WEBVTT 00:06.990 --> 00:08.160 Welcome back. 00:08.160 --> 00:13.920 Now that we have a function to save the world, we need a function to load the world. 00:13.920 --> 00:16.200 So let's go to aura game mode base. 00:16.200 --> 00:21.240 And just under save World state we'll make a new function called Load World State. 00:22.620 --> 00:27.990 And this can also take in a you world pointer called world. 00:29.670 --> 00:33.480 Let's go ahead and generate the definition for this. 00:36.820 --> 00:40.990 And let's think about how we can go about loading the world state. 00:41.140 --> 00:44.380 Well, first of all, we need to know what that world name is. 00:44.380 --> 00:49.930 And just like we did up here and save world State, we're going to get the world name through git map 00:49.930 --> 00:54.430 name and remove from the start of it the streaming levels prefix. 00:55.010 --> 00:57.680 So let's get those two lines right here. 00:57.800 --> 01:00.920 And I'd also like the game instance. 01:00.920 --> 01:06.470 So I'm going to get these two lines where I'm getting or a game instance as well. 01:06.470 --> 01:08.060 We'll go ahead and get those. 01:08.060 --> 01:13.880 And next I want to check to see if the save game exists. 01:13.880 --> 01:16.850 It has to exist if we hope to load it. 01:16.850 --> 01:21.350 So we're going to check if you gameplay statics. 01:23.690 --> 01:31.370 Does save game exist and we're going to check for the slot name using Aura Jai. 01:33.120 --> 01:40.020 Load slot name and or a GI load slot index. 01:41.610 --> 01:49.710 If this save game object exists, we can then proceed to iterate over the actors in the world, at least 01:49.710 --> 01:54.300 those that implement our save interface, and we can load them. 01:54.300 --> 02:02.670 We can do anything we wish, such as restore those serialized variables that we serialized and perhaps 02:02.670 --> 02:04.470 call a load function on them. 02:04.470 --> 02:06.420 They have an interface, after all. 02:06.420 --> 02:10.680 So what we're going to do is iterate, just like we did up here. 02:10.800 --> 02:16.380 We're going to use f actor iterator, iterating over the actors in the world. 02:16.380 --> 02:20.220 I'm going to copy the line where we dereference the iterator as well. 02:21.290 --> 02:24.380 We're just going to need a closing curly brace there. 02:24.560 --> 02:29.990 And once we have that actor, we can filter out actors that don't implement the interface. 02:29.990 --> 02:38.660 We can say if not actor implements the you save interface. 02:38.690 --> 02:40.850 Don't forget your parentheses there. 02:40.850 --> 02:42.830 And we can use continue. 02:43.010 --> 02:49.100 And that way we only continue for actors that do implement the interface. 02:49.430 --> 02:50.060 Okay. 02:50.060 --> 02:51.170 So what next. 02:51.170 --> 02:58.850 Well I want to get all the actors in the array for the f saved map that has this map name in our save 02:58.850 --> 03:00.080 game object. 03:00.080 --> 03:02.000 So where's our save game object. 03:02.000 --> 03:03.410 We need to get that don't we. 03:03.410 --> 03:08.120 Right here inside of does save game exist our if statement. 03:08.360 --> 03:09.740 Let's load it. 03:09.740 --> 03:13.730 Let's use you load screen save game. 03:13.730 --> 03:20.990 We'll call it save game and we'll cast to you load screen save game. 03:20.990 --> 03:22.430 What are we going to cast? 03:22.430 --> 03:23.840 Well let's load it with you. 03:23.840 --> 03:25.460 Gameplay statics. 03:27.710 --> 03:33.020 Load game from slot using our aura GI. 03:34.610 --> 03:40.880 Load slot name and our aura GI load slot index. 03:42.580 --> 03:44.530 Don't forget your semicolon. 03:44.530 --> 03:47.650 Now we have our load screen save game here. 03:47.650 --> 03:48.280 Right. 03:48.280 --> 03:49.630 Let's check if it's null. 03:49.630 --> 03:54.190 Let's say if save game equals null pointer. 03:54.190 --> 03:58.660 And let's go ahead and log an error. 03:58.660 --> 04:02.290 Let's use u log log ora. 04:04.430 --> 04:13.940 Error text and we'll just go ahead and say failed to load slot and we'll return. 04:16.070 --> 04:18.020 So something's gone wrong. 04:18.020 --> 04:20.330 If we haven't been able to load. 04:20.330 --> 04:27.560 Now that we have our save game down here, let's iterate over its map that has the world name that we 04:27.560 --> 04:28.310 want. 04:28.430 --> 04:38.120 So in other words, let's say for f saved actor, saved actor and save game and we have a function get 04:38.120 --> 04:43.760 saved map with map name passing in world name. 04:44.270 --> 04:52.370 Now this is the F saved map, which contains the array of saved actors which we can access through the 04:52.370 --> 04:54.650 dot operator like so. 04:54.650 --> 04:56.750 So we're getting our save game object. 04:56.750 --> 05:01.580 We're getting the map with this name and looping over it saved actors. 05:01.580 --> 05:04.970 And for each saved actor we're getting that data. 05:04.970 --> 05:11.570 And this is already inside of a for loop looping over all the actors, at least those that implement 05:11.570 --> 05:12.410 the interface. 05:12.410 --> 05:14.510 So let's check if the names coincide. 05:14.510 --> 05:23.210 Let's say if saved actor dot actor name equals actor get f name. 05:23.390 --> 05:26.090 That's how we got it in the first place, after all. 05:26.390 --> 05:31.100 And if these actors have the same name, we want to load it up. 05:31.100 --> 05:33.500 Now remember we saved the transform. 05:33.500 --> 05:36.110 But my checkpoints are not mobile. 05:36.110 --> 05:39.440 They're not something that we should update the transform for. 05:39.440 --> 05:40.640 That's okay. 05:40.640 --> 05:46.610 We can give our save interface a function that can return a boolean. 05:46.610 --> 05:51.740 If we want to know whether or not we should update the transform for whatever reason, right. 05:51.740 --> 06:01.130 So we can take our saved interface and create a bool returning function should load transform and we 06:01.130 --> 06:02.240 can give it a new function. 06:02.240 --> 06:04.340 Let's give it blueprint callable. 06:04.340 --> 06:06.680 Let's give it blueprint native event. 06:08.020 --> 06:09.520 To make it easy to call. 06:09.520 --> 06:12.940 And let's give our checkpoint the function. 06:12.940 --> 06:20.350 Let's go ahead and make a comment here that says save interface. 06:20.350 --> 06:23.830 Let's close it off with end save interface. 06:24.160 --> 06:31.660 And let's override bool should load transform implementation override. 06:31.660 --> 06:34.870 And for this I'm just going to implement it here. 06:34.870 --> 06:36.010 Return false. 06:36.010 --> 06:39.310 And this should have the virtual specifier of course. 06:39.310 --> 06:40.990 So for checkpoints it's easy. 06:40.990 --> 06:42.040 Don't do it right. 06:42.040 --> 06:45.400 Don't update transform on load. 06:45.400 --> 06:47.950 And here in the Or game mode we can check that. 06:47.950 --> 06:57.040 We can say if and we'll use I save interface execute should load transform passing in the actor. 06:58.310 --> 07:01.400 It has to be the actor, not the saved actor, right? 07:01.400 --> 07:04.160 The saved actor is just a puny little struct. 07:04.160 --> 07:06.650 This function needs the real actor. 07:06.650 --> 07:11.180 And if we should, which our checkpoints are returning false. 07:11.180 --> 07:21.350 Here we're going to take the actor and set actor transform to the transform and our saved actor struct. 07:21.950 --> 07:29.600 So just there, in case you happen to have actors you do want to update the transform for, just remember 07:29.600 --> 07:32.630 you have to implement should load transform. 07:32.630 --> 07:35.180 If you implemented it this way that we did here. 07:35.180 --> 07:44.180 Now we also are going to want to deserialize all those variables that we serialized using the fancy 07:44.180 --> 07:45.560 archives above. 07:45.560 --> 07:51.290 Now, those fancy archives kind of work the same way in reverse. 07:51.290 --> 07:54.170 So we make an F memory reader. 07:56.680 --> 07:59.380 We can call it memory reader. 07:59.380 --> 08:10.600 We initialize it with the saved actor dot bytes, and we create an F object and name string proxy archive. 08:10.840 --> 08:15.160 We can call it archive and we initialize it with the memory reader. 08:15.160 --> 08:17.860 And true just like last time. 08:17.860 --> 08:19.630 And it's for a saved game. 08:19.630 --> 08:26.920 So we take archive dot R is save game and make that true. 08:27.040 --> 08:34.420 And then to deserialize our actor we take the actor and we call serialize on it. 08:34.420 --> 08:41.200 Yes, it's serialized and not deserialize, but in this case we are deserializing it. 08:41.200 --> 08:45.730 And all of those binary bytes are converted back into variables. 08:45.730 --> 08:51.730 We'll say converts binary bytes back bytes. 08:52.240 --> 08:54.100 I don't know why I want to put an L there. 08:54.100 --> 08:58.510 Bytes back into variables. 08:58.510 --> 08:59.320 There we go. 08:59.770 --> 09:00.400 Okay. 09:00.400 --> 09:03.310 So we've deserialized all those bytes. 09:03.310 --> 09:09.190 And the last thing we can do is anything else we want to do when loading something. 09:09.190 --> 09:09.820 Right. 09:09.820 --> 09:14.620 For instance our checkpoint has a reached variable. 09:14.620 --> 09:21.490 And if we want that checkpoint to be glowing and disabled as far as its overlap sphere is concerned, 09:21.700 --> 09:28.060 as soon as we load it, then we can have a function on our save interface for loading up the actor. 09:28.060 --> 09:31.990 So we can say right here and save interface, we can make a new function. 09:31.990 --> 09:38.260 By the way, I forgot my semicolon there, but we can make a new function called void load actor, for 09:38.260 --> 09:39.100 example. 09:40.570 --> 09:47.290 And let's just make this a blueprint callable blueprint native event and go ahead and implement this 09:47.290 --> 09:48.460 in the checkpoint. 09:48.460 --> 09:56.590 So right here next to our other save interface function it'll be virtual void load actor implementation. 09:56.590 --> 10:04.330 And here in load actor implementation let's just say we want to check our be reached variable. 10:04.330 --> 10:11.950 We can say if be reached then we can just start glowing and deactivate basically everything we did in 10:11.950 --> 10:14.680 Handle Glow effects sphere collision enabled. 10:14.680 --> 10:16.360 Set that to no collision. 10:16.360 --> 10:21.850 Replace the material with the dynamic material instance and then call checkpoint reached, which is 10:21.850 --> 10:25.840 a blueprint implementable event that will run a timeline and glow. 10:25.840 --> 10:33.190 So load actor implementation if reached is true, we can simply call handle glow effects. 10:37.150 --> 10:45.040 So now that there's this load actor interface function, whenever we load an actor, we can call that 10:45.040 --> 10:52.930 we can take I save, interface and execute load actor and pass that actor in the real actor, not the 10:52.930 --> 10:55.390 saved actor struct proxy. 10:55.390 --> 10:56.110 All right. 10:56.110 --> 10:59.980 So now we have functions to save and to load world state. 10:59.980 --> 11:02.860 And the crazy thing is these could both be const. 11:02.860 --> 11:06.460 So we might as well be const correct here. 11:06.460 --> 11:09.160 And make them both const while we're here. 11:09.160 --> 11:13.870 So we can add those to both the function declaration and the definition. 11:13.870 --> 11:15.190 There's save world state. 11:15.190 --> 11:16.510 Here's load world state. 11:16.510 --> 11:19.840 And now that we have these we need to decide when to call them. 11:19.960 --> 11:23.650 Now I'd like to save the world state every time we reach a checkpoint. 11:23.650 --> 11:30.160 So in on sphere overlap when we're telling our player interface execute save progress. 11:30.160 --> 11:36.160 So basically for our aura character we're telling it go ahead and save your progress. 11:36.160 --> 11:37.510 Handle glow effects. 11:37.510 --> 11:44.470 While I'm at it, I'd like to first of all, first things first set be reached to true. 11:44.950 --> 11:50.020 Because if we save world state before setting this boolean, it will not be serialized. 11:50.020 --> 11:57.310 So we have to do that first and then after setting be reached to true, I'd like to get the game mode 11:57.310 --> 12:00.490 and tell it to save the world state. 12:00.490 --> 12:01.810 Let's do that. 12:01.810 --> 12:05.080 We'll make sure after we set be reach to true. 12:05.080 --> 12:16.360 So we're going to say a aura game mode base header included their aura GM equals cast to A or a game 12:16.360 --> 12:19.180 mode base, and we'll get it with you. 12:19.180 --> 12:19.660 Gameplay. 12:19.660 --> 12:20.770 Statics. 12:22.560 --> 12:24.030 Get game mode. 12:24.360 --> 12:26.490 Passing in a world context object. 12:26.490 --> 12:27.720 You know what it is. 12:27.720 --> 12:28.920 And. 12:30.350 --> 12:31.820 If this is valid. 12:34.290 --> 12:39.150 We'll take Aurum and call save world state. 12:39.150 --> 12:42.210 And it takes a world so we can pass in get world. 12:42.840 --> 12:46.710 So on sphere overlap, we'll go ahead and save the world state. 12:46.740 --> 12:48.210 Now when do we load it? 12:48.240 --> 12:53.910 Well, let's go ahead and load the world state when we're loading up all of our player variables in 12:53.910 --> 12:59.280 the character class, let's go to private character or a character dot cpp. 13:00.030 --> 13:03.180 Oh, I'm noticing I have a dead include here for the game instance. 13:03.180 --> 13:11.670 I'm going to get that out and I'm going to find possessed by where we're calling load progress. 13:11.670 --> 13:17.850 Right here is where I'd like to actually call load World State as well. 13:17.850 --> 13:21.000 I'm going to copy this line where we're getting our game mode. 13:21.000 --> 13:22.920 I'm going to wrap it in an if statement. 13:25.050 --> 13:32.730 And take our A game mode and call load world state passing in get world. 13:32.880 --> 13:35.070 And with that we're saving. 13:35.070 --> 13:36.090 We're loading. 13:36.630 --> 13:39.720 All we have to do is test things out. 13:40.110 --> 13:41.880 So let's compile and launch. 13:42.240 --> 13:43.140 Okay. 13:43.140 --> 13:51.330 So I'm going to first of all go into my maps and to load menu I'm going to press play. 13:51.330 --> 13:54.000 And I'm going to delete this slot and make a new one. 13:55.580 --> 13:57.440 Select it, press play. 13:57.440 --> 14:00.020 Let's go ahead and reach a checkpoint. 14:00.530 --> 14:01.610 There we go. 14:01.610 --> 14:06.320 We can exit, come back, select that slot and press play. 14:06.320 --> 14:07.460 And look at that. 14:07.460 --> 14:09.650 It's starting to glow now. 14:09.650 --> 14:17.270 The cool thing is I can go over to this checkpoint over here and reach it and exit and come back. 14:18.320 --> 14:23.570 And not only are we at this checkpoint, but it's already glowing and we can come back and check the 14:23.570 --> 14:28.340 other checkpoint we've previously reached, and it's glowing as well. 14:28.340 --> 14:30.140 So we're saving the world state. 14:30.140 --> 14:33.230 We're saving that breached boolean. 14:33.230 --> 14:41.150 And you know, we went through an awful lot of effort just to serialize and save one single boolean. 14:41.150 --> 14:44.450 But the implications are much vaster than that. 14:44.450 --> 14:50.330 We can now save an arbitrary number of variables that have the save game specifier. 14:50.330 --> 14:59.210 And we can save not only an arbitrary number of actors per level that have our save interface implemented, 14:59.210 --> 15:06.050 but we can also save different actors in different levels, because that's my whole goal here, is to 15:06.050 --> 15:13.940 be able to transition from one level to another and back again, and load up all of the saved data for 15:13.940 --> 15:14.930 each world. 15:14.930 --> 15:21.110 I'd like to be able to remember which actors we've saved, which checkpoints we've reached, in which 15:21.110 --> 15:21.740 level. 15:21.740 --> 15:23.630 That's what I'm interested in. 15:23.630 --> 15:29.360 If I reach this beacon here, then go off to another level and then come back, I want this beacon to 15:29.360 --> 15:30.020 be reached. 15:30.020 --> 15:30.560 Still. 15:30.560 --> 15:34.910 I want it to still be lit up because I've reached it already. 15:35.060 --> 15:37.640 So that's what we'll do in the videos to come. 15:37.640 --> 15:44.210 We'll develop a system to travel from level to level and remember what we've saved. 15:44.600 --> 15:46.400 Great job and I'll see you soon.