staggartcreations / UnityTerrainLayerSampler

Scripting functionality to efficiently read terrain layer weights. Can be used to drive physics, VFX and/or SFX.

Terrain Layer Sampler for Unity

Scripting functionality to efficiently read terrain layer weights in realtime.

Motivations

The painted strength of a terrain layer is stored in a channel of an RGBA splatmap texture. Reading this back using Texture2D.GetPixel is too slow for realtime uses.

Instead this script can pre-bake this information into a ScriptableObject, and provides an API for sampling the data at any given world-space position. The weight/strength for each terrain layer is returned as an array.

• Sampling is performed using bi-linear interpolation, providing smoothly interpolated data between splatmap texels.
• Data is automatically updated for areas that are modified through terrain texture painting. This ensures fast updates and retains common workflows.

Example use cases

• Controlling particle effects for feet and/or wheels.
• Driving audio events or parameters.
• Deriving physics properties from the terrain surface (eg. checking if the ground is icy or wet).
• Prefab spawning, based on textures.

Adding it to a project

via Package Manager:

• Press the "+" icon in the top-left
• Choose "Add package from git URL"
• Paste in https://github.com/staggartcreations/UnityTerrainLayerSampler.git.

via Git:

• Clone the repo as usual via cmd/terminal or in your favourite Git GUI software.
• Checkout the 'master' branch

via browser

• Click the green "Code" button at the top of the page, and choose "Download ZIP"
• Extract the folder to your Assets folder

Usage instructions

• Add the TerrainLayerComponent to your terrain(s)

A TerrainLayerData asset will automatically be created, and will be saved on the component with the scene. You can however choose to use a ScriptableObject that is saved on disk. In order to do so, right-click in the Project window and choose Create/TerrainLayerData and assign it. The context menu on the component has a "Bake" option.

• See the Example/TerrainLayerSampler script for further practical details.

Scripting Workflow

• Find a reference to the terrain you are on (either through Raycasting, or a custom look-up method). This is likely needed anyway (eg. checking if feet are grounded).
• Once found, the TerrainLayerComponent can be fetched through GetComponent, and its data field can be accessed.
• Finally, the data.Sample(Vector3 position, bool interpolated) function can be called, which returns a float[] array. Each array element corresponds to a layer on the terrain (in the same order as they are added to it). The float values represent the strength a layer at the given position (always between 0 and 1).