DirectX Large Models > 64k C++

Question

My DirectX11 C++ Engine uses uint16_t (short) for the vertex index buffer and all was working well.

I've evolved the models I use and now they have grown with over 64k indexes.

I've changed all references to my index buffer from short to uint32_t and the render was broken.

My variable defines are:

ID3D11Buffer        *IndexBuffer;     //DirectX Index Buffer
vector<int32_t>     primitiveIndices; //Vector array of indicies formally

I finally changed the line

Context->IASetIndexBuffer(IndexBuffer, DXGI_FORMAT_R16_UINT, 0); 

to

Context->IASetIndexBuffer(IndexBuffer, DXGI_FORMAT_R8G8B8A8_UINT, 0);

This was done to allow 32bit indexes. However it fails to render. I have also updated the

D3D11_BUFFER_DESC::ByteWidth

accordingly.

Any advice welcome.

Answer 1

What exactly do you think is the meaning of DXGI_FORMAT_R8G8B8A8_UINT as an index buffer format? If you check the documentation, you will find there are only two valid formats that IASetIndexBuffer() will accept. If your indices are std::uint32_t then the corresponding DXGI format to use would be DXGI_FORMAT_R32_UINT. Apart from that, I highly recommend to use a debug context and look at the debug output when debugging…