Questions about HLSL Semantics - directx-12

Question

I want to define the vertex struct like this:
struct VertexIn
{
float3 PosL : POSITION;
float3 NormalL : NORMAL;
float2 TexC : TEXCOORD;
float SH[9]; // ?
};
How to choose the vertex semantics of the 'SH' array? Can i define a semantic by myself?
Then I tried this:
// in hlsl:
struct VertexIn
{
float3 PosL : POSITION;
float3 NormalL : NORMAL;
float2 TexC : TEXCOORD;
float SH[9] : SHCOEFFICIENT; // ???
};
// cpp:
mInputLayout =
{
{ "POSITION", 0, DXGI_FORMAT_R32G32B32_FLOAT, 0, 0, D3D12_INPUT_CLASSIFICATION_PER_VERTEX_DATA, 0 },
{ "NORMAL", 0, DXGI_FORMAT_R32G32B32_FLOAT, 0, 12, D3D12_INPUT_CLASSIFICATION_PER_VERTEX_DATA, 0 },
{ "TEXCOORD", 0, DXGI_FORMAT_R32G32_FLOAT, 0, 24, D3D12_INPUT_CLASSIFICATION_PER_VERTEX_DATA, 0 },
{ "SHCOEFFICIENT", 0, DXGI_FORMAT_R32_FLOAT, 0, 32, D3D12_INPUT_CLASSIFICATION_PER_VERTEX_DATA, 0}, // ???
};
Of course, it's wrong.
So I split the array into 9 elements temporarily, but it looks stupid.

Answer 1

You can use SemanticIndex parameter. You could define your input layout
mInputLayout =
{
{ "POSITION", 0, DXGI_FORMAT_R32G32B32_FLOAT, 0, 0, D3D12_INPUT_CLASSIFICATION_PER_VERTEX_DATA, 0 },
{ "NORMAL", 0, DXGI_FORMAT_R32G32B32_FLOAT, 0, 12, D3D12_INPUT_CLASSIFICATION_PER_VERTEX_DATA, 0 },
{ "TEXCOORD", 0, DXGI_FORMAT_R32G32_FLOAT, 0, 24, D3D12_INPUT_CLASSIFICATION_PER_VERTEX_DATA, 0 },
{ "SHCOEFFICIENT", 0, DXGI_FORMAT_R32_FLOAT, 0, 32, D3D12_INPUT_CLASSIFICATION_PER_VERTEX_DATA, 0},
{ "SHCOEFFICIENT", 1, DXGI_FORMAT_R32_FLOAT, 0, 36, D3D12_INPUT_CLASSIFICATION_PER_VERTEX_DATA, 0},
{ "SHCOEFFICIENT", 2, DXGI_FORMAT_R32_FLOAT, 0, 40, D3D12_INPUT_CLASSIFICATION_PER_VERTEX_DATA, 0},
...
{ "SHCOEFFICIENT", 8, DXGI_FORMAT_R32_FLOAT, 0, 64, D3D12_INPUT_CLASSIFICATION_PER_VERTEX_DATA, 0}
};
Or like this:
mInputLayout =
{
{ "POSITION", 0, DXGI_FORMAT_R32G32B32_FLOAT, 0, 0, D3D12_INPUT_CLASSIFICATION_PER_VERTEX_DATA, 0 },
{ "NORMAL", 0, DXGI_FORMAT_R32G32B32_FLOAT, 0, 12, D3D12_INPUT_CLASSIFICATION_PER_VERTEX_DATA, 0 },
{ "TEXCOORD", 0, DXGI_FORMAT_R32G32_FLOAT, 0, 24, D3D12_INPUT_CLASSIFICATION_PER_VERTEX_DATA, 0 },
{ "SHCOEFFICIENT", 0, DXGI_FORMAT_R32G32B32_FLOAT, 0, 32, D3D12_INPUT_CLASSIFICATION_PER_VERTEX_DATA, 0},
{ "SHCOEFFICIENT", 1, DXGI_FORMAT_R32G32B32_FLOAT, 0, 44, D3D12_INPUT_CLASSIFICATION_PER_VERTEX_DATA, 0},
{ "SHCOEFFICIENT", 2, DXGI_FORMAT_R32G32B32_FLOAT, 0, 56, D3D12_INPUT_CLASSIFICATION_PER_VERTEX_DATA, 0},
};
but change your vertex
struct VertexIn
{
float3 PosL : POSITION;
float3 NormalL : NORMAL;
float2 TexC : TEXCOORD;
float3 SH[3] : SHCOEFFICIENT;
};