D3DDEVINFO_VCACHE structure

DirectX 8.1 and later versions only.

The D3DDEVINFO_VCACHE structure describes vertex-cache information of a device.

Syntax


typedef struct _D3DDEVINFO_VCACHE {
  DWORD Pattern;
  DWORD OptMethod;
  DWORD CacheSize;
  DWORD MagicNumber;
} D3DDEVINFO_VCACHE, *LPD3DDEVINFO_VCACHE;

Members

Pattern

Specifies the bit pattern. The driver must specify the bit pattern as the CACH four-character code (FOURCC) value. The driver can use the MAKEFOURCC macro as follows to specify the FOURCC value as CACH:


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

OptMethod

Specifies 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

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

MagicNumber

Specifies 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 set from 1 to the value in the CacheSize member. Typically, the best values are near CacheSize/2.

Remarks

DirectX 8.1 versions only. The Direct3D runtime calls a driver's D3dGetDriverState function to obtain vertex-cache information from the driver. In this D3dGetDriverState call, the runtime specifies the D3DDEVINFOID_VCACHE flag in the dwFlags member of the DD_GETDRIVERSTATEDATA structure that the runtime passes. The driver specifies vertex-cache information in a D3DDEVINFO_VCACHE structure and returns it at the lpdwStates member of DD_GETDRIVERSTATEDATA.

DirectX 9.0 and later versions only. The Direct3D runtime specifies D3DDP2OP_CREATEQUERY and D3DDP2OP_ISSUEQUERY commands in calls to the driver's D3dDrawPrimitives2 callback to create driver-side resources for the query and then to asynchronously query the driver for vertex-cache information. In the call with the D3DDP2OP_CREATEQUERY command, the runtime specifies the D3DQUERYTYPE_VCACHE query type in the QueryType member of the D3DHAL_DP2CREATEQUERY structure.

When the driver completes a vertex-cache query, the driver sets the total size of the response buffer in the dwErrorOffset member of the D3DHAL_DRAWPRIMITIVES2DATA structure and sets the ddrval member of D3DHAL_DRAWPRIMITIVES2DATA to D3D_OK for successful completion. The driver also overwrites the incoming command buffer with the outgoing response buffer. This response buffer contains a D3DHAL_DP2RESPONSEQUERY structure that identifies a response for the vertex-cache query. This D3DHAL_DP2RESPONSEQUERY is followed by the vertex-cache data in the D3DDEVINFO_VCACHE structure.

Requirements

Header

D3d9types.h (include D3d9types.h)

See also

D3DDP2OP_CREATEQUERY
D3DDP2OP_ISSUEQUERY
D3dDrawPrimitives2
D3dGetDriverState
D3DHAL_DP2CREATEQUERY
D3DHAL_DP2RESPONSEQUERY
D3DHAL_DRAWPRIMITIVES2DATA

 

 

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