In glTF, tangent W is -1 or +1 and carries tangent-basis handedness. The bitangent is derived as:
cross(normal, tangent.xyz) * tangent.w
Dropping W breaks normal mapping on mirrored UV islands unless some other path reconstructs the sign; no such path is retained in these imported structures.
Radient's glTF vertex layout should store tangent as float4, even if the generic Diligent default remains float3.
In glTF, tangent W is -1 or +1 and carries tangent-basis handedness. The bitangent is derived as:
Dropping W breaks normal mapping on mirrored UV islands unless some other path reconstructs the sign; no such path is retained in these imported structures.
Radient's glTF vertex layout should store tangent as
float4, even if the generic Diligent default remains float3.