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DX11 [D3D11] Creating a dynamic texture?

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I've been trying to figure out how to create a blank texture that I can fill with information that I would generate every frame.

I'm using DirectX11 and I guess I'm looking for something like the old DirectX 9 function D3DXCreateTexture... wich allowed you to create a blank texture and then lock it to be loaded with the desired information.

I've found D3DX11CreateTextureFromFile, D3DX11CreateTextureFromMemory, and D3DX11CreateTextureFromResource, but I don't think any of those are what I'm looking for since according to MSDN the first takes a pointer to a file, the second a pointer to a file stored in memory, and the third a handle to a resource (whatever that is).

I would store the information to be loaded into the texture in an array such as Texture[width][height]...

How do I create a texture that I can update every frame with information stored in memory? I guess another way to ask my question would be, how do I create a texture I can update with procedurally generated colour information?

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You can use the CreateTexture2D Method of your device to create a texture, and then the UpdateSubresource Method of a device-context to update the texture data.

There is also a Map method for the device-context that can be used to give you a pointer to the texture-memory. If you want to use that method to update your texture, you need to create it with the appropriate CPU access flags and dynamic usage. See the D3D11_TEXTURE2D_DESC Structure for information on all the flags. UpdateSubresource will probably be more efficient.

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I would say DXGI_FORMAT_R8G8B8A8_UNORM, if you want the texture to contain a normal image. That's a 32-bit format with 8 bits for each channel, which is the common display mode.

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Thank you.

The following code shows where I'm at now. I've created a 2d texture, pointed at by pTexture, and now I'm trying to map values for each pixel:

D3D11_MAPPED_SUBRESOURCE texmap;
pImmediateContext->Map(pTexture, 0, D3D11_MAP_WRITE_DISCARD, 0, &texmap);
for (UINT i = 0; i < Width; i++)
{
for (UINT j = 0; j < Height; j++)
{
//What code goes here to set the colour value for each pixel?
}
}
pImmediateContext->Unmap(pTexture, 0);




How do I set the colour value for each pixel?

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The member void* D3D11_MAPPED_SUBRESOURCE::pData points to the block of memory. Cast this to a BYTE* which will let you go through the data as bytes. In this way, every 4 bytes stand for a single RGBA vector. Write in the color data as you see fit.

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Thank you.

I've decided to also try UpdateSubresource.

This is the code so far:


for(UINT i=0; i<Width*Height(); i++)
{
UINT32 Colour = 0xFFFFFFFF;
pImmediateContext()->UpdateSubresource(pTexture2D(), 0, (D3D11_BOX *)(pTexture2D() + i), &Colour, /*??*/, /*??*/);
}



Assuming I've treated the other parameters correctly I'm confused as to what to input for the last two parameters, being UINT SrcRowPitch and UINT SrcDepthPitch respectively.

For UINT SrCRowPitch is it the width of the texture or the width of the texture multiplied by the sixe of a texel? For SrcRowPitch is it 0 (given that is 2D) or is it 1 (being 1 texel deep), or is it the size of a texel?

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Well, I tried UINT SrcRowPitch = 0, and UINT SrcDepthPitch = 0, (because I did that in another part of my code when I updated a constant buffer in my shader file with updatesubresource), and the code fills the texture with white as desired BUT, after a while of running the program I get tons of exceptions with the error messages:

D3D11: ERROR: ID3D11DeviceContext::UpdateSubresource: pDstBox is not a valid box, as the End coordinates must be greater than or equal to the Start. *pDstBox = { {1653043880,8880072, 8881048}, {8880256, 8880340,8881064} }. [ RESOURCE_MANIPULATION ERROR #288: UPDATESUBRESOURCE_INVALIDDESTINATIONBOX ]
D3D11: Removing Device.
D3D11: ERROR: ID3D11DeviceContext::UpdateSubresource: pDstBox is not a valid box for the destination subresource. *pDstBox = { {8880072,8881048, 8880256}, {8880340, 8881064,1144210505} }. DstSubresource = { {0,0, 0}, {1600, 900,1} }. [ RESOURCE_MANIPULATION ERROR #288: UPDATESUBRESOURCE_INVALIDDESTINATIONBOX ]
D3D11: ERROR: ID3D11DeviceContext::UpdateSubresource: pDstBox is not a valid box for the destination subresource. *pDstBox = { {8881048,8880256, 8880340}, {8881064, 1144210505,1700016433} }. DstSubresource = { {0,0, 0}, {1600, 900,1} }. [ RESOURCE_MANIPULATION ERROR #288: UPDATESUBRESOURCE_INVALIDDESTINATIONBOX ]
D3D11: ERROR: ID3D11DeviceContext::UpdateSubresource: pDstBox is not a valid box for the destination subresource. *pDstBox = { {8880256,8880340, 8881064}, {1144210505, 1700016433,1920300152} }. DstSubresource = { {0,0, 0}, {1600, 900,1} }. [ RESOURCE_MANIPULATION ERROR #288: UPDATESUBRESOURCE_INVALIDDESTINATIONBOX ]
D3D11: ERROR: ID3D11DeviceContext::UpdateSubresource: pDstBox is not a valid box, as the End coordinates must be greater than or equal to the Start. *pDstBox = { {8880340,8881064, 1144210505}, {1700016433, 1920300152,4469349} }. [ RESOURCE_MANIPULATION ERROR #288: UPDATESUBRESOURCE_INVALIDDESTINATIONBOX ]
D3D11: ERROR: ID3D11DeviceContext::UpdateSubresource: pDstBox is not a valid box, as the End coordinates must be greater than or equal to the Start. *pDstBox = { {8881064,1144210505, 1700016433}, {1920300152, 4469349,3131961357} }. [ RESOURCE_MANIPULATION ERROR #288: UPDATESUBRESOURCE_INVALIDDESTINATIONBOX ]
D3D11: ERROR: ID3D11DeviceContext::UpdateSubresource: pDstBox is not a valid box, as the End coordinates must be greater than or equal to the Start. *pDstBox = { {1144210505,1700016433, 1920300152}, {4469349, 3131961357,3131961357} }. [ RESOURCE_MANIPULATION ERROR #288: UPDATESUBRESOURCE_INVALIDDESTINATIONBOX ]


These errors are repeated many many times.

How can I fix that?

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The documentation for UpdateSubresource explains how to use the destination box and source pitch. If you want to update your entire texture, you can specify NULL for the destination box.
SrcRowPitch is the distance in bytes from the start of one row of pixels to the start of the next, in the source data that is to be copied to the texture. Depth-pitch is only used for 3D textures. For constant-buffers or 1D-textures the row-pitch is also unused, since there is only one row.

Also, you don't need to loop over your texture and call UpdateSubresource multiple times, as one call can update the entire texture.

I would recommend doing it something like this:

desc.Format = DXGI_FORMAT_R8G8B8A8_UNORM;
desc.Usage = D3D11_USAGE_DEFAULT;
// dont need any CPU flags for UpdateSubresource
CreateTexture2D(...);

UINT32 *textureData = new UINT32[width * height];
textureData[0] = pixel 1;
textureData[1] = pixel 2;
...

// Note width*4 as each pixel is 4 bytes
pContext->UpdateSubresource(pTexture, 0, NULL, textureData, width*4, 0);


You can use the destination box if you only want to update part of the texture.

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