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本帖最后由 毒游小行家 于 2021-9-13 14:59 编辑
为 AAA 游戏制作头发和胡须 文/Aleksandr Sosa
Aleksandr Sosa 分享了他的 Hairstyle and Beard for Games 项目背后的工作流程的深入分解，展示了头发的最佳宽度，并解释了如何为 Marmoset、Unreal Engine 4/5 和 Unity 制作通用纹理集。
介绍大家好，我叫 Aleksandr Sosa，我是来自俄罗斯的 3D 艺术家。我做CG已经三年了。现在我在莫斯科的尖叫学校学习。今天我想跟大家分享一下我为AAA游戏制作各种男士发型和胡须的经验。 在《最后生还者 2》、《对马岛之魂》、《刺客信条：英灵殿》、《暗影小希望》、《地平线：零之曙光》、《博德之门 3》等现代游戏中，你可以看到惊人的毛发发育水平。发型是角色中最重要、最令人难忘的元素之一，所以你需要花足够的时间来达到一个好的效果。这条管道已经被描述了很多次，所以我不会给它带来任何新的东西，但我会尽量专注于对你的工作有帮助的不明显的点、困难和生活窍门。我们还将讨论其他有趣的观点。让我们开始吧。
参考
搜索参考！立即了解您想在决赛中看到什么发型非常重要，为此您需要参考。如您所见，我不仅收集了我需要的发型，还收集了其他几种发型，这有助于了解长头发的行为。
在这个阶段，了解头部和面部的毛发向哪个方向生长非常重要。我的发型比中短发的发型更容易做，因为我的发型上只有一个点是所有卷发都倾向于的，所以我只是忽略了生长方向。如果你做短发型一定要考虑头发的生长方向。胡须也应采用相同的方法。
雕刻
我的建议是在 ZBrush 中对头发和胡须进行一些基本的雕刻。这将为您在接下来的步骤中节省大量时间。此时，标记发际线很重要。基本上，发际线的高度等于鼻子的长度，你可以把这条线抬高一点，这样性格就会看起来更成熟。
纹理布局
下一阶段的工作，对我来说是最重要的工作之一，是纹理的布局。我在 Photoshop 中执行此操作。现在我们正在计划卷发的外观、形状、长度、可变性、数量和厚度。这应该是一个粗略的草图，但比例正确。 在第一张图片中，我用刷子画了卷发并指示了区域。红色是我将用于第一层头发和胡须的卷发，黄色是第二层和第三层，绿色是最后一层。你可以看到胡须的头发比发型的头发更浓密和弯曲，有必要让胡须显得缠结和浓密。在这个阶段计划它。不要忘记分析参考文献。
现在我们有了卷发的布局，我们可以前往 Maya 使用 XGen 来模拟草图中的锁。从 XGen 创建纹理到在 XNormal 中烘焙的整个过程在 CGMA Hair Creation for Games的课程中得到了完美的展示。
实际上，人的头发的厚度是 0.06-0.1 微米。作为一名美术师，我的任务是在游戏引擎的美观和技术要求之间找到平衡。对厚度进行试验，我得出以下结论：如果您使用的是 4096x4096 的纹理，那么如果纹理 2048x2048 的宽度为 0.03，则将宽度设置为 0.02。对于胡须，4k 可以使用 0.03 的宽度，2k 可以使用 0.35 的宽度，因为胡须上的头发总是比头上的厚
运行后，你应该有这些纹理：Alpha、ID、Depth、Root、Normal。
接下来，我们转到 Maya，将高度贴图加载到材质中，使头发不是白色，调整 Ambient Color 和 Diffuse。接下来，您需要正确切割几何体。在此阶段，您不需要为零件添加大量多边形。
完全透明的区域越少，对引擎越好。
接下来，我们将切片的几何形状收集成大量的卷发。卷曲由 3-4 部分组成。可以有很多选择，现在你的想象力更发挥作用，但你不需要做太多，8-10个就足够了。在所有工作的过程中，将添加更多卷发选项。重要的一点是边缘是水平的，以便变形器正常工作。
为了更好地显示头发，请使用此设置：
为了控制卷曲，我使用了三个变形器：Bend、Twist 和 Flare。和软选择来调整结果。很重要的一点，让卷曲的几何形状不进入头的几何形状，它应该位于头顶。这是为了让根部看起来自然。
从较粗的卷发开始，向下移动到稀疏的卷发。随着每一层新头发，头发应该越来越少。对于前三层，尝试完全重新创建所需的发型体积。4-5层为与主发型相撞的发型添加混乱的卷发。在第 1、2 和 3 层上，我使用了大量对称来加快处理速度。 如您所见，每个新图层都接近发际线。这有助于实现平稳过渡。胡须的制作方法相同，但对于胡须，三层对我来说已经足够了。
对于这个发型，我使用了 2 个生活窍门。第一的。这种发型由3个元素组成：发髻、马尾辫和头上的头发。在使用变形器时，这项技术为我节省了大量时间，并减少了整个发型的多边形数。由于这些元素的交界处隐藏在发带下，所以一切看起来都很稳固。 第二个技巧是我只沿着生长线放置卷发。由于在这种发型中，卷发相互重叠，我只将卷发放在绿色区域。红色区域没有头发。这个技巧在使用变形器时为我节省了大量时间，并大大减少了整个发型的多边形数量。在最后的镜头中，发型看起来很丰满，并且看不透
这些技巧不适用于胡须。我将模具放在下颚的整个表面上。
+6在的方向。试着让它们变得有趣。给一个有趣和独特的形状，使发型看起来不错。
为了改善根部的外观，您需要在 Photoshop 中通过多层将渐变映射应用于 Alpha 并调整色阶。
完成所有操作后，我们获得了 Marmoset、Unreal Engine 4/5 和 Unity 的通用纹理集。
结论
如果您有任何问题，可以发送给我，我会尽力回答。这种发型更漂亮的渲染图在我的ArtStation 上，所以也请查看它们。希望这对您有所帮助，感谢您的关注，祝您好运！
英文原版
Making Hair and Beards for AAA Games
Aleksandr Sosa shared an in-depth breakdown of the workflow behind his Hairstyle and Beard for Games project, showed the optimal width for hair, and explained how to make a universal set of textures for Marmoset, Unreal Engine 4/5, and Unity.
Introduction
Hello everyone, my name’s Aleksandr Sosa, I’m a 3D Artist from Russia. I’ve been doing CG for three years now. Now I’m studying at the Scream School in Moscow. Today I want to tell you about my experience of creating various men's hairstyles and beards for AAA games. In modern games such as The Last of Us 2, Ghost of Tsushima, Assassin’s Creed: Valhalla, The Dark Pictures Little Hope, Horizon: Zero Dawn, Baldur’s Gate 3, etc. you can see an amazing level of hair development. The hairstyle is one of the most important and memorable elements in the character, so you need to devote enough time to it to achieve a good result. This pipeline has been described MANY times, so I'm not going to bring anything new to it, but I will try to focus on non-obvious points, difficulties, and life hacks that will help you in your work. We will discuss other interesting points as well. Let's get started.
References
Search for references! It is very important to immediately understand what hairstyle you want to see in the final, for this you need references. As you can see, I had collected not only the hairstyle I needed but also several others, this is good in order to understand how long hair behaves.​
At this stage, it is very important to understand in which direction the hair on the head and face grow. My hairstyle is easier to do than a hairstyle with short and medium hair because there is only one point on my hairstyle that all curls tend to, so I just ignored the direction of growth. If you do a short hairstyle be sure to consider the direction of hair growth. The same approach should be used for the beard.​
Sculpting
My advice is to do some basic sculpting of hair and beard in ZBrush. This will save you a lot of time in the next steps. At this point, it is important to mark the hairline. Basically, the height of the hairline is equal to the length of the nose, you can raise this line higher, then the character will look more mature.​
Layout of TexturesThe next stage of work, one of the most important for me, is the layout of the textures. I do this in Photoshop. Now we are planning how the curls will look, shape, length, variability, quantity, and thickness. This should be a rough sketch, but with the correct proportions. In the first picture, I drew the curls with a brush and indicated the zones. Red is the curls that I will use for the first layer of hair and beard, yellow is the second and third layers, green is the final layer. You can see that the hair for the beard is thicker and curvier than the hair for the hairstyle, it is necessary to make the beard appear tangled and thick. Plan it at this stage. Do not forget to analyze the references.​
Now that we have the layout of the curls, we can head to Maya to use XGen to simulate the locks from our sketch. The whole process of creating textures from XGen to baking in XNormal is perfectly shown in the course from CGMA Hair Creation for Games.
In reality, the thickness of a human hair is 0.06-0.1 micron. My task as an artist is to find the balance between good looks and technical requirements for the game engine. Experimenting with the thickness, I came to the following conclusion: if you are using a texture of 4096x4096 then set the width to by 0.02 if the texture 2048x2048 has a width of 0.03. For a beard, you can use a width of 0.03 for 4k and 0.35 for 2k, since the hair on the beard is always thicker than on the head​
After running, you should have these textures: Alpha, ID, Depth, Root, Normal.
Next, we go to Maya, load the Height Map into the material so that the hair is not white, adjust the Ambient Color and Diffuse. Next, you need to cut the geometry correctly. At this stage, you don't need to add a lot of polygons for the parts.
The fewer areas with full transparency, the better for the engine.
Next, we collect the sliced geometry into voluminous curls. The curl consists of 3-4 parts. There can be many options, now your imagination works more, but you don't need to do too much, 8-10 is enough. In the course of all the work, even more options for curls will be added. The important point is that the edges are level for the deformers to work properly.​
For better hair display use this setting:
To control the curls, I used three deformers: Bend, Twist, and Flare. And soft selection to adjust the result​. A very important point so that the geometry of the curl does not enter the geometry of the head, it should lie on the top of the head. This is to make the roots look natural.​
Start with thicker curls, moving down to sparse curls. With each new layer of hair, there should be less and less hair. For the first three layers, try to completely recreate the required volume of the hairstyle. 4-5 layers add chaotic curls to the hairstyle that are knocked out of the main hairstyle. On layers 1, 2, and 3, I used a lot of symmetry to speed up the process. As you can see, each new layer approaches the hairline. This helped to achieve a smooth transition. The beard was created the same way, but for the beard, three layers were enough for me.​
For this hairstyle, I used 2 life hacks. First. This hairstyle consists of 3 elements: bun, ponytail, and hair on the head. This technique saved me a lot of time when working with deformers and reduced the polycount of the entire hairstyle. Since the junction of these elements is hidden under the scrunchie, everything looks solid. The second trick is that I only placed the curls along the growth line. Since in this hairstyle the curls fall on top of each other, I place the curls only in the green zone. There is no hair in the red zone. This trick saved me a lot of time when working with deformers and reduced the polycount of the entire hairstyle a lot. In the final shots, the hairstyle looks voluminous and is not visible through and through
These tricks do not work with the beard. I placed the dies over the entire surface of the jaw.
Pay attention to the green lines, they show the direction in which the strands of hair are located. Try to make them interesting. Give an interesting and unique shape so that the hairstyle looks good.
To improve the appearance of the roots, you need to apply a Gradient Map to the Alpha through multi-layer in Photoshop and adjust the Levels.
After all the actions are done, we got a universal set of textures for Marmoset, Unreal Engine 4/5, and Unity.
Conclusion
If you have any questions, you can send them to me and I will try to answer them. More beautiful renders of this hairstyle are on my ArtStation so check them out too. Hope this was helpful, thanks for your attention, and good luck!\
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