WEBVTT 00:00.770 --> 00:02.900 That we have the Shield's drawing. 00:02.900 --> 00:09.070 I'd like to be able to collide them missiles that the player shoots. 00:09.260 --> 00:27.350 So up here and then to make a new function call it it is collision and it can take a position for a 00:27.350 --> 00:28.490 projectile 00:31.350 --> 00:34.330 and then take all the shields 00:38.330 --> 00:40.730 in a number of shields. 00:46.800 --> 00:54.510 And I'm also going to have in out only parameter called 00:56.830 --> 01:02.400 Shields collision point. 01:02.410 --> 01:15.370 So essentially this will return me the search turns the shield index into our shield array of which 01:15.370 --> 01:24.390 one got hit which Shield got hit. 01:25.430 --> 01:27.950 And it will return. 01:28.680 --> 01:30.490 Not in play I guess. 01:32.110 --> 01:37.440 If nothing was hit. 01:39.320 --> 01:45.530 And also I'm going to return out a shield collision point. 01:45.590 --> 02:00.210 So also turns the shield collision point of of like whatever point of the Shield got hit. 02:00.240 --> 02:02.030 So I look here. 02:02.030 --> 02:16.010 So if say this one got hit then I'll return you know 0 1 to the first of the first part of the Great. 02:16.490 --> 02:22.310 So you'll actually tell me where in the shield you got hit. 02:22.410 --> 02:26.370 It does kind of two two things. 02:26.370 --> 02:34.310 So let's start implementing this in this once again. 02:34.310 --> 02:36.420 This one's a little bit trickier function. 02:38.500 --> 02:46.190 It's not too tricky but it's tricky to know that this is the signature that you really want. 02:46.270 --> 02:47.820 OK. 02:48.990 --> 03:00.060 So she'll collision point docked X is going to put it to be not play initially or. 03:00.100 --> 03:07.030 So whatever they pass in we're not going to have it in play. 03:07.120 --> 03:07.340 Now 03:10.490 --> 03:13.850 we're all shoes too. 03:13.880 --> 03:14.740 Ellen Glasheen 03:21.800 --> 03:24.200 conclusion that. 03:25.070 --> 03:33.440 So initially if we didn't hit anything then this won't be set to anything. 03:34.310 --> 03:45.860 So now we will say if we have an actual projectile if the projectile is not equal to not play. 03:45.890 --> 03:54.070 So if it isn't way. 03:57.070 --> 04:00.330 Then we're going to loop through all the shields 04:09.930 --> 04:18.230 like that and are going at the current shield and we're not going to change the shield in any way says 04:18.480 --> 04:19.200 Konst 04:26.780 --> 04:27.840 that. 04:28.850 --> 04:34.370 And now we have to check to see where it collided. 04:34.880 --> 04:38.990 So say if the projectile 04:41.680 --> 04:58.910 x is greater than the shield not position X and the projectile X is less than the shield position dot 04:59.120 --> 05:03.720 x y a shield. 05:03.830 --> 05:04.810 Right. 05:07.000 --> 05:09.920 With. 05:10.610 --> 05:22.960 So this is saying is it is correct that this is saying is it on the same. 05:23.240 --> 05:24.890 Or is it in line horizontal 05:35.220 --> 05:36.210 project or on 05:39.240 --> 05:47.880 like so is that so is it actually. 05:47.890 --> 05:59.590 So is the project tells x x component within the width of this current shield is what this is saying. 05:59.590 --> 06:09.580 So if it's greater than the greater than or equal to than the shields position rain and again the shields 06:09.580 --> 06:18.380 position is kind of the top guess is the top left yes of the shields right. 06:18.430 --> 06:29.770 So if it's if it's greater than or equal to the left most portion of the shield and it's less than the 06:29.770 --> 06:39.720 rightmost portion of the shield which is this right then it's then it's in line horizontally. 06:40.240 --> 06:46.550 But we also have to say and is it in line vertically 06:49.760 --> 06:57.280 is it in mind vertically some shield or is it projectile 07:01.810 --> 07:10.170 Why is greater than or equal to shield position Y and 07:14.880 --> 07:32.100 you dial Y is less than shield position Y plus shield separate CH Right. 07:52.570 --> 07:53.720 You know on your 08:02.660 --> 08:02.980 it's 08:14.870 --> 08:15.440 this 08:34.310 --> 08:36.390 see this. 08:36.590 --> 08:41.530 So is it inline vertically as well. 08:41.530 --> 08:42.100 All right. 08:43.580 --> 08:46.270 I think that's right. 08:46.840 --> 08:51.130 So is it in line vertically as well. 08:51.470 --> 08:54.670 That's that's kind of what this is saying. 08:55.690 --> 09:01.330 So is the projectile within the show you 09:04.440 --> 09:09.300 show you in here so say the projectile was here. 09:10.180 --> 09:19.180 This so it's within the boundary of the width of the shield and it's also in boundary of the height 09:19.960 --> 09:21.030 of the shield. 09:21.200 --> 09:21.630 OK. 09:21.670 --> 09:30.820 So that's that's where those two two vines are saying as far as a new another one. 09:31.150 --> 09:40.700 And the shield sprites and then projectile 09:42.920 --> 09:45.010 wind minus shield 09:47.360 --> 09:50.370 and why. 09:52.890 --> 10:06.370 Project X minus shield position and x is not equal to an empty space. 10:06.370 --> 10:07.630 Right. 10:07.780 --> 10:10.690 So in within the action. 10:10.690 --> 10:13.230 So as long as these two are true. 10:13.370 --> 10:13.720 OK. 10:13.750 --> 10:17.490 So then it's within the actual shields right. 10:17.860 --> 10:29.170 And if the projectiles position in the shields upright is not a space right then then this must be a 10:29.170 --> 10:29.860 collision. 10:30.020 --> 10:35.980 And so we collide. 10:36.730 --> 10:41.390 If you're not truly understanding this quite yet. 10:41.410 --> 10:46.100 Just pause the video and really kind of look at what it's saying. 10:46.110 --> 10:56.350 So it's really just saying in line horizontally the first line is it in line vertically. 10:56.490 --> 10:56.800 Right. 10:56.820 --> 10:58.360 That's the second line. 10:58.510 --> 11:03.210 And the third line is racing does it 11:06.130 --> 11:11.800 collide with part of the shield. 11:15.150 --> 11:20.910 Or alternatively saying does it not collide with an empty space OK. 11:24.530 --> 11:25.250 Right. 11:25.460 --> 11:29.870 So if all of these are true then we collided. 11:29.870 --> 11:41.290 So the shield point will be this shield collision point X will be exactly this projectile 11:45.150 --> 11:54.600 is checked dial X minus the shield position X 12:01.400 --> 12:08.730 which point is and the shield collision point which 12:11.640 --> 12:16.090 y seem trip down. 12:16.130 --> 12:21.050 Why is this shield position. 12:21.150 --> 12:23.410 Why is that. 12:23.530 --> 12:26.530 OK so we're going to be returning this by the way. 12:26.550 --> 12:35.810 And also we return the actual shield effects so we all sort of turn k. 12:36.180 --> 12:41.680 So otherwise we didn't find it and quite an 12:48.150 --> 12:49.440 AM I IN LINE. 12:49.570 --> 12:51.990 Horizontally and vertically. 12:52.090 --> 12:56.810 Does it collide with an actual physical part of the shield. 12:57.250 --> 13:00.000 It's not it hasn't collided there before. 13:00.010 --> 13:00.540 Right. 13:00.820 --> 13:07.480 If so then we take the position that it collided in relative to the shield. 13:07.540 --> 13:07.870 Right. 13:07.900 --> 13:08.490 Right. 13:08.860 --> 13:11.120 And we returned it. 13:11.800 --> 13:18.760 So hopefully this makes sense again posit really kind of look at it and really try to understand what's 13:18.760 --> 13:20.250 happening here. 13:20.310 --> 13:22.740 This is pretty important. 13:23.500 --> 13:28.010 Collision detection is always kind of kind of hard to understand at first. 13:28.060 --> 13:33.100 So really tried to try to grasp it as best you can. 13:33.730 --> 13:37.770 So if it collided then it will also need some kind of. 13:37.810 --> 13:40.760 So this just checks to see if it collided or not. 13:40.780 --> 13:46.160 We still need to resolve the collision. 13:46.350 --> 14:03.030 So resolve shield collision and this will be much easier as shield shields and shield index in the position. 14:05.370 --> 14:13.450 It's designed to change shield collision point. 14:15.340 --> 14:21.550 And this one's pretty easy to say shields of shield index 14:24.720 --> 14:31.220 Sprite and then say shield 14:33.510 --> 14:37.280 collision point. 14:37.520 --> 14:47.120 Why and shield collision point dot x is empty 14:53.900 --> 14:56.560 groan is complaining to me. 14:57.440 --> 15:00.800 OK so just set the actual. 15:00.980 --> 15:07.410 So for whatever SHIELL index it was set wherever it collided to be. 15:09.060 --> 15:12.970 So all the heavy lifting is in the actual collision. 15:12.970 --> 15:14.940 Check. 15:14.950 --> 15:20.580 So now we need to actually call these. 15:20.590 --> 15:23.890 And also probably cleared him already. 15:27.480 --> 15:31.350 He declared the collision. 15:32.460 --> 15:50.830 So now in the game we'll say the positions of position the shield region point and pass it in. 15:51.170 --> 15:53.780 Actually before this if were in say 15:56.390 --> 15:58.550 we're going to make a shield 16:01.160 --> 16:08.170 index in we're going to call is collision 16:12.540 --> 16:20.020 take it takes the projectile the shield say and the number of shields and shoot collision. 16:20.360 --> 16:22.530 It's so 16:25.560 --> 16:29.090 you project is a player. 16:30.320 --> 16:30.830 So 16:33.290 --> 16:39.870 the shields have a shield to pass in. 16:40.280 --> 16:41.990 You see 16:46.090 --> 16:50.590 there is so as you 16:55.510 --> 16:57.040 number Shield's 17:02.710 --> 17:05.620 copy is a copy 17:08.330 --> 17:09.150 these 17:13.580 --> 17:20.270 can that see shields and the number. 17:20.490 --> 17:20.850 It's 17:24.060 --> 17:28.550 an impasse in the shield collision point 17:34.340 --> 17:35.030 right. 17:36.870 --> 17:55.970 And basically were to check to see if the shield index is not equal to not play. 17:56.030 --> 18:03.130 So if if this is true then we know it hit right. 18:03.380 --> 18:08.260 Because if it's if it's if it does return not in play. 18:08.280 --> 18:09.880 I mean no it didn't hit at all. 18:10.070 --> 18:10.780 OK. 18:11.030 --> 18:15.150 So we're going to say reset the missile because it hit 18:18.160 --> 18:29.350 that and we're going to say resolve shield collision shields shield 18:31.750 --> 18:33.730 index and the 18:36.250 --> 18:38.020 shield collision which 18:40.660 --> 18:41.100 that 18:43.970 --> 18:57.310 and now in the game we also have to pass in the shields in the shields that. 18:57.440 --> 19:00.530 So now we run this 19:05.130 --> 19:12.980 you should see that the shields get broken any time the time you hit they 19:15.760 --> 19:16.170 that 19:21.520 --> 19:21.880 day. 19:21.920 --> 19:25.290 So it's working just great. 19:28.710 --> 19:40.850 So in the next lecture I want to start doing are getting the the aliens to start drawing on the screen. 19:40.850 --> 19:41.680 OK. 19:41.770 --> 19:43.880 I'll see you in the next lecture.