1 00:00:03,990 --> 00:00:09,630 ‫So we're going to create a fire function and we're going to associate this function with our left mouse 2 00:00:09,630 --> 00:00:10,110 ‫button. 3 00:00:10,110 --> 00:00:16,350 ‫And here you can see that I'm drawing debug spheres at the tip of our turret barrel just to prove that 4 00:00:16,350 --> 00:00:18,210 ‫this action mapping is working. 5 00:00:18,210 --> 00:00:21,360 ‫Whenever I click the left mouse button, something is happening. 6 00:00:21,720 --> 00:00:23,090 ‫Hey, welcome back. 7 00:00:23,100 --> 00:00:28,770 ‫In this video, we're going to talk about creating a fire function or a function we can use for when 8 00:00:28,770 --> 00:00:31,020 ‫we want to spawn our projectiles. 9 00:00:31,020 --> 00:00:36,090 ‫So we're going to create a fire function and we're going to bind it to an action mapping. 10 00:00:36,090 --> 00:00:38,370 ‫Now, we've been using axis mappings. 11 00:00:38,370 --> 00:00:40,260 ‫An action mapping is similar. 12 00:00:40,260 --> 00:00:41,550 ‫Let's talk about it now. 13 00:00:41,550 --> 00:00:47,280 ‫Here's a section of a screenshot of the fire action mapping that we have in our project settings. 14 00:00:47,280 --> 00:00:51,690 ‫You'll see that we have the left mouse button assigned to the fire action mapping. 15 00:00:51,690 --> 00:00:55,290 ‫Now an action mapping is very much like an axis mapping. 16 00:00:55,290 --> 00:00:57,720 ‫You can assign a key or a button to it. 17 00:00:57,720 --> 00:01:03,420 ‫And just like an axis mapping, it requires a function that can be bound to the action mapping. 18 00:01:03,420 --> 00:01:07,440 ‫Now, axis mappings fire off every single frame of the game. 19 00:01:07,440 --> 00:01:12,840 ‫They're like the tic function and the float value passed in changes depending on which buttons are being 20 00:01:12,840 --> 00:01:13,590 ‫pressed. 21 00:01:13,590 --> 00:01:15,930 ‫Action mappings are slightly different. 22 00:01:15,960 --> 00:01:22,740 ‫A callback function bound to an action mapping takes no input parameters, and all that happens is when 23 00:01:22,740 --> 00:01:25,200 ‫you press the button, the function gets called. 24 00:01:25,200 --> 00:01:29,430 ‫What goes on inside of the function is up to us as the developer. 25 00:01:29,430 --> 00:01:31,590 ‫Now, action mappings are one offs. 26 00:01:31,590 --> 00:01:33,030 ‫They don't happen every frame. 27 00:01:33,030 --> 00:01:35,790 ‫They only happen once when you press the button. 28 00:01:35,790 --> 00:01:40,950 ‫So if you release the button and press it again, the function will be called once more. 29 00:01:40,980 --> 00:01:47,280 ‫Now, when we bound functions to the axis mappings, we used bind axis for action mappings we use a 30 00:01:47,280 --> 00:01:52,650 ‫function called bind action and it takes inputs similar to bind axis. 31 00:01:52,650 --> 00:01:56,400 ‫It takes the name of the action mapping as a string literal. 32 00:01:56,430 --> 00:01:58,710 ‫It also requires a pointer to the class. 33 00:01:58,710 --> 00:02:04,470 ‫We're binding the function on for which we can use this, and it takes, of course, a callback function. 34 00:02:04,470 --> 00:02:11,580 ‫Now an additional parameter it takes that bind axis does not require as an enum constant specifying 35 00:02:11,580 --> 00:02:17,130 ‫whether or not we'd like this function to be called when we press the button or when we release the 36 00:02:17,130 --> 00:02:17,640 ‫button. 37 00:02:17,640 --> 00:02:24,000 ‫So there are two options for this input parameter the enum constant, i.e. pressed and the enum constant, 38 00:02:24,000 --> 00:02:25,350 ‫i.e. released. 39 00:02:25,350 --> 00:02:31,110 ‫This means we can call bind action passing in i.e. pressed if we'd like to bind a callback function 40 00:02:31,110 --> 00:02:36,960 ‫for when we press the button and instead if we used i.e. released then our callback function would be 41 00:02:36,960 --> 00:02:40,380 ‫called when the button was released for our fire function. 42 00:02:40,380 --> 00:02:42,900 ‫We're concerned with when we press the button. 43 00:02:42,900 --> 00:02:46,890 ‫So let's make a fire function and bind it to the fire action mapping. 44 00:02:46,890 --> 00:02:53,490 ‫Now I'm here in base spawn and the reason I'm here in base pond is because this fire function is something 45 00:02:53,490 --> 00:02:57,270 ‫that we can use in the tank class and in the tower class. 46 00:02:57,270 --> 00:03:03,030 ‫So if we place it here in base pond, then both Tank and tower will inherit this function. 47 00:03:03,030 --> 00:03:08,850 ‫And since both the tank and the tower are going to fire projectiles, then they can simply inherit the 48 00:03:08,850 --> 00:03:10,230 ‫function and use it. 49 00:03:10,260 --> 00:03:16,530 ‫Now, since I'd like access to the function in both the child classes, I can place this function here 50 00:03:16,530 --> 00:03:19,500 ‫in the protected section, just like rotate turret. 51 00:03:19,500 --> 00:03:26,220 ‫So under rotate turret I'm going to create a void function called fire that takes no inputs and we can 52 00:03:26,220 --> 00:03:30,780 ‫go ahead and define the fire function in based upon CPP. 53 00:03:30,780 --> 00:03:36,990 ‫So here's based upon CPP and just under rotate turret, I'm going to place the fire function and we 54 00:03:36,990 --> 00:03:41,430 ‫need to fully qualify this function name and give it a function body. 55 00:03:41,430 --> 00:03:43,680 ‫So now we have a fire function. 56 00:03:43,680 --> 00:03:47,040 ‫Now the next step is to bind this to an action mapping. 57 00:03:47,040 --> 00:03:53,190 ‫Now we only want to bind this function in the tank class because the tank is the only class that will 58 00:03:53,190 --> 00:03:54,720 ‫be taking user input. 59 00:03:54,720 --> 00:03:59,610 ‫We'll be calling the fire function in the tower class later, but that will be as a result of code we 60 00:03:59,610 --> 00:04:02,820 ‫create and not as a result of user input. 61 00:04:02,820 --> 00:04:08,730 ‫So we're here in Tank CP and we're going to bind this and set up player input component just like we 62 00:04:08,730 --> 00:04:10,290 ‫used bind axis. 63 00:04:10,290 --> 00:04:12,900 ‫So we're going to use the player input component. 64 00:04:12,900 --> 00:04:18,720 ‫So player input component and the function is going to be bind action. 65 00:04:18,720 --> 00:04:24,150 ‫Now the first input is going to be the string literal, which we're going to wrap in a text macro as 66 00:04:24,150 --> 00:04:24,780 ‫usual. 67 00:04:24,780 --> 00:04:27,810 ‫And this action mapping is called fire. 68 00:04:27,960 --> 00:04:34,080 ‫Now the next parameter is going to be that enum constant that determines whether or not we'd like this 69 00:04:34,080 --> 00:04:39,000 ‫function to be called when we press the button versus when we release the button. 70 00:04:39,000 --> 00:04:42,150 ‫And we're going to use, I underscore pressed. 71 00:04:43,170 --> 00:04:46,260 ‫Since we'd like our function called when we press the button. 72 00:04:46,260 --> 00:04:49,520 ‫Now, next is the user class object that's going to be this. 73 00:04:49,530 --> 00:04:55,620 ‫And finally we have our callback function so we can say a tank fire. 74 00:04:55,770 --> 00:05:00,690 ‫And now our fire function is bound to the fire action mapping. 75 00:05:00,690 --> 00:05:07,200 ‫So we know that our fire function is bound to the fire action mapping, but we'd like some visual confirmation 76 00:05:07,200 --> 00:05:09,900 ‫and that's what your challenge is going to be. 77 00:05:09,900 --> 00:05:14,130 ‫So in the fire function, I'd like you to draw a debug sphere. 78 00:05:14,130 --> 00:05:19,440 ‫We've already seen how to do this, so go ahead and fill in the parameters with values that you think 79 00:05:19,440 --> 00:05:20,640 ‫are appropriate. 80 00:05:20,670 --> 00:05:24,030 ‫Use the location of the projectile spawn point. 81 00:05:24,270 --> 00:05:30,210 ‫Now the projectile spawn point is a use scene component and you've seen components have a function called 82 00:05:30,210 --> 00:05:32,100 ‫get component location. 83 00:05:32,100 --> 00:05:33,780 ‫This returns an F vector. 84 00:05:33,810 --> 00:05:38,220 ‫This is what you can use to get the projectile spawn point location. 85 00:05:38,220 --> 00:05:45,630 ‫Now when you call draw debug sphere, use a duration of about 3 seconds so we can see that sphere for 86 00:05:45,630 --> 00:05:47,760 ‫a little while before it disappears. 87 00:05:47,760 --> 00:05:50,460 ‫Pause the video and do this now. 88 00:05:53,360 --> 00:05:53,550 ‫Okay. 89 00:05:53,660 --> 00:05:56,810 ‫So I'm back here in Bass Pond and here in Bass Pond. 90 00:05:57,110 --> 00:06:00,770 ‫CP I'm going to include draw debug helpers. 91 00:06:00,770 --> 00:06:03,500 ‫So we have access to draw debug sphere. 92 00:06:03,500 --> 00:06:07,010 ‫So I'm going to say include draw debug helpers. 93 00:06:08,240 --> 00:06:12,320 ‫And now down here in the fire function, we can draw the debug sphere. 94 00:06:12,350 --> 00:06:18,050 ‫Now, the first thing I want to do though is get the location of the projectile spawn point. 95 00:06:18,080 --> 00:06:26,240 ‫Now I can create a local f vector for this and I can call this projectile spawn point location and I 96 00:06:26,240 --> 00:06:29,870 ‫can initialize it using the projectile spawn point. 97 00:06:32,030 --> 00:06:35,780 ‫And calling get component location. 98 00:06:35,780 --> 00:06:43,100 ‫So now I have the location of the projectile spawn point and this is what I can use when calling draw 99 00:06:43,100 --> 00:06:43,850 ‫debug sphere. 100 00:06:43,850 --> 00:06:46,130 ‫So I'm going to call draw debug sphere. 101 00:06:47,450 --> 00:06:53,720 ‫And for the first input we need the world and we know that we can get the world using get world next. 102 00:06:53,720 --> 00:06:59,810 ‫We need the center of the sphere that's going to be our projectile spawn point location. 103 00:06:59,810 --> 00:07:04,190 ‫So that will be what I pass in as the second parameter. 104 00:07:04,190 --> 00:07:06,190 ‫And next we need the radius of the sphere. 105 00:07:06,200 --> 00:07:08,330 ‫Now I'm going to have a small sphere. 106 00:07:08,480 --> 00:07:15,920 ‫I'll give it a radius of say 25 F for the number of segments I'm just going to use 12 and for the color 107 00:07:15,920 --> 00:07:17,690 ‫I can use F color. 108 00:07:18,680 --> 00:07:21,380 ‫Read Now four draw persistent lines. 109 00:07:21,380 --> 00:07:27,500 ‫We're going to have our lines hang around for 3 seconds so we can make this false because we don't want 110 00:07:27,500 --> 00:07:28,910 ‫them to persist forever. 111 00:07:28,940 --> 00:07:36,380 ‫We're going to give this debug sphere a lifetime of three F So let's go ahead and compile this now and 112 00:07:36,380 --> 00:07:42,230 ‫I'm going to hit play and click and now we can see our debug sphere and of course it goes away after 113 00:07:42,230 --> 00:07:43,310 ‫3 seconds. 114 00:07:43,640 --> 00:07:49,880 ‫Now this is good confirmation that our action mapping is working and it's also giving us verification 115 00:07:49,880 --> 00:07:53,450 ‫of the location of the projectile spawn point. 116 00:07:53,450 --> 00:07:59,600 ‫So once we actually start spawning projectiles, we know that they will spawn at the correct location 117 00:07:59,600 --> 00:08:02,420 ‫as indicated by the debug sphere. 118 00:08:02,420 --> 00:08:03,500 ‫So this is great. 119 00:08:03,650 --> 00:08:09,470 ‫So in this video we created a fire function and we bound it to the fire action mapping. 120 00:08:09,740 --> 00:08:15,800 ‫And to prove that it was working, we drew a debug sphere at the projectile spawn point whenever we 121 00:08:15,830 --> 00:08:21,710 ‫click the left mouse button so we have a fire function, we're almost ready to start spawning projectiles. 122 00:08:21,710 --> 00:08:25,250 ‫And we've also placed this function in the base pong class. 123 00:08:25,250 --> 00:08:27,980 ‫So that way our tower can also use it. 124 00:08:27,980 --> 00:08:32,990 ‫So in the next video, we're going to discuss how our tower is going to use this function. 125 00:08:33,530 --> 00:08:34,460 ‫I'll see you soon.