WEBVTT 00:00.120 --> 00:00.950 Hello again! 00:00.960 --> 00:05.490 In this video, we are going to modify the strength of the bricks in the game. 00:06.000 --> 00:12.000 We have just been through a couple of videos which were, maybe, a bit hard going. So I apologize for that, 00:12.390 --> 00:15.570 and I hope this one will be a bit more enjoyable. 00:17.560 --> 00:22.210 At the moment, when a ball hits the brick, the brick immediately disappears. 00:22.780 --> 00:23.860 We are going to change that. 00:23.860 --> 00:28.270 So the brick needs to be hit a few times before it is finally destroyed. 00:28.720 --> 00:34.270 In the meantime, the colour of the brick will change to indicate that it has been weakened. 00:36.460 --> 00:37.030 To do this, 00:37.030 --> 00:42.370 We are going to add a member to the brick class, which will indicate the strength of the brick. 00:42.610 --> 00:47.410 So every time the ball hits the brick, the brick is weakened. It loses strength. 00:47.830 --> 00:52.000 And if the strength goes down to zero, then the brick is destroyed. 00:54.640 --> 01:01.150 So far, we have only used the pre-defined colours from the SFML library, but we can choose our own. 01:01.720 --> 01:08.020 There is a Color class, with the American spelling. And this has the usual four components that you 01:08.020 --> 01:09.580 get with computer graphics. 01:09.790 --> 01:16.090 So we have the three primary colours: red, green and blue. And we can mix these in different proportions 01:16.090 --> 01:17.710 to get any colour we want. 01:18.550 --> 01:24.670 There is also this "alpha", which will control how much of the background is visible, through the colour. 01:26.890 --> 01:32.830 These components are represented by 8-bit unsigned integers. So they can have values between 0 01:32.830 --> 01:34.330 and 255. 01:34.930 --> 01:40.080 And these indicate the contribution that each component makes to the resulting colour. 01:41.000 --> 01:47.320 0 means there is no contribution and 255 means it is making the maximum possible. 01:48.190 --> 01:54.910 For example, if we have a colour where red is 255, green is 0 and blue is 0, then 01:54.910 --> 01:58.360 that will be a pure red colour, without any green or blue in it. 01:59.410 --> 02:08.080 If we have red 127, green 127 and blue 127, then that represents an equal mixture 02:08.080 --> 02:14.080 of each primary colour, in the middle of its intensity, and that will probably be some shade of grey. 02:16.060 --> 02:21.460 Alpha is the opacity of the colour. Or, if you like, the inverse transparency. 02:22.060 --> 02:28.030 If alpha is 0, then the colour is completely transparent, and we can see the background and nothing 02:28.030 --> 02:28.510 else. 02:29.410 --> 02:35.380 Alpha of 255 represents a completely opaque colour, so there is no contribution from the background at 02:35.380 --> 02:35.800 all. 02:36.760 --> 02:42.340 In cases like these, where we do not specify the alpha value, then the default is 255. 02:42.610 --> 02:46.720 So this red colour will not have any of the background coming through at all. 02:49.180 --> 02:54.250 We need to change the code which handles collisions between a ball and brick. 02:54.760 --> 02:57.910 So at the moment we are just destroying the brick automatically. 02:58.480 --> 03:05.140 Now we need to weaken the brick, and we do not destroy the brick unless the strength is equal to zero. 03:06.460 --> 03:08.820 And if the strength is not 0, we just leave it alone. 03:08.860 --> 03:11.140 So it is going to be drawn next time. 03:11.620 --> 03:16.270 In the update() memory function of brick, where currently we are doing nothing, we need to set the colour 03:16.270 --> 03:19.300 of the brick. And that will depend on its strength. 03:21.740 --> 03:26.870 In the constants file, I have added another parameter: brick_strength. 03:27.290 --> 03:32.090 So this will represent how many times a brick can be hit before it is destroyed. 03:32.480 --> 03:37.550 So we are saying here that a brick needs to be hit 3 times before it disappears. 03:39.770 --> 03:43.730 In the brick header, we have this member for the strength. 03:43.850 --> 03:48.680 So this will tell us how many more impacts the brick can take, before it is destroyed. 03:49.370 --> 03:53.220 Initially, it has this brick_strength value so it can take 3 hits. 03:53.240 --> 03:56.050 If there is a collision, then the strength will go down to 2. 03:56.060 --> 03:57.710 So it can take 2 more hits. 03:58.070 --> 04:03.620 The next collision takes it down to 1, so it can take one more hit. And then the next collision 04:03.620 --> 04:06.650 will take this down to 0. And then it is destroyed. 04:07.970 --> 04:13.430 We also have some helper functions for working with this member. So we can set the member. 04:13.730 --> 04:20.450 We can weaken the brick by decrementing the strength. And we can find out if the brick needs to be destroyed. 04:23.600 --> 04:29.150 In the source code, we create our colour objects of the sf::Color class. 04:29.750 --> 04:33.110 So these are going to represent the different states of the brick. 04:33.470 --> 04:36.710 This one will represent a brick which has not been hit at all. 04:36.740 --> 04:38.600 So it can take 3 impacts. 04:39.710 --> 04:42.890 This will represent a brick which can take 2 impacts. 04:43.190 --> 04:46.400 And this will represent a brick which can take 1 impact. 04:46.640 --> 04:48.740 So it is going to be destroyed next time. 04:49.910 --> 04:52.550 We are going to make all these, different shades of green. 04:53.330 --> 04:55.580 These are all going to be pure green. 04:55.580 --> 04:57.050 So red is 0. 04:57.080 --> 04:59.530 Blue is 0, and green is 255. 04:59.930 --> 05:05.840 But we are going to use different alpha values, to indicate the different states. With a brick which has not 05:05.840 --> 05:06.740 been hit at all, 05:06.770 --> 05:08.290 alpha will be 255. 05:08.300 --> 05:10.940 So that is going to be a bright green with no background. 05:11.690 --> 05:14.240 If it has been hit once, the opacity is a bit lower. 05:14.330 --> 05:17.150 So we are going to get some contribution from the background. 05:17.480 --> 05:19.070 And that will give a medium green. 05:19.640 --> 05:24.140 And then, when it is getting near the end of its life, there is quite a lot of background. 05:24.920 --> 05:26.660 And that will be a dull green. 05:28.040 --> 05:33.230 Then we have our member functions for setting the strength, decrementing it, and comparing it for 05:33.230 --> 05:34.790 equality to 0. 05:36.940 --> 05:43.870 In the update() member function, we set the colour of the brick. And that will depend on its strength. 05:47.870 --> 05:49.460 In the interactions code. 05:49.460 --> 05:51.350 We need to change this. 05:51.350 --> 05:58.250 So first we weaken the block, and then we check if the block needs to be destroyed. And only then do we 05:58.250 --> 05:59.030 destroy it. 06:01.220 --> 06:02.840 So let's try this out. 06:04.250 --> 06:09.650 So you can see the bricks become darker when they are hit for the first time. And then they become much 06:09.650 --> 06:11.330 darker when they are hit for the second time. 06:13.740 --> 06:16.410 And on the third impact, if we can get one. 06:16.980 --> 06:21.210 (Whoops! I'm really not very good at this game.) 06:24.280 --> 06:25.510 (I am trying to talk at the same time.) 06:25.510 --> 06:26.440 (That is my problem!) 06:26.740 --> 06:27.270 There you are. 06:27.280 --> 06:29.410 So you can see on the third hit, it disappears. 06:30.060 --> 06:31.630 Okay, so that is it for this video. 06:31.720 --> 06:32.590 I will see you next time. 06:32.590 --> 06:34.960 But until then, keep coding!