Direct3D 10 Hardware Instancing using Structured Buffers

Question

I am trying to implement hardware instancing with Direct3D 10+ using Structured Buffers for the per instance data but I've not used them before.

I understand how to implement instancing when combining the per vertex and per instance data into a single structure in the Vertex Shader - i.e. you bind two vertex buffers to the input assembler and call the DrawIndexedInstanced function.

Can anyone tell me the procedure for binding the input assembler and making the draw call etc. when using Structured Buffers with hardware instancing? I can't seem to find a good example of it anywhere.

It's my understanding that Structured Buffers are bound as ShaderResourceViews, is this correct?

Answer 1

Yup, that's exactly right. Just don't put any per-instance vertex attributes in your vertex buffer or your input layout and create a ShaderResourceView of the buffer and set it on the vertex shader. You can then use the SV_InstanceID semantic to query which instance you're on and just fetch the relevant struct from your buffer.

StructuredBuffers are very similar to normal buffers. The only differences are that you specify the D3D11_RESOURCE_MISC_BUFFER_STRUCTURED flag on creation, fill in StructureByteStride and when you create a ShaderResourceView the Format is DXGI_UNKNOWN (the format is specified implicitly by the struct in your shader).

StructuredBuffer<MyStruct> myInstanceData : register(t0);

is the syntax in HLSL for a StructuredBuffer and you just access it using the [] operator like you would an array.

Is there anything else that's unclear?