Unity: CopyTexture to External texture2D

Question

I need to expose a Unity texture/Rendertexture to some native plugin, which requires the "D3D11_RESOURCE_MISC_SHARED" flag on the texture.

textures created by unity doesn't have this flag, so, I created it from the plugin side, and then created a reference texture within unity using CreateExternalTexture, and copied the contents to this native texture using Graphics.CopyTexture.

the 2 textures have the same dimension, same size, same format, and same mipCount(0)

the problem is, when I show it in unity (for debugging purpose), I can see nothing and no error occurs.

btw, if I copy by ReadPixel, an error occures :

ReadPixels called on undefined image 0 (valid values are 0 - -1

if I create the texture using unity api, CopyTexture succeeds and result can be seen. but then, I lose the "D3D11_RESOURCE_MISC_SHARED" flag.

so, maybe the texture I created is not valid? my code:

    D3D11_TEXTURE2D_DESC desc = { 0 };
desc.Width = width;
desc.Height = height;
desc.MipLevels = 0;
desc.ArraySize = 1;
desc.Format = DXGI_FORMAT_R8G8B8A8_UNORM;//这里,格式能不能调整?比如,A8是需要的吗?
desc.SampleDesc.Count = 1;
desc.Usage = D3D11_USAGE_DEFAULT;
desc.BindFlags = D3D11_BIND_SHADER_RESOURCE;//普通资源
//desc.CPUAccessFlags = D3D11_CPU_ACCESS_READ;//应该不需要cpu访问的,不是read也不是write
desc.MiscFlags = D3D11_RESOURCE_MISC_SHARED;//for "OpenSharedHandle" d3d11 api

HRESULT hr = E_FAIL;
if (FAILED(hr = pDevice->CreateTexture2D(&desc, nullptr, &g_unityEquirectTexture)))
{
    Log(" Create Shared Texture Failed!");
    return NULL;
}
Log("CreateSharedTexture success");
//return g_unityEquirectTexture;

Unity CopyTexture Code:

        if (output == null)
    {
        Debug.Log($"limit = {QualitySettings.masterTextureLimit}");
        //output = new Texture2D(equirect.width, equirect.height, TextureFormat.RGBA32,false);//uncomment this line and then copyTexture below succeeds
        IntPtr externalTextureData = CGDKInterOp.cgdk_c_CreateExternalTexture(equirectLeft.GetNativeTexturePtr(), equirectLeft.width * 2, equirectLeft.height);
        if (externalTextureData != IntPtr.Zero)
        {
            output = Texture2D.CreateExternalTexture(equirectLeft.width * 2, equirectLeft.height, TextureFormat.RGBA32, false, true, externalTextureData);
        }
    }
    if (output == null)
    {
        Debug.LogError("create texture from external failed!");
        return;
    }

    //RenderTexture.active = equirect;
    //output.ReadPixels(new Rect(0, 0, equirect.width, equirect.height), 0, 0);
    //RenderTexture.active = null;
    Graphics.CopyTexture(equirect, output);

Answer 1

OK, solved by myself.

the problem is: Miplevel == 0.this causes d3d11 creating a texture with 0B memory allocated! change Miplevel to 1 solved the problem

note: In unity inspector, we can see the memory allocated by textures. I found that my texture has 0B memory from the inspector and then, I search using this clue and found the solution