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D3DDDIDEVINFO_VCACHE structure

The D3DDDIDEVINFO_VCACHE structure describes the vertex-cache information of a device.

Syntax


typedef struct _D3DDDIDEVINFO_VCACHE {
  UINT Pattern;
  UINT OptMethod;
  UINT CacheSize;
  UINT MagicNumber;
} D3DDDIDEVINFO_VCACHE;

Members

Pattern

[out] The bit pattern. The driver must specify the bit pattern as a CACH four-character code (FOURCC) value. The driver can use the following MAKEFOURCC macro to specify the FOURCC value as CACH:


MAKEFOURCC('C', 'A', 'C', 'H');

OptMethod

[out] The method of mesh optimization. The driver can use one of the following values to specify the mesh optimization that it uses.

ValueMeaning

D3DXMESHOPT_STRIPREORDER (0)

Longest strips optimization

D3DXMESHOPT_VCACHE (1)

Vertex-cache-based optimization

 

CacheSize

[out] The effective size, in entries, that the driver optimizes the vertex cache for. The actual cache size is not required to be the size that is specified in CacheSize because the actual cache size is larger in most situations. The driver specifies an optimized size in CacheSize only if it also specifies D3DXMESHOPT_VCACHE in the OptMethod member.

MagicNumber

[out] The number that should be used as part of a trial-and-error procedure when determining when to restart the strips list. This number can be from 1 to the value that is specified in the CacheSize member. Typically, the best values are near CacheSize/2. The driver specifies a number in MagicNumber only if it also specifies D3DXMESHOPT_VCACHE in the OptMethod member.

Remarks

Direct3D runtime version 9.0 and later. The Microsoft Direct3D runtime calls the driver's CreateQuery function to create driver-side resources for the vertex-cache query. In this CreateQuery call, the runtime specifies the D3DDDIQUERYTYPE_VCACHE query type in the QueryType member of the D3DDDIARG_CREATEQUERY structure. The driver should allocate a D3DDDIDEVINFO_VCACHE structure. The runtime then calls the driver's IssueQuery function to process the vertex-cache query. The driver should insert a graphics processing unit (GPU) instruction to write the vertex-cache data to an allocation. To retrieve the vertex-cache information from the driver, the runtime calls the driver's GetQueryData function. In this GetQueryData call, the driver should lock the allocation and return the vertex-cache data at the pData member of the D3DDDIARG_GETQUERYDATA structure that is pointed to by the pData parameter.

Direct3D runtime version 8.1 only. The Direct3D runtime calls the driver's GetInfo function to obtain vertex-cache information from the driver. In this GetInfo call, the runtime passes the D3DDDIDEVINFOID_VCACHE flag in the DevInfoID parameter. The driver specifies vertex-cache information in a D3DDDIDEVINFO_VCACHE structure and returns it at the pDevInfoStruct parameter.

Requirements

Version

Available in Windows Vista and later versions of the Windows operating systems.

Header

D3dumddi.h (include D3dumddi.h)

See also

CreateQuery
D3DDDIARG_CREATEQUERY
D3DDDIARG_GETQUERYDATA
GetInfo
GetQueryData
IssueQuery

 

 

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