PositionAndColorStruct.cs

// 座標と色情報を持つ頂点データ
struct VertexData
{
    public Vector3 position;
    public Vector3 color;
    
    // この頂点データの容量
    public static int SizeInBytes => System.Runtime.InteropServices.Marshal.SizeOf(typeof(VertexData));

    public static InputElement[] VertexInputElements = new[]
    {
        new InputElement
        {
            SemanticName = "SV_Position",
            Format = Format.R32G32B32_Float
        },
        new InputElement
        {
            SemanticName = "COLOR",
            Format = Format.R32G32B32_Float,
            // アドレスの自動配置
            AlignedByteOffset = InputElement.AppendAligned
        }
    };
}