anchor.diff:          (%viewport-origin-y viewport) (floor (v:y value)))
     value)
   
  -;;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
  +;;------------------------------------------------------------
   
   (defun2 %viewport (viewport)
     (%gl:viewport
  
positive.code: (defun2 viewport-resolution-y (viewport)
    (%viewport-resolution-y viewport))
  
  ;;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
  
  (defun2 viewport-origin (viewport)
    (v! (%viewport-origin-x viewport)
  
negative.code: (in-package :cepl.viewports)
  
  ;;------------------------------------------------------------
  
  (defn-inline viewport-eql ((v0 viewport) (v1 viewport)) boolean
    (and (= (%viewport-resolution-x v0) (%viewport-resolution-x v1))
         (= (%viewport-resolution-y v0) (%viewport-resolution-y v1))
         (= (%viewport-origin-x v0) (%viewport-origin-x v1))
         (= (%viewport-origin-y v0) (%viewport-origin-y v1))))
  
  ;;------------------------------------------------------------
  
  (defn %set-current-viewport ((cepl-context cepl-context)
                               (viewport viewport))
  