Godot Weird y Axis Offset using ArrayMesh

using Godot;
using System.Collections.Generic;
using Array = Godot.Collections.Array;

public class HexMeshGenerator : Spatial {

    private MeshInstance mMeshInstance;
    private ArrayMesh mHexMesh;

    public const int CHUNK_LENGTH = 2;
    public const float INNER_HEX_EDGE_LENGTH = 0.8F;
    public const float OUTER_HEX_EDGE_LENGTH = 1.0F;

    public const float HEX_RADIUS_TO_EDGE_DISTANCE_RATIO = 0.866025404f;

    public const float HEX_CHUNK_SIZE_X = CHUNK_LENGTH * OUTER_HEX_EDGE_LENGTH * HEX_RADIUS_TO_EDGE_DISTANCE_RATIO * 2;
    public const float HEX_CHUNK_SIZE_Y = CHUNK_LENGTH * OUTER_HEX_EDGE_LENGTH * 1.5F;

    public override void _Ready() {

        mMeshInstance = GetNode<MeshInstance>("MeshInstance");
        mHexMesh = new ArrayMesh();

        int hexSum = CHUNK_LENGTH * CHUNK_LENGTH;
        Vector3[] vertices = new Vector3[hexSum * (int)EHexVertices.VERTICE_AMOUNT_PER_HEX];
        Color[] colors = new Color[vertices.Length];
        List<int> indices = new List<int>();

        for (int x = 0; x < CHUNK_LENGTH; x++) {

            for (int y = 0; y < CHUNK_LENGTH; y++) {

                int baseIndex = (x + y * CHUNK_LENGTH) * (int)EHexVertices.VERTICE_AMOUNT_PER_HEX;

                Vector3 centerPoint = new Vector3(x * OUTER_HEX_EDGE_LENGTH * HEX_RADIUS_TO_EDGE_DISTANCE_RATIO * 2 +
                                                  (y % 2 == 0
                                                      ? (OUTER_HEX_EDGE_LENGTH * HEX_RADIUS_TO_EDGE_DISTANCE_RATIO)
                                                      : 0),
                    0,
                    y * OUTER_HEX_EDGE_LENGTH * 1.5F);

                vertices[baseIndex + (int)EHexVertices.CENTER] = centerPoint;

                // All the following stuff could also easily be done by just using sin/cos and rotating by 60 degree for each step...
                // But that would have been just too easy....
                vertices[baseIndex + (int)EHexVertices.INNER_HEX_TOP] =
                    centerPoint + new Vector3(0, 0, -INNER_HEX_EDGE_LENGTH);

                vertices[baseIndex + (int)EHexVertices.INNER_HEX_RIGHT_TOP] = centerPoint +
                                                                              new Vector3(INNER_HEX_EDGE_LENGTH * HEX_RADIUS_TO_EDGE_DISTANCE_RATIO,
                                                                                  0,
                                                                                  -0.5F * INNER_HEX_EDGE_LENGTH);

                vertices[baseIndex + (int)EHexVertices.INNER_HEX_RIGHT_BOTTOM] = centerPoint +
                    new Vector3(INNER_HEX_EDGE_LENGTH * HEX_RADIUS_TO_EDGE_DISTANCE_RATIO, 0, 0.5F * INNER_HEX_EDGE_LENGTH);

                vertices[baseIndex + (int)EHexVertices.INNER_HEX_BOTTOM] =
                    centerPoint + new Vector3(0, 0, INNER_HEX_EDGE_LENGTH);

                vertices[baseIndex + (int)EHexVertices.INNER_HEX_LEFT_BOTTOM] = centerPoint +
                    new Vector3(-INNER_HEX_EDGE_LENGTH * HEX_RADIUS_TO_EDGE_DISTANCE_RATIO, 0, 0.5F * INNER_HEX_EDGE_LENGTH);

                vertices[baseIndex + (int)EHexVertices.INNER_HEX_LEFT_TOP] = centerPoint +
                                                                             new Vector3(-INNER_HEX_EDGE_LENGTH * HEX_RADIUS_TO_EDGE_DISTANCE_RATIO, 0,
                                                                                 -0.5F * INNER_HEX_EDGE_LENGTH);

                // Outer Hex
                vertices[baseIndex + (int)EHexVertices.OUTER_HEX_TOP] =
                    centerPoint + new Vector3(0, 0, -OUTER_HEX_EDGE_LENGTH);

                vertices[baseIndex + (int)EHexVertices.OUTER_HEX_RIGHT_TOP] = centerPoint +
                                                                              new Vector3(OUTER_HEX_EDGE_LENGTH * HEX_RADIUS_TO_EDGE_DISTANCE_RATIO, 0,
                                                                                  -0.5F * OUTER_HEX_EDGE_LENGTH);

                vertices[baseIndex + (int)EHexVertices.OUTER_HEX_RIGHT_BOTTOM] = centerPoint +
                    new Vector3(OUTER_HEX_EDGE_LENGTH * HEX_RADIUS_TO_EDGE_DISTANCE_RATIO, 0, 0.5F * OUTER_HEX_EDGE_LENGTH);

                vertices[baseIndex + (int)EHexVertices.OUTER_HEX_BOTTOM] =
                    centerPoint + new Vector3(0, 0, OUTER_HEX_EDGE_LENGTH);

                vertices[baseIndex + (int)EHexVertices.OUTER_HEX_LEFT_BOTTOM] = centerPoint +
                    new Vector3(-OUTER_HEX_EDGE_LENGTH * HEX_RADIUS_TO_EDGE_DISTANCE_RATIO, 0, 0.5F * OUTER_HEX_EDGE_LENGTH);

                vertices[baseIndex + (int)EHexVertices.OUTER_HEX_LEFT_TOP] = centerPoint +
                                                                             new Vector3(-OUTER_HEX_EDGE_LENGTH * HEX_RADIUS_TO_EDGE_DISTANCE_RATIO, 0,
                                                                                 -0.5F * OUTER_HEX_EDGE_LENGTH);

                // Adding indices
                // Inner
                // Inner Top to Right
                indices.Add(baseIndex + (int)EHexVertices.INNER_HEX_TOP);
                indices.Add(baseIndex + (int)EHexVertices.INNER_HEX_RIGHT_TOP);
                indices.Add(baseIndex + (int)EHexVertices.CENTER);

                // Inner TopRight to BottomRight
                indices.Add(baseIndex + (int)EHexVertices.INNER_HEX_RIGHT_TOP);
                indices.Add(baseIndex + (int)EHexVertices.INNER_HEX_RIGHT_BOTTOM);
                indices.Add(baseIndex + (int)EHexVertices.CENTER);

                // Inner BottomRight to Bottom
                indices.Add(baseIndex + (int)EHexVertices.INNER_HEX_RIGHT_BOTTOM);
                indices.Add(baseIndex + (int)EHexVertices.INNER_HEX_BOTTOM);
                indices.Add(baseIndex + (int)EHexVertices.CENTER);

                // Inner Bottom to LeftBottom
                indices.Add(baseIndex + (int)EHexVertices.INNER_HEX_BOTTOM);
                indices.Add(baseIndex + (int)EHexVertices.INNER_HEX_LEFT_BOTTOM);
                indices.Add(baseIndex + (int)EHexVertices.CENTER);

                // Inner LeftBottom to LeftTop
                indices.Add(baseIndex + (int)EHexVertices.INNER_HEX_LEFT_BOTTOM);
                indices.Add(baseIndex + (int)EHexVertices.INNER_HEX_LEFT_TOP);
                indices.Add(baseIndex + (int)EHexVertices.CENTER);

                // Inner LeftTop to Top
                indices.Add(baseIndex + (int)EHexVertices.INNER_HEX_LEFT_TOP);
                indices.Add(baseIndex + (int)EHexVertices.INNER_HEX_TOP);
                indices.Add(baseIndex + (int)EHexVertices.CENTER);

                // =====================================================
                // Outer
                // Outer Outer Top to RightTop
                indices.Add(baseIndex + (int)EHexVertices.OUTER_HEX_TOP);
                indices.Add(baseIndex + (int)EHexVertices.OUTER_HEX_RIGHT_TOP);
                indices.Add(baseIndex + (int)EHexVertices.INNER_HEX_TOP);

                //// Outer Inner Top to RightTop
                indices.Add(baseIndex + (int)EHexVertices.INNER_HEX_TOP);
                indices.Add(baseIndex + (int)EHexVertices.OUTER_HEX_RIGHT_TOP);
                indices.Add(baseIndex + (int)EHexVertices.INNER_HEX_RIGHT_TOP);

                //// Outer Outer RightTop to RightBottom
                indices.Add(baseIndex + (int)EHexVertices.OUTER_HEX_RIGHT_TOP);
                indices.Add(baseIndex + (int)EHexVertices.OUTER_HEX_RIGHT_BOTTOM);
                indices.Add(baseIndex + (int)EHexVertices.INNER_HEX_RIGHT_TOP);

                //// Outer Inner RightTop to RightBottom
                indices.Add(baseIndex + (int)EHexVertices.INNER_HEX_RIGHT_TOP);
                indices.Add(baseIndex + (int)EHexVertices.OUTER_HEX_RIGHT_BOTTOM);
                indices.Add(baseIndex + (int)EHexVertices.INNER_HEX_RIGHT_BOTTOM);

                //// Outer Outer RightBottom to Bottom
                indices.Add(baseIndex + (int)EHexVertices.INNER_HEX_RIGHT_BOTTOM);
                indices.Add(baseIndex + (int)EHexVertices.OUTER_HEX_RIGHT_BOTTOM);
                indices.Add(baseIndex + (int)EHexVertices.OUTER_HEX_BOTTOM);

                //// Outer Inner RightBottom to Bottom
                indices.Add(baseIndex + (int)EHexVertices.INNER_HEX_RIGHT_BOTTOM);
                indices.Add(baseIndex + (int)EHexVertices.OUTER_HEX_BOTTOM);
                indices.Add(baseIndex + (int)EHexVertices.INNER_HEX_BOTTOM);

                //// Outer Outer Bottom to LeftBottom
                indices.Add(baseIndex + (int)EHexVertices.INNER_HEX_BOTTOM);
                indices.Add(baseIndex + (int)EHexVertices.OUTER_HEX_BOTTOM);
                indices.Add(baseIndex + (int)EHexVertices.OUTER_HEX_LEFT_BOTTOM);

                //// Outer Inner Bottom to LeftBottom
                indices.Add(baseIndex + (int)EHexVertices.INNER_HEX_BOTTOM);
                indices.Add(baseIndex + (int)EHexVertices.OUTER_HEX_LEFT_BOTTOM);
                indices.Add(baseIndex + (int)EHexVertices.INNER_HEX_LEFT_BOTTOM);

                //// Outer Outer LeftBottom to LeftTop
                indices.Add(baseIndex + (int)EHexVertices.OUTER_HEX_LEFT_TOP);
                indices.Add(baseIndex + (int)EHexVertices.INNER_HEX_LEFT_BOTTOM);
                indices.Add(baseIndex + (int)EHexVertices.OUTER_HEX_LEFT_BOTTOM);

                //// Outer Inner LeftBottom to LeftTop
                indices.Add(baseIndex + (int)EHexVertices.OUTER_HEX_LEFT_TOP);
                indices.Add(baseIndex + (int)EHexVertices.INNER_HEX_LEFT_TOP);
                indices.Add(baseIndex + (int)EHexVertices.INNER_HEX_LEFT_BOTTOM);

                //// Outer Outer LeftTop to Top
                indices.Add(baseIndex + (int)EHexVertices.OUTER_HEX_TOP);
                indices.Add(baseIndex + (int)EHexVertices.INNER_HEX_LEFT_TOP);
                indices.Add(baseIndex + (int)EHexVertices.OUTER_HEX_LEFT_TOP);

                //// Outer Inner LeftTop to Top
                indices.Add(baseIndex + (int)EHexVertices.OUTER_HEX_TOP);
                indices.Add(baseIndex + (int)EHexVertices.INNER_HEX_TOP);
                indices.Add(baseIndex + (int)EHexVertices.INNER_HEX_LEFT_TOP);

                // Colors
                colors[baseIndex + (int)EHexVertices.CENTER] = new Color(0, 0, 1);

                colors[baseIndex + (int)EHexVertices.INNER_HEX_TOP] = new Color(1, 0, 0);
                colors[baseIndex + (int)EHexVertices.INNER_HEX_LEFT_TOP] = new Color(1, 0, 0);
                colors[baseIndex + (int)EHexVertices.INNER_HEX_LEFT_BOTTOM] = new Color(1, 0, 0);
                colors[baseIndex + (int)EHexVertices.INNER_HEX_RIGHT_TOP] = new Color(1, 0, 0);
                colors[baseIndex + (int)EHexVertices.INNER_HEX_RIGHT_BOTTOM] = new Color(1, 0, 0);
                colors[baseIndex + (int)EHexVertices.INNER_HEX_BOTTOM] = new Color(1, 0, 0);

                colors[baseIndex + (int)EHexVertices.OUTER_HEX_TOP] = new Color(0, 1, 0);
                colors[baseIndex + (int)EHexVertices.OUTER_HEX_LEFT_TOP] = new Color(0, 1, 0);
                colors[baseIndex + (int)EHexVertices.OUTER_HEX_LEFT_BOTTOM] = new Color(0, 1, 0);
                colors[baseIndex + (int)EHexVertices.OUTER_HEX_RIGHT_TOP] = new Color(0, 1, 0);
                colors[baseIndex + (int)EHexVertices.OUTER_HEX_RIGHT_BOTTOM] = new Color(0, 1, 0);
                colors[baseIndex + (int)EHexVertices.OUTER_HEX_BOTTOM] = new Color(0, 1, 0);
            }
        }

        // Create ArrayMesh
        Array meshArrays = new Array();

        meshArrays.Resize((int)ArrayMesh.ArrayType.Max);

        meshArrays[(int)ArrayMesh.ArrayType.Vertex] = vertices;
        meshArrays[(int)ArrayMesh.ArrayType.Index] = indices.ToArray();
        meshArrays[(int)ArrayMesh.ArrayType.Color] = colors;

        mHexMesh.AddSurfaceFromArrays(Mesh.PrimitiveType.Triangles, meshArrays);

        mMeshInstance.Mesh = mHexMesh;
    }

    public override void _Process(float delta) {


    }

    public enum EHexVertices {

        CENTER = 0,
        INNER_HEX_TOP = 1,
        INNER_HEX_RIGHT_TOP = 2,
        INNER_HEX_RIGHT_BOTTOM = 3,
        INNER_HEX_BOTTOM = 4,
        INNER_HEX_LEFT_BOTTOM = 5,
        INNER_HEX_LEFT_TOP = 6,
        OUTER_HEX_TOP = 7,
        OUTER_HEX_RIGHT_TOP = 8,
        OUTER_HEX_RIGHT_BOTTOM = 9,
        OUTER_HEX_BOTTOM = 10,
        OUTER_HEX_LEFT_BOTTOM = 11,
        OUTER_HEX_LEFT_TOP = 12,
        VERTICE_AMOUNT_PER_HEX = 13,
    }
}