TerrainDetector.cs

using UnityEngine;

public class TerrainDetector
{
    private TerrainData terrainData;
    private int alphamapWidth;
    private int alphamapHeight;
    private float[,,] splatmapData;
    private int numTextures;

    public TerrainDetector()
    {
        terrainData = Terrain.activeTerrain.terrainData;
        alphamapWidth = terrainData.alphamapWidth;
        alphamapHeight = terrainData.alphamapHeight;

        splatmapData = terrainData.GetAlphamaps(0, 0, alphamapWidth, alphamapHeight);
        numTextures = splatmapData.Length / (alphamapWidth * alphamapHeight);
    }

    private Vector3 ConvertToSplatMapCoordinate(Vector3 worldPosition)
    {
        Vector3 splatPosition = new Vector3();
        Terrain ter = Terrain.activeTerrain;
        Vector3 terPosition = ter.transform.position;
        splatPosition.x = ((worldPosition.x - terPosition.x) / ter.terrainData.size.x) * ter.terrainData.alphamapWidth;
        splatPosition.z = ((worldPosition.z - terPosition.z) / ter.terrainData.size.z) * ter.terrainData.alphamapHeight;
        return splatPosition;
    }

    public int GetActiveTerrainTextureIdx(Vector3 position)
    {
        Vector3 terrainCord = ConvertToSplatMapCoordinate(position);
        int activeTerrainIndex = 0;
        float largestOpacity = 0f;

        for (int i = 0; i < numTextures; i++)
        {
            if (largestOpacity < splatmapData[(int)terrainCord.z, (int)terrainCord.x, i])
            {
                activeTerrainIndex = i;
                largestOpacity = splatmapData[(int)terrainCord.z, (int)terrainCord.x, i];
            }
        }

        return activeTerrainIndex;
    }

}

At Line 17 you call GetAlphaMaps and cache the data into a float array. Is there no way to directly access the data within the terrain instead of duplicating some of the data?

At Line 17 you call GetAlphaMaps and cache the data into a float array. Is there no way to directly access the data within the terrain instead of duplicating some of the data?

This is for speed. GetAlphaMaps is slow and you don't want to do it with each footstep.