/// <summary>
        /// Upload the alphamaps (TerrainLayers) into heightfield network.
        /// </summary>
        /// <param name="session"></param>
        /// <param name="idt"></param>
        /// <param name="baseVolumeInfo">The valid base height HAPI_VolumeInfo</param>
        /// <param name="bMaskSet">This is set to true if a mask layer was uploaded</param>
        /// <returns>True if successfully uploaded all layers</returns>
        public bool UploadAlphaMaps(HEU_SessionBase session, HEU_InputDataTerrain idt, ref HAPI_VolumeInfo baseVolumeInfo, out bool bMaskSet)
        {
            bool bResult = true;

            bMaskSet = false;

            int alphaLayers = idt._terrainData.alphamapLayers;

            if (alphaLayers < 1)
            {
                return(bResult);
            }

            int sizeX     = idt._terrainData.alphamapWidth;
            int sizeY     = idt._terrainData.alphamapHeight;
            int totalSize = sizeX * sizeY;

            float[,,] alphaMaps = idt._terrainData.GetAlphamaps(0, 0, sizeX, sizeY);

            float[][] alphaMapsConverted = new float[alphaLayers][];

            // Convert the alphamap layers to double arrays.
            for (int m = 0; m < alphaLayers; ++m)
            {
                alphaMapsConverted[m] = new float[totalSize];
                for (int j = 0; j < sizeY; j++)
                {
                    for (int i = 0; i < sizeX; i++)
                    {
                        // Flip for coordinate system change
                        float h = alphaMaps[i, (sizeY - j - 1), m];

                        alphaMapsConverted[m][i + j * sizeX] = h;
                    }
                }
            }

            // Create volume layers for all alpha maps and upload values.
            bool bMaskLayer      = false;
            int  inputLayerIndex = 1;

            for (int m = 0; m < alphaLayers; ++m)
            {
#if UNITY_2018_3_OR_NEWER
                string layerName = idt._terrainData.terrainLayers[m].name;
#else
                string layerName = "unity_alphamap_" + m + 1;
#endif

                // The Unity layer name could contain '.terrainlayer' and spaces. Remove them because Houdini doesn't allow
                // spaces, and the extension isn't necessary.
                layerName = layerName.Replace(" ", "_");
                int extIndex = layerName.LastIndexOf(HEU_Defines.HEU_EXT_TERRAINLAYER);
                if (extIndex > 0)
                {
                    layerName = layerName.Remove(extIndex);
                }
                //HEU_Logger.Log("Processing terrain layer: " + layerName);

                HAPI_NodeId alphaLayerID = HEU_Defines.HEU_INVALID_NODE_ID;

                if (layerName.Equals(HEU_Defines.HAPI_HEIGHTFIELD_LAYERNAME_HEIGHT))
                {
                    // Skip height (base) layer (since it has been uploaded already)
                    continue;
                }
                else if (layerName.Equals(HEU_Defines.HAPI_HEIGHTFIELD_LAYERNAME_MASK))
                {
                    //HEU_Logger.Log("Mask layer found! Skipping creating the HF.");
                    bMaskSet     = true;
                    bMaskLayer   = true;
                    alphaLayerID = idt._maskNodeID;

                    float[,] heights = idt._terrainData.GetHeights(0, 0, idt._terrainData.heightmapResolution, idt._terrainData.heightmapResolution);
                    int heightsSizeX = heights.GetLength(0);
                    int heightsSizeY = heights.GetLength(1);
                    alphaMapsConverted[m] = HEU_TerrainUtility.ResampleData(alphaMapsConverted[m], sizeX, sizeY, heightsSizeX, heightsSizeY);
                }
                else
                {
                    bMaskLayer = false;

                    if (!session.CreateHeightfieldInputVolumeNode(idt._heightfieldNodeID, out alphaLayerID, layerName,
                                                                  Mathf.RoundToInt(sizeX * idt._voxelSize), Mathf.RoundToInt(sizeY * idt._voxelSize), idt._voxelSize))
                    {
                        bResult = false;
                        HEU_Logger.LogError("Failed to create input volume node for layer " + layerName);
                        break;
                    }
                }

                //HEU_Logger.Log("Uploading terrain layer: " + layerName);

                if (!SetHeightFieldData(session, alphaLayerID, 0, alphaMapsConverted[m], layerName, ref baseVolumeInfo))
                {
                    bResult = false;
                    break;
                }

#if UNITY_2018_3_OR_NEWER
                SetTerrainLayerAttributesToHeightField(session, alphaLayerID, 0, idt._terrainData.terrainLayers[m]);
#endif

                if (!session.CommitGeo(alphaLayerID))
                {
                    bResult = false;
                    HEU_Logger.LogError("Failed to commit volume layer " + layerName);
                    break;
                }

                if (!bMaskLayer)
                {
                    // Connect to the merge node but starting from index 1 since index 0 is height layer
                    if (!session.ConnectNodeInput(idt._mergeNodeID, inputLayerIndex + 1, alphaLayerID, 0))
                    {
                        bResult = false;
                        HEU_Logger.LogError("Unable to connect new volume node for layer " + layerName);
                        break;
                    }

                    inputLayerIndex++;
                }
            }

            return(bResult);
        }
        /// <summary>
        /// Upload the base height layer into heightfield network.
        /// </summary>
        /// <param name="session"></param>
        /// <param name="idt"></param>
        /// <returns></returns>
        public bool UploadHeightValuesWithTransform(HEU_SessionBase session, HEU_InputDataTerrain idt, ref HAPI_VolumeInfo volumeInfo)
        {
            // Get Geo, Part, and Volume infos
            HAPI_GeoInfo geoInfo = new HAPI_GeoInfo();

            if (!session.GetGeoInfo(idt._heightNodeID, ref geoInfo))
            {
                HEU_Logger.LogError("Unable to get geo info from heightfield node!");
                return(false);
            }

            HAPI_PartInfo partInfo = new HAPI_PartInfo();

            if (!session.GetPartInfo(geoInfo.nodeId, 0, ref partInfo))
            {
                HEU_Logger.LogError("Unable to get part info from heightfield node!");
                return(false);
            }

            volumeInfo = new HAPI_VolumeInfo();
            if (!session.GetVolumeInfo(idt._heightNodeID, 0, ref volumeInfo))
            {
                HEU_Logger.LogError("Unable to get volume info from heightfield node!");
                return(false);
            }

            if ((volumeInfo.xLength - 1) != Mathf.RoundToInt(idt._numPointsX / idt._voxelSize) ||
                (volumeInfo.yLength - 1) != Mathf.RoundToInt(idt._numPointsY / idt._voxelSize) ||
                idt._terrainData.heightmapResolution != volumeInfo.xLength ||
                idt._terrainData.heightmapResolution != volumeInfo.yLength)
            {
                HEU_Logger.LogWarning("Created heightfield in Houdini differs in voxel size from input terrain! Terrain may require resampling.");
            }

            // Update volume infos, and set it. This is required.
            volumeInfo.tileSize  = 1;
            volumeInfo.type      = HAPI_VolumeType.HAPI_VOLUMETYPE_HOUDINI;
            volumeInfo.storage   = HAPI_StorageType.HAPI_STORAGETYPE_FLOAT;
            volumeInfo.transform = idt._transform;

            volumeInfo.minX = 0;
            volumeInfo.minY = 0;
            volumeInfo.minZ = 0;

            volumeInfo.tupleSize = 1;
            volumeInfo.tileSize  = 1;

            volumeInfo.hasTaper = false;
            volumeInfo.xTaper   = 0f;
            volumeInfo.yTaper   = 0f;

            if (!session.SetVolumeInfo(idt._heightNodeID, partInfo.id, ref volumeInfo))
            {
                HEU_Logger.LogError("Unable to set volume info on input heightfield node!");
                return(false);
            }

            // Now set the height data
            float[,] heights = idt._terrainData.GetHeights(0, 0, idt._terrainData.heightmapResolution, idt._terrainData.heightmapResolution);
            int sizeX     = heights.GetLength(0);
            int sizeY     = heights.GetLength(1);
            int totalSize = sizeX * sizeY;

            // Convert to single array
            float[] heightsArr = new float[totalSize];
            for (int j = 0; j < sizeY; j++)
            {
                for (int i = 0; i < sizeX; i++)
                {
                    // Flip for coordinate system change
                    float h = heights[i, (sizeY - j - 1)];

                    heightsArr[i + j * sizeX] = h * idt._heightScale;
                }
            }

            if (volumeInfo.xLength != volumeInfo.yLength)
            {
                HEU_Logger.LogError("Error: Houdini heightmap must be square!");
                return(false);
            }

            if (idt._terrainData.heightmapResolution != volumeInfo.xLength)
            {
                // Resize heightsArr to idt._terrainData.heightmapResolution
                HEU_Logger.LogWarningFormat("Attempting to resize landscape from ({0}x{1}) to ({2}x{3})", idt._terrainData.heightmapResolution, idt._terrainData.heightmapResolution, volumeInfo.xLength, volumeInfo.xLength);
                heightsArr = HEU_TerrainUtility.ResampleData(heightsArr, idt._terrainData.heightmapResolution, idt._terrainData.heightmapResolution, volumeInfo.xLength, volumeInfo.xLength);
                sizeX      = volumeInfo.xLength;
                sizeY      = volumeInfo.yLength;
                totalSize  = sizeX * sizeY;
            }

            // Set the base height layer
            if (!session.SetHeightFieldData(idt._heightNodeID, 0, HEU_Defines.HAPI_HEIGHTFIELD_LAYERNAME_HEIGHT, heightsArr, 0, totalSize))
            {
                HEU_Logger.LogError("Unable to set height values on input heightfield node!");
                return(false);
            }

            SetTerrainDataAttributesToHeightField(session, geoInfo.nodeId, 0, idt._terrainData);

            SetTreePrototypes(session, geoInfo.nodeId, 0, idt._terrainData);

            if (!session.CommitGeo(idt._heightNodeID))
            {
                HEU_Logger.LogError("Unable to commit geo on input heightfield node!");
                return(false);
            }

            return(true);
        }