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Terrain Footsteps Unity
using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using System.Linq;
public class TerrainSounds : MonoBehaviour
public Terrain terrain;
public List<TerrainTexDef> terrainLayers = new List<TerrainTexDef>();
private Dictionary<TerrainLayer, int> terrainLayerPosLookUp = new Dictionary<TerrainLayer, int>();
private Dictionary<TerrainUtils.TerrainTypes, TerrainTexDef> terrainLayerLookUp = new Dictionary<TerrainUtils.TerrainTypes, TerrainTexDef>();
private void Start()
foreach (TerrainTexDef ttd in terrainLayers)
terrainLayerPosLookUp.Add(ttd.terrainlayer, terrainLayerPosLookUp.Count);
terrainLayerLookUp.Add(ttd.type, ttd);
float[,,] currentSplatmapData;
public void GetFootstepSound()
//for safety
if (terrain == null || terrainLayerLookUp.Count == 0 || terrain.terrainData.terrainLayers.Length == 0) return;
currentSplatmapData = TerrainUtils.GetSplatMapAtPos(transform.position, terrain);
TerrainUtils.TerrainTypes typeHighestWeight = TerrainUtils.TerrainTypes.None;
float highestValue = -1;
for (int i = 0; i < terrain.terrainData.terrainLayers.Length; i++)
//terrainlayer weight on splatmap
float currentValue = currentSplatmapData[0, 0, i];
//make sure the terrain layer has been assigned in our dictionary
if (!terrainLayerPosLookUp.ContainsKey(terrain.terrainData.terrainLayers[i])) continue;
//get all the values for the terrain layer in our dictionary
int posInLookUP = terrainLayerPosLookUp[terrain.terrainData.terrainLayers[i]];
TerrainTexDef ttd = terrainLayerLookUp.ElementAt(posInLookUP).Value;
//assign the new terrain layer weight back to our dictionary
ttd.currentWeight = currentValue;
Debug.Log( + ": " + currentValue);
if (ttd.footsteps != null) PlayAudio(ttd);
if (currentValue < highestValue) continue;
highestValue = currentValue;
typeHighestWeight = ttd.type;
//foreach (KeyValuePair<TerrainTypes, TerrainTexDef> tlv in terrainLayerLookUp)
// Debug.Log(tlv.Key + ": " + tlv.Value.currentWeight);
Debug.Log("The highest weight is: " + typeHighestWeight);
void PlayAudio(TerrainTexDef ttd)
//if (ttd.footsteps.isPlaying) return;
ttd.footsteps.volume = ttd.currentWeight;
public static class TerrainUtils
public enum TerrainTypes
public static float[,,] GetSplatMapAtPos(Vector3 worldPos, Terrain terrain)
// calculate which splat map cell the worldPos falls within (ignoring y)
int mapX = (int)(((worldPos.x - terrain.transform.position.x) / terrain.terrainData.size.x) * terrain.terrainData.alphamapWidth);
int mapZ = (int)(((worldPos.z - terrain.transform.position.z) / terrain.terrainData.size.z) * terrain.terrainData.alphamapHeight);
// get the splat data for this cell as a 1x1xN 3d array (where N = number of textures)
return terrain.terrainData.GetAlphamaps(mapX, mapZ, 1, 1);
public class TerrainTexDef
public TerrainLayer terrainlayer;
public TerrainUtils.TerrainTypes type = TerrainUtils.TerrainTypes.None;
public float currentWeight = -1;
public AudioSource footsteps = null;

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@ziplock9000 ziplock9000 commented Aug 19, 2019

Calling GetSplatMapAtPos every time there's a footstep is very expensive, it's copying a huge 3d array each time from the terrain. This instead should be stored in an array on Awake and the footsteps should sample that.

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