5 replies to this topic

[Jeason]

I load a mesh from Xfile using CDXUTXfileMesh::Create. Then i clone the mesh using CloneMesh( D3DXMESH_WRITEONLY ).

Which memory pool does the new mesh resides, POOL_MANAGED or POOL_DEFAULT?

[Tom KQT]

You can specify the memory pool in the first parameter, you can write for example:
CloneMesh(D3DXMESH_MANAGED | D3DXMESH_WRITEONLY, blablabla....)

[programci_84]

D3DXMESH_MANAGED means D3DPOOL_MANAGED for vertex and index buffer of the mesh. Like this one, D3DXMESH_WRITEONLY means D3DUSAGE_WRITEONLY for both vertex and index bufferof the mesh.

So, you can check DX docs for D3DUSAGE and D3DPOOL. Docs say about D3DUSAGE_WRITEONLY: "Buffers created with D3DPOOL_DEFAULT that do not specify D3DUSAGE_WRITEONLY might suffer a severe performance penalty."

[Jeason]

Thank you, TomKQT and programci_84.

I know how to specify memory pool. But don't know if not specify memory pool, just giving only D3DUSAGE_WRITEONLY, which memory pool it resides.

I had found the sentence---"Buffers created with D3DPOOL_DEFAULT that do not specify D3DUSAGE_WRITEONLY might suffer a severe performance penalty.".
But I don't understand it well, does it mean if specify D3DUSAGE_WRITEONLY, the memory pool is D3DPOOL_DEFAULT?

maybe that's it meaning.

[programci_84]

I know how to specify memory pool. But don't know if not specify memory pool, just giving only D3DUSAGE_WRITEONLY, which memory pool it resides.

You've 2 memory pool parameters for D3DX Mesh functions: D3DXMESH_MANAGED and D3DXMESH_SYSTEMMEM. If you don't specify one of'em, the function will choose D3DPOOL_DEFAULT for both vertex and index buffer of the mesh. So, if you specify only D3DXMESH_WRITEONLY, buffers will reside default memory pool.

I had found the sentence---"Buffers created with D3DPOOL_DEFAULT that do not specify D3DUSAGE_WRITEONLY might suffer a severe performance penalty.".
But I don't understand it well, does it mean if specify D3DUSAGE_WRITEONLY, the memory pool is D3DPOOL_DEFAULT?

maybe that's it meaning.

As far as I understand, the sentence says: "Unless you specify D3DUSAGE_WRITEONLY, D3DPOOL_DEFAULT is a bad choice for memory pool. i.e. D3DPOOL_DEFAULT works well with only D3DUSAGE_WRITEONLY".

hth.
-R

[Jeason]

Thank you, programci_84!

You have given a good lesson to me.