WEBVTT 00:00.000 --> 00:04.720 Blender 4.2 has been released and I want to take the opportunity to go over some of 00:04.721 --> 00:06.560 the things that are new for geometry nodes. 00:07.340 --> 00:10.260 In this video, we'll take a look at the new matrix socket. 00:10.880 --> 00:13.139 There is also another video about what is new 00:13.140 --> 00:15.380 for node tools that you can check out afterwards. 00:15.880 --> 00:20.540 If you go to the release nodes page on blender.org and you scroll down to the 00:20.541 --> 00:23.624 geometry nodes section, you find that there is a whole 00:23.625 --> 00:26.600 new socket type in geometry nodes for matrices now. 00:27.140 --> 00:32.500 This little demo file here shows how this new socket can be used to handle 00:32.501 --> 00:35.580 transformations much more easily than was possible before. 00:35.980 --> 00:40.280 In this case, to make a little stacking modifier for this pile of pizza boxes. 00:40.780 --> 00:44.560 Let me first give you a quick introduction to what the purpose of this new socket 00:44.561 --> 00:47.508 type is, and then walk you through the creation of 00:47.509 --> 00:50.141 the modifier in this demo in a little bit more detail. 00:50.920 --> 00:53.060 So, what even is the point of a matrix? 00:53.061 --> 00:57.200 Well, there's a lot of mathematical background that can be covered when 00:57.201 --> 01:00.500 talking about matrices, but that's not really important right now. 01:01.160 --> 01:05.200 The most important thing to understand for using the matrix socket in blender's 01:05.201 --> 01:09.557 geometry node is that a 4x4 matrix is a very 01:09.558 --> 01:12.841 useful way to represent a transformation. 01:13.220 --> 01:15.260 That is also what blender does under the hood. 01:16.100 --> 01:22.000 A transformation in general is made up of the three components for translating, 01:23.160 --> 01:24.500 rotating and scaling. 01:24.860 --> 01:31.840 So, instead of thinking about a matrix as a grid or 4x4, which doesn't really help 01:31.841 --> 01:36.300 you to understand what exactly is going on, you can just think of it in the 01:36.301 --> 01:40.980 context of transformations of translation, rotation and scale. 01:40.981 --> 01:46.468 So, for that, the easiest way to create a matrix in blender's 01:46.469 --> 01:51.000 geometry nodes now is to use the combine transform node. 01:52.020 --> 01:54.784 There you simply get the option to plug in your values for 01:54.785 --> 01:58.720 translation, rotation and scale, and out comes the matrix. 01:59.680 --> 02:05.400 But you can also retrieve your transformation directly from, let's say, an object. 02:05.680 --> 02:10.040 So, here on the modifier of this cube, for example, let's drag and drop the 02:10.041 --> 02:14.900 camera object into the node tree, and there you can see that besides the 02:14.901 --> 02:18.158 object transformations for location, rotation and 02:18.159 --> 02:22.400 scale, we also get the transform matrix as one socket. 02:23.040 --> 02:26.456 This one transform socket now encapsulates all the 02:26.457 --> 02:30.120 transform information from these three individual sockets. 02:31.200 --> 02:34.140 And that can make it a lot easier to handle in the node tree. 02:34.940 --> 02:43.000 For example, if we now want to move the cube into the same transformation as the 02:43.001 --> 02:47.801 camera, we can very easily do that using the transform 02:47.802 --> 02:51.980 geometry node, and then setting it to the matrix mode. 02:53.020 --> 02:57.660 And then connecting the transform of the camera to the transform of the operation 02:57.661 --> 03:00.482 puts the cube directly into the exact same 03:00.483 --> 03:04.181 position, rotation and scale as the camera. 03:04.360 --> 03:08.180 So, if you move that around now, you can see how it's really constrained to 03:08.181 --> 03:11.540 the camera directly, all using geometry nodes. 03:12.840 --> 03:16.400 This would have been possible before using the location, rotation and scale, 03:17.080 --> 03:19.000 but it would have been a little bit more tedious. 03:19.480 --> 03:22.960 And with this transform now, we can also do some additional things. 03:23.880 --> 03:26.900 Like, for example, we can combine it with another transform. 03:27.580 --> 03:29.960 So, let's use the combine transform node. 03:29.961 --> 03:33.271 And then to do both of these transformations 03:33.272 --> 03:36.700 at once, we can use a multiply matrices node. 03:37.800 --> 03:41.620 Again, I'm not going to go into the mathematical detail of why this works, 03:42.320 --> 03:46.066 but multiplying two matrices basically just means 03:46.067 --> 03:49.260 combining both of the transformations in this context. 03:49.880 --> 03:55.720 So, if I plug both the matrices in here and then add some value in the 03:55.721 --> 03:59.458 translation, you can see how that also moves the cube 03:59.459 --> 04:03.380 on top of the transformation we did into the camera. 04:04.100 --> 04:10.000 But here, you can see that the translation vector that we plug in for a positive X 04:10.001 --> 04:15.340 value doesn't actually move the cube along the X axis of the object. 04:16.100 --> 04:20.300 And this is where the order of these two inputs comes into play. 04:20.301 --> 04:27.640 Since we have the transformation of the camera first, this means that this 04:27.641 --> 04:32.200 transformation happens in the space of the camera. 04:33.220 --> 04:37.480 So, we're currently moving the cube along the X axis of the camera. 04:39.620 --> 04:45.100 If I reverse the order of these two inputs, you can see how now this vector 04:45.101 --> 04:49.600 has an effect on the X axis of the cube object. 04:49.601 --> 04:52.647 So, this is something to be wary of when 04:52.648 --> 04:55.741 you're combining matrices for transformations. 04:56.600 --> 05:00.336 Another thing you can do, for example, to change 05:00.337 --> 05:03.800 the transformation around is to invert the matrix. 05:04.420 --> 05:07.820 For transformation, this also does exactly what you would think it does. 05:08.140 --> 05:11.980 It inverts the transformation by doing the exact opposite. 05:11.981 --> 05:17.861 These kinds of transformations between different spaces 05:17.862 --> 05:21.920 from global to local and between different objects, etc. 05:22.560 --> 05:24.700 can get quite complicated quite quickly. 05:25.240 --> 05:30.280 So, it's very nice to just combine the whole concept of the transformation in a 05:30.281 --> 05:35.480 single socket with simple applications rather than having to handle them 05:35.481 --> 05:38.120 individually as location, rotation and scale. 05:38.900 --> 05:44.680 Another aspect of this matrix socket is that it doesn't simply just work for a 05:44.681 --> 05:47.780 single matrix that is carried from these links. 05:48.260 --> 05:54.541 Since it is a whole new socket type, it can also be applied to fields and attributes. 05:54.760 --> 05:59.840 So, we can store a whole transformation matrix for each element of your geometry, 06:00.480 --> 06:02.560 for example, for each point of the mesh. 06:03.080 --> 06:06.540 This will come in handy in just a second when we go over the demo file. 06:07.760 --> 06:10.580 Alright, so let's get to stacking some pizza boxes. 06:11.480 --> 06:15.800 If you download the demo file from the release notes page, you can see that there 06:15.801 --> 06:21.820 is a relatively simple scene with this guy carrying pizza boxes on a Vespa. 06:23.140 --> 06:27.760 And there is just one modifier on the pizza stack that has some controls for you 06:27.761 --> 06:30.555 to control the height of the stack and then 06:30.556 --> 06:33.421 some additional settings for randomization. 06:35.200 --> 06:39.064 And this is heavily relying on the use of matrices to 06:39.065 --> 06:42.700 propagate the transformations between these different boxes. 06:43.860 --> 06:51.320 So, one thing, for example, is that as I increase this random rotation or the 06:51.321 --> 06:57.200 random offset, the pizza boxes don't just simply move individually. 06:57.940 --> 06:59.620 They all affect each other. 06:59.621 --> 07:04.360 So, just like on a real stack of pizza boxes, if I just draw a really crude 07:04.361 --> 07:11.380 example here, the orientation of the lower box will affect the ones above it. 07:11.780 --> 07:15.168 So, if there is a box with a slight tilt to it, 07:15.169 --> 07:18.941 the ones atop it will have the tilt as well. 07:19.720 --> 07:25.400 That was previously not that simple to do, but now with the matrix node, it's pretty 07:25.401 --> 07:31.640 easy to get the transformation of one element to affect the other ones above it. 07:32.220 --> 07:33.700 So, let's go over how that works. 07:34.740 --> 07:40.460 Another aspect of this example case is that you can see clearly when I crank up 07:40.461 --> 07:44.050 the number very high, there is a slight bounce that 07:44.051 --> 07:49.660 goes through the pizza stack as the Vespa is jittering. 07:49.880 --> 07:52.860 And this is actually going from the bottom all the way to the top. 07:53.520 --> 07:59.800 For that, it's also using the matrix socket in a very simple simulation setup. 08:01.140 --> 08:03.296 And of course, this can break the laws of 08:03.297 --> 08:06.821 physics to create this very fun-looking effect. 08:07.180 --> 08:09.280 So then, let's get to stacking those boxes. 08:10.200 --> 08:13.040 First off, we'll start with a brand new cube. 08:14.340 --> 08:18.362 There, I'll go into edit mode on and then scale it to 0.5 08:18.363 --> 08:22.900 size, because that means that each edge is exactly one unit. 08:24.260 --> 08:28.317 And then move it up on the Z axis by 0.5, which 08:28.318 --> 08:32.120 means that it's standing nicely on its origin point. 08:33.200 --> 08:35.240 That will be useful for the node setup. 08:36.200 --> 08:40.000 So let's start by creating a new geometry nodes modifier. 08:40.940 --> 08:43.200 Let's call that one pizza stack. 08:44.060 --> 08:47.220 And then now let's start by setting up the base for this stack. 08:47.221 --> 08:51.124 What I want to start with is a whole bunch of instances 08:51.125 --> 08:54.480 of this cube, which are going to be my pizza boxes. 08:55.800 --> 08:58.320 For that, I'm going to start out with a 08:58.321 --> 09:02.181 points node to give me a bunch of base points. 09:02.800 --> 09:04.480 Set that to 25 for now. 09:05.720 --> 09:09.040 And then an instance on points node. 09:10.160 --> 09:14.900 And what we'll instance as the geometry is going to be my input from the cube. 09:15.900 --> 09:18.874 And as you can see in the spreadsheet editor, now 09:18.875 --> 09:21.741 we end up with 25 instances of that same cube. 09:22.340 --> 09:26.238 So let's squish them a little bit more into pizza box shape 09:26.239 --> 09:29.880 by using a random value node and then tweaking the settings. 09:30.900 --> 09:33.999 So let's start with one on the XY axis, but go a 09:34.000 --> 09:38.620 little bit higher to have some more randomness to 1.5. 09:38.820 --> 09:41.740 And then on the Z axis, I want only low values. 09:41.741 --> 09:46.560 So let's go from 0.05 to 0.3. 09:47.200 --> 09:49.620 And then we get a nice variation of shapes. 09:51.080 --> 09:57.840 Now all of these different instances have their exact size as the scale. 09:58.580 --> 10:03.480 And that is something that we can simply use with the instance scale node. 10:04.840 --> 10:10.040 So this is where we get the information of the height of each of these cubes. 10:10.041 --> 10:12.640 And that is something that we'll need to create the stack. 10:13.220 --> 10:15.485 To get a better view of what we're looking at, 10:15.486 --> 10:18.801 let me just go into local view on this object. 10:18.840 --> 10:21.500 So how do we now get these boxes into the right place? 10:21.820 --> 10:25.298 The main node that we'll use to orient these 10:25.299 --> 10:28.501 instances is the set instance transform node. 10:29.060 --> 10:32.632 This one lets us directly set the exact transformations 10:32.633 --> 10:36.140 for all of these boxes using the new matrix socket. 10:36.141 --> 10:44.360 So if I now add a combine transform node, you can see that all of the scale that 10:44.361 --> 10:47.078 we've been randomizing before is now set 10:47.079 --> 10:49.760 back to exactly what is defined in this node. 10:50.540 --> 10:55.440 So let's combine the instance scale in there to make sure that we keep that around. 10:56.000 --> 11:00.200 And then the translation and rotation, we can just set to any other value, 11:00.540 --> 11:02.580 and those will be applied to all the instances. 11:02.581 --> 11:07.040 Now we just need to figure out where they actually should be for each instance. 11:07.900 --> 11:10.840 For that I'm going to show you a little trick that is very useful. 11:11.740 --> 11:14.040 Let's use the accumulate field node. 11:14.880 --> 11:21.000 So what this node does is that for a domain of the geometry, in our case that 11:21.001 --> 11:26.660 is going to be the instance domain, it goes through all the different elements 11:26.661 --> 11:33.400 within the same group, and then accumulates the values of a certain field. 11:34.540 --> 11:38.560 In our case that is going to be a transform field. 11:39.300 --> 11:41.620 So let's set the data type to transform. 11:42.280 --> 11:46.600 And then what that does is that this node will go through all the individual 11:46.601 --> 11:50.580 instances for these cubes, and then accumulate the transforms. 11:50.940 --> 11:56.480 So instead of each cube just knowing its own transformation, this will go through 11:56.481 --> 11:59.585 all of the previous ones and add them on top of each 11:59.586 --> 12:02.240 other, which is exactly what we need for this stack. 12:02.740 --> 12:04.020 Let me show you how that works. 12:04.480 --> 12:10.700 Let's connect the trailing output of this node to a separate transform node. 12:10.940 --> 12:15.680 And for this we only want the translation and the rotation, so we plug that into our 12:15.681 --> 12:18.860 combine node, because the scale is already taken care of. 12:19.140 --> 12:24.020 Right now the input for this accumulate field node is nothing, so we are not 12:24.021 --> 12:27.520 applying any transformation at all for each of these instances. 12:28.100 --> 12:34.020 But now, as I use another combine transform node to give me a matrix field, 12:34.420 --> 12:40.220 and I tweak these values, you can see how each of these cubes is moved a little bit 12:40.221 --> 12:46.300 more than all the previous ones combined, rather than just moving them all at once. 12:46.840 --> 12:50.680 And that is the same also for the rotation and the scale. 12:51.340 --> 12:56.540 So there you can see that it's very useful to just use the concept of a transform and 12:56.541 --> 13:00.000 the accumulation, rather than having to do all the math yourself. 13:01.020 --> 13:05.600 So all the previous pizza boxes are influencing the ones on top. 13:07.060 --> 13:12.100 So now let me just zero this out again, and then we can actually use the exact 13:12.101 --> 13:15.262 information that we have over the size of all 13:15.263 --> 13:18.460 these cubes for the translation offset of them. 13:18.461 --> 13:25.240 We only need the Z component, so let's use a multiply node and multiply it with the 13:25.241 --> 13:28.820 001 to cancel out the X and the Y component. 13:29.320 --> 13:33.040 And as we connect this, you can already see how this works perfectly. 13:33.720 --> 13:41.180 So what is happening right now is that each cube is being offset by the 13:41.181 --> 13:45.840 accumulation of all of the sizes of the cubes that came before it. 13:45.841 --> 13:50.780 So this cube is set exactly to the combination of the height of the two 13:50.781 --> 13:56.061 before it, and then the next cube is set on top of the three before it, and so on. 13:56.920 --> 14:01.980 And if I change the bounds of the random scale, you can really see how this works 14:01.981 --> 14:06.060 perfectly, even if I have very different heights for all of these cubes. 14:06.640 --> 14:11.160 And this is already a very useful little stacking setup that you can use in a more 14:11.161 --> 14:15.120 generic way for other applications as well, with just a few nodes. 14:15.760 --> 14:18.560 So now, let's give this stack a bit more variation. 14:18.860 --> 14:21.618 Let's frame this as our main stacking part of the 14:21.619 --> 14:25.400 modifier, and then also add some variation to the rotation. 14:25.740 --> 14:31.480 For that, let's simply just connect this to a random value node, and you can 14:31.481 --> 14:33.560 already see how it is crumbling up on itself. 14:34.100 --> 14:38.400 Let's put the range from negative one to one to get it centered around zero, 14:38.760 --> 14:42.480 and then scale the vector by a value. 14:43.360 --> 14:46.640 So now we have fine control over the strength of this effect. 14:47.140 --> 14:51.460 And here you can see this is basically what we had in the final setup to control 14:51.461 --> 14:53.680 some variation in how the stack is leaning. 14:54.180 --> 14:57.860 And if I change the random seed, it changes the overall shape. 14:58.820 --> 15:02.220 And again, this is quite different from what it would look like if we just rotated 15:02.221 --> 15:07.401 all the pizza boxes on their own, since they really have an effect on each other. 15:07.980 --> 15:12.200 So let's do the same thing to introduce a slight offset to the translation. 15:13.000 --> 15:20.841 I'll just add another add node, and then use yet another random value node. 15:21.500 --> 15:25.080 But we don't want any offset in the z direction, so let's set that to zero, 15:26.020 --> 15:30.100 and then we want it centered around zero, so let's put the minimum bounds to 15:30.101 --> 15:32.257 negative one, and then also add another scale 15:32.258 --> 15:35.421 node to control the strength of that effect. 15:37.180 --> 15:42.040 Now we can just very easily expose these as controllable parameters in the modifier 15:42.041 --> 15:46.420 by typing in input and creating a new group input. 15:47.680 --> 15:51.420 Just make sure to name them accordingly so you don't forget what they actually mean. 15:52.500 --> 15:54.980 Let's also expose the number of cartons. 15:55.340 --> 15:58.320 And there you go, that's a big chunk of the setup already done. 15:58.580 --> 16:02.726 We can dynamically control the amount and the random 16:02.727 --> 16:06.400 offset, giving us a very wild stack of pizza boxes. 16:07.860 --> 16:10.349 So next up, let's create the bounce effect that goes 16:10.350 --> 16:13.080 through the whole stack as the Vespers jittering. 16:13.620 --> 16:15.500 The idea for that is quite simple. 16:16.040 --> 16:18.841 This setup already has a control empty that 16:18.842 --> 16:21.360 bounces around with the movement of the vehicle. 16:21.640 --> 16:26.640 And then this is what we're going to use to move the bottom-most pizza box. 16:27.440 --> 16:30.720 We're basically going to just constrain it exactly to that. 16:30.721 --> 16:36.260 And then we're going to create a simulation to get the offset from that 16:36.261 --> 16:38.860 transformation and move it along through the stack. 16:39.280 --> 16:42.630 So there's going to be a little bit of delay to move all of 16:42.631 --> 16:46.080 the additional pizza boxes on top by that transformation. 16:46.820 --> 16:49.760 And each frame, it's going to move a little bit further through the stack. 16:49.960 --> 16:52.260 And that way, go all the way to the top. 16:52.920 --> 16:55.886 So let's start with that setup by making a bit 16:55.887 --> 16:58.840 more space and then adding in the simulation zone. 16:58.841 --> 17:03.300 To get familiar with how the simulation zone works in general, there is also 17:03.301 --> 17:06.620 another video on the Blender YouTube channel if you want to check that out. 17:07.120 --> 17:10.140 Here I'm not going to go into full detail explaining that. 17:10.840 --> 17:13.819 But essentially how it works is that we get some 17:13.820 --> 17:16.600 geometry in on the very first frame of the simulation. 17:17.180 --> 17:22.060 And then for each frame afterwards, there is a simulation loop happening 17:22.061 --> 17:24.920 between the output node and the input node. 17:25.440 --> 17:30.540 Where everything we pass out on one frame is passed back in on the next one. 17:31.580 --> 17:34.375 In this case, the data that we want to simulate 17:34.376 --> 17:37.360 over is going to be exactly a new matrix attribute. 17:38.220 --> 17:42.060 So with this simulation selected, let's go to the properties panel, 17:42.320 --> 17:46.260 and then in the node panel, add a new entry for simulation data. 17:47.180 --> 17:51.280 Let's call this the transform and then change the socket type to matrix. 17:51.960 --> 17:54.818 Here we also need to keep in mind that the geometry that we 17:54.819 --> 17:59.300 are working with is made up from instances and not meshes. 17:59.460 --> 18:03.180 So the attribute domain needs to be changed to instance as well. 18:04.300 --> 18:07.100 Let's make a very little test setup to see how this works. 18:07.620 --> 18:10.435 So let's add another set instance transform 18:10.436 --> 18:13.021 node and then connect that transform attribute. 18:13.460 --> 18:15.900 As well as a viewer node with control shift click. 18:16.360 --> 18:20.020 And right now it just resets all of the transforms to one. 18:20.240 --> 18:26.640 But if we connect this to complete the loop, and then also do a multiplication 18:27.860 --> 18:34.000 with another transform matrix, and then type in some value, we can see 18:34.001 --> 18:38.740 how now this actually changes the transformation of the cubes over time. 18:39.180 --> 18:44.840 So with each frame, this transformation is applied on top of the previous state. 18:45.320 --> 18:47.420 And that is what the simulation is doing. 18:48.240 --> 18:50.280 So this is working perfectly fine. 18:50.900 --> 18:52.820 Now let's get rid of these nodes. 18:53.920 --> 18:58.828 And I want to be able to control the very first pizza box 18:58.829 --> 19:02.660 in the stack with the controller empty from the vehicle. 19:04.100 --> 19:06.020 So let's add a object info node. 19:06.380 --> 19:08.680 And then I already have the empty in place. 19:08.880 --> 19:14.140 So now I can just use the eyedropper tool to select the wiggle control empty. 19:15.200 --> 19:18.780 Let's set the position to relative to get it into the right space. 19:18.781 --> 19:23.120 And now we can use the transform output to get it into the right place. 19:23.440 --> 19:27.540 But we only want that to happen for the very first pizza box in the stack. 19:28.440 --> 19:29.980 So let's use a switch node. 19:31.840 --> 19:38.640 And for the switch input, we can compare the index to zero, and check that only 19:38.641 --> 19:42.740 when the index is equal to zero, we want to set this transform. 19:43.360 --> 19:47.260 But now we actually need to apply this information to our stack. 19:47.261 --> 19:52.620 Right now we only stack up all the boxes at the very end with our randomization setup. 19:53.120 --> 19:57.780 So what I want to do is combine this with the simulation that we're doing. 19:58.260 --> 20:01.680 And we're going to do this very similarly to what we've done before. 20:02.180 --> 20:07.801 So let's combine the output from the simulation with another accumulate field node. 20:07.860 --> 20:10.480 Make sure to set the domain to instance. 20:12.900 --> 20:15.380 And then this just as well will accumulate 20:15.381 --> 20:17.940 all the transforms throughout the whole stack. 20:18.400 --> 20:22.860 And the transformations that we're going to get out of the simulation are just 20:22.861 --> 20:26.040 going to be the additional offset that we get from the bounds. 20:26.640 --> 20:31.140 So let's combine these two transformations with another multiply matrices node. 20:31.760 --> 20:36.020 Let's connect the offset in the first slot and then the stacking into the second. 20:36.740 --> 20:41.280 And you can see how the stack already snaps to the control of the empty. 20:41.920 --> 20:45.832 This is working because the very first pizza box is 20:45.833 --> 20:49.160 getting exactly that transform set from the simulation. 20:49.600 --> 20:53.085 And then the accumulate field node will give us this 20:53.086 --> 20:56.120 exact transform for all the boxes on top of it as well. 20:57.080 --> 21:02.800 The reason why we're using the leading output here while we were using the 21:02.801 --> 21:07.495 trailing output before is that now for the offset you want 21:07.496 --> 21:11.500 to include the transformation value for each box itself. 21:11.501 --> 21:16.640 So here the offset transformation for the bounds is used 21:16.641 --> 21:20.140 for the box itself plus all the previous ones combined. 21:20.700 --> 21:24.420 For the stacking itself we did not want to consider the 21:24.421 --> 21:27.540 height of the box itself but only the previous ones. 21:28.220 --> 21:32.199 So right now with this base setup the entire stack 21:32.200 --> 21:35.121 moves perfectly along with the control empty. 21:35.500 --> 21:37.120 But that's not actually what we want. 21:37.620 --> 21:42.520 Now that we have the bounds of the empty stored on the very first pizza box let's 21:42.521 --> 21:45.740 try and propagate that through the stack for each frame. 21:46.000 --> 21:51.860 So instead of storing nothing as the transformation for the other boxes we're 21:51.861 --> 21:57.160 going to take the information of the previous frame and then use an evaluated 21:57.161 --> 22:02.740 index node to plug that into the false input of the switch. 22:03.040 --> 22:05.660 Make sure to set the domain to instance. 22:06.360 --> 22:13.561 And then for the index input we're going to duplicate this index node and subtract one. 22:14.400 --> 22:17.764 And that will, with each frame pass through the 22:17.765 --> 22:21.300 transformation of the box below all the way through the stack. 22:22.180 --> 22:25.420 At this point we get a little bit of a problem where everything just disappears 22:26.140 --> 22:31.040 but as you take a close look this is happening over a couple of frames. 22:32.280 --> 22:33.840 And everything is just shrinking. 22:34.780 --> 22:38.480 The reason for that is that there's a difference in scale 22:38.481 --> 22:42.280 between the pizza box object and the controller empty. 22:42.720 --> 22:47.880 Here we don't really care about the scale we just want things to rotate and offset. 22:48.180 --> 22:51.864 So what we can do is do a separate and then a combine of the 22:51.865 --> 22:56.360 individual transform components and just leave out the scale. 22:58.060 --> 23:00.631 Now the pizza boxes are way too big but we can just 23:00.632 --> 23:03.241 manually scale them down to the size that we need. 23:03.900 --> 23:08.000 And if I play this you can see how now this is working perfectly fine. 23:08.180 --> 23:11.735 With each frame the bounce from the first box is 23:11.736 --> 23:15.081 propagated like a wave all the way through the stack. 23:16.660 --> 23:20.255 If I increase the size of the stack we need to go back 23:20.256 --> 23:23.100 to the very first frame to actually see the effect. 23:24.360 --> 23:27.260 But you can see how this effect is very clearly visible. 23:27.800 --> 23:30.795 To actually change the height of the stack in real 23:30.796 --> 23:33.640 time we need to change the setup a little bit. 23:33.641 --> 23:39.020 Instead of just passing in the geometry through the simulation input and then 23:39.021 --> 23:43.684 using that later on which will store the very first frame that 23:43.685 --> 23:47.120 the simulation is running we need to pass it in differently. 23:47.500 --> 23:55.060 So let's add a sample index node into the simulation set this to matrix and then 23:55.061 --> 24:02.280 instance and instead of directly using the matrix input from the simulation we are 24:02.281 --> 24:07.329 going to sample it exactly from the same index 24:07.330 --> 24:12.021 and then connect the outside of the simulation. 24:13.100 --> 24:19.020 This means that each frame we update the new stack with the changed height which 24:19.021 --> 24:22.332 can have a different amount of instances and then 24:22.333 --> 24:25.500 sample the simulated data from the previous frame. 24:26.720 --> 24:31.120 So now if I play back the simulation you can see how we can dynamically change the 24:31.121 --> 24:34.100 height of the stack and the simulation adapts to that. 24:34.340 --> 24:38.140 And those are the most important aspects of this demo setup done. 24:38.480 --> 24:42.600 There are a few additional things that I am doing in the demo file so if you are 24:42.601 --> 24:45.740 interested you can check those out but I hope this should give 24:45.741 --> 24:48.340 you a good kickstart to understand what you are looking at. 24:48.780 --> 24:50.770 And that covers most of what you need to know to 24:50.771 --> 24:53.900 get started using the matrix socket in Blender 4.2. 24:53.980 --> 24:57.540 Make sure to also check out the video about the new things in node tools to 24:57.541 --> 25:00.160 learn another application of using the matrix socket.