Version: 2018.2 (switch to 2018.3b or 2017.4)
Terrain Textures
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Trees

Unity terrains can be furnished with trees. Patches of trees can be painted onto a terrain in much the same way that heightmaps and textures are painted but the trees are solid 3D objectsA 3D GameObject such as a cube, terrain or ragdoll. More info
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that grow from the surface. Unity uses optimisations (eg, billboarding for distant trees) to maintain good renderingThe process of drawing graphics to the screen (or to a render texture). By default, the main camera in Unity renders its view to the screen. More info
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performance, so you can have dense forests with thousands of trees and still keep an acceptable framerate.

Terrain with trees
Terrain with trees

Enabling trees

The tree button on the toolbarA row of buttons and basic controls at the top of the Unity Editor that allows you to interact with the Editor in various ways (e.g. scaling, translation). More info
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enables tree painting.

Initially, the terrain will have no trees available but if you click the Edit Trees button and select Add Tree you will see a window to select a tree assetAny media or data that can be used in your game or project. An asset may come from a file created outside of Unity, such as a 3D model, an audio file or an image. You can also create some asset types in Unity, such as an Animator Controller, an Audio Mixer or a Render Texture. More info
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from your project.

The Add Tree window
The Add Tree window

Unity comes with several sample SpeedTree tree objects in the Standard Assets packages for prototyping purposes Assets > Import Package > Terrain Assets) but you can also create suitable objects with SpeedTree Modeler app, Unity Tree Creator tools or other 3D modelling apps.

If the selected tree object is created by the Tree Creator, the window will show Bend factor for adjusting the wind responsiveness. See the section on Making trees bend in the wind below.

Painting trees

With a tree selected, you can paint onto the landscape in the same way you paint textures or heightmaps. You can remove trees from an area by holding the shift key while you paint and remove just the currently selected tree type by holding down the control key. The familiar Brush Size option is available for tree painting but the Opacity property is replaced by Tree Density, which controls the average number of trees painted into a given unit of area.

There is a ranged slider for you to control the tree’s minimal height and maximal height. If you disable Random, you can specify a value for all tree’s height. By default a tree’s width is locked to height so that trees are always scaled uniformly. However you can disable Lock Width to Height option and specify the width separately.

There is also a control for Color Variation and Random Tree Rotation. The variation options help to create the impression of a random, natural-looking forest rather than an artificial plantation of identical trees.

The Mass Place Trees button is a very useful way to create an overall covering of trees without painting over the whole landscape. Following a mass placement, you can still use painting to add or remove trees to create denser or sparser areas.

SpeedTree/LOD trees

From Unity 5, you can use SpeedTree Modeler from IDV, Inc. to create trees with advanced visual effects such as smooth LODA system for building multiplayer capabilities for Unity games. It is built on top of the lower level transport real-time communication layer, and handles many of the common tasks that are required for multiplayer games. More info
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transition, fast billboarding and natural wind animation. Please refer to their site for detailed information. You can also freely import SpeedTree assets into your project folder from asset storeA growing library of free and commercial assets created by Unity and members of the community. Offers a wide variety of assets, from textures, models and animations to whole project examples, tutorials and Editor extensions. More info
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packages or other third party sources.

See here for more information.

Tree Creator trees

Unity has its own Tree creator that you can use to produce new tree assets but you can also use a standard 3D modelling app for the task. The tree meshThe main graphics primitive of Unity. Meshes make up a large part of your 3D worlds. Unity supports triangulated or Quadrangulated polygon meshes. Nurbs, Nurms, Subdiv surfaces must be converted to polygons. More info
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should have fewer than 2000 triangles (for performance reasons) and the anchor point should be right at the base of the tree where it emerges from the ground. The mesh should always have exactly two materials, one for the tree body and the other for the leaves.

Trees must use the Nature/Soft Occlusion Leaves and Nature/Soft Occlusion Bark shaderA small script that contains the mathematical calculations and algorithms for calculating the Color of each pixel rendered, based on the lighting input and the Material configuration. More info
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. In order to use those shaders you also have to place the tree in a special folder that contains the name “Ambient-Occlusion”. When you place a model in such a folder and reimport it, Unity will calculate soft ambient occlusionA method to approximate how much ambient lighting (lighting not coming from a specific direction) can hit a point on a surface. More info
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in a way that is specifically designed for trees. The “Nature/Soft Occlusion” shaders rely on the folder naming convention and the tree won’t render correctly if you don’t follow it.

When you save a tree asset from the modelling app, you will need to click the Refresh button (shown in the inspector when the tree painting tool is selected) in order to see the updated trees on your terrain.

Using colliders with trees

You can add a Capsule Collider to a new tree asset by instantiating it in the scene, adding the collider (menu: Component > Physics > Capsule Collider) and creating a new prefab for the modified tree object. When you add the tree to the terrain for painting, make sure you select the prefab with the collider rather than the original object. You should also enable Create Tree Colliders in the terrain’s Terrain Collider component inspector.

Making trees bend in the wind

The first thing you will need to do is create a wind zone. You can do this by selecting from the menu: Game Object > 3D Object > Wind Zone.

At this point, you will need to make sure that your trees are set to bend. Select your TerrainThe landscape in your scene. A Terrain GameObject adds a large flat plane to your scene and you can use the Terrain’s Inspector window to create a detailed landscape. More info
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, click the Place trees button in the InspectorA Unity window that displays information about the currently selected GameObject, Asset or Project Settings, alowing you to inspect and edit the values. More info
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and then select Edit Trees > Edit Tree. Setting the Bend Factor to 1 will cause the trees to adjust if you have not already done this.

You may notice that your trees are moving about quite violently. To fix this, you can change your bend value, but it is probably easier to set the values on the Wind ZoneA GameObject that adds the effect of wind to your terrain. For instance, Trees within a wind zone will bend in a realistic animated fashion and the wind itself will move in pulses to create natural patterns of movement among the tree. More info
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directly, keeping your tree bend factor set to 1. To keep the trees from fluttering around too much, adjust the wind turbulence down to around 0.1 to 0.3 and everything will become much smoother. If you don’t want the trees blowing all the way to one side, set the Wind Main value down to the same value as your turbulence.


  • 2017–09–19 Page amended with limited editorial review

  • GameObject menu changed in Unity 4.6

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Terrain Textures
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