Issue with read vertex / index buffer with structured buffer in DXR

Question

Scene is just like above image(Sponza scene), and I think texture index for each geometry is good, but texture coordinate seems wrong

I'm currently upload descriptor in descriptor heap like this:

(instance 0 textures(0 to 74)) (vertex buffer for each geometry(75 to 467)) (index buffer for each geometry(468 to 861)) (geometryInfo(862)) (intstance 1 textures)...

but currently I'm uploading only one instance (and all scene geometrys are in same one BLAS)

start index of vertex / index buffer is uploads by per-instance buffer like this:

cbuffer InstanceCB : register(b1)
{
    uint GeometryInfoIndex : packoffset(c0.x);
    uint VertexAttribIndex : packoffset(c0.y);
    uint IndexBufferIndex : packoffset(c0.z);
}

and geometryInfo have texture materials like this:

struct GeometryInfo
{
    uint AlbedoTextureIndex;
    uint MetalicTextureIndex;
    uint RoughnessTextureIndex;
    uint NormalMapTextureIndex;
    uint OpacityMapTextureIndex;
};

and I'm reading vertex buffer or index buffer by dynamic resource feature added in hlsl 6.6 just like this:

Vertex GetHitSurface(in BuiltInTriangleIntersectionAttributes attr, in uint geometryIdx)
{
    float3 barycentrics = float3(1 - attr.barycentrics.x - attr.barycentrics.y, attr.barycentrics.x, attr.barycentrics.y);

    StructuredBuffer<Vertex> VertexBuffer = ResourceDescriptorHeap[VertexAttribIndex + geometryIdx];
    StructuredBuffer<uint> IndexBuffer = ResourceDescriptorHeap[IndexBufferIndex + geometryIdx];
    
    uint primIndex = PrimitiveIndex();
    
    uint i0 = IndexBuffer[primIndex * 3 + 0];
    uint i1 = IndexBuffer[primIndex * 3 + 1];
    uint i2 = IndexBuffer[primIndex * 3 + 2];
    
    Vertex v0 = VertexBuffer[i0];
    Vertex v1 = VertexBuffer[i1];
    Vertex v2 = VertexBuffer[i2];

    return VertexBarycentricLerp(v0, v1, v2, barycentrics);
}

in NSight, vertex buffer is initialized well and i checked VertexAttribIndex and IndexBufferIndex is good but result is bad.

and vertex buffer seems like good for me, because position-normal-texcoord-tangent-bitangent values are correctly uploaded like above screenshot(it's from NSight)

I've checked everything what I can, but every parameter seems good, and still can't find why texture cooredinate that I got is wrong.

Shader debugging might be helpful, but there's no shader debugging feature for RT in every(or most of) grahpics debugger...

And this is why I can't doubt parameters...

in above screen shot, you can find 75, 468 index is bound of vertex / index buffer(because of it's format)

this is my GitHub repository link: https://github.com/kcjsend2/Chulsu

Answer 1

Found it.

SRV Descriptor for Structured Buffer was wrong.

Before fix it, it was just like this:

D3D12_SHADER_RESOURCE_VIEW_DESC srvDesc{};
srvDesc.Shader4ComponentMapping = D3D12_DEFAULT_SHADER_4_COMPONENT_MAPPING;
srvDesc.Format = DXGI_FORMAT_R32_FLOAT;
srvDesc.ViewDimension = D3D12_SRV_DIMENSION_BUFFER;

srvDesc.Buffer.FirstElement = 0;
srvDesc.Buffer.NumElements = mVerticesCount * 14;
srvDesc.Buffer.StructureByteStride = 0;
srvDesc.Buffer.Flags = D3D12_BUFFER_SRV_FLAG_NONE;

Format and NumElements, StructureByteStride must be just like this:

srvDesc.Shader4ComponentMapping = D3D12_DEFAULT_SHADER_4_COMPONENT_MAPPING;
srvDesc.Format = DXGI_FORMAT_UNKNOWN;
srvDesc.ViewDimension = D3D12_SRV_DIMENSION_BUFFER;

srvDesc.Buffer.FirstElement = 0;
srvDesc.Buffer.NumElements = mVerticesCount;
srvDesc.Buffer.StructureByteStride = sizeof(Vertex);
srvDesc.Buffer.Flags = D3D12_BUFFER_SRV_FLAG_NONE;