public void GetPartsByOutputType(List <HEU_PartData> meshParts, List <HEU_PartData> volumeParts)
        {
            int numParts = _parts.Count;

            for (int i = 0; i < numParts; ++i)
            {
                HEU_PartData part = _parts[i];
                if (part.IsPartMesh() || part.IsPartCurve())
                {
                    meshParts.Add(part);
                }
                else if (part.IsPartVolume())
                {
                    volumeParts.Add(part);
                }
            }
        }