Can we not set a vertex's tangent or bitangent in Ultra? I only found these in the Mesh class for vertices.
virtual void SetVertexPosition(const uint32_t v, const Vec3& position);
virtual void SetVertexNormal(const uint32_t v, const Vec3& normal);
virtual void SetVertexTexCoords(const uint32_t v, const Vec2& texcoords, const int index = 0);
virtual void SetVertexColor(const uint32_t v, const Vec4& color);