植被：创作技巧

Set the visibility distances for LODs by enabling the Combine By Postfixes option and adjusting values in the import settings.通过启用Combine By Postfixes选项并在导入设置中调整值来设置LOD的可见距离。

警告

The video tutorial is created using SDK version 2.13. The general workflow demonstrated in the tutorial is applicable for versions up to 2.19. However, specific details such as UI may differ across various versions.视频教程使用SDK 2.13版本创建。教程中演示的一般工作流程适用于2.19及以下版本。但是，UI等具体细节可能因版本而异。

Shadow LOD

阴影LOD#

If the Import Materials flag was enabled in the import options, all necessary materials are already generated and assigned to the surfaces of the tree. Let's consider material parameters that worth being noted:如果在导入选项中启用了 Import Materials 标志，则所有必要的材质都已生成并分配给树的表面。让我们考虑一些值得注意的材质参数：

• Make the leaves material Alpha-Test to cut out texels according to the Alpha channel of the Albedo texture.使叶子材质为 Alpha-Test，以根据 Albedo 纹理的 Alpha 通道剪切纹理像素。

• If specular highlights are incorrect, it is recommended to set the Specular value to 0.如果高光不正确，建议将 Specular 值设置为 0。

  

  Incorrect lighting on the Reflections Rendering Debug preview (left) and the result image (right)反射渲染调试预览（左）和结果图像（右）中的光照不正确

• Consider enabling the Two Sided option for the material to make the foliage denser. Be careful, as it may significantly affect performance if there are too many polygons in the scene.考虑启用材质的Two Sided选项以使树叶更密集。请注意，如果场景中有太多多边形，这可能会显著影响性能。

  It may be better to switch the Backside Normal mode to the To Front Side option since it usually provides more realistic results for foliage.将Backside Normal（背面法线）模式切换为To Front Side（向前）选项，因为这通常为树叶提供更逼真的结果。

• If textures make it evident that foliage is made of flat chunks, a great solution to this is the Angle Fade feature that cuts out polygons faced to the camera at extreme angles.如果纹理显示树叶由平面块组成，一个很好的解决方案是使用Angle Fade（角度淡出）功能，该功能在极端角度下剪切面向摄像机的多边形。

  

  注意

  This feature may work incorrectly for meshes that have modified normals.此功能可能对修改过法线的网格无法正常工作。

• Adjusting translucency for the foliage material is necessary for a better look. Increase the Translucent value to permit light to pass through the object.调整树叶材质的半透明度以获得更好的外观。增加Translucent（半透明）值以允许光线穿过对象。

  

  You can also enable the use of the Translucent Map in the States tab to specify a single-channel texture that will define parts of the object that aren't translucent (such as branches).您还可以在States（状态）选项卡中启用Translucent Map（半透明贴图），以指定定义对象不透明部分（如树枝）的单通道纹理。

  注意

  There is no need to paint fibers and small features of leaves on the Translucent texture if the Normal map is used and defines such surface irregularities.如果使用了法线贴图并定义了此类表面细节，则无需在半透明纹理上绘制叶子的纤维和小细节。

  Albedo texture反照率纹理

  Translucent texture半透明纹理

• Enable the Terrain Lerp flag for the material of the bottom part of the tree to blend your tree with a Terrain in your scene.启用底部树干的材质的Terrain Lerp（地形插值）标志，以将您的树与场景中的地形混合。

  

The fact that foliage is composed of flat chunks results in inaccurate shading. To counteract this and hide the flatness of the mesh, adjust vertex normals and improve the way the foliage is shaded.由于树叶由平面块组成，导致着色不准确。为了抵消这一点并隐藏网格的平面性，调整顶点法线并影响树叶的着色。

The following solutions are possible:以下是可能的解决方案：

• Enable the Normals Rotated To Camera option so all surface normals will be oriented towards the camera, ignoring the geometry normals. This feature checks out as a quick solution, although it makes all polygons shaded the same way.启用 Normals Rotated To Camera（法线旋转到摄像机）选项，使所有表面法线朝向摄像机，忽略几何法线。此功能作为快速解决方案，尽管它使所有多边形以相同的方式着色。

  

• Edit vertex normals manually in your modeling software. Transfer vertex normals from a boundary cage to make the foliage look like a smooth and dense tree crown.在建模软件中手动编辑顶点法线。从边界笼传输顶点法线，使树叶看起来像光滑而密集的树冠。

  注意

  It is recommended to use a dome-like boundary cage with the sides elongated to the ground to avoid shading errors on lower polygons.建议使用圆顶状的边界笼，边向地面拉长，以避免较低多边形上的着色错误。

  

  Transferring normals from a boundary cage从边界笼转移法线

  As a result, the flatness of foliage geometry is less evident (on the right):结果，树叶几何的平面性不那么明显（右侧）：

  

The MipMapping technique, supported by UNIGINE renderer, implies sampling lower textures for smaller and distant polygons. At that, minor features of foliage start wiping away with the distance. In some cases, branches and leaves look thicker when far from the camera than on a close-up view.UNIGINE 渲染器支持的MipMapping技术意味着为较小和较远的多边形采样较低的纹理。在这种情况下，树叶的微小特征会随着距离的增加而逐渐消失。在某些情况下，远离摄像机的树枝和树叶看起来比近距离视图更厚。

MIP mapsMIP 映射

This issue can be resolved via these approaches:可以通过以下方法解决此问题：

• Engage the Mip Bias feature to shift the distance at which the switch between MIP-levels is performed. This option significantly affects the performance.使用 Mip Bias 功能来来调整MIP级别之间切换的距离。此选项显著影响性能。
• By default, MIP maps for a texture are generated automatically on import using the Box filtering that may provide too blurred results. Consider switching to the Point filtering type to get sharper MIP maps.默认情况下，纹理的 MIP 贴图在导入时使用 Box 过滤自动生成，可能会提供过于模糊的结果。考虑切换到 Point 过滤类型以获得更清晰的MIP贴图。

• You can also prepare custom MIP maps in third-party software. For example, here is a comparison between MIP maps generated using the Box filtering and the sharper Kaiser filtering:您还可以在第三方软件中准备自定义MIP贴图。例如，以下是使用Box过滤和更清晰的Kaiser过滤生成的MIP贴图的比较：

  

  To import a texture with custom MIP-levels, use the Combine option for a texture with laid out MIP-levels or save them to a .texture format and import the texture with the Unchanged option enabled.要导入具有自定义MIP级别的纹理，请使用Combine（组合）选项导入具有布局MIP级别的纹理，或将其保存为.texture格式并启用Unchanged（未更改）选项导入纹理。

Stem animation applies vertex movement based on spatial 3D noise to simulate bending of the plant's trunk or stem caused by wind. The mesh's pivot point is considered fixed, and the further the vertex is along the Z axis, the stronger movement is applied to it.茎干动画基于空间3D噪声应用顶点移动，以模拟由风引起的植物树干或茎干的弯曲。网格的枢轴点被认为是固定的，顶点沿Z轴越远，应用的移动越强。

Thus, it is necessary to place the pivot point at the correct position (usually, it is the bottommost point of the stem) and orient the model, so the Z axis goes upwards.因此，必须将枢轴点放置在正确的位置（通常是茎干的最底部），并调整模型的方向，使Z轴向上。

Stem animation example茎干动画示例

A set of Parameters controls the animation.一套控制动画的参数

Please note that all surfaces of the plant must have identical stem animation parameters in order to synchronize their movement.请注意，植物的所有表面必须具有相同的茎干动画参数才能同步它们的运动。

Different stem animation parameters result in not synchronized parts of the tree不同的茎干动画参数导致树的部分不同步

The Leaves animation is another layer of vertex shader animation mainly applied to foliage, providing additional detail bending. Using this type of animation requires preliminary adjustment to geometry on the modeling stage.树叶是顶点着色器动画的另一层，主要用于树叶，提供额外的细节弯曲。使用此类型的动画需要在建模阶段对几何体进行初步调整。

Several approaches of leaves animation are available out of the box. Choose the type of animation using the Leaves option.有几种种现成的树叶动画方法。使用Leaves（树叶）选项选择动画类型。

Geometry Vertex Color Based

基于顶点颜色的几何#

This recommended approach providing the best control over foliage implies that leaves are rendered as polygons, and vertex colors are used for animation.这种推荐的方法提供了对树叶的最佳控制，意味着树叶作为多边形渲染，并使用顶点颜色进行动画。

Vegetation movements are defined by RGB channels of vertex colors as follows:植被运动由顶点颜色的RGB通道定义如下：

	Red channel is used for animation of smaller or peripheral parts of vegetation (leaves). Bright parts are animated, and dark parts are stiff.红色通道用于较小或外围植被部分（树叶）的动画。明亮部分被动画化，暗部分僵硬。
	Green channel is used to define the movement order for branches in order to desynchronize them. The movement sequence starts from the brightest element to the darkest.绿色通道用于定义树枝的运动顺序以使其不同步。运动序列从最亮的元素开始到最暗的元素。
	Blue channel is used to define which parts of branches can be bent. Brighter parts indicate bendable portions, and darker parts — stiff portions.蓝色通道用于定义树枝的哪些部分可以弯曲。较亮的部分表示可弯曲的部分，较暗的部分表示僵硬的部分。

The animation parameters control vertices movement:动画参数控制顶点运动：

It is also a regular practice to animate branches using this technique even if they are attached to the trunk:这也是使用此技术动画树枝的常规做法，即使它们附着在树干上：

The Green and Blue channels define the movement of vertices; the Red channel is not used for branches绿色和蓝色通道定义顶点的运动；红色通道不用于树枝

At that, related surfaces must have the same vertex colors on adjacent vertices and identical animation parameters in order to synchronize their movement:在这种情况下，相关表面必须在相邻顶点上具有相同的顶点颜色和相同的动画参数，以同步它们的运动：

The colors of adjacent vertices of the trunk and foliage are the same, so the geometry stays connected when animated树干和树叶的相邻顶点的颜色相同，因此在动画时几何体保持连接

Geometry Vertex Color Based leaves animation基于几何顶点颜色的树叶动画

Geometry UV-based

基于UV的几何#

This is a rather legacy approach when leaves are rendered as standard polygons. It requires the UV Channel 2 to be defined for the mesh.这是一种较为过时的方法，当树叶作为标准多边形渲染时。它需要为网格定义UV通道2。

Geometry UV-based animation基于 UV 的几何动画

UV Channel 2: the stiffest vertices are in the top left cornerUV 通道 2：最硬的顶点在左上角

Animation uses UV channel 2 of an object as follows: in the UV grid, [0,1] is the pivot point for the object's movements and the stiffest part of the object, and towards [1,0], the object becomes more flexible.动画使用物体的UV通道2如下：在UV网格中，[0,1]是物体运动的轴心点，也是物体最硬的部分，朝向[1,0]，物体变得更加灵活.

Control the vertices movement via the same Animation Parameters.通过相同的控制顶点移动动画参数。

Billboard

Billboard（广告牌）#

Billboard is the most performance-friendly way of animating distant vegetation: all quads are rendered as billboards that always face the camera; the UV Channel 2 defines the size and movement of polygons. Hence, the foliage mesh should contain only quad polygons for leaves.Billboard（广告牌）是最节省性能的动画远距离植被的方式：所有四边形都作为广告牌渲染，始终面向摄像机；UV通道2定义多边形的大小和运动。因此，树叶网格应仅包含用于树叶的四边形多边形。

A billboards-based bush基于广告牌的灌木

The mesh of the bush灌木的网格

Animation uses UV channel 2 of an object as follows: in the UV grid, [0,1] is the pivot point for the billboard's movements, and the billboard's size can be changed by scaling the polygon in the UV channel.动画使用对象的UV通道2如下：在UV网格中，[0,1]是广告牌运动的轴心点，可以通过缩放UV通道中的多边形来改变广告牌的大小。

UV Channel 1UV 通道 1

UV Channel 2UV 通道 2

Mesh (above) and the result (below)网格（上）和结果（下）

Control the polygons movement via the same Animation Parameters.通过相同的控制多边形运动动画参数。

Stem and leaves animation are also controlled by the global Vegetation Animation Parameters. Via these settings, you can adjust stem and leaves animation intensity, speed, and wind effect globally and control the weather conditions per world.茎干和树叶动画也由全局植被动画参数控制。通过这些设置，您可以全局调整茎干和树叶动画的强度、速度和风效果，并控制每个世界的天气条件。

Note that the global parameters are just multipliers for the per-material animation parameters.请注意，全局参数只是每个材质动画参数的乘数。