<D3D9>求教获取BackBuffer地址的问题.

含笑

LPDIRECT3DSURFACE9 g_pBackBuffer = NULL;
g_pD3dDevice->GetBackBuffer(0, 0, D3DBACKBUFFER_TYPE_MONO, &g_pBackBuffer);
g_pBackBuffer->LockRect(&BackBuffer, NULL, D3DLOCK_DISCARD | D3DLOCK_DONOTWAIT);

用LockRect为什么无法获取BackBuffer地址?
BackBuffer.Pitch和BackBuffer.pBits都是0.
但同样在离屏表面上却都是可以获得Pitch和pBits.
请高人指点.谢谢!!!

bigbook2000

Remarks

If the D3DLOCK_DONOTWAIT flag is specified and the driver cannot lock the surface immediately, IDirect3DSurface9:ockRect will return D3DERR_WASSTILLDRAWING so that an application can use the CPU cycles while waiting for the driver to lock the surface.

The only lockable format for a depth-stencil surface is D3DFMT_D16_LOCKABLE. See D3DFORMAT.

For performance reasons, dirty regions are recorded only for level zero of a texture. Dirty regions are automatically recorded when IDirect3DSurface9::LockRect is called without D3DLOCK_NO_DIRTY_UPDATE or D3DLOCK_READONLY. See IDirect3DDevice9::UpdateTexture for more information.

A multisample back buffer cannot be locked.

This method cannot retrieve data from a surface that is is contained by a texture resource created with D3DUSAGE_RENDERTARGET because such a texture must be assigned to D3DPOOL_DEFAULT memory and is therefore not lockable. In this case, use instead IDirect3DDevice9::GetRenderTargetData to copy texture data from device memory to system memory.

lingjingqiu

在创建设备的时候注意，要把后备缓冲的Lockable打开。具体参见SDK，我忘了。

含笑

3Q!!!

KeenBlue

伪码描述如下：
1：D3Dpp.Flags = D3DPRESENTFLAG_LOCKABLE_BACKBUFFER;  // 允许锁住后备缓冲
2：Device->GetBackBuffer( 0, D3DBACKBUFFER_TYPE_MONO, &Surface)
3：D3DLOCKED_RECT d3dl_rect; （这个是32位色的版本，改为16位色很简单）
     Surface->LockRect(&d3dl_rect, NULL, NULL );
     int Pitch32 = d3dl_rect.Pitch / 4;
     DWORD* p = (DWORD*) d3dl_rect.pBits;  // 这个P就是想要的东东了，尽情F吧！
     Surface->UnlockRect();

TaoshaGod

学习