頻繁な更新を行うためにメッシュを最適化します
Call this before assigning vertices to get better performance when continually updating the Mesh.
Internally, this makes the Mesh use "dynamic buffers" in the underlying graphics API, which
are more efficient when Mesh data changes often.
If you want to manipulate mesh data from native code plugins, then in most
cases you'll need to call MarkDynamic as well, before getting pointers to the native mesh buffers
(see GetNativeIndexBufferPtr and GetNativeVertexBufferPtr). Default mesh buffers
are optimized for "static" access, which on many platforms makes them immutable or non-CPU-writable.
See Also: vertices, normals, triangles, UploadMeshData.