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Graphics.UI.GLUT.Initialization | Portability | portable | Stability | stable | Maintainer | sven.panne@aedion.de |
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Description |
Actions and state variables in this module are used to initialize GLUT state.
The primary initialization routine is initialize, which should only be
called exactly once in a GLUT program. No other GLUT or OpenGL actions should
be called before initialize, apart from getting or setting the state
variables in this module.
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
initialize. For example, initialWindowSize can be set to (Size
400 400) before initialize is called to indicate 400 by 400 is the
program's default window size. Setting the initial window size or position
before initialize allows the GLUT program user to specify the initial size
or position using command line arguments.
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Synopsis |
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Primary initialization
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initialize |
:: String | The program name.
| -> [String] | The command line arguments
| -> IO [String] | Non-GLUT command line arguments
| Given the program name and command line arguments, initialize the GLUT
library and negotiate a session with the window system. During this
process, initialize 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.
initialize 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.
X Implementation Notes: The X Window System specific options parsed by
initialize are as follows:
- -display DISPLAY: Specify the X server to connect to. If not specified,
the value of the DISPLAY environment variable is used.
- -geometry WxH+X+Y: Determines where windows should be created on the
screen. The parameter following -geometry 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
initialWindowSize or initialWindowPosition were modified directly.
- -iconic: Requests all top-level windows be created in an iconic state.
- -indirect: Force the use of indirect OpenGL rendering contexts.
- -direct: 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 -indirect or -direct are used to force a
particular behavior, GLUT will attempt to use direct rendering if
possible and otherwise fallback to indirect rendering.
- -gldebug: After processing callbacks and/or events, call
reportErrors to check if there are any pending
OpenGL errors. Using this option is helpful in detecting OpenGL run-time
errors.
- -sync: Enable synchronous X protocol transactions. This option makes
it easier to track down potential X protocol errors.
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getArgsAndInitialize :: IO (String, [String]) |
Convenience action: Initialize GLUT, returning the program name and any
non-GLUT command line arguments.
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Initial window geometry
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initialWindowPosition :: StateVar Position |
Controls the initial window position. Windows created by
createWindow will be requested to be created with
the current initial window position. The initial value of the initial
window position GLUT state is Size (-1) (-1). If either the X or Y
component of the initial window position is negative, the actual window
position is left to the window system to determine.
The intent of the initial window position 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.
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initialWindowSize :: StateVar Size |
Controls the initial window size. Windows created by
createWindow will be requested to be created with
the current initial window size. The initial value of the initial window
size GLUT state is Size 300 300. If either the width or the height
component of the initial window size is non-positive, the actual window
size is left to the window system to determine.
The intent of the initial window size 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.
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Setting the initial display mode (I)
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data DisplayMode |
A single aspect of a window which is to be created, used in conjunction
with initialDisplayMode.
| Constructors | RGBAMode | Select an RGBA mode window. This is the default if neither RGBAMode nor IndexMode are specified.
| RGBMode | An alias for RGBAMode.
| IndexMode | Select a color index mode window. This overrides RGBAMode if it is also specified.
| LuminanceMode | Select a window with a "luminance" 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 numColorMapEntries
and looked up in a per-window color map to determine the color of pixels within the window. The initial
colormap of LuminanceMode windows is initialized to be a linear gray ramp, but can be modified with GLUT's
colormap actions. Implementation Notes: LuminanceMode is not supported on most OpenGL platforms.
| WithAlphaComponent | Select a window with an alpha component to the color buffer(s).
| WithAccumBuffer | Select a window with an accumulation buffer.
| WithDepthBuffer | Select a window with a depth buffer.
| WithStencilBuffer | Select a window with a stencil buffer.
| WithAuxBuffers Int | (freeglut only) Select a window with n (1 .. 4) auxiliary buffers. Any n outside the range 1 .. 4 is a fatal error.
| SingleBuffered | Select a single buffered window. This is the default if neither DoubleBuffered nor SingleBuffered are specified.
| DoubleBuffered | Select a double buffered window. This overrides SingleBuffered if it is also specified.
| Multisampling | 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 GLX_SAMPLE_SGIS extension for multisampling to be available.
| Stereoscopic | Select A Stereo Window.
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initialDisplayMode :: StateVar [DisplayMode] |
Controls the initial display mode used when creating top-level windows,
subwindows, and overlays to determine the OpenGL display mode for the
to-be-created window or overlay.
Note that RGBAMode selects the RGBA color model, but it does not request any
bits of alpha (sometimes called an alpha buffer or destination alpha)
be allocated. To request alpha, specify WithAlphaComponent. The same
applies to LuminanceMode.
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displayModePossible :: GettableStateVar Bool |
Contains True if the current display mode is supported, False
otherwise.
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Setting the initial display mode (II)
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data DisplayCapability |
Capabilities for initialDisplayCapabilities, most of them are extensions
of the constructors of DisplayMode.
| Constructors | DisplayRGBA | Number of bits of red, green, blue, and alpha in the RGBA
color buffer. Default is "IsAtLeast 1" for red,
green, blue, and alpha capabilities, and "IsEqualTo
1" for the RGBA color model capability.
| DisplayRGB | Number of bits of red, green, and blue in the RGBA color
buffer and zero bits of alpha color buffer precision.
Default is "IsAtLeast 1" for the red, green, and
blue capabilities, and "IsNotLessThan 0" for alpha
capability, and "IsEqualTo 1" for the RGBA color
model capability.
| DisplayRed | Red color buffer precision in bits. Default is
"IsAtLeast 1".
| DisplayGreen | Green color buffer precision in bits. Default is
"IsAtLeast 1".
| DisplayBlue | Blue color buffer precision in bits. Default is
"IsAtLeast 1".
| DisplayIndex | Boolean if the color model is color index or not. True is
color index. Default is "IsAtLeast 1".
| DisplayBuffer | Number of bits in the color index color buffer. Default
is "IsAtLeast 1".
| DisplaySingle | Boolean indicate the color buffer is single buffered.
Default is "IsEqualTo 1".
| DisplayDouble | Boolean indicating if the color buffer is double
buffered. Default is "IsEqualTo 1".
| DisplayAccA | Red, green, blue, and alpha accumulation buffer precision
in bits. Default is "IsAtLeast 1" for red, green,
blue, and alpha capabilities.
| DisplayAcc | Red, green, and green accumulation buffer precision in
bits and zero bits of alpha accumulation buffer precision.
Default is "IsAtLeast 1" for red, green, and blue
capabilities, and "IsNotLessThan 0" for the alpha
capability.
| DisplayAlpha | Alpha color buffer precision in bits. Default is
"IsAtLeast 1".
| DisplayDepth | Number of bits of precsion in the depth buffer. Default
is "IsAtLeast 12".
| DisplayStencil | Number of bits in the stencil buffer. Default is
"IsNotLessThan 1".
| DisplaySamples | Indicates the number of multisamples to use based on
GLX's SGIS_multisample extension (for antialiasing).
Default is "IsNotGreaterThan 4". This default means
that a GLUT application can request multisampling if
available by simply specifying "With DisplaySamples".
| DisplayStereo | Boolean indicating the color buffer is supports
OpenGL-style stereo. Default is "IsEqualTo 1".
| DisplayLuminance | Number of bits of red in the RGBA and zero bits of green,
blue (alpha not specified) of color buffer precision.
Default is "IsAtLeast 1" for the red capabilitis,
and "IsEqualTo 0" for the green and blue
capabilities, and "IsEqualTo 1" for the RGBA color
model capability, and, for X11, "IsEqualTo 1" for
the DisplayXStaticGray 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.
| DisplayAux | (freeglut only) Number of auxiliary buffers. Default is
"IsEqualTo 1".
| DisplayNum | A special capability name indicating where the value
represents the Nth frame buffer configuration matching
the description string. When not specified,
initialDisplayCapabilities also uses the first
(best matching) configuration. Num requires a relation
and numeric value.
| DisplayConformant | Boolean indicating if the frame buffer configuration is
conformant or not. Conformance information is based on
GLX's EXT_visual_rating extension if supported. If the
extension is not supported, all visuals are assumed
conformant. Default is "IsEqualTo 1".
| DisplaySlow | Boolean indicating if the frame buffer configuration is
slow or not. Slowness information is based on GLX's
EXT_visual_rating 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
"IsAtLeast 0". This default means that slow visuals
are used in preference to fast visuals, but fast visuals
will still be allowed.
| DisplayWin32PFD | Only recognized on GLUT implementations for Win32, this
capability name matches the Win32 Pixel Format Descriptor
by number. DisplayWin32PFD can only be used with Where.
| DisplayXVisual | Only recongized on GLUT implementations for the X Window
System, this capability name matches the X visual ID by
number. DisplayXVisual requires a relation and numeric value.
| DisplayXStaticGray | Only recongized on GLUT implementations for the X Window
System, boolean indicating if the frame buffer
configuration's X visual is of type StaticGray.
Default is "IsEqualTo 1".
| DisplayXGrayScale | Only recongized on GLUT implementations for the X Window
System, boolean indicating if the frame buffer
configuration's X visual is of type GrayScale. Default
is "IsEqualTo 1".
| DisplayXStaticColor | Only recongized on GLUT implementations for the X Window
System, boolean indicating if the frame buffer
configuration's X visual is of type StaticColor.
Default is "IsEqualTo 1".
| DisplayXPseudoColor | Only recongized on GLUT implementations for the X Window
System, boolean indicating if the frame buffer
configuration's X visual is of type PsuedoColor.
Default is "IsEqualTo 1".
| DisplayXTrueColor | Only recongized on GLUT implementations for the X Window
System, boolean indicating if the frame buffer
configuration's X visual is of type TrueColor. Default
is "IsEqualTo 1".
| DisplayXDirectColor | Only recongized on GLUT implementations for the X Window
System, boolean indicating if the frame buffer
configuration's X visual is of type DirectColor.
Default is "IsEqualTo 1".
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data Relation |
A relation between a DisplayCapability
and a numeric value.
| Constructors | IsEqualTo | Equal.
| IsNotEqualTo | Not equal.
| IsLessThan | Less than and preferring larger difference (the least
is best).
| IsNotGreaterThan | Less than or equal and preferring larger difference
(the least is best).
| IsGreaterThan | Greater than and preferring larger differences (the
most is best).
| IsAtLeast | 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 IsNotLessThan relation.
| IsNotLessThan | 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.
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data DisplayCapabilityDescription |
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initialDisplayCapabilities :: SettableStateVar [DisplayCapabilityDescription] |
Controls the initial display mode 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 (IsGreaterThan, IsLessThan, etc.). Exact criteria (IsEqualTo,
IsNotEqualTo) must match exactly so precedence is not relevant.
Unspecified capability descriptions will result in unspecified criteria being
generated. These unspecified criteria help initialDisplayCapabilities
behave sensibly with terse display mode descriptions.
Here is an example using initialDisplayCapabilities:
initialDisplayCapabilities $= [ With DisplayRGB,
Where DisplayDepth IsAtLeast 16,
With DisplaySamples,
Where DisplayStencil IsNotLessThan 2,
With DisplayDouble ]
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.
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Controlling the creation of rendering contexts
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data RenderingContext |
How rendering context for new windows are created.
| Constructors | CreateNewContext | Create a new context via glXCreateContext or wglCreateContext
(default).
| UseCurrentContext | Re-use the current rendering context.
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renderingContext :: StateVar RenderingContext |
(freeglut only) Controls the creation of rendering contexts for new
windows.
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Direct/indirect rendering
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data DirectRendering |
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.
| Constructors | ForceIndirectContext | Rendering is always done through the X server. This corresponds to
the command line argument -indirect, see initialize.
| AllowDirectContext | Try to use direct rendering, silently using indirect rendering if this
is not possible.
| TryDirectContext | Try to use direct rendering, issue a warning and use indirect
rendering if this is not possible.
| ForceDirectContext | Try to use direct rendering, issue an error and terminate the program
if this is not possible.This corresponds to the command line argument
-direct, see initialize.
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directRendering :: StateVar DirectRendering |
(freeglut on X11 only) Controls which kind of rendering context is
created when a new one is required.
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Produced by Haddock version 0.8 |