Re: [HOpenGL] Plans for more extensions?

13 Jun 2005


      Sven Panne wrote:
...
BTW: I still fail to see a good "Haskellish" API for NURBS. Again, API
proposals are highly welcome.
The obvious Haskellisation would seem to be along the lines of:
...
newtype NurbsRendererObj = NurbsRendererObj (Ptr ())
-- GLUnurbsObj*
...
withNurbsRendererObj :: (NurbsRendererObj -> IO a) -> IO a
-- gluNewNurbsRenderer, gluDeleteNurbsRenderer
...
renderCurve :: NurbsRendererObj -> IO a -> IO a
-- gluBeginCurve, gluEndCurve
...
renderSurface :: NurbsRendererObj -> IO a -> IO a
-- gluBeginSurface, gluEndSurface
...
trimNurbs :: NurbsRendererObj -> IO a -> IO a
-- gluBeginTrim, gluEndTrim
...
pwlCurve :: NurbsRendererObj
  -> [GLfloat]		-- vertices
  -> MapTarget		-- type
  -> IO ()
-- gluPwlCurve
...
nurbsCurve :: NurbsRendererObj
  -> [GLfloat]		-- knots
  -> [GLfloat]		-- control points
  -> MapTarget		-- type
  -> IO ()
-- gluNurbsCurve
...
nurbsSurface :: NurbsRendererObj
  -> [GLfloat]		-- s knots
  -> [GLfloat]		-- t knots
  -> [[GLfloat]]		-- control points
  -> MapTarget		-- type
  -> IO ()
-- gluNurbsSurface
[The control points would arguably better as an Array, but the above
matches how 2D evaluators are handled.]
...
various :: NurbsRendererObj -> StateVar a
-- gluNurbsProperty, gluGetNurbsProperty
...
samplingMatrices :: Matrix m => NurbsRendererObj
  -> SettableStateVar (m GLfloat, m GLfloat, (Position, Size))
-- gluLoadSamplingMatrices
...
data NurbsCallbackTarget = ...
...
nurbsCallback :: NurbsRendererObj
  -> NurbsCallbackTarget	-- which
  -> SettableStateVar (IO ())
-- gluNurbsCallback
For the functions which can only be called within a begin/end pair,
you might want to stuff the NurbsRendererObj into an IORef rather than
having to pass it around .

-- 
Glynn Clements