Re: [wxhaskell-users] GLCanvas doesn't work

[Daan L. <da...@cs...>]

Patrick Scheibe wrote:
> Hi,
> 
> A friend of mine helped me solving the problem.
> It was really confusing. I just added any printouts in the display function of 
> opengl and found out that wxhaskell called this display func. But why should 
> it be called and even though nothing appeared in the frame.

Ah, this is really good to hear,
I have been playing with the sample but couldn't find
a solution myself.

Good luck with your further experiments,
-- Daan.


> 
> We figured out that it is probably the best way to have a look at the GTK 
> opengl sample. So we changed some lines in the source relating to the c++ 
> sample code.
> I won't have time to find some more out but here is the modified sample that 
> runs on our machines.. (mainly for Mike who wants the news)
> 
> It shows just a white square on a black background. Compilation with 
> ghc -package wx -package OpenGL  foobar.hs
> 
> Cheers
> Patrick
> 
> 
> module Main
> where
> import Graphics.Rendering.OpenGL
> import qualified Graphics.UI.WX as WX
> import qualified Graphics.Rendering.OpenGL as GL
> 
> main = start gui
> 
> convWG (WX.Size w h) = (GL.Size (convInt32  w) (convInt32  h))
> convInt32 = fromInteger . toInteger
> 
> gui = do
>    f <- frame [ text := "Simple OpenGL" ]
>    glCanvas <- glCanvasCreateEx f 0 (Rect 0 0 200 200)
>         0 "GLCanvas" [GL_RGBA] nullPalette
>    initme glCanvas
>    let glWidgetLayout = (fill . widget) glCanvas
>    WX.set f [ on paintRaw := paintGL glCanvas
>             , layout := glWidgetLayout 
>             ]
> 
> paintGL :: GLCanvas a -> DC() -> WX.Rect ->  [WX.Rect] -> IO ()
> paintGL canvas dc rect _ = do
>    reshape $ convWG $ rectSize rect
>    display canvas
>    
>    return ()         
> 
> initme :: GLCanvas a -> IO ()
> initme canvas = do
>   glCanvasSetCurrent canvas
> 
> display canvas = do
>    clear [ ColorBuffer]   
>    preservingMatrix $ do
>    stdQuad
>    putStrLn "Display"
>    flush
>    glCanvasSwapBuffers canvas
> 
> 
> reshape size@(GL.Size w h) = do
>    viewport $= (Position 0 0, size)
>    matrixMode $= Projection
>    loadIdentity
>    let wf = fromIntegral w
>        hf = fromIntegral h
>    if w <= h
>       then ortho (-4.0) 4.0 (-4.0*hf/wf) (4.0*hf/wf) (-4.0) 4.0
>       else ortho (-4.0*wf/hf) (4.0*wf/hf) (-4.0) 4.0 (-4.0) 4.0
>    matrixMode $= Modelview 0
>    loadIdentity
> 
> vertex3f :: Vertex3 GLfloat -> IO ()
> vertex3f = vertex :: Vertex3 GLfloat -> IO ()
> 
> stdQuad :: IO ()
> stdQuad = do
>   renderPrimitive Polygon $ mapM_ vertex3f [
>     Vertex3 0 0 0,
>     Vertex3 0 1 0,
>     Vertex3 1 1 0,
>     Vertex3 1 0 0
>     ]
> 
> 
> 
> 
> 
> On Tuesday 04 January 2005 19:58, Mike Gunter wrote:
> 
>>Too bad.  Do let me know if you figure this out.
>>
>>	thanks,
>>	mike
>>
>>Patrick Scheibe <mai...@st...> writes:
>>
>>>Hi,
>>>
>>>I try to run the GLCanvas sample from the source of wxHaskell and the
>>>only thing I get is a blank screen. Mike said I should try to recompile
>>>all stuff (wxGTK and wxHaskell) with the --with-opengl option.
>>>But this was what I did in the first time. The opengl sample in the wxGTK
>>>source (penguin and so on) runs perfectly.
>>>I can compile wxHaskell with opengl without any error.
>>>But the sample shows just the blank screen.
>>>
>>>I figured out that it doesn't matter when I don't give the -package
>>>OpenGL option to ghc. The sample compiles without error and runs in the
>>>same way. Does wxHaskell add the Gl libs itself?
>>>
>>>Has anybody a compiled wxhaskell where this sample runs and can he help
>>>me by showing his configuration of ghc, gtk, wxgkt, glib, wxhaskell, ...
>>>I have a running SuSe distribution.
>>>
>>>Cheers
>>>Patrick
>>>
>>>On Monday 03 January 2005 19:50, Mike Gunter wrote:
>>>
>>>>I was seeing the same behavior.  Responding to my question, Sean
>>>>Seefried pointed out that both wxWidgets and wxHaskell must be built
>>>>with OpenGL support (by passing --with-opengl to their configure
>>>>scripts).  I haven't had time to determine if that's the issue for me.
>>>>Perhaps it is for you?  (If you do figure out why you're seeing the
>>>>behavior you are, please let me know ...)
>>>>
>>>>	mike
> 
> 
> 
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