WEBVTT 00:00:00.000 --> 00:00:03.220 So you've finally gotten your hot little hands 00:00:03.220 --> 00:00:09.000 on a shiny new graphics card for your PC, and you're confident that by pushing it to its limits, 00:00:09.000 --> 00:00:13.520 you'll be able to run any game at mouth-watering settings. 00:00:15.560 --> 00:00:18.840 But it turns out there's a long-standing bottleneck 00:00:18.840 --> 00:00:21.920 that limits how many frames your GPU can push. 00:00:21.920 --> 00:00:25.920 And we're not talking about your CPU or the PCI Express slot. 00:00:25.920 --> 00:00:31.040 It's actually the GPU's pipeline, the set of steps that visual data has to go through 00:00:31.040 --> 00:00:35.260 in order to become a fully rendered image. But how does that pipeline bottleneck 00:00:35.260 --> 00:00:39.840 your gaming experience? Let's find out by learning how a graphics pipeline works. 00:00:39.840 --> 00:00:44.680 And we'd like to extend our warm thanks to Jianye Liu, Senior Program Manager at Microsoft 00:00:44.680 --> 00:00:49.780 for helping us understand the problem and the solution that's starting to gain adoption. 00:00:51.360 --> 00:00:56.160 The first three steps of the pipeline, called the geometry pipeline, are really important 00:00:56.160 --> 00:01:01.200 and actually end up being where the bottleneck is. Step one is when the raw visual data, 00:01:01.200 --> 00:01:07.160 basically just numbers, plain numbers, like mama used to make them, goes through an input assembler, 00:01:07.160 --> 00:01:11.360 which takes the vertices of the triangles that ultimately make up a finished image 00:01:11.360 --> 00:01:14.760 and organizes them so that they're pointing at each other correctly. 00:01:14.760 --> 00:01:20.000 Step two takes this organized set of vertices and puts them through a vertex shader, 00:01:20.000 --> 00:01:24.320 which raises or lowers the vertices to create a 3D mesh of sorts. 00:01:24.320 --> 00:01:29.600 For example, the vertex shader can create a bumpy texture on a wall or ripples on a pond. 00:01:29.600 --> 00:01:35.360 The third step is a rasterizer. This is the bit that puts pixels inside each triangle 00:01:35.360 --> 00:01:39.200 to fill out the image. Now, there are other steps beyond these three, 00:01:39.200 --> 00:01:42.240 namely pixel shading, which gives each pixel 00:01:42.240 --> 00:01:47.080 the appropriate color and lighting, and the output merger, which puts different visual elements 00:01:47.080 --> 00:01:51.240 together, such as ensuring a character standing in front of a wall is displayed properly 00:01:51.280 --> 00:01:54.920 so you only see the character and not the wall behind them. 00:01:54.920 --> 00:01:59.600 However, the big bottleneck we're talking about today involves those first three steps. 00:01:59.600 --> 00:02:03.720 But why are they such a bottleneck? I mean, the process seems pretty straightforward. 00:02:03.720 --> 00:02:08.920 Well, there are a few big reasons for this. One is that that first step, the input assembler, 00:02:08.920 --> 00:02:12.680 can only understand data that's organized in a very specific way. 00:02:12.680 --> 00:02:17.080 Typically, it can't accept compressed data that can be moved around more quickly. 00:02:17.080 --> 00:02:20.220 Or if a developer thinks of a more efficient way to organize their data, 00:02:20.220 --> 00:02:25.740 the input assembler simply won't be able to understand it. Two, there are actually several optional stages 00:02:25.740 --> 00:02:29.660 after the vertex shader. For example, one is called a geometry shader 00:02:29.660 --> 00:02:34.780 that can take a point and expand it out to a particular shape, such as a strand of hair. 00:02:34.780 --> 00:02:39.900 This is quicker than drawing a bunch of new triangles, but the geometry shader and other optional steps 00:02:39.900 --> 00:02:43.460 have been added over the years as games have become more complex. 00:02:43.460 --> 00:02:48.900 They're essentially glommed onto the pipeline in a rigid, sequential way that can't be processed 00:02:48.940 --> 00:02:53.860 in parallel, meaning they take longer. Three, because of this rigid sequence, 00:02:53.860 --> 00:02:57.740 you have to wait until you get to the rasterizer to start culling. 00:02:57.740 --> 00:03:01.780 Sounds dangerous. Or throwing away unused triangles that are way off 00:03:01.780 --> 00:03:06.820 in the distance or obscured by an object on the screen. This is a problem because by the time the data 00:03:06.820 --> 00:03:11.740 has gotten to the rasterizer phase of the pipeline, the GPU has already done a ton of legwork 00:03:11.740 --> 00:03:14.900 rendering unnecessary triangles. 00:03:14.900 --> 00:03:20.100 Sounds like my typical Wednesday evening. So because the geometry pipeline is so inflexible, 00:03:20.100 --> 00:03:25.340 the solution isn't to retool it. It's to replace it completely. 00:03:25.340 --> 00:03:30.860 This is where mesh shading comes in, one of the biggest features in the DirectX 12 Ultimate API. 00:03:30.860 --> 00:03:34.300 Instead of having discrete steps before the rasterizer, 00:03:34.300 --> 00:03:39.500 the mesh shader is one stage that can do a few really cool things. 00:03:39.500 --> 00:03:42.940 First, the data that you feed into it can be much more arbitrary 00:03:42.940 --> 00:03:47.940 so it can understand compressed data and other data sets an old school input assembler couldn't. 00:03:47.940 --> 00:03:52.500 You can't handle this new data old man. Essentially, the mesh shader is almost 00:03:52.500 --> 00:03:57.180 like a mini programmable computer. So if a developer wants to accomplish some rendering task 00:03:57.180 --> 00:04:02.300 more efficiently, they can just code it in. Each of the processes above can also intelligently 00:04:02.300 --> 00:04:06.580 communicate with each other within a mesh shader. So instead of waiting to cull triangles 00:04:06.580 --> 00:04:11.300 so late in the process, it can be done earlier. And the geometry can even be arranged in a way 00:04:11.300 --> 00:04:15.540 to make culling easier, demanding even less GPU power. 00:04:15.540 --> 00:04:20.540 Oh, and we haven't even talked about the whole reason it's called mesh shading in the first place. 00:04:20.540 --> 00:04:23.540 It's a really fun term, meshlets. 00:04:23.540 --> 00:04:27.980 Instead of working on one triangle at once, your GPU can instead work on meshes 00:04:27.980 --> 00:04:33.900 of multiple triangles in parallel. So instead of making a decision about culling one triangle, 00:04:33.900 --> 00:04:38.340 your GPU can instead do them in batches. Throwing out data, it doesn't need a process 00:04:38.340 --> 00:04:43.900 and saving precious resources. Older vertex shaders only saw a soup of points 00:04:43.900 --> 00:04:47.940 instead of an actual mesh, but mesh shaders are much smarter 00:04:47.940 --> 00:04:51.620 and they can know exactly what they're working with much earlier in the rendering process. 00:04:51.620 --> 00:04:56.300 So what does all of this mean? Well, because your GPU doesn't have to work 00:04:56.300 --> 00:05:00.500 as hard for each frame, it means faster frame rates and more detailed environments. 00:05:00.500 --> 00:05:03.660 Ultimately, the things we all want from our graphics cards. 00:05:03.660 --> 00:05:08.220 Currently, many game developers are looking at the best ways to implement mesh shading into their titles 00:05:08.260 --> 00:05:12.100 because it's such a customizable tool and the old geometry pipeline 00:05:12.100 --> 00:05:16.580 has been around for such a long time. It might take a few years before we see widespread adoption 00:05:16.580 --> 00:05:20.140 of mesh shading in popular games. The good news though, is that there's already 00:05:20.140 --> 00:05:23.260 hardware support for it with newer consumer graphics cards. 00:05:23.260 --> 00:05:28.300 So by the time we see these games on the market, chances are we'll all have next-gen graphics cards 00:05:28.300 --> 00:05:31.380 that support these new features. Every one of us. 00:05:33.380 --> 00:05:35.940 Yes! I can't wait. 00:05:36.940 --> 00:05:41.180 Well guys, that's a Techquickie video. Not sure if you've ever seen one before, 00:05:41.180 --> 00:05:45.220 but that's what it's like. Hey, speaking of like, you wanna like the video 00:05:45.220 --> 00:05:48.980 if you liked it? Hey, do you have a like? Do you have a like to give out? 00:05:48.980 --> 00:05:52.900 Please, we love your likes. Also check out other videos, 00:05:52.900 --> 00:05:57.300 comment below with video suggestions and don't forget to subscribe and follow Techquickie. 00:05:57.300 --> 00:05:58.140 Love you.