[Haskell-cafe] Re: Combining Gtk2hs and Fieldtrip

[Andy Stewart]

Hi Herng,

You can use gtk2hs with OpenGL, then use OpenGL render your 3D graphics.

You can use command
   cabal install install gtkglext
to try it, demo at http://code.haskell.org/gtkglext/demo/

About multi-threaded, yes, you must post all *gtk* code to gtk+
main thread, otherwise bad thing will happened.

But you can unsafeInitGUIForThreadedRTS with "-thread" to enable
multi-thread, then use other threads calculate *non-graphics* code,
and use postGUIAsync post all *gtk* code to gtk main-thread.

Of course, if OpenGL still slow, perhaps algorithm problem or hardware
performance problem.

Cheers,

  -- Andy

Herng Yi Cheng <herngyi at gmail.com> writes:

> Recently I wrote a 3D graphics viewer using Gtk2hs and Cairo, and it works ok, aside from the fact
> that it got quite slow
> when it got to displaying about 1000 polygons. It works something like this: The three-dimensional
> coordinates of polygons
> are given, and the program sorts the polygons using a BSP Tree (following the Painter's Algorithm),
> then it projects the
> polygons onto the plane of vision and renders each polygon to the screen using Cairo. After some
> investigation, I realised
> that my bottleneck was the rendering of polygons, but I could not speed up the rendering using
> parallel programming since
> the rendering order is crucial in the Painter's Algorithm. Even if I switched to an algorithm based
> on Hidden Surface
> Removal so I could render all my "obscured" polygons at once, Gtk2hs "is single threaded and its
> functions cannot be called
> from other threads".
>
> Then I heard about FieldTrip, which uses the GPU to process rendering efficiently. I decided to
> switch to using FieldTrip in
> conjunction with Gtk2hs to write applications, but it doesn't seem that easy because (i) there
> doesn't seem to be any
> version of GHC where Gtk2hs, Glade and Fieldtrip can work together on Windows and (ii) unlike Cairo,
> there is no Gtk2hs
> support for Fieldtrip in the sense that there are no Gtk2hs functions that render FieldTrip output
> to a Gtk2hs widget, like
> the DrawWindow. The latter would mean that Gtk2hs can't interact easily with FieldTrip.
>
> I really like Gtk2hs because it is very comprehensive and its interface can be designed using
> Glade. Does anyone know if
> there is a project linking Gtk2hs and FieldTrip? Otherwise, does anyone know if user interfaces can
> be written using
> Reactive (since it's linked to FieldTrip) with the usual functionality (e.g. menus, buttons,
> FieldTrip display reacting to
> mouseclicks etc)? If that is possible then I might have to switch to Reactive, but I'd miss Glade a
> lot :)
>
> regards,
> Herng Yi
>
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