Animate trees with Wind Zones

To create the effect of wind on your trees and particle systems, you can add one or more GameObjectsThe fundamental object in Unity scenes, which can represent characters, props, scenery, cameras, waypoints, and more. A GameObject’s functionality is defined by the Components attached to it. More info
See in Glossary with Wind Zone components. Trees within a wind zone bend in a realistic animated fashion, and the wind itself moves in pulses to create natural patterns of movement among the trees.

Wind for Terrain

To create a Wind Zone GameObject, from the main menu, select GameObject > 3D Object > Wind Zone.

Wind modes

There are two modes for wind:

• In Directional mode, the wind affects the whole 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
  See in Glossary at once. This is useful for creating effects like the natural movement of the trees.
• In Spherical mode, the wind blows outwards within a sphere defined by the Radius property. This is useful for creating special effects like explosions (for a particle system) or a local eddy (for trees).

The Main property determines the overall strength of the wind. Use Turbulence for randomised variation.

The wind blows over the trees in pulses to create a more natural effect, where the wind speed isn’t a constant but rather falls and rises with gusts. You can control the strength of the pulses with Pulse Magnitude, and the time interval between them with Pulse Frequency.

Tree-specific properties

Wind Zones work on an area of the terrain or an entire tile. However, different trees have different behaviors in the same wind conditions. Use the Tree Editor to control how the branches and leaves of each tree model react to wind.

You can’t control SpeedTree animation behavior in Unity; use SpeedTree to change wind animation and import your trees again.

Using multiple Wind Zones

You can use more than one Wind Zone GameObject in your terrain. This creates different wind conditions in different areas of the terrain. For example, you can create a strong wind in one area and a gentle breeze in another.

You can use a Directional mode on the whole terrain and a Spherical mode to create local conditions (these are added to the Directional wind), or use only Spherical mode winds that together cover the whole terrain. Don’t use multiple Directional mode winds; a Directional wind covers the entire terrain, so using two Directional winds doesn’t create local conditions.

Wind for particle systems

The main use of wind is to animate trees, but it can also affect particles in a particle system that uses the External Forces module. Refer to Particle SystemA component that simulates fluid entities such as liquids, clouds and flames by generating and animating large numbers of small 2D images in the scene. More info
See in Glossary for more information.

To add a Wind Zone to an existing particle system:

1. In the InspectorA Unity window that displays information about the currently selected GameObject, asset or project settings, allowing you to inspect and edit the values. More info
   See in Glossary window, select the particle system GameObject.
2. From the main menu, select Component > Miscellaneous > Wind Zone.

Wind for SpeedTree trees

Trees from SpeedTree rely on their own wind behavior, which is imported with them. Refer to Games wind for more information.

Wind for grass

Wind Zones don’t apply to grass on the terrain. To animate grass, refer to Terrain Settings reference.

Additional resources

• Wind reference
• Terrain Settings reference
• Create trees with Tree Editor
• SpeedTree Games wind mode
• Particle System