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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>Graphics.UI.GLUT.Initialization</title><link href="ocean.css" rel="stylesheet" type="text/css" title="Ocean" /><script src="haddock-util.js" type="text/javascript"></script><script type="text/javascript">//<![CDATA[
window.onload = function () {pageLoad();setSynopsis("mini_Graphics-UI-GLUT-Initialization.html");};
//]]>
</script></head><body><div id="package-header"><ul class="links" id="page-menu"><li><a href="src/Graphics-UI-GLUT-Initialization.html">Source</a></li><li><a href="index.html">Contents</a></li><li><a href="doc-index.html">Index</a></li></ul><p class="caption">GLUT-2.1.2.1: A binding for the OpenGL Utility Toolkit</p></div><div id="content"><div id="module-header"><table class="info"><tr><th>Portability</th><td>portable</td></tr><tr><th>Stability</th><td>stable</td></tr><tr><th>Maintainer</th><td>sven.panne@aedion.de</td></tr><tr><th>Safe Haskell</th><td>Safe-Infered</td></tr></table><p class="caption">Graphics.UI.GLUT.Initialization</p></div><div id="table-of-contents"><p class="caption">Contents</p><ul><li><a href="#g:1">Primary initialization
</a></li><li><a href="#g:2">Initial window geometry
</a></li><li><a href="#g:3">Setting the initial display mode (I)
</a></li><li><a href="#g:4">Setting the initial display mode (II)
</a></li><li><a href="#g:5">Controlling the creation of rendering contexts
</a></li><li><a href="#g:6">Direct/indirect rendering
</a></li><li><a href="#g:7">OpenGL 3.x context support
</a></li></ul></div><div id="description"><p class="caption">Description</p><div class="doc"><p>Actions and state variables in this module are used to initialize GLUT state.
 The primary initialization routine is <code><a href="Graphics-UI-GLUT-Initialization.html#v:initialize">initialize</a></code>, which should only be
 called exactly once in a GLUT program. No other GLUT or OpenGL actions should
 be called before <code><a href="Graphics-UI-GLUT-Initialization.html#v:initialize">initialize</a></code>, apart from getting or setting the state
 variables in this module.
</p><p>The reason is that these state variables can be used to set default window
 initialization state that might be modified by the command processing done in
 <code><a href="Graphics-UI-GLUT-Initialization.html#v:initialize">initialize</a></code>. For example, <code><a href="Graphics-UI-GLUT-Initialization.html#v:initialWindowSize">initialWindowSize</a></code> can be set to <code>(<code><a href="/usr/share/doc/libghc-opengl-doc/html/Graphics-Rendering-OpenGL-GL-CoordTrans.html#t:Size">Size</a></code>
 400 400)</code> before <code><a href="Graphics-UI-GLUT-Initialization.html#v:initialize">initialize</a></code> is called to indicate 400 by 400 is the
 program's default window size. Setting the initial window size or position
 before <code><a href="Graphics-UI-GLUT-Initialization.html#v:initialize">initialize</a></code> allows the GLUT program user to specify the initial size
 or position using command line arguments.
</p></div></div><div id="synopsis"><p id="control.syn" class="caption expander" onclick="toggleSection('syn')">Synopsis</p><ul id="section.syn" class="hide" onclick="toggleSection('syn')"><li class="src short"><a href="#v:initialize">initialize</a> :: <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-String.html#t:String">String</a> -&gt; [<a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-String.html#t:String">String</a>] -&gt; <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/System-IO.html#t:IO">IO</a> [<a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-String.html#t:String">String</a>]</li><li class="src short"><a href="#v:getArgsAndInitialize">getArgsAndInitialize</a> :: <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/System-IO.html#t:IO">IO</a> (<a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-String.html#t:String">String</a>, [<a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-String.html#t:String">String</a>])</li><li class="src short"><a href="#v:exit">exit</a> :: <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/System-IO.html#t:IO">IO</a> <a href="/usr/share/doc/ghc-doc/html/libraries/ghc-prim-0.2.0.0/GHC-Tuple.html#t:-40--41-">()</a></li><li class="src short"><a href="#v:initialWindowPosition">initialWindowPosition</a> :: <a href="/usr/share/doc/libghc-opengl-doc/html/Graphics-Rendering-OpenGL-GL-StateVar.html#t:StateVar">StateVar</a> <a href="/usr/share/doc/libghc-opengl-doc/html/Graphics-Rendering-OpenGL-GL-CoordTrans.html#t:Position">Position</a></li><li class="src short"><a href="#v:initialWindowSize">initialWindowSize</a> :: <a href="/usr/share/doc/libghc-opengl-doc/html/Graphics-Rendering-OpenGL-GL-StateVar.html#t:StateVar">StateVar</a> <a href="/usr/share/doc/libghc-opengl-doc/html/Graphics-Rendering-OpenGL-GL-CoordTrans.html#t:Size">Size</a></li><li class="src short"><span class="keyword">data</span>  <a href="#t:DisplayMode">DisplayMode</a> <ul class="subs"><li>= <a href="#v:RGBAMode">RGBAMode</a>  </li><li>| <a href="#v:RGBMode">RGBMode</a>  </li><li>| <a href="#v:IndexMode">IndexMode</a>  </li><li>| <a href="#v:LuminanceMode">LuminanceMode</a>  </li><li>| <a href="#v:WithAlphaComponent">WithAlphaComponent</a>  </li><li>| <a href="#v:WithAccumBuffer">WithAccumBuffer</a>  </li><li>| <a href="#v:WithDepthBuffer">WithDepthBuffer</a>  </li><li>| <a href="#v:WithStencilBuffer">WithStencilBuffer</a>  </li><li>| <a href="#v:WithAuxBuffers">WithAuxBuffers</a> <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Int.html#t:Int">Int</a>  </li><li>| <a href="#v:SingleBuffered">SingleBuffered</a>  </li><li>| <a href="#v:DoubleBuffered">DoubleBuffered</a>  </li><li>| <a href="#v:Multisampling">Multisampling</a>  </li><li>| <a href="#v:WithSamplesPerPixel">WithSamplesPerPixel</a> <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Int.html#t:Int">Int</a>  </li><li>| <a href="#v:Stereoscopic">Stereoscopic</a>  </li><li>| <a href="#v:Captionless">Captionless</a>  </li><li>| <a href="#v:Borderless">Borderless</a>  </li></ul></li><li class="src short"><a href="#v:initialDisplayMode">initialDisplayMode</a> :: <a href="/usr/share/doc/libghc-opengl-doc/html/Graphics-Rendering-OpenGL-GL-StateVar.html#t:StateVar">StateVar</a> [<a href="Graphics-UI-GLUT-Initialization.html#t:DisplayMode">DisplayMode</a>]</li><li class="src short"><a href="#v:displayModePossible">displayModePossible</a> :: <a href="/usr/share/doc/libghc-opengl-doc/html/Graphics-Rendering-OpenGL-GL-StateVar.html#t:GettableStateVar">GettableStateVar</a> <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Bool.html#t:Bool">Bool</a></li><li class="src short"><span class="keyword">data</span>  <a href="#t:DisplayCapability">DisplayCapability</a> <ul class="subs"><li>= <a href="#v:DisplayRGBA">DisplayRGBA</a>  </li><li>| <a href="#v:DisplayRGB">DisplayRGB</a>  </li><li>| <a href="#v:DisplayRed">DisplayRed</a>  </li><li>| <a href="#v:DisplayGreen">DisplayGreen</a>  </li><li>| <a href="#v:DisplayBlue">DisplayBlue</a>  </li><li>| <a href="#v:DisplayIndex">DisplayIndex</a>  </li><li>| <a href="#v:DisplayBuffer">DisplayBuffer</a>  </li><li>| <a href="#v:DisplaySingle">DisplaySingle</a>  </li><li>| <a href="#v:DisplayDouble">DisplayDouble</a>  </li><li>| <a href="#v:DisplayAccA">DisplayAccA</a>  </li><li>| <a href="#v:DisplayAcc">DisplayAcc</a>  </li><li>| <a href="#v:DisplayAlpha">DisplayAlpha</a>  </li><li>| <a href="#v:DisplayDepth">DisplayDepth</a>  </li><li>| <a href="#v:DisplayStencil">DisplayStencil</a>  </li><li>| <a href="#v:DisplaySamples">DisplaySamples</a>  </li><li>| <a href="#v:DisplayStereo">DisplayStereo</a>  </li><li>| <a href="#v:DisplayLuminance">DisplayLuminance</a>  </li><li>| <a href="#v:DisplayAux">DisplayAux</a>  </li><li>| <a href="#v:DisplayNum">DisplayNum</a>  </li><li>| <a href="#v:DisplayConformant">DisplayConformant</a>  </li><li>| <a href="#v:DisplaySlow">DisplaySlow</a>  </li><li>| <a href="#v:DisplayWin32PFD">DisplayWin32PFD</a>  </li><li>| <a href="#v:DisplayXVisual">DisplayXVisual</a>  </li><li>| <a href="#v:DisplayXStaticGray">DisplayXStaticGray</a>  </li><li>| <a href="#v:DisplayXGrayScale">DisplayXGrayScale</a>  </li><li>| <a href="#v:DisplayXStaticColor">DisplayXStaticColor</a>  </li><li>| <a href="#v:DisplayXPseudoColor">DisplayXPseudoColor</a>  </li><li>| <a href="#v:DisplayXTrueColor">DisplayXTrueColor</a>  </li><li>| <a href="#v:DisplayXDirectColor">DisplayXDirectColor</a>  </li></ul></li><li class="src short"><span class="keyword">data</span>  <a href="#t:Relation">Relation</a> <ul class="subs"><li>= <a href="#v:IsEqualTo">IsEqualTo</a>  </li><li>| <a href="#v:IsNotEqualTo">IsNotEqualTo</a>  </li><li>| <a href="#v:IsLessThan">IsLessThan</a>  </li><li>| <a href="#v:IsNotGreaterThan">IsNotGreaterThan</a>  </li><li>| <a href="#v:IsGreaterThan">IsGreaterThan</a>  </li><li>| <a href="#v:IsAtLeast">IsAtLeast</a>  </li><li>| <a href="#v:IsNotLessThan">IsNotLessThan</a>  </li></ul></li><li class="src short"><span class="keyword">data</span>  <a href="#t:DisplayCapabilityDescription">DisplayCapabilityDescription</a> <ul class="subs"><li>= <a href="#v:Where">Where</a> <a href="Graphics-UI-GLUT-Initialization.html#t:DisplayCapability">DisplayCapability</a> <a href="Graphics-UI-GLUT-Initialization.html#t:Relation">Relation</a> <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Int.html#t:Int">Int</a>  </li><li>| <a href="#v:With">With</a> <a href="Graphics-UI-GLUT-Initialization.html#t:DisplayCapability">DisplayCapability</a>  </li></ul></li><li class="src short"><a href="#v:initialDisplayCapabilities">initialDisplayCapabilities</a> :: <a href="/usr/share/doc/libghc-opengl-doc/html/Graphics-Rendering-OpenGL-GL-StateVar.html#t:SettableStateVar">SettableStateVar</a> [<a href="Graphics-UI-GLUT-Initialization.html#t:DisplayCapabilityDescription">DisplayCapabilityDescription</a>]</li><li class="src short"><span class="keyword">data</span>  <a href="#t:RenderingContext">RenderingContext</a> <ul class="subs"><li>= <a href="#v:CreateNewContext">CreateNewContext</a>  </li><li>| <a href="#v:UseCurrentContext">UseCurrentContext</a>  </li></ul></li><li class="src short"><a href="#v:renderingContext">renderingContext</a> :: <a href="/usr/share/doc/libghc-opengl-doc/html/Graphics-Rendering-OpenGL-GL-StateVar.html#t:StateVar">StateVar</a> <a href="Graphics-UI-GLUT-Initialization.html#t:RenderingContext">RenderingContext</a></li><li class="src short"><span class="keyword">data</span>  <a href="#t:DirectRendering">DirectRendering</a> <ul class="subs"><li>= <a href="#v:ForceIndirectContext">ForceIndirectContext</a>  </li><li>| <a href="#v:AllowDirectContext">AllowDirectContext</a>  </li><li>| <a href="#v:TryDirectContext">TryDirectContext</a>  </li><li>| <a href="#v:ForceDirectContext">ForceDirectContext</a>  </li></ul></li><li class="src short"><a href="#v:directRendering">directRendering</a> :: <a href="/usr/share/doc/libghc-opengl-doc/html/Graphics-Rendering-OpenGL-GL-StateVar.html#t:StateVar">StateVar</a> <a href="Graphics-UI-GLUT-Initialization.html#t:DirectRendering">DirectRendering</a></li><li class="src short"><a href="#v:initialContextVersion">initialContextVersion</a> :: <a href="/usr/share/doc/libghc-opengl-doc/html/Graphics-Rendering-OpenGL-GL-StateVar.html#t:StateVar">StateVar</a> (<a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Int.html#t:Int">Int</a>, <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Int.html#t:Int">Int</a>)</li><li class="src short"><span class="keyword">data</span>  <a href="#t:ContextFlag">ContextFlag</a> <ul class="subs"><li>= <a href="#v:DebugContext">DebugContext</a>  </li><li>| <a href="#v:ForwardCompatibleContext">ForwardCompatibleContext</a>  </li></ul></li><li class="src short"><a href="#v:initialContextFlags">initialContextFlags</a> :: <a href="/usr/share/doc/libghc-opengl-doc/html/Graphics-Rendering-OpenGL-GL-StateVar.html#t:StateVar">StateVar</a> [<a href="Graphics-UI-GLUT-Initialization.html#t:ContextFlag">ContextFlag</a>]</li></ul></div><div id="interface"><h1 id="g:1">Primary initialization
</h1><div class="top"><p class="src"><a name="v:initialize" class="def">initialize</a><a href="src/Graphics-UI-GLUT-Initialization.html#initialize" class="link">Source</a></p><div class="subs arguments"><p class="caption">Arguments</p><table><tr><td class="src">:: <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-String.html#t:String">String</a></td><td class="doc"><p>The program name.
</p></td></tr><tr><td class="src">-&gt; [<a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-String.html#t:String">String</a>]</td><td class="doc"><p>The command line arguments
</p></td></tr><tr><td class="src">-&gt; <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/System-IO.html#t:IO">IO</a> [<a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-String.html#t:String">String</a>]</td><td class="doc"><p>Non-GLUT command line arguments
</p></td></tr></table></div><div class="doc"><p>Given the program name and command line arguments, initialize the GLUT
 library and negotiate a session with the window system. During this
 process, <code><a href="Graphics-UI-GLUT-Initialization.html#v:initialize">initialize</a></code> may cause the termination of the GLUT program with an
 error message to the user if GLUT cannot be properly initialized.
 Examples of this situation include the failure to connect to the window
 system, the lack of window system support for OpenGL, and invalid command
 line options.
</p><p><code><a href="Graphics-UI-GLUT-Initialization.html#v:initialize">initialize</a></code> also processes command line options, but the specific options
 parsed are window system dependent. Any command line arguments which are
 not GLUT-specific are returned.
</p><p><em>X Implementation Notes:</em> The X Window System specific options parsed by
 <code><a href="Graphics-UI-GLUT-Initialization.html#v:initialize">initialize</a></code> are as follows:
</p><ul><li> <code>-display <em>DISPLAY</em></code>: Specify the X server to connect to. If not specified,
   the value of the <code>DISPLAY</code> environment variable is used.
</li><li> <code>-geometry <em>WxH+X+Y</em></code>: Determines where windows should be created on the
   screen. The parameter following <code>-geometry</code> should be formatted as a
   standard X geometry specification. The effect of using this option is to
   change the GLUT initial size and initial position the same as if
   <code><a href="Graphics-UI-GLUT-Initialization.html#v:initialWindowSize">initialWindowSize</a></code> or <code><a href="Graphics-UI-GLUT-Initialization.html#v:initialWindowPosition">initialWindowPosition</a></code> were modified directly.
</li><li> <code>-iconic</code>: Requests all top-level windows be created in an iconic state.
</li><li> <code>-indirect</code>: Force the use of indirect OpenGL rendering contexts.
</li><li> <code>-direct</code>: Force the use of direct OpenGL rendering contexts (not all GLX
   implementations support direct rendering contexts). A fatal error is
   generated if direct rendering is not supported by the OpenGL
   implementation. If neither <code>-indirect</code> or <code>-direct</code> are used to force a
   particular behavior, GLUT will attempt to use direct rendering if
   possible and otherwise fallback to indirect rendering.
</li><li> <code>-gldebug</code>: After processing callbacks and/or events, call
   <code><a href="Graphics-UI-GLUT-Debugging.html#v:reportErrors">reportErrors</a></code> to check if there are any pending
   OpenGL errors. Using this option is helpful in detecting OpenGL run-time
   errors.
</li><li> <code>-sync</code>: Enable synchronous X protocol transactions. This option makes
   it easier to track down potential X protocol errors.
</li></ul></div></div><div class="top"><p class="src"><a name="v:getArgsAndInitialize" class="def">getArgsAndInitialize</a> :: <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/System-IO.html#t:IO">IO</a> (<a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-String.html#t:String">String</a>, [<a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-String.html#t:String">String</a>])<a href="src/Graphics-UI-GLUT-Initialization.html#getArgsAndInitialize" class="link">Source</a></p><div class="doc"><p>Convenience action: Initialize GLUT, returning the program name and any
 non-GLUT command line arguments.
</p></div></div><div class="top"><p class="src"><a name="v:exit" class="def">exit</a> :: <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/System-IO.html#t:IO">IO</a> <a href="/usr/share/doc/ghc-doc/html/libraries/ghc-prim-0.2.0.0/GHC-Tuple.html#t:-40--41-">()</a><a href="src/Graphics-UI-GLUT-Initialization.html#exit" class="link">Source</a></p><div class="doc"><p>(<em>freeglut only</em>) De-initialize GLUT. After this, one has to use
 <code><a href="Graphics-UI-GLUT-Initialization.html#v:initialize">initialize</a></code> or <code><a href="Graphics-UI-GLUT-Initialization.html#v:getArgsAndInitialize">getArgsAndInitialize</a></code> to initialize GLUT again.
</p></div></div><h1 id="g:2">Initial window geometry
</h1><div class="top"><p class="src"><a name="v:initialWindowPosition" class="def">initialWindowPosition</a> :: <a href="/usr/share/doc/libghc-opengl-doc/html/Graphics-Rendering-OpenGL-GL-StateVar.html#t:StateVar">StateVar</a> <a href="/usr/share/doc/libghc-opengl-doc/html/Graphics-Rendering-OpenGL-GL-CoordTrans.html#t:Position">Position</a><a href="src/Graphics-UI-GLUT-Initialization.html#initialWindowPosition" class="link">Source</a></p><div class="doc"><p>Controls the <em>initial window position</em>.  Windows created by
 <code><a href="Graphics-UI-GLUT-Window.html#v:createWindow">createWindow</a></code> will be requested to be created with
 the current <em>initial window position</em>. The initial value of the /initial
 window position/ GLUT state is <code><code><a href="/usr/share/doc/libghc-opengl-doc/html/Graphics-Rendering-OpenGL-GL-CoordTrans.html#t:Size">Size</a></code> (-1) (-1)</code>. If either the X or Y
 component of the <em>initial window position</em> is negative, the actual window
 position is left to the window system to determine.
</p><p>The intent of the <em>initial window position</em> is to provide a suggestion to
 the window system for a window's initial position. The window system is
 not obligated to use this information. Therefore, GLUT programs should not
 assume the window was created at the specified position.
</p></div></div><div class="top"><p class="src"><a name="v:initialWindowSize" class="def">initialWindowSize</a> :: <a href="/usr/share/doc/libghc-opengl-doc/html/Graphics-Rendering-OpenGL-GL-StateVar.html#t:StateVar">StateVar</a> <a href="/usr/share/doc/libghc-opengl-doc/html/Graphics-Rendering-OpenGL-GL-CoordTrans.html#t:Size">Size</a><a href="src/Graphics-UI-GLUT-Initialization.html#initialWindowSize" class="link">Source</a></p><div class="doc"><p>Controls the <em>initial window size</em>.  Windows created by
 <code><a href="Graphics-UI-GLUT-Window.html#v:createWindow">createWindow</a></code> will be requested to be created with
 the current <em>initial window size</em>. The initial value of the /initial window
 size/ GLUT state is <code><code><a href="/usr/share/doc/libghc-opengl-doc/html/Graphics-Rendering-OpenGL-GL-CoordTrans.html#t:Size">Size</a></code> 300 300</code>. If either the width or the height
 component of the <em>initial window size</em> is non-positive, the actual window
 size is left to the window system to determine.
</p><p>The intent of the <em>initial window size</em> is to provide a suggestion to the
 window system for a window's initial size. The window system is not
 obligated to use this information. Therefore, GLUT programs should not
 assume the window was created at the specified size. A GLUT program should
 use the window's reshape callback to determine the true size of the
 window.
</p></div></div><h1 id="g:3">Setting the initial display mode (I)
</h1><div class="top"><p class="src"><span class="keyword">data</span>  <a name="t:DisplayMode" class="def">DisplayMode</a>  <a href="src/Graphics-UI-GLUT-Initialization.html#DisplayMode" class="link">Source</a></p><div class="doc"><p>A single aspect of a window which is to be created, used in conjunction
 with <code><a href="Graphics-UI-GLUT-Initialization.html#v:initialDisplayMode">initialDisplayMode</a></code>.
</p></div><div class="subs constructors"><p class="caption">Constructors</p><table><tr><td class="src"><a name="v:RGBAMode" class="def">RGBAMode</a></td><td class="doc"><p>Select an RGBA mode window. This is the default if neither <code><a href="Graphics-UI-GLUT-Initialization.html#v:RGBAMode">RGBAMode</a></code>
 nor <code><a href="Graphics-UI-GLUT-Initialization.html#v:IndexMode">IndexMode</a></code> are specified.
</p></td></tr><tr><td class="src"><a name="v:RGBMode" class="def">RGBMode</a></td><td class="doc"><p>An alias for <code><a href="Graphics-UI-GLUT-Initialization.html#v:RGBAMode">RGBAMode</a></code>.
</p></td></tr><tr><td class="src"><a name="v:IndexMode" class="def">IndexMode</a></td><td class="doc"><p>Select a color index mode window. This overrides <code><a href="Graphics-UI-GLUT-Initialization.html#v:RGBAMode">RGBAMode</a></code> if it is
 also specified.
</p></td></tr><tr><td class="src"><a name="v:LuminanceMode" class="def">LuminanceMode</a></td><td class="doc"><p>Select a window with a &quot;luminance&quot; color model. This model provides
 the functionality of OpenGL's RGBA color model, but the green and blue
 components are not maintained in the frame buffer. Instead each pixel's
 red component is converted to an index between zero and
  <code><a href="Graphics-UI-GLUT-Colormap.html#v:numColorMapEntries">numColorMapEntries</a></code> and looked up in a
 per-window color map to determine the color of pixels within the window.
 The initial colormap of <code><a href="Graphics-UI-GLUT-Initialization.html#v:LuminanceMode">LuminanceMode</a></code> windows is initialized to be a
 linear gray ramp, but can be modified with GLUT's colormap actions.
 <em>Implementation Notes:</em> <code><a href="Graphics-UI-GLUT-Initialization.html#v:LuminanceMode">LuminanceMode</a></code> is not supported on most OpenGL
 platforms.
</p></td></tr><tr><td class="src"><a name="v:WithAlphaComponent" class="def">WithAlphaComponent</a></td><td class="doc"><p>Select a window with an alpha component to the color buffer(s).
</p></td></tr><tr><td class="src"><a name="v:WithAccumBuffer" class="def">WithAccumBuffer</a></td><td class="doc"><p>Select a window with an accumulation buffer.
</p></td></tr><tr><td class="src"><a name="v:WithDepthBuffer" class="def">WithDepthBuffer</a></td><td class="doc"><p>Select a window with a depth buffer.
</p></td></tr><tr><td class="src"><a name="v:WithStencilBuffer" class="def">WithStencilBuffer</a></td><td class="doc"><p>Select a window with a stencil buffer.
</p></td></tr><tr><td class="src"><a name="v:WithAuxBuffers" class="def">WithAuxBuffers</a> <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Int.html#t:Int">Int</a></td><td class="doc"><p>(<em>freeglut only</em>) Select a window with <em>n</em> (1 .. 4) auxiliary buffers.
 Any <em>n</em> outside the range 1 .. 4 is a fatal error.
</p></td></tr><tr><td class="src"><a name="v:SingleBuffered" class="def">SingleBuffered</a></td><td class="doc"><p>Select a single buffered window. This is the default if neither
 <code><a href="Graphics-UI-GLUT-Initialization.html#v:DoubleBuffered">DoubleBuffered</a></code> nor <code><a href="Graphics-UI-GLUT-Initialization.html#v:SingleBuffered">SingleBuffered</a></code> are specified.
</p></td></tr><tr><td class="src"><a name="v:DoubleBuffered" class="def">DoubleBuffered</a></td><td class="doc"><p>Select a double buffered window. This overrides <code><a href="Graphics-UI-GLUT-Initialization.html#v:SingleBuffered">SingleBuffered</a></code> if it
 is also specified.
</p></td></tr><tr><td class="src"><a name="v:Multisampling" class="def">Multisampling</a></td><td class="doc"><p>Select a window with multisampling support. If multisampling is not
 available, a non-multisampling window will automatically be chosen.
 Note: both the OpenGL client-side and server-side implementations must
 support the <code>GLX_SAMPLE_SGIS</code> extension for multisampling to be
 available. Deprecated, use <code><a href="Graphics-UI-GLUT-Initialization.html#v:WithSamplesPerPixel">WithSamplesPerPixel</a></code>.
</p></td></tr><tr><td class="src"><a name="v:WithSamplesPerPixel" class="def">WithSamplesPerPixel</a> <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Int.html#t:Int">Int</a></td><td class="doc"><p>Select a window with multisampling, using the given samples per pixel.
</p></td></tr><tr><td class="src"><a name="v:Stereoscopic" class="def">Stereoscopic</a></td><td class="doc"><p>Select a stereo window.
</p></td></tr><tr><td class="src"><a name="v:Captionless" class="def">Captionless</a></td><td class="doc"><p>Select a window without a caption (<em>freeglut only</em>).
</p></td></tr><tr><td class="src"><a name="v:Borderless" class="def">Borderless</a></td><td class="doc"><p>Select a window without any borders (<em>freeglut only</em>).
</p></td></tr></table></div><div class="subs instances"><p id="control.i:DisplayMode" class="caption collapser" onclick="toggleSection('i:DisplayMode')">Instances</p><div id="section.i:DisplayMode" class="show"><table><tr><td class="src"><a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Eq.html#t:Eq">Eq</a> <a href="Graphics-UI-GLUT-Initialization.html#t:DisplayMode">DisplayMode</a></td><td class="doc empty">&nbsp;</td></tr><tr><td class="src"><a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Ord.html#t:Ord">Ord</a> <a href="Graphics-UI-GLUT-Initialization.html#t:DisplayMode">DisplayMode</a></td><td class="doc empty">&nbsp;</td></tr><tr><td class="src"><a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Text-Show.html#t:Show">Show</a> <a href="Graphics-UI-GLUT-Initialization.html#t:DisplayMode">DisplayMode</a></td><td class="doc empty">&nbsp;</td></tr></table></div></div></div><div class="top"><p class="src"><a name="v:initialDisplayMode" class="def">initialDisplayMode</a> :: <a href="/usr/share/doc/libghc-opengl-doc/html/Graphics-Rendering-OpenGL-GL-StateVar.html#t:StateVar">StateVar</a> [<a href="Graphics-UI-GLUT-Initialization.html#t:DisplayMode">DisplayMode</a>]<a href="src/Graphics-UI-GLUT-Initialization.html#initialDisplayMode" class="link">Source</a></p><div class="doc"><p>Controls the <em>initial display mode</em> used when creating top-level windows,
 subwindows, and overlays to determine the OpenGL display mode for the
 to-be-created window or overlay.
</p><p>Note that <code><a href="Graphics-UI-GLUT-Initialization.html#v:RGBAMode">RGBAMode</a></code> selects the RGBA color model, but it does not request any
 bits of alpha (sometimes called an <em>alpha buffer</em> or <em>destination alpha</em>)
 be allocated. To request alpha, specify <code><a href="Graphics-UI-GLUT-Initialization.html#v:WithAlphaComponent">WithAlphaComponent</a></code>. The same
 applies to <code><a href="Graphics-UI-GLUT-Initialization.html#v:LuminanceMode">LuminanceMode</a></code>.
</p></div></div><div class="top"><p class="src"><a name="v:displayModePossible" class="def">displayModePossible</a> :: <a href="/usr/share/doc/libghc-opengl-doc/html/Graphics-Rendering-OpenGL-GL-StateVar.html#t:GettableStateVar">GettableStateVar</a> <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Bool.html#t:Bool">Bool</a><a href="src/Graphics-UI-GLUT-Initialization.html#displayModePossible" class="link">Source</a></p><div class="doc"><p>Contains <code><a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Bool.html#v:True">True</a></code> if the <em>current display mode</em> is supported, <code><a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Bool.html#v:False">False</a></code>
 otherwise.
</p></div></div><h1 id="g:4">Setting the initial display mode (II)
</h1><div class="top"><p class="src"><span class="keyword">data</span>  <a name="t:DisplayCapability" class="def">DisplayCapability</a>  <a href="src/Graphics-UI-GLUT-Initialization.html#DisplayCapability" class="link">Source</a></p><div class="doc"><p>Capabilities for <code><a href="Graphics-UI-GLUT-Initialization.html#v:initialDisplayCapabilities">initialDisplayCapabilities</a></code>, most of them are extensions
 of the constructors of <code><a href="Graphics-UI-GLUT-Initialization.html#t:DisplayMode">DisplayMode</a></code>.
</p></div><div class="subs constructors"><p class="caption">Constructors</p><table><tr><td class="src"><a name="v:DisplayRGBA" class="def">DisplayRGBA</a></td><td class="doc"><p>Number of bits of red, green, blue, and alpha in the RGBA
   color buffer. Default is &quot;<code><a href="Graphics-UI-GLUT-Initialization.html#v:IsAtLeast">IsAtLeast</a></code> <code>1</code>&quot; for red,
   green, blue, and alpha capabilities, and &quot;<code><a href="Graphics-UI-GLUT-Initialization.html#v:IsEqualTo">IsEqualTo</a></code>
   <code>1</code>&quot; for the RGBA color model capability.
</p></td></tr><tr><td class="src"><a name="v:DisplayRGB" class="def">DisplayRGB</a></td><td class="doc"><p>Number of bits of red, green, and blue in the RGBA color
   buffer and zero bits of alpha color buffer precision.
   Default is &quot;<code><a href="Graphics-UI-GLUT-Initialization.html#v:IsAtLeast">IsAtLeast</a></code> <code>1</code>&quot; for the red, green, and
   blue capabilities, and &quot;<code><a href="Graphics-UI-GLUT-Initialization.html#v:IsNotLessThan">IsNotLessThan</a></code> <code>0</code>&quot; for alpha
   capability, and &quot;<code><a href="Graphics-UI-GLUT-Initialization.html#v:IsEqualTo">IsEqualTo</a></code> <code>1</code>&quot; for the RGBA color
   model capability.
</p></td></tr><tr><td class="src"><a name="v:DisplayRed" class="def">DisplayRed</a></td><td class="doc"><p>Red color buffer precision in bits. Default is
   &quot;<code><a href="Graphics-UI-GLUT-Initialization.html#v:IsAtLeast">IsAtLeast</a></code> <code>1</code>&quot;.
</p></td></tr><tr><td class="src"><a name="v:DisplayGreen" class="def">DisplayGreen</a></td><td class="doc"><p>Green color buffer precision in bits. Default is
   &quot;<code><a href="Graphics-UI-GLUT-Initialization.html#v:IsAtLeast">IsAtLeast</a></code> <code>1</code>&quot;.
</p></td></tr><tr><td class="src"><a name="v:DisplayBlue" class="def">DisplayBlue</a></td><td class="doc"><p>Blue color buffer precision in bits. Default is
   &quot;<code><a href="Graphics-UI-GLUT-Initialization.html#v:IsAtLeast">IsAtLeast</a></code> <code>1</code>&quot;.
</p></td></tr><tr><td class="src"><a name="v:DisplayIndex" class="def">DisplayIndex</a></td><td class="doc"><p>Boolean if the color model is color index or not. True is
   color index. Default is &quot;<code><a href="Graphics-UI-GLUT-Initialization.html#v:IsAtLeast">IsAtLeast</a></code> <code>1</code>&quot;.
</p></td></tr><tr><td class="src"><a name="v:DisplayBuffer" class="def">DisplayBuffer</a></td><td class="doc"><p>Number of bits in the color index color buffer. Default
   is &quot;<code><a href="Graphics-UI-GLUT-Initialization.html#v:IsAtLeast">IsAtLeast</a></code> <code>1</code>&quot;.
</p></td></tr><tr><td class="src"><a name="v:DisplaySingle" class="def">DisplaySingle</a></td><td class="doc"><p>Boolean indicate the color buffer is single buffered.
   Default is &quot;<code><a href="Graphics-UI-GLUT-Initialization.html#v:IsEqualTo">IsEqualTo</a></code> <code>1</code>&quot;.
</p></td></tr><tr><td class="src"><a name="v:DisplayDouble" class="def">DisplayDouble</a></td><td class="doc"><p>Boolean indicating if the color buffer is double
   buffered. Default is &quot;<code><a href="Graphics-UI-GLUT-Initialization.html#v:IsEqualTo">IsEqualTo</a></code> <code>1</code>&quot;.
</p></td></tr><tr><td class="src"><a name="v:DisplayAccA" class="def">DisplayAccA</a></td><td class="doc"><p>Red, green, blue, and alpha accumulation buffer precision
   in  bits. Default is &quot;<code><a href="Graphics-UI-GLUT-Initialization.html#v:IsAtLeast">IsAtLeast</a></code> <code>1</code>&quot; for red, green,
   blue, and alpha capabilities.
</p></td></tr><tr><td class="src"><a name="v:DisplayAcc" class="def">DisplayAcc</a></td><td class="doc"><p>Red, green, and green accumulation buffer precision in
   bits and zero bits of alpha accumulation buffer precision.
   Default is &quot;<code><a href="Graphics-UI-GLUT-Initialization.html#v:IsAtLeast">IsAtLeast</a></code> <code>1</code>&quot; for red, green, and blue
   capabilities, and &quot;<code><a href="Graphics-UI-GLUT-Initialization.html#v:IsNotLessThan">IsNotLessThan</a></code> <code>0</code>&quot; for the alpha
   capability.
</p></td></tr><tr><td class="src"><a name="v:DisplayAlpha" class="def">DisplayAlpha</a></td><td class="doc"><p>Alpha color buffer precision in bits. Default is
   &quot;<code><a href="Graphics-UI-GLUT-Initialization.html#v:IsAtLeast">IsAtLeast</a></code> <code>1</code>&quot;.
</p></td></tr><tr><td class="src"><a name="v:DisplayDepth" class="def">DisplayDepth</a></td><td class="doc"><p>Number of bits of precsion in the depth buffer. Default
   is &quot;<code><a href="Graphics-UI-GLUT-Initialization.html#v:IsAtLeast">IsAtLeast</a></code> <code>12</code>&quot;.
</p></td></tr><tr><td class="src"><a name="v:DisplayStencil" class="def">DisplayStencil</a></td><td class="doc"><p>Number of bits in the stencil buffer. Default is
   &quot;<code><a href="Graphics-UI-GLUT-Initialization.html#v:IsNotLessThan">IsNotLessThan</a></code> <code>1</code>&quot;.
</p></td></tr><tr><td class="src"><a name="v:DisplaySamples" class="def">DisplaySamples</a></td><td class="doc"><p>Indicates the number of multisamples to use based on
   GLX's <code>SGIS_multisample</code> extension (for antialiasing).
   Default is &quot;<code><a href="Graphics-UI-GLUT-Initialization.html#v:IsNotGreaterThan">IsNotGreaterThan</a></code> <code>4</code>&quot;. This default means
   that a GLUT application can request multisampling if
   available by simply specifying &quot;<code><a href="Graphics-UI-GLUT-Initialization.html#v:With">With</a></code> <code><a href="Graphics-UI-GLUT-Initialization.html#v:DisplaySamples">DisplaySamples</a></code>&quot;.
</p></td></tr><tr><td class="src"><a name="v:DisplayStereo" class="def">DisplayStereo</a></td><td class="doc"><p>Boolean indicating the color buffer is supports
   OpenGL-style stereo. Default is &quot;<code><a href="Graphics-UI-GLUT-Initialization.html#v:IsEqualTo">IsEqualTo</a></code> <code>1</code>&quot;.
</p></td></tr><tr><td class="src"><a name="v:DisplayLuminance" class="def">DisplayLuminance</a></td><td class="doc"><p>Number of bits of red in the RGBA and zero bits of green,
   blue (alpha not specified) of color buffer precision.
   Default is &quot;<code><a href="Graphics-UI-GLUT-Initialization.html#v:IsAtLeast">IsAtLeast</a></code> <code>1</code>&quot; for the red capabilitis,
   and &quot;<code><a href="Graphics-UI-GLUT-Initialization.html#v:IsEqualTo">IsEqualTo</a></code> <code>0</code>&quot; for the green and blue
   capabilities, and &quot;<code><a href="Graphics-UI-GLUT-Initialization.html#v:IsEqualTo">IsEqualTo</a></code> <code>1</code>&quot; for the RGBA color
   model capability, and, for X11, &quot;<code><a href="Graphics-UI-GLUT-Initialization.html#v:IsEqualTo">IsEqualTo</a></code> <code>1</code>&quot; for
   the <code><a href="Graphics-UI-GLUT-Initialization.html#v:DisplayXStaticGray">DisplayXStaticGray</a></code> capability. SGI InfiniteReality (and
   other future machines) support a 16-bit luminance (single
   channel) display mode (an additional 16-bit alpha channel
   can also be requested). The red channel maps to gray
   scale and green and blue channels are not available. A
   16-bit precision luminance display mode is often
   appropriate for medical imaging applications. Do not
   expect many machines to support extended precision
   luminance display modes.
</p></td></tr><tr><td class="src"><a name="v:DisplayAux" class="def">DisplayAux</a></td><td class="doc"><p>(<em>freeglut only</em>) Number of auxiliary buffers. Default is
   &quot;<code><a href="Graphics-UI-GLUT-Initialization.html#v:IsEqualTo">IsEqualTo</a></code> <code>1</code>&quot;.
</p></td></tr><tr><td class="src"><a name="v:DisplayNum" class="def">DisplayNum</a></td><td class="doc"><p>A special capability name indicating where the value
   represents the Nth frame buffer configuration matching
   the description string. When not specified,
   <code><a href="Graphics-UI-GLUT-Initialization.html#v:initialDisplayCapabilities">initialDisplayCapabilities</a></code> also uses the first
   (best matching) configuration. <code><a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Prelude.html#t:Num">Num</a></code> requires a relation
   and numeric value.
</p></td></tr><tr><td class="src"><a name="v:DisplayConformant" class="def">DisplayConformant</a></td><td class="doc"><p>Boolean indicating if the frame buffer configuration is
   conformant or not. Conformance information is based on
   GLX's <code>EXT_visual_rating</code> extension if supported. If the
   extension is not supported, all visuals are assumed
   conformant. Default is &quot;<code><a href="Graphics-UI-GLUT-Initialization.html#v:IsEqualTo">IsEqualTo</a></code> <code>1</code>&quot;.
</p></td></tr><tr><td class="src"><a name="v:DisplaySlow" class="def">DisplaySlow</a></td><td class="doc"><p>Boolean indicating if the frame buffer configuration is
   slow or not. Slowness information is based on GLX's
   <code>EXT_visual_rating</code> extension if supported. If the
   extension is not supported, all visuals are assumed fast.
   Note that slowness is a relative designation relative to
   other frame buffer configurations available. The intent
   of the slow capability is to help programs avoid frame
   buffer configurations that are slower (but perhaps higher
   precision) for the current machine. Default is
   &quot;<code><a href="Graphics-UI-GLUT-Initialization.html#v:IsAtLeast">IsAtLeast</a></code> <code>0</code>&quot;. This default means that slow visuals
   are used in preference to fast visuals, but fast visuals
   will still be allowed.
</p></td></tr><tr><td class="src"><a name="v:DisplayWin32PFD" class="def">DisplayWin32PFD</a></td><td class="doc"><p>Only recognized on GLUT implementations for Win32, this
   capability name matches the Win32 Pixel Format Descriptor
   by number. <code><a href="Graphics-UI-GLUT-Initialization.html#v:DisplayWin32PFD">DisplayWin32PFD</a></code> can only be used with <code><a href="Graphics-UI-GLUT-Initialization.html#v:Where">Where</a></code>.
</p></td></tr><tr><td class="src"><a name="v:DisplayXVisual" class="def">DisplayXVisual</a></td><td class="doc"><p>Only recongized on GLUT implementations for the X Window
   System, this capability name matches the X visual ID by
   number. <code><a href="Graphics-UI-GLUT-Initialization.html#v:DisplayXVisual">DisplayXVisual</a></code> requires a relation and numeric value.
</p></td></tr><tr><td class="src"><a name="v:DisplayXStaticGray" class="def">DisplayXStaticGray</a></td><td class="doc"><p>Only recongized on GLUT implementations for the X Window
   System, boolean indicating if the frame buffer
   configuration's X visual is of type <code>StaticGray</code>.
   Default is &quot;<code><a href="Graphics-UI-GLUT-Initialization.html#v:IsEqualTo">IsEqualTo</a></code> <code>1</code>&quot;.
</p></td></tr><tr><td class="src"><a name="v:DisplayXGrayScale" class="def">DisplayXGrayScale</a></td><td class="doc"><p>Only recongized on GLUT implementations for the X Window
   System, boolean indicating if the frame buffer
   configuration's X visual is of type <code>GrayScale</code>. Default
   is &quot;<code><a href="Graphics-UI-GLUT-Initialization.html#v:IsEqualTo">IsEqualTo</a></code> <code>1</code>&quot;.
</p></td></tr><tr><td class="src"><a name="v:DisplayXStaticColor" class="def">DisplayXStaticColor</a></td><td class="doc"><p>Only recongized on GLUT implementations for the X Window
   System, boolean indicating if the frame buffer
   configuration's X visual is of type <code>StaticColor</code>.
   Default is &quot;<code><a href="Graphics-UI-GLUT-Initialization.html#v:IsEqualTo">IsEqualTo</a></code> <code>1</code>&quot;.
</p></td></tr><tr><td class="src"><a name="v:DisplayXPseudoColor" class="def">DisplayXPseudoColor</a></td><td class="doc"><p>Only recongized on GLUT implementations for the X Window
   System, boolean indicating if the frame buffer
   configuration's X visual is of type <code>PsuedoColor</code>.
   Default is &quot;<code><a href="Graphics-UI-GLUT-Initialization.html#v:IsEqualTo">IsEqualTo</a></code> <code>1</code>&quot;.
</p></td></tr><tr><td class="src"><a name="v:DisplayXTrueColor" class="def">DisplayXTrueColor</a></td><td class="doc"><p>Only recongized on GLUT implementations for the X Window
   System, boolean indicating if the frame buffer
   configuration's X visual is of type <code>TrueColor</code>. Default
   is &quot;<code><a href="Graphics-UI-GLUT-Initialization.html#v:IsEqualTo">IsEqualTo</a></code> <code>1</code>&quot;.
</p></td></tr><tr><td class="src"><a name="v:DisplayXDirectColor" class="def">DisplayXDirectColor</a></td><td class="doc"><p>Only recongized on GLUT implementations for the X Window
   System, boolean indicating if the frame buffer
   configuration's X visual is of type <code>DirectColor</code>.
   Default is &quot;<code><a href="Graphics-UI-GLUT-Initialization.html#v:IsEqualTo">IsEqualTo</a></code> <code>1</code>&quot;.
</p></td></tr></table></div><div class="subs instances"><p id="control.i:DisplayCapability" class="caption collapser" onclick="toggleSection('i:DisplayCapability')">Instances</p><div id="section.i:DisplayCapability" class="show"><table><tr><td class="src"><a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Eq.html#t:Eq">Eq</a> <a href="Graphics-UI-GLUT-Initialization.html#t:DisplayCapability">DisplayCapability</a></td><td class="doc empty">&nbsp;</td></tr><tr><td class="src"><a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Ord.html#t:Ord">Ord</a> <a href="Graphics-UI-GLUT-Initialization.html#t:DisplayCapability">DisplayCapability</a></td><td class="doc empty">&nbsp;</td></tr><tr><td class="src"><a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Text-Show.html#t:Show">Show</a> <a href="Graphics-UI-GLUT-Initialization.html#t:DisplayCapability">DisplayCapability</a></td><td class="doc empty">&nbsp;</td></tr></table></div></div></div><div class="top"><p class="src"><span class="keyword">data</span>  <a name="t:Relation" class="def">Relation</a>  <a href="src/Graphics-UI-GLUT-Types.html#Relation" class="link">Source</a></p><div class="doc"><p>A relation between a <code><a href="Graphics-UI-GLUT-Initialization.html#t:DisplayCapability">DisplayCapability</a></code>
 and a numeric value.
</p></div><div class="subs constructors"><p class="caption">Constructors</p><table><tr><td class="src"><a name="v:IsEqualTo" class="def">IsEqualTo</a></td><td class="doc"><p>Equal.
</p></td></tr><tr><td class="src"><a name="v:IsNotEqualTo" class="def">IsNotEqualTo</a></td><td class="doc"><p>Not equal.
</p></td></tr><tr><td class="src"><a name="v:IsLessThan" class="def">IsLessThan</a></td><td class="doc"><p>Less than and preferring larger difference (the least
   is best).
</p></td></tr><tr><td class="src"><a name="v:IsNotGreaterThan" class="def">IsNotGreaterThan</a></td><td class="doc"><p>Less than or equal and preferring larger difference
   (the least is best).
</p></td></tr><tr><td class="src"><a name="v:IsGreaterThan" class="def">IsGreaterThan</a></td><td class="doc"><p>Greater than and preferring larger differences (the
   most is best).
</p></td></tr><tr><td class="src"><a name="v:IsAtLeast" class="def">IsAtLeast</a></td><td class="doc"><p>Greater than or equal and preferring more instead of
   less. This relation is useful for allocating
   resources like color precision or depth buffer
   precision where the maximum precision is generally
   preferred. Contrast with <code><a href="Graphics-UI-GLUT-Initialization.html#v:IsNotLessThan">IsNotLessThan</a></code> relation.
</p></td></tr><tr><td class="src"><a name="v:IsNotLessThan" class="def">IsNotLessThan</a></td><td class="doc"><p>Greater than or equal but preferring less instead of
   more. This relation is useful for allocating
   resources such as stencil bits or auxillary color
   buffers where you would rather not over-allocate.
</p></td></tr></table></div><div class="subs instances"><p id="control.i:Relation" class="caption collapser" onclick="toggleSection('i:Relation')">Instances</p><div id="section.i:Relation" class="show"><table><tr><td class="src"><a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Eq.html#t:Eq">Eq</a> <a href="Graphics-UI-GLUT-Initialization.html#t:Relation">Relation</a></td><td class="doc empty">&nbsp;</td></tr><tr><td class="src"><a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Ord.html#t:Ord">Ord</a> <a href="Graphics-UI-GLUT-Initialization.html#t:Relation">Relation</a></td><td class="doc empty">&nbsp;</td></tr><tr><td class="src"><a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Text-Show.html#t:Show">Show</a> <a href="Graphics-UI-GLUT-Initialization.html#t:Relation">Relation</a></td><td class="doc empty">&nbsp;</td></tr></table></div></div></div><div class="top"><p class="src"><span class="keyword">data</span>  <a name="t:DisplayCapabilityDescription" class="def">DisplayCapabilityDescription</a>  <a href="src/Graphics-UI-GLUT-Initialization.html#DisplayCapabilityDescription" class="link">Source</a></p><div class="doc"><p>A single capability description for <code><a href="Graphics-UI-GLUT-Initialization.html#v:initialDisplayCapabilities">initialDisplayCapabilities</a></code>.
</p></div><div class="subs constructors"><p class="caption">Constructors</p><table><tr><td class="src"><a name="v:Where" class="def">Where</a> <a href="Graphics-UI-GLUT-Initialization.html#t:DisplayCapability">DisplayCapability</a> <a href="Graphics-UI-GLUT-Initialization.html#t:Relation">Relation</a> <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Int.html#t:Int">Int</a></td><td class="doc"><p>A description of a capability with a specific relation to a numeric
   value.
</p></td></tr><tr><td class="src"><a name="v:With" class="def">With</a> <a href="Graphics-UI-GLUT-Initialization.html#t:DisplayCapability">DisplayCapability</a></td><td class="doc"><p>When the relation and numeric value are not specified, each capability
   has a different default, see the different constructors of
   <code><a href="Graphics-UI-GLUT-Initialization.html#t:DisplayCapability">DisplayCapability</a></code>.
</p></td></tr></table></div><div class="subs instances"><p id="control.i:DisplayCapabilityDescription" class="caption collapser" onclick="toggleSection('i:DisplayCapabilityDescription')">Instances</p><div id="section.i:DisplayCapabilityDescription" class="show"><table><tr><td class="src"><a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Eq.html#t:Eq">Eq</a> <a href="Graphics-UI-GLUT-Initialization.html#t:DisplayCapabilityDescription">DisplayCapabilityDescription</a></td><td class="doc empty">&nbsp;</td></tr><tr><td class="src"><a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Ord.html#t:Ord">Ord</a> <a href="Graphics-UI-GLUT-Initialization.html#t:DisplayCapabilityDescription">DisplayCapabilityDescription</a></td><td class="doc empty">&nbsp;</td></tr><tr><td class="src"><a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Text-Show.html#t:Show">Show</a> <a href="Graphics-UI-GLUT-Initialization.html#t:DisplayCapabilityDescription">DisplayCapabilityDescription</a></td><td class="doc empty">&nbsp;</td></tr></table></div></div></div><div class="top"><p class="src"><a name="v:initialDisplayCapabilities" class="def">initialDisplayCapabilities</a> :: <a href="/usr/share/doc/libghc-opengl-doc/html/Graphics-Rendering-OpenGL-GL-StateVar.html#t:SettableStateVar">SettableStateVar</a> [<a href="Graphics-UI-GLUT-Initialization.html#t:DisplayCapabilityDescription">DisplayCapabilityDescription</a>]<a href="src/Graphics-UI-GLUT-Initialization.html#initialDisplayCapabilities" class="link">Source</a></p><div class="doc"><p>Controls the <em>initial display mode</em> used when creating top-level windows,
 subwindows, and overlays to determine the OpenGL display mode for the
 to-be-created window or overlay. It is described by a list of zero or more
 capability descriptions, which are translated into a set of criteria used to
 select the appropriate frame buffer configuration. The criteria are matched
 in strict left to right order of precdence. That is, the first specified
 criterion (leftmost) takes precedence over the later criteria for non-exact
 criteria (<code><a href="Graphics-UI-GLUT-Initialization.html#v:IsGreaterThan">IsGreaterThan</a></code>, <code><a href="Graphics-UI-GLUT-Initialization.html#v:IsLessThan">IsLessThan</a></code>, etc.). Exact criteria (<code><a href="Graphics-UI-GLUT-Initialization.html#v:IsEqualTo">IsEqualTo</a></code>,
 <code><a href="Graphics-UI-GLUT-Initialization.html#v:IsNotEqualTo">IsNotEqualTo</a></code>) must match exactly so precedence is not relevant.
</p><p>Unspecified capability descriptions will result in unspecified criteria being
 generated. These unspecified criteria help <code><a href="Graphics-UI-GLUT-Initialization.html#v:initialDisplayCapabilities">initialDisplayCapabilities</a></code>
 behave sensibly with terse display mode descriptions.
</p><p>Here is an example using <code><a href="Graphics-UI-GLUT-Initialization.html#v:initialDisplayCapabilities">initialDisplayCapabilities</a></code>:
</p><pre>
    initialDisplayCapabilities $= [ With  DisplayRGB,
                                    Where DisplayDepth IsAtLeast 16,
                                    With  DisplaySamples,
                                    Where DisplayStencil IsNotLessThan 2,
                                    With  DisplayDouble ]
</pre><p>The above call requests a window with an RGBA color model (but requesting
 no bits of alpha), a depth buffer with at least 16 bits of precision but
 preferring more, multisampling if available, at least 2 bits of stencil
 (favoring less stencil to more as long as 2 bits are available), and double
 buffering.
</p></div></div><h1 id="g:5">Controlling the creation of rendering contexts
</h1><div class="top"><p class="src"><span class="keyword">data</span>  <a name="t:RenderingContext" class="def">RenderingContext</a>  <a href="src/Graphics-UI-GLUT-Initialization.html#RenderingContext" class="link">Source</a></p><div class="doc"><p>How rendering context for new windows are created.
</p></div><div class="subs constructors"><p class="caption">Constructors</p><table><tr><td class="src"><a name="v:CreateNewContext" class="def">CreateNewContext</a></td><td class="doc"><p>Create a new context via <code>glXCreateContext</code> or <code>wglCreateContext</code>
   (default).
</p></td></tr><tr><td class="src"><a name="v:UseCurrentContext" class="def">UseCurrentContext</a></td><td class="doc"><p>Re-use the current rendering context.
</p></td></tr></table></div><div class="subs instances"><p id="control.i:RenderingContext" class="caption collapser" onclick="toggleSection('i:RenderingContext')">Instances</p><div id="section.i:RenderingContext" class="show"><table><tr><td class="src"><a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Eq.html#t:Eq">Eq</a> <a href="Graphics-UI-GLUT-Initialization.html#t:RenderingContext">RenderingContext</a></td><td class="doc empty">&nbsp;</td></tr><tr><td class="src"><a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Ord.html#t:Ord">Ord</a> <a href="Graphics-UI-GLUT-Initialization.html#t:RenderingContext">RenderingContext</a></td><td class="doc empty">&nbsp;</td></tr><tr><td class="src"><a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Text-Show.html#t:Show">Show</a> <a href="Graphics-UI-GLUT-Initialization.html#t:RenderingContext">RenderingContext</a></td><td class="doc empty">&nbsp;</td></tr></table></div></div></div><div class="top"><p class="src"><a name="v:renderingContext" class="def">renderingContext</a> :: <a href="/usr/share/doc/libghc-opengl-doc/html/Graphics-Rendering-OpenGL-GL-StateVar.html#t:StateVar">StateVar</a> <a href="Graphics-UI-GLUT-Initialization.html#t:RenderingContext">RenderingContext</a><a href="src/Graphics-UI-GLUT-Initialization.html#renderingContext" class="link">Source</a></p><div class="doc"><p>(<em>freeglut only</em>) Controls the creation of rendering contexts for new
 windows.
</p></div></div><h1 id="g:6">Direct/indirect rendering
</h1><div class="top"><p class="src"><span class="keyword">data</span>  <a name="t:DirectRendering" class="def">DirectRendering</a>  <a href="src/Graphics-UI-GLUT-Initialization.html#DirectRendering" class="link">Source</a></p><div class="doc"><p>The kind of GLX rendering context used. Direct rendering provides a
 performance advantage in some implementations. However, direct rendering
 contexts cannot be shared outside a single process, and they may be unable
 to render to GLX pixmaps.
</p></div><div class="subs constructors"><p class="caption">Constructors</p><table><tr><td class="src"><a name="v:ForceIndirectContext" class="def">ForceIndirectContext</a></td><td class="doc"><p>Rendering is always done through the X server. This corresponds to
 the command line argument <code>-indirect</code>, see <code><a href="Graphics-UI-GLUT-Initialization.html#v:initialize">initialize</a></code>.
</p></td></tr><tr><td class="src"><a name="v:AllowDirectContext" class="def">AllowDirectContext</a></td><td class="doc"><p>Try to use direct rendering, silently using indirect rendering if this
 is not possible.
</p></td></tr><tr><td class="src"><a name="v:TryDirectContext" class="def">TryDirectContext</a></td><td class="doc"><p>Try to use direct rendering, issue a warning and use indirect
 rendering if this is not possible.
</p></td></tr><tr><td class="src"><a name="v:ForceDirectContext" class="def">ForceDirectContext</a></td><td class="doc"><p>Try to use direct rendering, issue an error and terminate the program
 if this is not possible.This corresponds to the command line argument
 <code>-direct</code>, see <code><a href="Graphics-UI-GLUT-Initialization.html#v:initialize">initialize</a></code>.
</p></td></tr></table></div><div class="subs instances"><p id="control.i:DirectRendering" class="caption collapser" onclick="toggleSection('i:DirectRendering')">Instances</p><div id="section.i:DirectRendering" class="show"><table><tr><td class="src"><a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Eq.html#t:Eq">Eq</a> <a href="Graphics-UI-GLUT-Initialization.html#t:DirectRendering">DirectRendering</a></td><td class="doc empty">&nbsp;</td></tr><tr><td class="src"><a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Ord.html#t:Ord">Ord</a> <a href="Graphics-UI-GLUT-Initialization.html#t:DirectRendering">DirectRendering</a></td><td class="doc empty">&nbsp;</td></tr><tr><td class="src"><a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Text-Show.html#t:Show">Show</a> <a href="Graphics-UI-GLUT-Initialization.html#t:DirectRendering">DirectRendering</a></td><td class="doc empty">&nbsp;</td></tr></table></div></div></div><div class="top"><p class="src"><a name="v:directRendering" class="def">directRendering</a> :: <a href="/usr/share/doc/libghc-opengl-doc/html/Graphics-Rendering-OpenGL-GL-StateVar.html#t:StateVar">StateVar</a> <a href="Graphics-UI-GLUT-Initialization.html#t:DirectRendering">DirectRendering</a><a href="src/Graphics-UI-GLUT-Initialization.html#directRendering" class="link">Source</a></p><div class="doc"><p>(<em>freeglut on X11 only</em>) Controls which kind of rendering context is
 created when a new one is required.
</p></div></div><h1 id="g:7">OpenGL 3.x context support
</h1><div class="top"><p class="src"><a name="v:initialContextVersion" class="def">initialContextVersion</a> :: <a href="/usr/share/doc/libghc-opengl-doc/html/Graphics-Rendering-OpenGL-GL-StateVar.html#t:StateVar">StateVar</a> (<a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Int.html#t:Int">Int</a>, <a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Int.html#t:Int">Int</a>)<a href="src/Graphics-UI-GLUT-Initialization.html#initialContextVersion" class="link">Source</a></p><div class="doc"><p>(<em>freeglut only</em>) Controls the API major/minor version of the OpenGL
 context. If a version less than or equal to 2.1 is requested, the context
 returned may implement any version no less than that requested and no
 greater than 2.1. If version 3.0 is requested, the context returned must
 implement exactly version 3.0. Versioning behavior once GL versions beyond
 3.0 are defined will be defined by an amendment to the OpenGL specification
 to define dependencies on such GL versions.
</p><p><code><a href="/usr/share/doc/libghc-opengl-doc/html/Graphics-Rendering-OpenGL-GL-StringQueries.html#v:glVersion">glVersion</a></code> and
 <code><a href="/usr/share/doc/libghc-opengl-doc/html/Graphics-Rendering-OpenGL-GL-StringQueries.html#v:majorMinor">majorMinor</a></code> will return the
 actual version supported by a context.
</p><p>The default context version is (1, 0), which will typically return an
 OpenGL 2.1 context, if one is available.
</p></div></div><div class="top"><p class="src"><span class="keyword">data</span>  <a name="t:ContextFlag" class="def">ContextFlag</a>  <a href="src/Graphics-UI-GLUT-Initialization.html#ContextFlag" class="link">Source</a></p><div class="doc"><p>A flag affecting the rendering context to create, used in conjunction
 with <code><a href="Graphics-UI-GLUT-Initialization.html#v:initialContextFlags">initialContextFlags</a></code>.
</p></div><div class="subs constructors"><p class="caption">Constructors</p><table><tr><td class="src"><a name="v:DebugContext" class="def">DebugContext</a></td><td class="doc"><p>Debug contexts are intended for use during application development,
 and provide additional runtime checking, validation, and logging
 functionality while possibly incurring performance penalties. The
 additional functionality provided by debug contexts may vary according
 to the implementation. In some cases a debug context may be identical
 to a non-debug context.
</p></td></tr><tr><td class="src"><a name="v:ForwardCompatibleContext" class="def">ForwardCompatibleContext</a></td><td class="doc"><p>Forward-compatible contexts are defined only for OpenGL versions 3.0
 and later. They must not support functionality marked as <em>deprecated</em>
 by that version of the API, while a non-forward-compatible context must
 support all functionality in that version, deprecated or not.
</p></td></tr></table></div><div class="subs instances"><p id="control.i:ContextFlag" class="caption collapser" onclick="toggleSection('i:ContextFlag')">Instances</p><div id="section.i:ContextFlag" class="show"><table><tr><td class="src"><a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Eq.html#t:Eq">Eq</a> <a href="Graphics-UI-GLUT-Initialization.html#t:ContextFlag">ContextFlag</a></td><td class="doc empty">&nbsp;</td></tr><tr><td class="src"><a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Data-Ord.html#t:Ord">Ord</a> <a href="Graphics-UI-GLUT-Initialization.html#t:ContextFlag">ContextFlag</a></td><td class="doc empty">&nbsp;</td></tr><tr><td class="src"><a href="/usr/share/doc/ghc-doc/html/libraries/base-4.5.0.0/Text-Show.html#t:Show">Show</a> <a href="Graphics-UI-GLUT-Initialization.html#t:ContextFlag">ContextFlag</a></td><td class="doc empty">&nbsp;</td></tr></table></div></div></div><div class="top"><p class="src"><a name="v:initialContextFlags" class="def">initialContextFlags</a> :: <a href="/usr/share/doc/libghc-opengl-doc/html/Graphics-Rendering-OpenGL-GL-StateVar.html#t:StateVar">StateVar</a> [<a href="Graphics-UI-GLUT-Initialization.html#t:ContextFlag">ContextFlag</a>]<a href="src/Graphics-UI-GLUT-Initialization.html#initialContextFlags" class="link">Source</a></p><div class="doc"><p>(<em>freeglut only</em>) Controls the set of flags for the rendering context.
</p></div></div></div></div><div id="footer"><p>Produced by <a href="http://www.haskell.org/haddock/">Haddock</a> version 2.10.0</p></div></body></html>