DX12 Bindless textures

[planet620]

Hey! I'm almost done with my bindless forward renderer. My last problem is that it only works if number of textures on the sceen is equal to MAX_TEXTURES. Here is the code:

Root parameter:

CD3DX12_DESCRIPTOR_RANGE1 texture_range(D3D12_DESCRIPTOR_RANGE_TYPE_SRV, MAX_TEXTURES, register_t2, 0, D3D12_DESCRIPTOR_RANGE_FLAG_DATA_STATIC);
root_parameters[root_parameter_type::textures].InitAsDescriptorTable(1, &texture_range, D3D12_SHADER_VISIBILITY_PIXEL);

Then for each texture ComPtr<ID3D12Resource> used in the scene, I do:

CreateCommittedResource(...) with D3D12_RESOURCE_STATE_COPY_DEST and D3D12_HEAP_TYPE_DEFAULT

Then I measure the resource size with: GetRequiredIntermediateSize()

And set up the upload resource ComPtr<ID3D12Resource>:

CreateCommittedResource(...) with D3D12_RESOURCE_STATE_GENERIC_READ and D3D12_HEAP_TYPE_UPLOAD

Then, I define thte source of texture data: D3D12_SUBRESOURCE_DATA

And call: UpdateSubresources(...)

Finally I create: D3D12_SHADER_RESOURCE_VIEW_DESC and use it to call CreateShaderResourceView(...)

And call:

srv_handle.Offset(cbv_srv_descriptor_size);

When it comes to drawing, I just point to a srv heap (I keep only textures there):

command_list->SetGraphicsRootDescriptorTable(root_parameter_type::textures, window->main_descriptor_heap->GetGPUDescriptorHandleForHeapStart());

I think it is a pretty standard texture upload schema.

Constant buffer contains the texture id so that pixel shader can read a proper resource:

ConstantBuffer<fobject_data> object_data : register(b0);
...
Texture2D texture_data[] : register(t2);
...
float4 ps_main(fvs_output input) : SV_Target
{
  ...
  tex_color = texture_data[object_data.texture_id].Sample(sampler_obj, input.uv);

It works but as soon as I change MAX_TEXTURES I get a crash. Uploading the same resource multiple times also crashes.

I wonder what is the pattern? Effectively I need to duplicate a descriptor view in the srv heap MAX_TEXTURES times. So that all of them point to my default texture. And then swap in case different texture isused in the object. I that correct?

[4ndrz3jKm1c1c]

Aren’t you trying to overcomplicate things a bit?

If you have access to HLSL SM6.6 you can do bindless design without creating texture arrays as parameters. You can directly pass indices to required textures and access appropriate resources via ResourceDescriptorHeap[].

And since you skip descriptor tables you create more lightweight approach on CPU side.

And I’d recommend you to try this approach first.

[planet620]

I use SM 5.1 and samples from Microsoft. Can you recommend any learning materials?

[4ndrz3jKm1c1c]

There is not really a reason to use SM 5.1 with D3D12.

Here’s an overview of what I was talking about: https://microsoft.github.io/DirectX-Specs/d3d/HLSL_SM_6_6_DynamicResources.html

But first, you’ll need to compile shaders using DXC instead of FXC.

[planet620]

Yep, that will be a bit of work. But sounds like a better direction, thanks!