:00.620 That way I don't have too long of a conditional in here. 13:00.620 --> 13:06.050 And then I'm going to check the knockback force and see if it's not zero. 13:06.050 --> 13:11.300 So I'll get knockback force and I'll call I'll use is nearly zero. 13:11.480 --> 13:13.460 And I'll put a tolerance in there. 13:13.460 --> 13:18.290 Something that's small but not that small, something like ten. 13:18.290 --> 13:26.810 So if knockback force is near zero with this tolerance, we could even make it smaller like one. 13:26.810 --> 13:31.310 Either way, if it's almost zero, we won't get into this if statement. 13:31.310 --> 13:34.910 But if it is zero, then we know what we can do. 13:34.910 --> 13:36.410 We can launch the character. 13:36.410 --> 13:43.220 Now in this case we have the character already and the function launch character is already on the character 13:43.220 --> 13:44.030 class. 13:44.030 --> 13:49.550 So we could just take props, dot target character and simply call launch character on it. 13:49.550 --> 13:52.370 No need to go through the trouble to make interface functions. 13:52.370 --> 13:54.050 If you did, that's fine. 13:54.470 --> 13:58.490 It was good practice, but you don't actually need to. 13:58.490 --> 14:05.150 In this case, you can just call launch character directly on the character and pass in launch velocity, 14:05.180 --> 14:12.680 we're going to pass in knockback force for the launch velocity and x y override along with z override. 14:12.680 --> 14:15.890 This is how we can control the knockback force a little bit. 14:15.890 --> 14:21.320 If we wanted to launch the character in the x y direction, we would pass in true. 14:21.320 --> 14:25.850 And if we don't want to launch the character in the Z, we would pass in false there. 14:25.850 --> 14:31.130 But I do want to launch the character in the Z as well, so I'm going to pass in both true true for 14:31.130 --> 14:32.270 launch character. 14:32.270 --> 14:38.390 Now this is going to be basically in the direction that the Firebolt was flying. 14:38.390 --> 14:44.030 But I'd like knockback to have a little bit of a pitch override. 14:44.120 --> 14:51.020 In other words, I like my knockback force to be angled up just a bit so we could really enjoy seeing 14:51.020 --> 14:52.940 those enemies fly all around. 14:52.940 --> 14:57.950 And for that reason, I'm going to go back to Aura Projectile when we're setting our. 14:58.090 --> 14:59.490 Knockback force. 14:59.500 --> 15:06.550 And as we got our actor forward vector here, we can rotate that actors forward vector. 15:06.640 --> 15:16.330 I'd like to say const f vector knockback direction equals get actor forward vector. 15:16.360 --> 15:23.260 But on this vector I'm going to call rotate angle axis, which will allow me to rotate the vector about 15:23.260 --> 15:25.420 some axis by some angle. 15:25.420 --> 15:30.550 And I'd like to rotate it upward by oh say 45 degrees. 15:30.550 --> 15:36.190 And the axis I'd like to rotate it about is the right vector. 15:36.220 --> 15:38.310 Get actor right vector. 15:38.320 --> 15:46.000 And if we want this to be a basically pitch override completely, we could zero out the forward vector. 15:46.000 --> 15:47.500 So that's one way to do it. 15:47.500 --> 15:52.240 But we could also say get actor rotation. 15:52.600 --> 15:56.230 And from that rotation we can get the vector. 15:56.230 --> 15:59.800 And if we want it get actor rotation. 15:59.800 --> 16:03.820 We could create an F rotator called rotation. 16:04.150 --> 16:09.730 And we could take this rotation dot pitch and set it to 45 degrees. 16:09.730 --> 16:12.520 So it's pointing 45 degrees up. 16:12.520 --> 16:17.080 And then we could take that knockback direction and make it out of rotation. 16:17.080 --> 16:22.000 We could say that knockback direction equals rotation vector. 16:22.210 --> 16:23.410 That would work too. 16:23.410 --> 16:28.600 And then we could take knockback direction and use it instead of the forward vector for our fireball. 16:28.600 --> 16:30.220 That's another thing we could do. 16:30.220 --> 16:34.240 And I'm just seeing now that I use knockback force. 16:34.330 --> 16:38.140 This should actually be knockback force magnitude, right? 16:38.140 --> 16:45.610 Because otherwise we'd be setting knockback force to knockback force times knockback direction. 16:45.610 --> 16:47.590 Knockback force is a zero vector. 16:47.590 --> 16:49.360 So we'd be setting this to zero. 16:49.690 --> 16:52.600 So now we're setting this to a knockback force. 16:52.630 --> 16:54.310 Let's go ahead and test this out. 16:55.520 --> 16:56.060 Okay. 16:56.060 --> 17:00.890 So let's go into Firebolt and let's change the knockback chance to 100. 17:01.250 --> 17:03.890 So 100% chance to knock back. 17:03.890 --> 17:05.570 And let's just see what happens. 17:07.220 --> 17:08.570 Ooh, look at that. 17:10.340 --> 17:11.780 Awesome. 17:13.720 --> 17:15.030 All right. 17:15.040 --> 17:16.930 Oh, and I just realized something. 17:16.930 --> 17:22.870 If we have knockback now, enemies can fly over, and we need to take care of that, don't we? 17:22.900 --> 17:29.470 Either the enemy should die shortly after falling off the edge, or they should just bounce and come 17:29.470 --> 17:30.310 back in. 17:30.430 --> 17:35.590 I personally like the option of having them bounce and come back in, because if you can knock an enemy 17:35.590 --> 17:40.000 over and kill them that way, it's kind of something that could be exploited in a way. 17:40.000 --> 17:42.760 So I kind of don't like that possibility. 17:42.760 --> 17:46.630 But there goes an enemy and he's flying away and his head's on fire. 17:46.660 --> 17:47.890 Cool. 17:47.890 --> 17:53.020 So okay, so knockback force magnitude of 1000 is a bit much. 17:53.020 --> 17:55.900 I think we can put it to 500 or so. 17:55.900 --> 18:01.840 And if we set the knockback chance down to say 20, then we won't always get a knockback. 18:01.840 --> 18:03.760 But every once in a while we will. 18:04.650 --> 18:06.060 Pretty cool. 18:06.620 --> 18:10.550 Now if we want to see knock back on aura two, we can do that. 18:10.550 --> 18:18.800 And all we'd have to do is go into blueprints, ability system, enemy abilities and check out melee 18:18.800 --> 18:22.460 and ranged attack and give them a knockback chance. 18:22.460 --> 18:30.020 I'd like the melee attack to maybe have a knockback chance of 20 with a knockback force magnitude of 18:30.020 --> 18:31.040 500. 18:31.070 --> 18:32.780 We'll do the ranged attack. 18:32.930 --> 18:39.350 The ranged attack will be a knockback chance of 10% knockback force magnitude of 400. 18:39.350 --> 18:47.630 But before we go on and move on with our lives, I'm going to set the melee knockback chance to 100 18:47.630 --> 18:51.470 just for testing and see what aura looks like knocked back. 18:53.550 --> 18:56.520 Okay not seeing the knockback happen. 18:57.260 --> 19:01.040 Oh, and of course, we're not setting the knockback vector, are we? 19:01.070 --> 19:06.050 We're only setting the knockback vector in the projectile on sphere overlap. 19:06.050 --> 19:10.070 So it's up to us to set that knockback force. 19:10.070 --> 19:17.420 So for example, here in melee attack, if we're about to say cause damage for example, that would 19:17.420 --> 19:20.570 be a good spot to set that knockback force. 19:20.570 --> 19:25.370 So here we have cause damage in the aura damage gameplay ability. 19:25.460 --> 19:26.870 Why don't we take a look at that. 19:26.870 --> 19:31.880 Let's go to Aura Damage gameplay ability I'm going to find cause damage. 19:31.880 --> 19:32.920 Here it is. 19:32.930 --> 19:38.570 So here is where we know we're going to cause damage. 19:38.570 --> 19:45.740 This would be an appropriate place to perhaps do it, but rather than just setting a knockback force 19:45.740 --> 19:51.320 for every damage gameplay ability, I'd like this to be custom per damage gameplay ability. 19:51.320 --> 19:58.430 So really cause damage would be a little bit easier to work with when it comes to setting things like 19:58.430 --> 20:04.010 parameters on the effect context, it would be a lot easier if caused damage could take in an effect 20:04.010 --> 20:05.030 context. 20:05.030 --> 20:10.580 So if we go back to our Aura ability system library, for example, and look at applied damage effect, 20:10.610 --> 20:11.390 we'll see that. 20:11.390 --> 20:14.000 First we make an effect context handle. 20:14.000 --> 20:14.540 Right. 20:14.540 --> 20:23.420 And then we make a spec handle using not only the damage gameplay effect class, but also the ability 20:23.420 --> 20:26.120 level and the effect context handle. 20:26.120 --> 20:34.160 So making a spec handle this way we could specify the effect context using an effect context handle. 20:34.160 --> 20:41.390 So using that cause damage function, we kind of bypass the effect context altogether. 20:41.780 --> 20:45.650 So there are a number of ways we can handle something like this. 20:46.260 --> 20:52.800 For one, we could make some damage effect params and we can go through the pipeline we created for 20:52.800 --> 20:55.980 aura projectile, namely make these params. 20:55.980 --> 21:05.430 First we can set the target for our damage effect and then we can use our ability system blueprint library 21:05.430 --> 21:07.710 function apply damage effect. 21:07.800 --> 21:13.380 If we wanted to make it a little bit easier to set that knockback force and any other things that we 21:13.380 --> 21:14.130 want to set. 21:14.130 --> 21:21.570 So really, if we're going to make a damage effect params from class defaults, we could expose this 21:21.570 --> 21:22.830 function to blueprint. 21:22.830 --> 21:26.640 For example, we can make it a blueprint pure. 21:28.540 --> 21:30.790 Why don't we see what happens if we do that? 21:30.790 --> 21:34.290 So I'm going to go ahead and close the editor. 21:34.300 --> 21:39.940 We'll save everything first and we'll launch after having made this blueprint here. 21:39.940 --> 21:46.690 And once we have damage effect params, we know that the ability system library has applied damage effect. 21:46.810 --> 21:49.360 So we could go about this a number of ways. 21:49.510 --> 21:56.830 We can make those damage effect params in blueprint, expose them to blueprint and set that knockback 21:56.830 --> 22:00.730 force in blueprint and then call Apply Damage effect in blueprint. 22:00.730 --> 22:05.470 Or we could make a blueprint callable function to do all of that for us. 22:05.590 --> 22:07.510 I'd like to show both solutions. 22:07.660 --> 22:12.700 So in aura ability types I'd like to expose all of these to blueprint. 22:12.700 --> 22:15.850 So I'll make them all blueprint read right. 22:15.850 --> 22:25.630 So for world context object damage effect class source ASC and target ASC base damage ability level 22:25.660 --> 22:35.110 damage type debuff chance debuff damage duration, frequency, impulse magnitude, death impulse, knockback 22:35.110 --> 22:39.160 force magnitude, knockback force chance, and knockback force. 22:39.160 --> 22:45.640 Now we could set those in the blueprint if we wanted to, but in addition to that, I'd like a function 22:45.640 --> 22:47.650 that can do all this for us. 22:47.650 --> 22:54.310 In fact, we can calculate that knockback force at least its direction if we know the knockback force 22:54.310 --> 23:03.880 magnitude and the effect params based on the avatar actor's location and the target actor's location. 23:03.880 --> 23:04.660 Right? 23:04.660 --> 23:11.350 In other words, what we could do is we could have a function on or a damage gameplay ability like this. 23:11.350 --> 23:19.270 Make damage effect params from class defaults that takes the target actor if it's not a null pointer, 23:19.270 --> 23:26.050 and calculates the knockback direction and the death impulse direction, and then if we don't set those 23:26.050 --> 23:32.680 later and overwrite them, then they'll at least have direction set for them. 23:32.680 --> 23:34.840 So here's what I'm going to do. 23:34.840 --> 23:40.780 If target actor is not a null pointer, then way down here. 23:41.200 --> 23:45.190 First we'll check if we'll see if it's valid is valid. 23:45.220 --> 23:47.710 Target actor first and foremost. 23:47.740 --> 23:56.650 And if it is valid, then I'd like to calculate a direction from the enemy to the target actor. 23:56.710 --> 24:03.100 Now the enemy is going to be the avatar actor of the owning ability system component. 24:03.100 --> 24:07.780 So we can call get avatar actor from actor info. 24:07.900 --> 24:14.830 And I'd like to get a vector from the avatar to the target, which will be a const f vector. 24:14.860 --> 24:27.040 We'll call it to target and it'll be target actor get actor location minus get avatar actor from actor 24:27.040 --> 24:29.440 info get actor location. 24:33.470 --> 24:35.960 Now this is not a normalized vector. 24:35.960 --> 24:42.830 So I'm going to wrap it in parentheses and call get safe normal. 24:43.850 --> 24:51.470 So we have a two target which is a normalized vector with the direction from the avatar to the target. 24:51.650 --> 24:57.500 Now if we wanted to give it a pitch override we could we could do it in a number of ways. 24:57.500 --> 25:02.210 We could make this a f rotator called rotation. 25:02.210 --> 25:04.910 And instead of calling get safe normal. 25:06.550 --> 25:15.280 We could call rotation, take rotation pitch and set that to 45. 25:16.360 --> 25:17.680 Just override it. 25:17.680 --> 25:20.650 That could be a parameter and the damage effect params. 25:20.650 --> 25:23.110 And then we can say const f vector. 25:24.190 --> 25:27.940 To target equals rotation vector. 25:29.460 --> 25:31.110 That's something we could do. 25:31.110 --> 25:34.350 And then we could set our knockback force and our death impulse. 25:34.350 --> 25:39.300 If we like, we can say params dot death impulse. 25:39.300 --> 25:43.560 We'll do that first equals to target. 25:44.640 --> 25:55.710 Times death impulse magnitude and we can say params dot knockback force equals to target times knockback 25:55.710 --> 25:57.090 force magnitude. 26:00.440 --> 26:08.720 So really, we're just making this set those directions to a default with a pitch override of 45 from 26:08.720 --> 26:12.770 the avatar to the target, but only if that target actor is set. 26:12.770 --> 26:15.980 And then we wouldn't have to go in and set it right. 26:15.980 --> 26:22.490 So we know that these will be set, of course, for the fireball we override those, but at least they're 26:22.490 --> 26:24.800 set by default if there is a target. 26:25.010 --> 26:33.800 So what I'm going to do in the melee attack here is I'm going to call make damage effect params from 26:33.800 --> 26:35.030 class defaults. 26:35.030 --> 26:40.250 And I know that this has a knockback force, but I exposed these parameters. 26:40.250 --> 26:45.080 If I wanted to say break damage effect params, I could. 26:45.110 --> 26:51.590 I could expand it and see all of them and if I wanted, I could drag off of one and say make damage 26:51.590 --> 27:00.110 effect params and then I could go in and take my knockback force and calculate it here in blueprint. 27:00.110 --> 27:06.710 If I wanted to do that, and then plug it in right here and then anything that I want to take from what's 27:06.710 --> 27:14.030 created by this function here, which we made blueprint pure, we could just pass it on in and overwrite 27:14.030 --> 27:17.480 anything here that we want to overwrite like this. 27:17.480 --> 27:20.120 So I figured I'd show you this way too. 27:20.150 --> 27:22.100 So we have flexibility in blueprint. 27:22.100 --> 27:28.100 But at the same time I know my knockback force is set so I don't have to break it. 27:28.100 --> 27:33.560 After all, I can just take it and then we can use an ability system component. 27:33.590 --> 27:38.330 Apply damage effect is what it's called and that takes the damage effect params. 27:38.330 --> 27:43.850 We have it there and when we make the damage effect params from class defaults. 27:43.850 --> 27:48.500 Here in the for loop we have the array element which is our target actor. 27:48.500 --> 27:50.660 We are passing in to cause damage. 27:50.660 --> 27:56.480 Now we can pass that in to make damage effect params from class defaults and instead of causing damage 27:56.480 --> 28:02.810 with cause damage, we can cause damage with apply damage effect on the ability system blueprint library. 28:02.810 --> 28:05.900 And now we know the knockback force will be applied. 28:05.900 --> 28:07.910 So let's test that out. 28:11.470 --> 28:17.980 Boom, and we have a knock back and we can do the same thing for the ranged attack as well. 28:17.980 --> 28:25.660 So the ranged attack, I believe, is spawning a projectile actually, and that is using spawn projectile 28:25.660 --> 28:30.580 on the aura projectile spell, which is actually making those effect parameters. 28:30.580 --> 28:33.220 So we could set a knockback force of 100 here. 28:33.220 --> 28:37.360 And we should see that knockback force from the slingshot rocks. 28:38.000 --> 28:39.050 And we do. 28:39.410 --> 28:40.200 Cool. 28:40.220 --> 28:46.400 So now that we know that's working, the only thing left is, well, it kind of looks funny for aura 28:46.400 --> 28:47.570 when she's in the air. 28:48.110 --> 28:48.680 Right. 28:48.680 --> 28:52.790 I'm not a big fan of her doing the running animation while she's in the air. 28:52.820 --> 28:54.650 We need to fix that. 28:54.650 --> 28:56.240 And we'll fix that real quick too. 28:56.270 --> 29:00.530 So we'll go to assets, characters, aura animations. 29:00.530 --> 29:03.980 And no, we need to go to blueprints. 29:03.980 --> 29:05.090 Character. 29:05.090 --> 29:05.990 Aura. 29:07.250 --> 29:08.070 AB aura. 29:08.090 --> 29:09.050 That's what I need. 29:09.080 --> 29:10.940 Her animation blueprint. 29:10.940 --> 29:17.110 And in the event graph, we should be calculating whether or not Ora is in the air. 29:17.120 --> 29:19.580 And we can get that from character movement. 29:19.940 --> 29:23.540 So I'm just going to make this a sequence node. 29:25.310 --> 29:31.280 The first thing we do is the stuff that we're doing here set the ground speed and should move. 29:31.460 --> 29:38.900 But in addition to this, I'd like to get the character movement and call is falling, and if is falling 29:38.900 --> 29:41.750 is true, then we'll use a different animation. 29:41.750 --> 29:46.640 So I'm going to promote this to a variable called is falling. 29:47.320 --> 29:49.090 And we'll be setting that too. 29:49.510 --> 29:56.440 And then we can go into main states, and we can have a state here for when or is in the air. 29:56.620 --> 30:00.580 So if or is in the air I want to play an in air animation. 30:00.580 --> 30:01.600 Here's one. 30:01.600 --> 30:03.610 I think this one will work. 30:03.610 --> 30:07.450 So I'm going to go ahead and drag that in and get a state machine for in air. 30:07.690 --> 30:14.130 And really if aura is falling, if that is falling Boolean is true. 30:14.140 --> 30:20.170 I want to transition into an air whether we're idling, whether we're running either one. 30:20.170 --> 30:22.120 I want a transition to in air. 30:22.150 --> 30:30.310 Now I could drag from idle to an air and from running to in air and add the same transition rule is 30:30.310 --> 30:31.600 falling for those. 30:31.600 --> 30:32.860 That's one way. 30:32.860 --> 30:35.980 Another way is to right click and use a state alias. 30:36.010 --> 30:40.510 We can call this to in air and bring it into an air. 30:40.510 --> 30:45.670 And then to an air can serve as an arrow coming from any number of nodes. 30:45.670 --> 30:48.310 By checking the checkboxes over here. 30:48.310 --> 30:54.760 So if we check running an Idle then this is the same as having two arrows coming to an air, both of 30:54.760 --> 30:57.220 which will have the same transition rule. 30:57.460 --> 31:03.490 Now I can open that transition rule and I can use is falling for that. 31:03.730 --> 31:05.440 So that makes it easier. 31:05.470 --> 31:08.560 Of course we need to transition out of in air. 31:08.860 --> 31:12.460 So if we're no longer falling we'll transition back. 31:12.460 --> 31:15.220 And this can be for is falling. 31:15.220 --> 31:17.200 Not so not boolean. 31:18.630 --> 31:20.490 We can transition there. 31:21.330 --> 31:28.170 We could even have a to idol as well if we wanted one of those, and then we could transition to idol 31:28.170 --> 31:29.430 from any states. 31:30.290 --> 31:31.610 I'll just show you what that looks like. 31:31.610 --> 31:40.280 We'll just do a state alias called to idle, and this goes to idle, and it'll have that transition 31:40.280 --> 31:40.970 rule there. 31:41.000 --> 31:44.900 That's fine if you want to do it either way, I'm just going to have one here. 31:44.900 --> 31:50.870 And use is falling with a not boolean hooked in there. 31:52.500 --> 31:54.780 And now when is falling? 31:54.930 --> 31:56.340 We should see. 31:57.400 --> 31:58.120 There we go. 31:58.150 --> 31:59.170 We're in the air. 32:00.250 --> 32:01.210 All right. 32:01.680 --> 32:02.100 Now. 32:02.100 --> 32:05.160 It's a little annoying when the enemies have 100% knockback. 32:05.190 --> 32:06.660 That's not what I want. 32:06.690 --> 32:08.550 That's just for testing purposes. 32:08.550 --> 32:10.800 We'll be setting that knockback chance down. 32:10.800 --> 32:17.190 And realistically, for games you would have like 0% knockback chance for most of your enemies and then 32:17.190 --> 32:19.890 some of your special enemies would have knockback, right? 32:19.950 --> 32:23.220 So you don't have to have knockback on all enemies. 32:23.220 --> 32:29.770 You could subclass your abilities for individual enemies and set those parameters differently for them. 32:29.790 --> 32:35.520 I'm going to have a knockback chance of, let's say 10% for the ranged attacker, but the knockback 32:35.520 --> 32:41.490 force magnitude could be a little higher 500 and the melee attack can have a knockback chance. 32:41.490 --> 32:47.280 And that's going to be probably, I'd say 1,520%. 32:47.550 --> 32:49.800 And with that we have knockback. 32:49.800 --> 32:52.410 And knockback works both ways. 32:52.410 --> 32:54.750 And auras. 32:54.750 --> 32:56.670 Firebolt spell. 32:56.940 --> 32:59.970 I'd like to have at least a little bit more knockback than that. 33:03.950 --> 33:08.870 So in GA firebolts knockback chance, I think 20 actually is fine. 33:08.870 --> 33:14.000 We'll leave it at 20 and 20% of the time we'll see them knock back. 33:16.010 --> 33:17.630 There was a knock back. 33:17.780 --> 33:18.680 Great. 33:18.800 --> 33:24.740 And the last, last, last thing I know, this lecture is getting long, but the very last thing is 33:24.740 --> 33:28.940 I wanted to make sure that enemies can't fly off the map. 33:28.940 --> 33:32.060 And for that, I'm going to get a blocking volume. 33:33.870 --> 33:35.400 So I'm going to get volumes. 33:35.400 --> 33:36.960 We're going to get a blocking volume. 33:36.960 --> 33:45.090 I'm going to drag one in and I'm just going to go to perspective top and get that blocking volume. 33:46.520 --> 33:47.960 Right about there. 33:48.200 --> 33:51.680 I don't want it encroaching into the play area. 33:51.680 --> 33:53.090 So it's going to be here. 33:55.300 --> 33:57.580 And I'm going to make it this big. 33:57.760 --> 34:00.430 I'm going to duplicate it and bring one down here. 34:01.120 --> 34:06.430 I'm going to duplicate it again with snapping on and bring one up here. 34:07.470 --> 34:08.660 And one here. 34:08.670 --> 34:12.570 I just don't want them flying off the edge, that's all. 34:12.600 --> 34:16.950 So going back to perspective, we can see we got some blocking volumes. 34:16.980 --> 34:21.810 Oh and I'm going to need to make them bigger in the Z dimension as well. 34:21.810 --> 34:24.360 So I'll go ahead and select all four. 34:25.580 --> 34:27.500 Not that volume. 34:31.700 --> 34:33.890 One, two, three. 34:35.630 --> 34:40.640 For press R and we'll scale them up nice and big. 34:45.020 --> 34:46.040 That should do it. 34:46.740 --> 34:53.520 And with that now we won't have the problem of enemies flying off the edge. 35:02.450 --> 35:03.310 All right. 35:03.320 --> 35:07.250 Awesome job in this lecture and I'll see you in the next one.