Template:Glapi viewport equations
$ x_{w}=(x_{nd}+1)\left({\tfrac {width}{2}}\right)+x $
$ y_{w}=(y_{nd}+1)\left({\tfrac {height}{2}}\right)+y $
$ x_{w}=(x_{nd}+1)\left({\tfrac {width}{2}}\right)+x $
$ y_{w}=(y_{nd}+1)\left({\tfrac {height}{2}}\right)+y $