GPGPU Programming for Games and Science

208 GPGPU Programming for Games and Science

FIGURE 4.12: Copying data between processors.

D3D11 MAPPED SUBRESOURCE s ub ;

context−>Map ( out put . b u f f e r , 0 , D3D11

MAP WRITE DISCARD, 0 , &sub ) ;

memcpy(sub .pData , input . data + input . offset , input .numActiveBytes );

context−>Unmap( output . buffer , 0);

LISTING 4.55: Updating an ID3D11Buffer object using mapped writes.

The

ID3D11DeviceContext::Map function [39] takes as input the buffer object,

the subresource index zero because buffers have only one subresource, a

D3D11 MAP value [29], and a D3D11 MAP FLAG value [30]; the function then

fills in a

D3D11 MAPPED SUBRESOURCE subresource data structure ...