How to use UpdateSubresource to update the texture in Direct3d - c++

Question

I have in my CreateDeviceResources method the following code: (the method is called at initial once).
What do i need to do to create a method change the texture?
void SetTexture(...textureinput...);
Do i need to run below code everytime a texture needs to be changed? or can I somehow just change some data in memory?
I have found that I would like to use ID3D11DeviceContext::UpdateSubresource, but havent been able to find a sample on how to use it.
auto textureData = reader->ReadData("SIn.Win8\\texturedata.bin");
D3D11_SUBRESOURCE_DATA textureSubresourceData = {0};
textureSubresourceData.pSysMem = textureData->Data;
// Specify the size of a row in bytes, known a priori about the texture data.
textureSubresourceData.SysMemPitch = 1024;
// As this is not a texture array or 3D texture, this parameter is ignored.
textureSubresourceData.SysMemSlicePitch = 0;
// Create a texture description from information known a priori about the data.
// Generalized texture loading code can be found in the Resource Loading sample.
D3D11_TEXTURE2D_DESC textureDesc = {0};
textureDesc.Width = 256;
textureDesc.Height = 256;
textureDesc.Format = DXGI_FORMAT_R8G8B8A8_UNORM;
textureDesc.Usage = D3D11_USAGE_DEFAULT;
textureDesc.CPUAccessFlags = 0;
textureDesc.MiscFlags = 0;
// Most textures contain more than one MIP level. For simplicity, this sample uses only one.
textureDesc.MipLevels = 1;
// As this will not be a texture array, this parameter is ignored.
textureDesc.ArraySize = 1;
// Don't use multi-sampling.
textureDesc.SampleDesc.Count = 1;
textureDesc.SampleDesc.Quality = 0;
// Allow the texture to be bound as a shader resource.
textureDesc.BindFlags = D3D11_BIND_SHADER_RESOURCE;
ComPtr<ID3D11Texture2D> texture;
DX::ThrowIfFailed(
m_d3dDevice->CreateTexture2D(
&textureDesc,
&textureSubresourceData,
&texture
)
);
// Once the texture is created, we must create a shader resource view of it
// so that shaders may use it. In general, the view description will match
// the texture description.
D3D11_SHADER_RESOURCE_VIEW_DESC textureViewDesc;
ZeroMemory(&textureViewDesc, sizeof(textureViewDesc));
textureViewDesc.Format = textureDesc.Format;
textureViewDesc.ViewDimension = D3D11_SRV_DIMENSION_TEXTURE2D;
textureViewDesc.Texture2D.MipLevels = textureDesc.MipLevels;
textureViewDesc.Texture2D.MostDetailedMip = 0;
ComPtr<ID3D11ShaderResourceView> textureView;
DX::ThrowIfFailed(
m_d3dDevice->CreateShaderResourceView(
texture.Get(),
&textureViewDesc,
&textureView
)
);
// Once the texture view is created, create a sampler. This defines how the color
// for a particular texture coordinate is determined using the relevant texture data.
D3D11_SAMPLER_DESC samplerDesc;
ZeroMemory(&samplerDesc, sizeof(samplerDesc));
samplerDesc.Filter = D3D11_FILTER_MIN_MAG_MIP_LINEAR;
// The sampler does not use anisotropic filtering, so this parameter is ignored.
samplerDesc.MaxAnisotropy = 0;
// Specify how texture coordinates outside of the range 0..1 are resolved.
samplerDesc.AddressU = D3D11_TEXTURE_ADDRESS_WRAP;
samplerDesc.AddressV = D3D11_TEXTURE_ADDRESS_WRAP;
samplerDesc.AddressW = D3D11_TEXTURE_ADDRESS_WRAP;
// Use no special MIP clamping or bias.
samplerDesc.MipLODBias = 0.0f;
samplerDesc.MinLOD = 0;
samplerDesc.MaxLOD = D3D11_FLOAT32_MAX;
// Don't use a comparison function.
samplerDesc.ComparisonFunc = D3D11_COMPARISON_NEVER;
// Border address mode is not used, so this parameter is ignored.
samplerDesc.BorderColor[0] = 0.0f;
samplerDesc.BorderColor[1] = 0.0f;
samplerDesc.BorderColor[2] = 0.0f;
samplerDesc.BorderColor[3] = 0.0f;
ComPtr<ID3D11SamplerState> sampler;
DX::ThrowIfFailed(
m_d3dDevice->CreateSamplerState(
&samplerDesc,
&sampler
)
);

Answer 1

If you want to update the same texture at runtime, you need to use Map
Maptype needs to be D3D11_MAP_WRITE_DISCARD
Also your texture needs to be created with the Dynamic flag instead of default, and cpu access flag needs to be set to D3D11_CPU_ACCESS_WRITE
If gives you access to D3D11_MAPPED_SUBRESOURCE , and you can set the new data using pData
Depending on the case it can be nicer to just recreate a texture, it's on a case by case basis (dynamic is nice if texture changes often)