Packs the 27-float (9 × RGB) coefficients into the std140 layout the SH shader buffer expects: 9 × vec4, with the 4th lane zero-padded. Returns 36 floats (144 bytes), matching SH_GPU_BYTE_SIZE.
Packs the 27-float (9 × RGB) coefficients into the std140 layout the SH shader buffer expects: 9 × vec4, with the 4th lane zero-padded. Returns
36 floats (144 bytes), matching SH_GPU_BYTE_SIZE.