게임 개발을 위한 고급 디테일 매핑 기술

### 텍스처 배열을 사용한 고급 디테일 매핑
* 🎨 이 튜토리얼에서는 언리얼 엔진이나 유니티와 같은 게임 엔진에서 **텍스처 배열을 사용하여 고급 디테일 매핑**을 구현하는 방법을 시연합니다.
* 👚 예시 시나리오에서는 **데님, 가죽, 린넨, 펠트 등 다양한 머티리얼에 대한 세부 노멀 맵**을 만들고 머티리얼 마스크를 기반으로 캐릭터 모델에 블렌딩하는 과정을 살펴봅니다.
* 📦 이를 수행하는 '잘못된 방법'은 **여러 노멀 맵을 개별적으로 샘플링**하고 머티리얼 마스크를 기반으로 블렌딩하는 것인데, 이는 **계산 비용이 빠르게 증가**할 수 있습니다.
* 🛠 이 효과를 얻기 위한 '올바른 방법'은 **텍스처 배열을 만드는 것**인데, 이는 기본적으로 텍스처를 하나의 에셋으로 결합한 스택입니다.
* 🎨 강사가 언리얼 엔진에서 텍스처 배열을 생성하고 머티리얼 마스크를 기반으로 샘플링하여 **캐릭터 모델에 다양한 디테일 노멀 맵을 블렌딩하는 방법**을 시연합니다.
* 👥 이 튜토리얼에서는 배열에 사용되는 모든 노멀 맵에 대해 **일관된 해상도와 포맷**으로 텍스처 배열을 만드는 것이 중요하다는 점을 강조합니다.
* 💻 Unity에서는 **강사가 개별 노멀 맵을 아틀라스 텍스처로 결합**한 후 이를 **텍스처 배열로 변환**합니다.
* 📊 텍스처 배열을 사용하면 여러 노멀 맵을 개별적으로 샘플링하는 '잘못된 방식'에 비해 **명령어와 텍스처 조회 수가 줄어들어 셰이더의 효율성이 향상**됩니다.

텍스처 어레이를 사용하여 캐릭터 머티리얼의 여러 디테일 노멀 맵을 블렌딩하면 3D 환경에서 효율적이고 디테일한 표면을 만들 수 있습니다.

Today, we're going to talk about advanced detail mapping. Let's get started. So last week, we talked about detail normal mapping, and I showed you this example of a rock, and we added this really nice tight detail to the rock that you can see here. So when we zoom in, even though the main textures lose their resolution and kind of break down, we still have detail because we're tiling this additional normal map texture and getting extra detail on the surface. And right at the end of that video, I talked about another case where what if we're making something like a character where instead of our mesh just being made out of one material like this rock is, if our character has an outfit on that has denim and linen and leather and multiple materials, the technique that we looked at last week only has the option of using one detail map here. So we just have a detail map for rock, but if we need to add additional materials, there's no way of using one detail map in one place and another detail map in another place. So that's

what we're going to take a look at today. I'm going to show you a technique for adding different detail depending on what material is placed where on your material sets. So the first thing that I want to do is show you the wrong way to do it, and then I'll get into the right way to do it. So the first thing that I did is I went ahead and I created four different detail normal maps. Let's take a look at those in Photoshop really quick. All right, so here we are in Photoshop, and you can see I have a detailed normal map here for denim. I have one for felt, one for leather, and one for linen. The objective of these detail maps is just to create some really tight surface detail of what happens really close up on these different materials. Here in the denim, you can see that there are all these different little thread loops in the normal map. In the leather, you can see that we've got this nice skin texture going on, and then in the linen, we have some

thread as well. So the idea of these is when you get up really close on your character and you want to take a look, uh, at their clothing or, or what their, um, what the various materials are made of, that the textures don't break down when you get up that close, but you actually start to see the details that you would in real life on a character like this. And so we need a way of blending these four different detail, uh, textures together and then applying them to the base textures as well. Okay, so let's switch to Unreal, and I'll show you that. Like I said, I'm going to show you the wrong way to do it. So first of all, I've created this mask texture where one material is red, another is green, another is blue, and then the other one is in the alpha channel. So here's our alpha channel. You can see my mask is white in the alpha channel in this area. So I basically have just four different masks. And you can see I've set my compression setting to masks because that's what they are.

so i've got my red, green, and blue, red, green, blue, and alpha masks here. And then I brought in my normal maps: my denim, felt, leather, linen. And then let's take a look at the material that I created. Okay, so here's my material, and this looks a little bit crazy, and it is, and you definitely shouldn't do it this way. This is the example of how not to do it. So I've got my four normal maps here. They each have their own different texture sample. So I'm sampling all of them, and I have a multiplier here for how often they should be tiled. So for example, I could set this to 8 and tile them really tightly. And if we look on the preview over here, you can see that this detail shows up when we zoom in really close. But just for now, I'm going to set this to one. Normally, you'd want this value to be kind of high so that the detail normals are really tight on the surface. But just so we can see a little bit

better what's going on in the preview. I'm going to set that value to 1. So I'm tiling my texture coordinates. I'm sampling all four of my normal maps. Then I multiply each of them by the mask. So this one's multiplied by red, the second one is multiplied by green, the third one is multiplied by blue, and the fourth one is multiplied by the alpha channel. Then I add the results together, and I use the blend angle correct normals that we talked about previously. And this normal map here represents the base normal of my character. So you know, this might have the folds of the cloth and that kind of thing. It's got the really big details. And then these detail normal maps here have the really tight small details. And then this mask defines where each of those are. So if I were doing this on a real character, I would look at my UV layout, and I would paint these various masks in the areas where those materials show up on the character. Okay, like I said, this is the way to not

do it. The reason is I'm sampling uh five different textures here to do the detail. And if I end up with a character that has, let's say, they have eight different types of cloth, then I would have to bring in eight different normal maps and sample nine textures, including my mask, in order to get this effect. The more different types of materials I have, the more texture samples I'm doing, and my shader just starts to get really heavy. If we look at, and this isn't even doing any of the other things that my shader might need to be doing, it's just doing the normal maps. If we take a look at the stats here, you can see that my base pass shader is 186 instructions, and we're doing six texture lookups. So, uh, keep that in mind, 186 and six texture lookups, because we're going to compare that with the next technique that we do, and this is the right way to do it. Alright, so a better way to do this so that we can make this less expensive and allow us to expand.

this and even use more materials without needing to sample a whole bunch more detail. Normal maps is to use something called a texture array, and in order to do this, I'm just going to move all of this stuff out of the way. I'm just going to move all of it up here, and let's start. Let's kind of start fresh because we don't want. We don't want to be using all of that. So, I'm just going to sample another texture here, and in this sample, I'm going to sample something called a texture array. Now, first of all, I need to explain what that is. A texture array is kind of like a stack of textures instead of just having one texture map. I've made an asset where I have multiple texture maps all together in a stack. So, let's go ahead and create one of those. I'm going to open up my content drawer here, switch over to textures, and I'm going to right-click here and pick materials and textures. Then I'm going to come down here, and I'm going to pick texture 2D array.

and it gives me a new array, and I'm just going to call this my cloth array. Then I'm going to open this up, and you can see that immediately it's completely blank. Well, why is that? It's because I haven't added anything to my stack yet. Right here where it says source textures zero array elements, that means my stack is empty. And we know that we're using four different textures. We're using denim, felt, leather, and linen. And so I'm just going to go ahead and click this add button right here and add four slots to put my normal maps in. Then I'm just going to go ahead and add each of those to the slots. So first of all, I have denim, and then felt, leather, and then my linen. Okay, and now I have a stack of four textures, and my preview here shows that there are these different slices that are arranged vertically. And this is not really how the array is going to look. It's just how Unreal has chosen to represent it. There are

actually, there are four textures here that are each square. But it's just showing like a little swatch of each of the four so that I can see that there are more than one texture in the array. Now, if I were using this technique in production, I would probably think about all of the different kinds of characters and the types of outfits they were going to have and what materials those outfits might have. And I would build myself one array that had all the different kinds of details for all the different kinds of materials that my characters might have. And I might end up with a stack of something like 16 different materials. In this case, I'm doing an array of 1024 detail normals, but I'd probably use lower resolution. I'd probably use 128 or 256. And I'd make myself a stack of 16 of those. And then I could use this array for all of the characters in my game. That's how I would go about it. And so I'm just showing you an example of how this can be done, but I hope that

you can take what you learned from this example and apply it to the characters in your game. Now, I might make one array for the characters, and then another array for like the props in the environment, and another array for, uh, I'd split things up into different categories. Okay, so now that I have my array, I need to switch back to my material. Just go ahead and save this here, and I've got my texture sample, and I'm gonna drop this down, and I'm gonna type in my cloth array. All right, so now I'm texturing, or now I'm sampling that array, so we need to take a look at it. Looks like it's doing nothing so far. Let's go ahead and hook this up to our normal socket and see what happens, and you can see I get an error here. It says texture sample uvw input required for texture array sample. So, we need some uvs. So, I'll go ahead and add a texture coordinate node and plug that in, and I'm still getting the same error. It says, uh, texture sample ud uvw input required for.

texture array sample well what is we know that this node is giving us uv but what is a w well a w is the value that it uses to tell which of the items in my array stack i want to sample so what i need to do is add an append here so and i can append a value so i'm going to hold down the one key and click which will give me just a float value and here i've got a value of zero so i'm going to append this so now i've got my uvs coming in here and then this becomes my w value so now if i pass this into my uv socket ah now i get something showing up so i can see my denim normal map all right okay if i change this value to a one now i can see my felt normal map and if i change this value to a two now i can see my leather and if i change it to a three now i can see my linen so by changing this value i'm able to go ahead and

look at all of the different textures that i have in my array. Before i go further, I want to switch over to Unity and take a look at how to set up an array texture in that game engine. Alright, so here we are in Unity, and you can see that I've done things a little bit differently here. I took my four normal maps and combined them into a single texture in Photoshop by just laying them each out in a grid like this. This is sometimes called an atlas texture. So here I have my denim, my felt, my leather, and my linen, and I've combined them all into one texture. Now the next thing that I need to do is make them into an array. So I'm going to come up here to the top of the properties, and first of all where it says texture type, I'm going to pick normal map because that's what this is. And then texture shape, I'm going to pick 2D array. And then it gives me these values for columns and rows, and what it wants to do now is how many

textures do i have in the vertical dimension, and that's two. And then how many textures do I have in the horizontal dimension, and that's also two. So with these settings set, if I come down to the bottom here and hit apply, now you can see that I've turned it into an array. And it says cloth array down here. And then it's using... And then you can see that it says 1024x1024 with four slices. So I've turned this into an array texture. And just like I did in Unreal, I can now use this texture to sample the four different maps in different locations. But in Unity, I had to combine those textures together into one atlas texture in order to turn it into an array. I'll come back to Unity in a second and show you how to create the shader there. But let's switch back to Unreal for now and finish making our array material. Alright, so here we are back in Unreal. And what you can see is that I'm able to sample a single normal map and choose which

normal map. I want to sample with my w value here, but what I really want to do is to be able to tell it, you know, I maybe what I want denim over here, and I want felt over here, and leather over here. I want to be able to define what parts of my character have the different materials. How do I do that? Well, I need to create a texture in Photoshop, a map or a mask that defines where on my character the different materials are. All right, so here we are back in Photoshop, and I have something that looks similar to that color mask that we had from before, but this one is only black and white. Let me explain what's going on here. This dark area here is for one material. Each of these different shades or values is for where I want the different materials to show up. And you might be asking, how did you decide which colors to use for these four different values? Well, let's take a look at this gradient here. I know that I have four normal maps that I want to be able to

blend between and so I want to have these values that represent my four different maps. So what I did is I divided the gradient from black to white into four different quadrants: the darkest ones, the medium two, and then the brightest areas. And what I did is I picked a value that's kind of right in the middle of each of these quadrants. So here my value would be around 31 or 32. Here my value would be right around 96. Here my value would be like 160 something. And then here my value would be like 220 ish. And so I can sample these values and paint them into my mask. And then I can use this mask to determine which of the four normal maps to apply as detailed texture. Now if I were to use something, if I were to use an array that had more elements, I would need to split up my gradient into more than four values. Right now I've got it split into four, but if I were to have 16, then I would need to split it up into 16 and find the

the values along the gradient that go along with that. So basically, in my mask here, I would be painting 16 different hue values or brightness shades instead of four like I'm doing now. Okay, let's switch back to Unreal. Okay, so we're back in Unreal, and I created a new texture sample here. And for this one, I need to find my cloth mask. So here it is. You can see that I've got my four different shades here. And if I just plug this into the base color, you can see that I've got my four different shades of gray that determine where the different values go. But what I want to do is use this to replace this one value here. I know that if I pass something in the range of between 0 and 3, that I will get my different normal maps. But this texture here is in the range of zero to one. And so the first thing that I have to do is multiply this by a value of three so that it can go between 0 and 3. So I'm going to set my mask multiplied

by 3. And now the next thing that I would want to do is I want to round it because I want each of these shades to represent a whole number. So I'm going to add a round. So this first shade is going to get rounded down to zero. The next shade is going to get rounded to one. The third shade is going to get rounded to two. And then the fourth shade is going to get rounded to three. So each of these values, instead of being between zero and one, now they're going to be zero, one, two, and three. So if I pass this value into my w coordinate, now you can see that I've been able to use my mask here to define the areas of my character where the leather should appear, where the felt should appear, where the denim should appear, and where the linen should appear. That's pretty cool. All right. And then for the last little touch, I just need to combine it with my base normal map. So here's the normal map I've been using to represent the base normal map of my character.

i can wire this into base of my blend angle. Correct normals, and then wire this into the additional normal, and then finally connect that to my normal. And now you can see I have a character. Well, I've been calling this a character all along. It's really just the preview cube, um, but this is supposed to represent the character that I have with multiple materials. But you can see that I have my base normals, and then they're also combined with my detail normal, detail normals, and, uh, what I'm also going to do here just really quickly is multiply this by, let's say, by a value of 4, just so that I get a little bit tighter detail so that I can tile my normals. Now you can see I have the leather in this portion, I have the linen in this portion, I have the felt over here, and then up here I have the denim. I think I might have mixed that up a little bit. The denim is over in this part, but anyway, you can see how instead of sampling a whole bunch of

different textures. I was able to combine those textures into a single array texture and make the effect a bunch cheaper. Let's take a look at our instruction count. Now you can see that I'm only using 162 instructions and only doing three texture lookups, as opposed to what I was doing before where I was doing, uh, well, let's connect it up and see. Now I'm doing 186 instructions and six texture lookups. And that's only with four different detail materials. Like I said before, you can go pretty high with these if you want to. You can use, I think I've used up to 16 in the past, and you would not be able to do that with this technique because that's just too many texture samples. But here where you're able to combine them into a single array, you can get an effect that's a lot cheaper. 162 compared with 186 and just three texture samples instead of six. So great technique. All right, let's switch over to unity and I'll show you how to finish up.

there, okay, so here we are in Unity. And you can see that I've created a very similar type of shader. I have the base texture that represents the base normal map of my character, and I have my cloth mask that represents the mask. And in this case, it's looking red. And that's because I have it saved to a texture compression format that just compresses it into a single channel. In this case, it's compressing it into the red channel. So you can see here I'm sampling from the red channel, and then that mask I'm multiplying by 3 so that I can have my range between 0 and 3. And then I round those values so that I can get 0, 1, 2, or 3 out of my mask. And then I use that 0, 1, 2, or 3 value from my mask to tell my 2D array which slice of that stack of normal maps I want to sample. And then for my UV coordinates, I'm just bringing those in, isolating the x and y with my swizzle.

node, and then multiplying these by two. In this case, this is how many times I want to tile my detail normal. And then I'm sampling my array of normal maps here, my cloth array, and I'm using this node to unpack the normal map. And then I'm using the normal blend node to combine that with my base normal, and then passing that into the normal port on my master stack. Let's take a look at our preview here. If I zoom in, you can see that I've got my leather in this portion, my felt here, my linen, and my denim there. So just like I did in Unreal, I'm using this array texture to only make one texture sample and still be able to get all of these different materials. So one more time, just to review, if I were using this in production, I would create myself a set of normal maps and make a stack or an array of those normal maps that represent all of the different kinds of cloth, rubber, metal, and fabric that my characters are going to be made of.

and then I would make an array, and I would sample that array in all of my different character textures. And for each character, I would paint a mask that defines the different materials, what part of the character is made up of each of those different materials. And then I can use that array to make each of those material types look more detailed up close. Now, one important thing about making this array is all of the normal maps need to be the same resolution, and they also need to be the same texture format. So I can't do one that's like a DXT1 compression, and another one that's like a BC7 compression. They all need to match, so their sizes need to match, and their compression types need to match. But once I have that array, then I can sample that in all my different characters, and all I need to do is paint a different mask for each of the characters that determines where those materials are on the characters. And I can get nice tight detail when I get up close, and as I back out, I can still have

decent material with the base texture maps, and you may even find that you can get away with a lower resolution base normal map because you've got extra detail in your detail normal maps. Anyway, I hope you enjoyed today's video and that you learned something, that you learned how to use the sample texture 2D array node in Unity, and that you learned how to create texture arrays in Unreal as well, and that you can now use this technique to make your characters or your props more realistic looking when you get up close. Thanks for watching, everybody. Next week, we're going to come back and do the smooth step video that I've been talking about for a while. I know I got a little bit sidetracked on this normal map tangent, but yeah, be sure to come back next week and we'll talk about the smooth step node. Until then, have a great week and we'll see you next week, everybody. [Music]

Advanced Detail Mapping - Shader Graph Basics - Episode 14

Shader creation and other game dev tips and tricks in Unity and Unreal. My opinions are my own and do not represent the positions of my employer.

Ben Cloward has been a game dev for over 20 years and has been creating shaders since 2003.  He was a co-creator of ShaderFX, a plugin (originally for 3ds Max) that allows artists to create real-time shaders using a node-based interface.  ShaderFX is now built in to Max and Maya as the main way that real-time shaders are created.  Ben was the original author of the Uber shader used in Maya's viewport. In 2007, Ben joined Bioware in Austin, Texas as a Cg Supervisor focused on graphics, performance, and shaders - on titles such as Star Wars The Old Republic, and Anthem.  Ben now works for Unity on the Shader Graph team.  Ben has given numerous talks at industry events such as Siggraph, and GDC.  He loves to share what he has learned.

Ben Cloward

고급 디테일 매핑: 머티리얼 세트에 다양성 추가하기

디테일 매핑을 사용하면 기본 텍스처의 해상도가 떨어지는 경우에도 텍스처에 표면 디테일을 추가할 수 있습니다.

기존 기법에서는 하나의 디테일 맵만 허용하기 때문에 여러 머티리얼을 다룰 때 문제가 발생합니다.

해결책은 각 머티리얼에 대해 서로 다른 디테일 노멀 맵을 만들고 블렌딩한 다음 마스크 텍스처를 사용하여 머티리얼에 따라 다양한 디테일을 허용하는 방식으로 기본 텍스처에 적용하는 것입니다.

3D 머티리얼 생성 시 다중 텍스처의 비효율적인 사용

각 디테일에 여러 개의 노멀 맵과 텍스처 샘플을 사용하면 셰이더가 무겁고 비효율적일 수 있습니다.

현재 방식은 여러 텍스처 룩업이 필요하고 인스트럭션 수가 많아 셰이더에 부담이 될 수 있습니다.

3D 머티리얼 제작의 효율성과 확장성을 개선하려면 보다 비용 효율적인 접근 방식이 필요합니다.

3D 머티리얼용 텍스처 배열 만들기

텍스처 배열을 사용하면 데님, 펠트, 가죽, 리넨과 같은 여러 텍스처 맵을 쌓을 수 있어 3D 에셋의 머티리얼을 보다 효율적으로 처리할 수 있습니다.

캐릭터 의상마다 다양한 머티리얼 디테일을 포함하도록 배열을 사용자 지정할 수 있으며, 모든 게임 캐릭터에 사용할 수 있는 16가지 머티리얼 스택을 포함할 수도 있습니다.

프로덕션에서 사용할 때는 성능을 최적화하기 위해 텍스처 배열에 128 또는 256과 같은 낮은 해상도를 사용하는 것이 좋습니다.

캐릭터 디자인에 배열 텍스처 사용

배열은 게임 디자인에서 캐릭터와 환경 소품 모두에 사용할 수 있습니다.

텍스처 배열을 사용할 때는 텍스처 좌표 노드와 "w" 컴포넌트에 대한 실수 값을 UV 좌표에 추가하여 다양한 텍스처를 선택하고 표시해야 합니다.

Unity에서는 프로퍼티에서 텍스처 유형을 노멀 맵으로, 텍스처 모양을 2D 배열로 선택하면 여러 노멀 맵을 하나의 텍스처로 결합하여 배열로 전환할 수 있습니다.

머티리얼 매핑을 위한 배열 텍스처 만들기

이 프로세스에는 4개의 슬라이스로 1024x1024 배열 텍스처를 생성하여 서로 다른 머티리얼을 매핑하는 작업이 포함됩니다.

Unity에서는 텍스처를 아틀라스 텍스처로 결합하여 배열을 형성해야 하지만, Unreal에서는 캐릭터의 머티리얼 분포를 정의하기 위해 포토샵 마스크를 사용합니다.

마스크는 서로 다른 머티리얼의 영역을 나타내기 위해 서로 다른 흑백 음영으로 구성되며, 흑백의 그라데이션에 따라 선택된 값으로 네 가지 맵을 블렌딩할 수 있습니다.

캐릭터 디자인을 위한 텍스처 음영 조정

이 과정에는 텍스처 음영을 조정하여 캐릭터 디자인에 다양한 색조와 밝기 수준을 만드는 것이 포함됩니다.

마스크 값에 3을 곱하고 반올림하면 범위가 0-1에서 0-3으로 변환되어 더 많은 변형이 가능합니다.

마지막 단계에서는 기본 노멀 맵과 조정된 텍스처를 결합하여 다양한 머티리얼 모양과 향상된 디테일의 캐릭터를 만듭니다.

비용 효율적인 효과를 위한 텍스처 사용 최적화

서로 다른 텍스처를 단일 배열 텍스처로 결합하면 명령어가 186개에서 162개로 줄어들고 텍스처 룩업이 6개에서 3개로 줄어듭니다.

이 기법을 사용하면 더 적은 텍스처 샘플을 사용하여 더 비용 효율적인 효과를 얻을 수 있습니다.

Unity에서도 동일한 방법을 적용하여 유사한 유형의 셰이더를 사용하여 다양한 머티리얼에 대한 노멀 맵 스택을 생성함으로써 궁극적으로 제작 시 텍스처 사용을 최적화합니다.

디테일한 캐릭터 텍스처를 위한 텍스처 배열 만들기

이 프로세스에는 각 머티리얼 유형에 대해 서로 다른 캐릭터 텍스처와 페인트 마스크를 샘플링하는 배열을 만드는 작업이 포함됩니다.

모든 노멀 맵의 해상도와 텍스처 형식이 배열에 동일하게 적용되는 것이 중요합니다.

이 기술을 사용하면 가까이에서 세밀한 디테일을 표현할 수 있고 캐릭터를 더욱 사실적으로 만들 수 있습니다.