Index Buffer Descriptions (Windows Embedded CE 6.0)
1/6/2010
An index buffer is described in terms of its capabilities: if it can exist only in system memory, if it is only used for write operations, and the type and number of indices it can contain. These traits are held in a D3DMINDEXBUFFER_DESC structure.
Index buffer descriptions tell your application how an existing buffer was created. You provide an empty description structure for the system to fill with the capabilities of a previously created index buffer. For more information about this task, see Using Index Buffers.
The Format member describes the surface format of the index buffer data.
The Type identifies the resource type of the index buffer.
The Usage structure member contains general capability flags. The presence of the D3DUSAGE_WRITEONLY flag in Usage indicates that the index buffer memory is used only for write operations. This frees the driver to place the index data in the best memory location to enable fast processing and rendering. If the D3DUSAGE_WRITEONLY flag is not used, the driver is less likely to put the data in a location that is inefficient for read operations. This sacrifices some processing and rendering speed. If this flag is not specified, it is assumed that applications perform read and write operations on the data in the index buffer.
Pool specifies the memory class allocated for the index buffer. The D3DMPOOL_SYSTEMMEM flag (see D3DMPOOL) indicates that the system created the index buffer in system memory.
The Size member simply stores the size, in bytes, of the vertex buffer data.