mesh生成時候的注意事項

頂點數爲要繪製的三角形的頂點數總和，包括重複的

索引一定要是short（int16）類型

根據dx左手座標系，從左下角爲0,開始計算索引，一定要是順時針方向繪製

CODE

  Dim countX As Integer = mdata.PointCountX
        Dim countY As Integer = mdata.PointCountY
        Dim Indices((countX - 1) * (countY - 1) * 6 - 1) As Short
        Dim Vertices(countX * countY - 1) As CustomVertex.PositionColored
        ' Create mesh 
        For j As Integer = 0 To countY - 1
            For i As Integer = 0 To countX - 1
                Vertices(j * countX + i) = New CustomVertex.PositionColored(CSng(mdata.ValueX(i)), CSng(mdata.GetPointValue(i, j)), CSng(mdata.ValueY(j)), mdata.GetPointColor(i, j))
            Next
        Next
        '' Calculate the index buffer.
        Dim idx As Integer = 0
        For y As Integer = 0 To (countY - 2)
            For x As Integer = 0 To (countX - 2)
                idx = (y * (countX - 1) + x) * 6
                Dim vertexIndex As Integer = y * countX + x
                Indices(idx) = CShort(vertexIndex)
                Indices((idx + 1)) = CShort(vertexIndex + countX)
                Indices((idx + 2)) = CShort(vertexIndex + countX + 1)
                Indices((idx + 3)) = CShort(vertexIndex)
                Indices((idx + 4)) = CShort(vertexIndex + countX + 1)
                Indices((idx + 5)) = CShort(vertexIndex + +1)
            Next x
        Next y
        Dim mesh As New Mesh(countX * countY * 2, countX * countY * 3, MeshFlags.Managed, CustomVertex.PositionColored.Format, device)
        mesh.VertexBuffer.SetData(Vertices, 0, LockFlags.None)
        mesh.IndexBuffer.SetData(Indices, 0, LockFlags.None)
        Return mesh