Direct3D12 bgfx::blit to a cubemap face and mip produces black.

[unravel-dev]

Direct3D12 blit texture to a cubemap face and mip produces black.

using bgfx::blit to fill a cuemap's face and mip does't really work properly. It works great on all other backends
dx11,opengl,vulkan. I suspect this to be a problem in the dx12 renderer implementation but i am not an expert and couldn't find anything obvious.

Here is an example code:

//bgfx::TextureInfo of the output cubemap
 const auto& ti = params.output_cube->info;

        for(uint8_t face = 0; face < 6; ++face)
        {
            // input_faces is just an array of Frame Buffers for each face already filled and has mips.
            auto src = params.input_faces[face]->native_handle();
            for(uint8_t mip = 0; mip < max_mips; ++mip)
            {
                uint16_t dim = ti.width >> mip;
                bgfx::blit(pass.id, output_cube->native_handle(), mip, 0, 0, face, src, mip, 0, 0, 0, dim, dim, 1);
            }
        }

Here is the result on Mip 0

Mip 1 and beyond is just black.

And here is the output on DX11/Vulkan/OpenGL
Mip 0

Mip 1 and beyond

[unravel-dev]

Hi. Any progress or idea on this?

[vbousquet]

Did you check that the texture format you use has the BGFX_CAPS_FORMAT_TEXTURE_MIP_AUTOGEN caps flag ?
In our project, this was supported on DX11 but not DX12 (NVidia driver), so we had to perform our mipmap generation ourself, using compute shaders.

[unravel-dev]

@vbousquet Yes it says it supports it. It is a RGBA8 format not any special one.