Ok I stripped this down to the barest form and I still get segmentation faults here is the code. I am at a loss as this seems to be identical to C code posted in examples all over the web. Any thoughts?<br><br><div><div>main = do</div>
<div>  (progname, _) ←  getArgsAndInitialize</div><div>  createWindow &quot;Ben Christy Assignment 2&quot;</div><div>  windowSize $= Size 800 600</div><div>  matrixMode $= Projection  </div><div>  loadIdentity</div><div>  depthFunc $= Just Less</div>
<div>  viewport   $= (Position 0 0, Size 800 600) </div><div>  perspective 60 1.333 1 120      </div><div>  changesRef ←  newIORef Map.empty   </div><div>  --sceneRef ←  newIORef buildSSG</div><div>  sceneRef ←  newIORef  (SimpleRootNode &quot;HomeWork3&quot; [</div>
<div>        TransformNode &quot;camera&quot; (Rotate 0 90 0) (Translate 0 0 (-1))</div><div>        [</div><div>            TransformNode &quot;ground&quot; (Rotate  0 0 0) (Translate (-4) (-1.5) (-4))</div><div>            [</div>
<div>                ModelNode &quot;groundModel&quot; (Just (buildModel ModernGL (heightMapToVerts(genHeightMap 2 1 1.6 1.2 1.7) 0.1 0 3)</div><div>                                         (0,0,0) (buildShader defaultVertexShader defaultFragmentShader)))</div>
<div>            ]</div><div>         ]        </div><div>    ])</div><div>  --pollsRot ←  newIORef 0</div><div>  --evenState ←  newIORef BackAgain</div><div>  --evenPos ←  newIORef 0.25</div><div>  --oddState ←  newIORef There</div>
<div>  --oddPos ←  newIORef 0.15</div><div>  --balloonNumSteps ←  newIORef 100</div><div>  reshapeCallback $= Just reshape</div><div>  displayCallback $= (displayScene sceneRef changesRef )</div><div>  --addTimerCallback  10 (animate sceneRef pollsRot changesRef evenState evenPos oddState oddPos)</div>
<div>  --keyboardMouseCallback $= Just (handleInput sceneRef changesRef)</div><div>  mainLoop</div><div>  </div><div>displayScene  sceneRef changesRef= do</div><div>  --changes ←  readIORef changesRef</div><div>  --oldSceneGraph ←  readIORef sceneRef</div>
<div>  --sceneGraph ←  return $ updateSceneGraph changes oldSceneGraph</div><div>  --render identityMatrix sceneGraph</div><div>  --writeIORef changesRef Map.empty</div><div>  --writeIORef sceneRef sceneGraph</div><div>   clear [ColorBuffer, DepthBuffer]</div>
<div>   lighting $= Enabled</div><div>   light (Light 0) $= Enabled</div><div>   matrixMode $= Modelview 0</div><div>   loadIdentity</div><div>   [vbo] ←  genObjectNames 1 :: IO [BufferObject]</div><div>   bindBuffer ArrayBuffer $= Just vbo</div>
<div>   tempArray ←  newListArray (0, 8) [0,0,0,0,0.5,0,0.5,0.5,0.5] :: IO(StorableArray Int GLfloat)</div><div>   withStorableArray tempArray (λptr -&gt;</div><div>        bufferData ArrayBuffer $= ((fromIntegral (9*4), ptr, StaticDraw)))</div>
<div>   print &quot; Setting attrib pointer&quot;</div><div>   vertexAttribArray (AttribLocation 1) $= Enabled</div><div>   GLRaw.glVertexAttribPointer 1 3 GLRaw.gl_FLOAT 0 0 (plusPtr nullPtr (0))</div><div>   clientState VertexArray $= Enabled</div>
<div>   print &quot;before draw&quot;</div><div>   drawArrays Triangles 0 3</div><div>   print &quot;after draw&quot;</div><div>        --resetAttribPtr program</div><div>   bindBuffer ArrayBuffer $= Nothing</div><div>   clientState VertexArray $= Disabled</div>
<div>   return ()</div><div>   </div><div>reshape (Size w h) = do</div><div>  print &quot;resize&quot;</div><div>  matrixMode $= Projection</div><div>  loadIdentity </div><div>  depthFunc $= Just Less</div><div>  viewport   $= (Position 0 0, Size w h)</div>
<div>  perspective 60 1.333 0.01 120</div><div>  matrixMode $= Modelview 0</div><div>  loadIdentity</div><div>  postRedisplay Nothing</div><div><br></div><div><br><div class="gmail_quote">On Thu, Nov 18, 2010 at 10:37 AM, Ben Christy <span dir="ltr">&lt;<a href="mailto:ben.christy@gmail.com">ben.christy@gmail.com</a>&gt;</span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">I have tried<div><div> drawElements Triangles (fromIntegral 1) UnsignedInt nullPtr--(fromIntegral count)</div><div> </div>
<div>Test.withArray [ (i) | i&lt;-[0..count-1] ] $ \p -&gt; drawElements Points10 UnsignedInt p</div>
<div>        </div><div>drawArrays Points 1 10</div><div><br></div>All three of which cause a segmentation thought. I am kind of at a loss, is it possible that the buffers are empty? If so what is the best way to check?<div>
<div></div><div class="h5"><br>
<div class="gmail_quote">On Thu, Nov 18, 2010 at 8:20 AM, Balazs Komuves <span dir="ltr">&lt;<a href="mailto:bkomuves@gmail.com" target="_blank">bkomuves@gmail.com</a>&gt;</span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">

<br>Hi,<br><br>I&#39;m just guessing here, but I believe the problem is with the line<div><br><br><blockquote style="border-left:1px solid rgb(204, 204, 204);margin:0pt 0pt 0pt 0.8ex;padding-left:1ex" class="gmail_quote">


drawElements Triangles (fromIntegral count) UnsignedInt nullPtr<br></blockquote></div><div><br>Look up &#39;drawElements&#39; in the OpenGL specification <br>(page 29 in <a href="http://www.opengl.org/documentation/specs/version2.0/glspec20.pdf" target="_blank">http://www.opengl.org/documentation/specs/version2.0/glspec20.pdf</a>):<br>


<br><blockquote style="border-left:1px solid rgb(204, 204, 204);margin:0pt 0pt 0pt 0.8ex;padding-left:1ex" class="gmail_quote">The command<br><br><blockquote style="border-left:1px solid rgb(204, 204, 204);margin:0pt 0pt 0pt 0.8ex;padding-left:1ex" class="gmail_quote">


  void DrawElements( enum mode, sizei count, enum type, void *indices );<br></blockquote><br>constructs a sequence of geometric primitives using the count elements whose indices are stored in indices. type must be one of UNSIGNED BYTE, UNSIGNED SHORT, or UNSIGNED INT, indicating that the values in indices are indices of GL type ubyte, ushort, or uint respectively. Mode specifies what kind of primitives are constructed; it accepts the same token values as the mode<br>


parameter of the Begin command. The effect of DrawElements (mode, count, type, indices); is the same as the effect of the command sequence<br><br><blockquote style="border-left:1px solid rgb(204, 204, 204);margin:0pt 0pt 0pt 0.8ex;padding-left:1ex" class="gmail_quote">


if (mode, count, or type is invalid )<br>  generate appropriate error<br>else {<br>  Begin(mode);<br>  for (int i = 0; i &lt; count ; i++)<br>    ArrayElement(indices[i]);<br>  End();<br>  }<br></blockquote></blockquote>

<div>
<br>So, I think you actually want to use &#39;drawArrays&#39; instead. But without seeing the full source, I&#39;m again just guessing.<br><br>I believe &#39;drawElements&#39; should be used like this (I&#39;m writing this from the top of head, so take it with a grain of salt):<br>


<br><blockquote style="border-left:1px solid rgb(204, 204, 204);margin:0pt 0pt 0pt 0.8ex;padding-left:1ex" class="gmail_quote">withArray [ (3*i :: GLuint) | i&lt;-[0..count-1] ] $ \p -&gt; drawElements Triangles count UnsignedInt p<br>


</blockquote><br> <br></div>Balazs<br><br></div><br><div class="gmail_quote"><div><div></div><div>On Thu, Nov 18, 2010 at 2:53 AM, Ben Christy <span dir="ltr">&lt;<a href="mailto:ben.christy@gmail.com" target="_blank">ben.christy@gmail.com</a>&gt;</span> wrote:<br>


</div></div><blockquote class="gmail_quote" style="border-left:1px solid rgb(204, 204, 204);margin:0pt 0pt 0pt 0.8ex;padding-left:1ex"><div><div></div><div>I am having a issue getting a seg fault with drawElements.  Honestly I can not tell where the problem is. It seems as far as all I have read that it should work and being its written in haskell I am asking here first before asking in an opengl chat room.<div>



I init my VBOs with</div><div><br></div><div><div>initModelIBO :: Int →  IO BufferObject</div><div>initModelIBO listLen = do</div><div>   print &quot;list length&quot;</div><div>   print listLen</div><div>   print &quot;gen ibo bytes&quot;</div>



<div>   print sizeOfList</div><div>   [ibo] ←  genObjectNames 1 :: IO [BufferObject]</div><div>   bindBuffer ElementArrayBuffer $= Just ibo</div><div>   tempArray2 ←  newListArray (0, listLen  - 1) indexList :: IO(StorableArray Int GLuint)</div>



<div>   withStorableArray tempArray2 (λptr -&gt;</div><div>        bufferData ElementArrayBuffer $= ((fromIntegral sizeOfList), ptr, StaticDraw))</div><div>   bindBuffer ElementArrayBuffer $= Nothing</div><div>   return ibo</div>



<div>   where</div><div>    elementSize = 4</div><div>    sizeOfList = listLen * elementSize</div><div>    indexList = [i | i ←  [0..(fromIntegral listLen)]] :: [GLuint]</div><div>    </div><div>initModelVBO :: [Vert] →  IO BufferObject</div>



<div>initModelVBO vertexList = do</div><div>   print &quot;list length&quot;</div><div>   print listLen</div><div>   print &quot;gen vbo bytes&quot;</div><div>   print sizeOfList</div><div>   [vbo] ←  genObjectNames 1 :: IO [BufferObject]</div>



<div>   bindBuffer ArrayBuffer $= Just vbo</div><div>   tempArray ←  newListArray (0, listLen - 1) vertList :: IO(StorableArray Int GLfloat)</div><div>   withStorableArray tempArray (λptr -&gt;</div><div>        bufferData ArrayBuffer $= ((fromIntegral sizeOfList), ptr, StaticDraw))</div>



<div>   bindBuffer ArrayBuffer $= Nothing</div><div>   return vbo</div><div>   where</div><div>    elementsPerVert = 10</div><div>    vertList = vertsToList vertexList</div><div>    listLen = length vertList</div><div>    elementSize = 4</div>



<div>    sizeOfList = listLen * elementSize</div></div><div><br></div><div>My Vert type is</div><div><div>data Vert = Vert {</div><div>                vertX   ::GLfloat,</div><div>                vertY   ::GLfloat,</div>


<div>
                vertZ   ::GLfloat,</div><div>                --normalX ::GLfloat,</div><div>                --normalY ::GLfloat,</div><div>                --normalZ ::GLfloat,</div><div>                colorR  ::GLfloat,</div>



<div>                colorG  ::GLfloat,</div><div>                colorB  ::GLfloat,</div><div>                specR   ::GLfloat,</div><div>                specG   ::GLfloat,</div><div>                specB   ::GLfloat,</div>



<div>                shiny   ::GLfloat}</div><div>    deriving (Show)</div></div><div><br></div><div>I set vertex attributes with</div><div><div>setAttribPtr (Just program) = do</div><div>    print &quot; Setting attrib pointer&quot;</div>



<div><br></div><div>     --vertexAttribPointer (AttribLocation 1) $= (KeepIntegral, (VertexArrayDescriptor 3 Float ((4) *10) (plusPtr nullPtr (0*4))))</div><div>    GLRaw.glVertexAttribPointer 1 3 GLRaw.gl_FLOAT 0 stride (plusPtr nullPtr (0))</div>



<div>    vertexAttribArray (AttribLocation 1) $= Enabled</div><div>    --vertexAttribPointer (AttribLocation 2) $= (KeepIntegral, (VertexArrayDescriptor 3 Float ((4) *10) (plusPtr nullPtr (3*4))))</div><div>    GLRaw.glVertexAttribPointer 2 3 GLRaw.gl_FLOAT 0 stride (plusPtr nullPtr (12))</div>



<div>    vertexAttribArray (AttribLocation 2) $= Enabled</div><div>    --vertexAttribPointer (AttribLocation 3) $= (KeepIntegral, (VertexArrayDescriptor 3 Float ((4) *10) (plusPtr nullPtr (6*4))))</div><div>    GLRaw.glVertexAttribPointer 3 3 GLRaw.gl_FLOAT 0 stride (plusPtr nullPtr (24))</div>



<div>    vertexAttribArray (AttribLocation 3) $= Enabled</div><div><br></div><div>    --vertexAttribPointer (AttribLocation 4) $= (KeepIntegral, (VertexArrayDescriptor 1 Float ((4) *10) (plusPtr nullPtr (9*4))))</div><div>



    GLRaw.glVertexAttribPointer 4 1 GLRaw.gl_FLOAT 0 stride (plusPtr nullPtr (36))</div><div>    vertexAttribArray (AttribLocation 4) $= Enabled</div><div>    return ()</div><div>    where</div><div>        stride = 40</div>



</div><div><br></div><div>I build a shader program with</div><div><div>buildShader vertexShader fragmentShader = do</div><div>    [vertObj] ←  genObjectNames 1 ::IO [VertexShader]</div><div>    shaderSource vertObj  $= [vertexShader]</div>



<div>    compileShader vertObj</div><div>    vsLog ←  get (shaderInfoLog vertObj)</div><div>    print &quot;vertex shader status&quot;</div><div>    print vsLog</div><div>    [fragObj] ←  genObjectNames 1 ::IO [FragmentShader]</div>



<div>    shaderSource fragObj  $= [fragmentShader]</div><div>    compileShader fragObj</div><div>    fsLog ←  get (shaderInfoLog fragObj)</div><div>    print &quot;fragment shader status&quot;</div><div>    print fsLog</div>



<div>    [programObj] ←  genObjectNames 1 ::IO [Program]</div><div>    attachedShaders programObj $= ([vertObj], [fragObj])</div><div>    attribLocation programObj &quot;position&quot; $= AttribLocation 1</div><div>    attribLocation programObj &quot;color&quot; $= AttribLocation 2</div>



<div>    attribLocation programObj &quot;spec&quot; $= AttribLocation 3</div><div>    attribLocation programObj &quot;shiny&quot; $= AttribLocation 4</div><div>    linkProgram programObj</div><div>    progLog ←  get(programInfoLog programObj)</div>



<div>    print &quot;Shader Program status&quot;</div><div>    print progLog</div><div>    return (Just programObj)</div></div><div><br></div><div>Finally my render function </div><div><br></div><div><div>instance RenderSimpleSceneGraph Model where</div>



<div>    render matrix (ModernModel vbo ibo shader count) = do</div><div>        clientState VertexArray $= Enabled</div><div>        version ←  get (majorMinor glVersion)</div><div>        tempVBO ←  vbo</div><div>        tempIBO ←  ibo</div>



<div>        print &quot;Render Modern Model&quot;</div><div>        program ←  shader</div><div>        currentProgram $= program</div><div>        bindBuffer ArrayBuffer $= Just tempVBO</div><div>        setAttribPtr program</div>



<div>        bindBuffer ElementArrayBuffer $= Just tempIBO</div><div>        print &quot;here&quot;</div><div>        drawElements Triangles (fromIntegral count) UnsignedInt nullPtr</div><div>        print &quot;here1&quot;</div>



<div>        resetAttribPtr program</div><div>        bindBuffer ArrayBuffer $= Nothing</div><div>        clientState VertexArray $= Disabled</div></div>
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