Microsoft DirectX 9.0

Accessing Surface Memory Directly

You can directly access the surface memory by using the IDirect3DSurface9::LockRect method. When you call this method, the pRect parameter is a pointer to a RECT structure that describes the rectangle on the surface to access directly. To request that the entire surface be locked, set pRect to NULL. Also, you can specify a RECT that covers only a portion of the surface. Providing that no two rectangles overlap, two threads or processes can simultaneously lock multiple rectangles in a surface. Note that a multisample back buffer cannot be locked.

The IDirect3DSurface9::LockRect method fills a D3DLOCKED_RECT structure with all the information to properly access the surface memory. The structure includes information about the pitch and has a pointer to the locked bits. When you finish accessing the surface memory, call the IDirect3DSurface9::UnlockRect method to unlock it.

While you have a surface locked, you can directly manipulate the contents. The following list describes some tips for avoiding common problems with directly rendering surface memory.

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