I have been trying to get my head around DX11, but some things don't make sense. I can load and display textures. I can create, set the data within the texture, and display those textures. I can't seem to lock (map) a loaded texture to save my life!

This is the relevant line for loading (this part works fine):

D3DX11CreateShaderResourceViewFromFileW(ge->Graphics.dev, filename, NULL, NULL, &m_texture, NULL);

Then I try to get to the data:

	HRESULT hr;
	ID3D11Resource *ppResource=NULL;
	gGE.TextureList[Texture].m_texture->GetResource(&ppResource);
	ID3D11Texture2D *pTexture=NULL;
	pTexture=reinterpret_cast<ID3D11Texture2D*>( ppResource );
	D3D11_MAPPED_SUBRESOURCE mappedrec;
	hr=gGE.Graphics.devcon->Map(pTexture,0,D3D11_MAP_READ,NULL,&mappedrec);
	if (FAILED(hr)) MessageBoxW(ghWnd,L"Texture Map",L"mapping failed",MB_OK);

It fails when I try to Map the subresource. Does anyone have example code or can tell me what I'm doing wrong?

it throws a negative number. -2147024809.

E_INVALIDARG

That doesn't help...... It has something to do with the way DX11 does resources.

Here is what I'm wanting to do:

-load a texture from the disk

-make a "collision map" by sampling the alpha channel.

I'm using the texture as a sprite for purposes of a GUI. I don't want to have to deal with only rectangular buttons so I need a collision map for the mouse.

*****SOLUTION******

	HRESULT hr;
	ID3D11Resource *ppResource;
	gGE.TextureList[Texture].m_texture->GetResource(&ppResource);
	D3D11_RESOURCE_DIMENSION pResourceDimension;
	ppResource->GetType(&pResourceDimension);

	auto txt=reinterpret_cast<ID3D11Texture2D*>( ppResource );

	D3D11_TEXTURE2D_DESC desc;
	txt->GetDesc(&desc);
	desc.Usage = D3D11_USAGE_STAGING;
	desc.BindFlags = 0;
	desc.CPUAccessFlags = D3D11_CPU_ACCESS_READ;
	
	ID3D11Texture2D *pTexture = NULL;
	hr=gGE.Graphics.dev->CreateTexture2D( &desc, NULL, &pTexture );
	if (hr==D3DERR_INVALIDCALL) MessageBoxW(ghWnd,L"Texture Map",L"D3DERR_INVALIDCALL",MB_OK);
	if (hr==E_FAIL) MessageBoxW(ghWnd,L"Texture Map",L"E_FAIL",MB_OK);
	if (hr==E_INVALIDARG) MessageBoxW(ghWnd,L"Texture Map",L"E_INVALIDARG",MB_OK);
	if (hr==E_OUTOFMEMORY) MessageBoxW(ghWnd,L"Texture Map",L"E_OUTOFMEMORY",MB_OK);
	if (hr==E_NOTIMPL) MessageBoxW(ghWnd,L"Texture Map",L"E_NOTIMPL",MB_OK);
	if (hr==S_FALSE) MessageBoxW(ghWnd,L"Texture Map",L"S_FALSE",MB_OK);
	gGE.Graphics.devcon->CopyResource(pTexture,txt);
	D3D11_MAPPED_SUBRESOURCE mappedrec;
	hr=gGE.Graphics.devcon->Map(pTexture,0,D3D11_MAP_READ,NULL,&mappedrec);
	if (FAILED(hr)) MessageBoxW(ghWnd,L"Texture Map",L"mapping failed",MB_OK);

	sx=gGE.TextureList[Texture].Width;
	sy=gGE.TextureList[Texture].Height;
	UINT W=UINT(sx);
	UINT H=UINT(sy);

	CollisionMap=new byte*[W];
	for (UINT i=0;i<W;i++) CollisionMap[i]=new byte[H];
	
	COLOR *C=(COLOR*)mappedrec.pData;
	for (UINT x=0;x<W;x++){
		for (UINT y=0;y<H;y++){
			UINT Loc=(y*W)+x;
			CollisionMap[x][y]=C[Loc].a;

		}
	}
	gGE.Graphics.devcon->Unmap(pTexture,0);
	pTexture->Release();

The key was in the D3D11_TEXTURE2D_DESC. I had to set the BindFlags to 0 because everything else gave me errors. I suppose that's right. The other two parameters I found from reading LOTS of Microsoft DX11 pages. Also, if you set :

desc.CPUAccessFlags = D3D11_CPU_ACCESS_READ|D3D11_CPU_ACCESS_WRITE;

and

hr=gGE.Graphics.devcon->Map(pTexture,0,D3D11_MAP_READ_WRITE,NULL,&mappedrec);

you can do both read and write to that texture (resource)......