com.trolltech.qt.opengl
Class QGLFormat

java.lang.Object
  extended by com.trolltech.qt.internal.QSignalEmitterInternal
      extended by com.trolltech.qt.QSignalEmitter
          extended by com.trolltech.qt.QtJambiObject
              extended by com.trolltech.qt.opengl.QGLFormat
All Implemented Interfaces:
QtJambiInterface, java.lang.Cloneable

public class QGLFormat
extends QtJambiObject
implements java.lang.Cloneable

The QGLFormat class specifies the display format of an OpenGL rendering context. A display format has several characteristics:

You can also specify preferred bit depths for the depth buffer, alpha buffer, accumulation buffer and the stencil buffer with the functions: setDepthBufferSize(), setAlphaBufferSize(), setAccumBufferSize() and setStencilBufferSize().

Note that even if you specify that you prefer a 32 bit depth buffer (e.g. with setDepthBufferSize(32)), the format that is chosen may not have a 32 bit depth buffer, even if there is a format available with a 32 bit depth buffer. The main reason for this is how the system dependant picking algorithms work on the different platforms, and some format options may have higher precedence than others.

You create and tell a QGLFormat object what rendering options you want from an OpenGL rendering context.

OpenGL drivers or accelerated hardware may or may not support advanced features such as alpha channel or stereographic viewing. If you request some features that the driver/hardware does not provide when you create a QGLWidget, you will get a rendering context with the nearest subset of features.

There are different ways to define the display characteristics of a rendering context. One is to create a QGLFormat and make it the default for the entire application:

    QGLFormat fmt = new QGLFormat();
    fmt.setAlpha(true);
    fmt.setStereo(true);
    QGLFormat.setDefaultFormat(fmt);
Or you can specify the desired format when creating an object of your QGLWidget subclass:
    QGLFormat fmt = new QGLFormat();
    fmt.setDoubleBuffer(false);                 // single buffer
    fmt.setDirectRendering(false);              // software rendering
    MyGLWidget myWidget = new MyGLWidget(fmt);
After the widget has been created, you can find out which of the requested features the system was able to provide:
    QGLFormat fmt = new QGLFormat();
    fmt.setOverlay(true);
    fmt.setStereo(true);
    MyGLWidget myWidget = new MyGLWidget(fmt);
    if (!myWidget.format().stereo()) {
        // ok, goggles off
        if (!myWidget.format().hasOverlay()) {
        throw new RuntimeException("Cool hardware required");
        }
    }
OpenGL is a trademark of Silicon Graphics, Inc. in the United States and other countries.

See also:
QGLContext, and QGLWidget.


Nested Class Summary
static class QGLFormat.OpenGLVersionFlag
          This enum describes the various OpenGL versions that are recognized by Qt.
static class QGLFormat.OpenGLVersionFlags
           
 
Nested classes/interfaces inherited from class com.trolltech.qt.QSignalEmitter
QSignalEmitter.AbstractSignal, QSignalEmitter.PrivateSignal0, QSignalEmitter.PrivateSignal1, QSignalEmitter.PrivateSignal2, QSignalEmitter.PrivateSignal3, QSignalEmitter.PrivateSignal4, QSignalEmitter.PrivateSignal5, QSignalEmitter.PrivateSignal6, QSignalEmitter.PrivateSignal7, QSignalEmitter.PrivateSignal8, QSignalEmitter.PrivateSignal9, QSignalEmitter.Signal0, QSignalEmitter.Signal1, QSignalEmitter.Signal2, QSignalEmitter.Signal3, QSignalEmitter.Signal4, QSignalEmitter.Signal5, QSignalEmitter.Signal6, QSignalEmitter.Signal7, QSignalEmitter.Signal8, QSignalEmitter.Signal9
 
Nested classes/interfaces inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
com.trolltech.qt.internal.QSignalEmitterInternal.AbstractSignalInternal
 
Field Summary
 
Fields inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
currentSender
 
Constructor Summary
QGLFormat()
          Constructs a QGLFormat object with the factory default settings.
QGLFormat(QGL.FormatOptions options)
          Creates a QGLFormat object that is a copy of the current application default format.
QGLFormat(QGL.FormatOptions options, int plane)
          Creates a QGLFormat object that is a copy of the current application default format.
QGLFormat(QGLFormat other)
          Constructs a copy of other.
 
Method Summary
 boolean accum()
          Returns true if the accumulation buffer is enabled; otherwise returns false.
 int accumBufferSize()
          Returns the accumulation buffer size.
 boolean alpha()
          Returns true if the alpha buffer in the framebuffer is enabled; otherwise returns false.
 int alphaBufferSize()
          Returns the alpha buffer size.
 int blueBufferSize()
          Returns the blue buffer size.
 QGLFormat clone()
          This method is reimplemented for internal reasons
static QGLFormat defaultFormat()
          Returns the default QGLFormat for the application.
static QGLFormat defaultOverlayFormat()
          Returns the default QGLFormat for overlay contexts.
 boolean depth()
          Returns true if the depth buffer is enabled; otherwise returns false.
 int depthBufferSize()
          Returns the depth buffer size.
 boolean directRendering()
          Returns true if direct rendering is enabled; otherwise returns false.
 boolean doubleBuffer()
          Returns true if double buffering is enabled; otherwise returns false.
 int greenBufferSize()
          Returns the green buffer size.
static boolean hasOpenGL()
          Returns true if the window system has any OpenGL support; otherwise returns false.
static boolean hasOpenGLOverlays()
          Returns true if the window system supports OpenGL overlays; otherwise returns false.
 boolean hasOverlay()
          Returns true if overlay plane is enabled; otherwise returns false.
static QGLFormat.OpenGLVersionFlags openGLVersionFlags()
          Identifies, at runtime, which OpenGL versions that are supported by the current platform.
 int plane()
          Returns the plane of this format.
 int redBufferSize()
          Returns the red buffer size.
 boolean rgba()
          Returns true if RGBA color mode is set.
 boolean sampleBuffers()
          Returns true if multisample buffer support is enabled; otherwise returns false.
 int samples()
          Returns the number of samples per pixel when multisampling is enabled.
 void setAccum(boolean enable)
          If enable is true enables the accumulation buffer; otherwise disables the accumulation buffer.
 void setAccumBufferSize(int size)
          Set the preferred accumulation buffer size, where size is the bit depth for each RGBA component.
 void setAlpha(boolean enable)
          If enable is true enables the alpha buffer; otherwise disables the alpha buffer.
 void setAlphaBufferSize(int size)
          Set the preferred alpha buffer size to size.
 void setBlueBufferSize(int size)
          Set the preferred blue buffer size to size.
static void setDefaultFormat(QGLFormat f)
          Sets a new default QGLFormat for the application to f.
static void setDefaultOverlayFormat(QGLFormat f)
          Sets a new default QGLFormat for overlay contexts to f.
 void setDepth(boolean enable)
          If enable is true enables the depth buffer; otherwise disables the depth buffer.
 void setDepthBufferSize(int size)
          Set the minimum depth buffer size to size.
 void setDirectRendering(boolean enable)
          If enable is true enables direct rendering; otherwise disables direct rendering.
 void setDoubleBuffer(boolean enable)
          If enable is true sets double buffering; otherwise sets single buffering.
 void setGreenBufferSize(int size)
          Set the preferred green buffer size to size.
 void setOption(QGL.FormatOption[] opt)
          This is an overloaded method provided for convenience.
 void setOption(QGL.FormatOptions opt)
          Sets the format option to opt.
 void setOverlay(boolean enable)
          If enable is true enables an overlay plane; otherwise disables the overlay plane.
 void setPlane(int plane)
          Sets the requested plane to plane.
 void setRedBufferSize(int size)
          Set the preferred red buffer size to size.
 void setRgba(boolean enable)
          If enable is true sets RGBA mode.
 void setSampleBuffers(boolean enable)
          If enable is true, a GL context with multisample buffer support is picked; otherwise ignored.
 void setSamples(int numSamples)
          Set the preferred number of samples per pixel when multisampling is enabled to numSamples.
 void setStencil(boolean enable)
          If enable is true enables the stencil buffer; otherwise disables the stencil buffer.
 void setStencilBufferSize(int size)
          Set the preferred stencil buffer size to size.
 void setStereo(boolean enable)
          If enable is true enables stereo buffering; otherwise disables stereo buffering.
 void setSwapInterval(int interval)
          Set the preferred swap interval.
 boolean stencil()
          Returns true if the stencil buffer is enabled; otherwise returns false.
 int stencilBufferSize()
          Returns the stencil buffer size.
 boolean stereo()
          Returns true if stereo buffering is enabled; otherwise returns false.
 int swapInterval()
          Returns the currently set swap interval.
 boolean testOption(QGL.FormatOption[] opt)
          This is an overloaded method provided for convenience.
 boolean testOption(QGL.FormatOptions opt)
          Returns true if format option opt is set; otherwise returns false.
 
Methods inherited from class com.trolltech.qt.QtJambiObject
dispose, disposed, equals, finalize, reassignNativeResources, tr, tr, tr
 
Methods inherited from class com.trolltech.qt.QSignalEmitter
blockSignals, disconnect, disconnect, signalsBlocked, signalSender, thread
 
Methods inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
__qt_signalInitialization
 
Methods inherited from class java.lang.Object
getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 
Methods inherited from interface com.trolltech.qt.QtJambiInterface
disableGarbageCollection, nativeId, nativePointer, reenableGarbageCollection, setJavaOwnership
 

Constructor Detail

QGLFormat

public QGLFormat()
Constructs a QGLFormat object with the factory default settings.


QGLFormat

public QGLFormat(QGL.FormatOptions options)
Creates a QGLFormat object that is a copy of the current application default format.

If options is not 0, this copy is modified by these format options. The options parameter should be FormatOption values OR'ed together.

This constructor makes it easy to specify a certain desired format in classes derived from QGLWidget, for example:

    // The rendering in MyGLWidget depends on using
    // stencil buffer and alpha channel
        class MyGLWidget extends QGLWidget {
        public MyGLWidget(QWidget parent)
        {
        super(new QGLFormat(new QGL.FormatOptions(QGL.FormatOption.StencilBuffer, QGL.FormatOption.AlphaChannel)), parent);
        if (!format().stencil())
            System.err.println("Could not get stencil buffer; results will be suboptimal");
        if (!format().alpha())
            System.err.println("Could not get alpha channel; results will be suboptimal");
        // ...
        }
    }
Note that there are FormatOption values to turn format settings both on and off, e.g. DepthBuffer and NoDepthBuffer, DirectRendering and IndirectRendering, etc.

The plane parameter defaults to 0 and is the plane which this format should be associated with. Not all OpenGL implementations supports overlay/underlay rendering planes.

See also:
defaultFormat(), and setOption().


QGLFormat

public QGLFormat(QGL.FormatOptions options,
                 int plane)
Creates a QGLFormat object that is a copy of the current application default format.

If options is not 0, this copy is modified by these format options. The options parameter should be FormatOption values OR'ed together.

This constructor makes it easy to specify a certain desired format in classes derived from QGLWidget, for example:

    // The rendering in MyGLWidget depends on using
    // stencil buffer and alpha channel
        class MyGLWidget extends QGLWidget {
        public MyGLWidget(QWidget parent)
        {
        super(new QGLFormat(new QGL.FormatOptions(QGL.FormatOption.StencilBuffer, QGL.FormatOption.AlphaChannel)), parent);
        if (!format().stencil())
            System.err.println("Could not get stencil buffer; results will be suboptimal");
        if (!format().alpha())
            System.err.println("Could not get alpha channel; results will be suboptimal");
        // ...
        }
    }
Note that there are FormatOption values to turn format settings both on and off, e.g. DepthBuffer and NoDepthBuffer, DirectRendering and IndirectRendering, etc.

The plane parameter defaults to 0 and is the plane which this format should be associated with. Not all OpenGL implementations supports overlay/underlay rendering planes.

See also:
defaultFormat(), and setOption().


QGLFormat

public QGLFormat(QGLFormat other)
Constructs a copy of other.

Method Detail

accum

public final boolean accum()
Returns true if the accumulation buffer is enabled; otherwise returns false. The accumulation buffer is disabled by default.

See also:
setAccum(), and setAccumBufferSize().


accumBufferSize

public final int accumBufferSize()
Returns the accumulation buffer size.

See also:
setAccumBufferSize(), accum(), and setAccum().


alpha

public final boolean alpha()
Returns true if the alpha buffer in the framebuffer is enabled; otherwise returns false. The alpha buffer is disabled by default.

See also:
setAlpha(), and setAlphaBufferSize().


alphaBufferSize

public final int alphaBufferSize()
Returns the alpha buffer size.

See also:
alpha(), setAlpha(), and setAlphaBufferSize().


blueBufferSize

public final int blueBufferSize()
Returns the blue buffer size.

See also:
setBlueBufferSize().


depth

public final boolean depth()
Returns true if the depth buffer is enabled; otherwise returns false. The depth buffer is enabled by default.

See also:
setDepth(), and setDepthBufferSize().


depthBufferSize

public final int depthBufferSize()
Returns the depth buffer size.

See also:
depth(), setDepth(), and setDepthBufferSize().


directRendering

public final boolean directRendering()
Returns true if direct rendering is enabled; otherwise returns false.

Direct rendering is enabled by default.

See also:
setDirectRendering().


doubleBuffer

public final boolean doubleBuffer()
Returns true if double buffering is enabled; otherwise returns false. Double buffering is enabled by default.

See also:
setDoubleBuffer().


greenBufferSize

public final int greenBufferSize()
Returns the green buffer size.

See also:
setGreenBufferSize().


hasOverlay

public final boolean hasOverlay()
Returns true if overlay plane is enabled; otherwise returns false.

Overlay is disabled by default.

See also:
setOverlay().


plane

public final int plane()
Returns the plane of this format. The default for normal formats is 0, which means the normal plane. The default for overlay formats is 1, which is the first overlay plane.

See also:
setPlane().


redBufferSize

public final int redBufferSize()
Returns the red buffer size.

See also:
setRedBufferSize().


rgba

public final boolean rgba()
Returns true if RGBA color mode is set. Returns false if color index mode is set. The default color mode is RGBA.

See also:
setRgba().


sampleBuffers

public final boolean sampleBuffers()
Returns true if multisample buffer support is enabled; otherwise returns false.

The multisample buffer is disabled by default.

See also:
setSampleBuffers().


samples

public final int samples()
Returns the number of samples per pixel when multisampling is enabled. By default, the highest number of samples that is available is used.

See also:
setSampleBuffers(), sampleBuffers(), and setSamples().


setAccum

public final void setAccum(boolean enable)
If enable is true enables the accumulation buffer; otherwise disables the accumulation buffer.

The accumulation buffer is disabled by default.

The accumulation buffer is used to create blur effects and multiple exposures.

See also:
accum(), and setAccumBufferSize().


setAccumBufferSize

public final void setAccumBufferSize(int size)
Set the preferred accumulation buffer size, where size is the bit depth for each RGBA component.

See also:
accum(), setAccum(), and accumBufferSize().


setAlpha

public final void setAlpha(boolean enable)
If enable is true enables the alpha buffer; otherwise disables the alpha buffer.

The alpha buffer is disabled by default.

The alpha buffer is typically used for implementing transparency or translucency. The A in RGBA specifies the transparency of a pixel.

See also:
alpha(), and setAlphaBufferSize().


setAlphaBufferSize

public final void setAlphaBufferSize(int size)
Set the preferred alpha buffer size to size. This function implicitly enables the alpha channel.

See also:
setRedBufferSize(), setGreenBufferSize(), and alphaBufferSize().


setBlueBufferSize

public final void setBlueBufferSize(int size)
Set the preferred blue buffer size to size.

See also:
blueBufferSize(), setRedBufferSize(), setGreenBufferSize(), and setAlphaBufferSize().


setDepth

public final void setDepth(boolean enable)
If enable is true enables the depth buffer; otherwise disables the depth buffer.

The depth buffer is enabled by default.

The purpose of a depth buffer (or Z-buffering) is to remove hidden surfaces. Pixels are assigned Z values based on the distance to the viewer. A pixel with a high Z value is closer to the viewer than a pixel with a low Z value. This information is used to decide whether to draw a pixel or not.

See also:
depth(), and setDepthBufferSize().


setDepthBufferSize

public final void setDepthBufferSize(int size)
Set the minimum depth buffer size to size.

See also:
depthBufferSize(), setDepth(), and depth().


setDirectRendering

public final void setDirectRendering(boolean enable)
If enable is true enables direct rendering; otherwise disables direct rendering.

Direct rendering is enabled by default.

Enabling this option will make OpenGL bypass the underlying window system and render directly from hardware to the screen, if this is supported by the system.

See also:
directRendering().


setDoubleBuffer

public final void setDoubleBuffer(boolean enable)
If enable is true sets double buffering; otherwise sets single buffering.

Double buffering is enabled by default.

Double buffering is a technique where graphics are rendered on an off-screen buffer and not directly to the screen. When the drawing has been completed, the program calls a swapBuffers() function to exchange the screen contents with the buffer. The result is flicker-free drawing and often better performance.

See also:
doubleBuffer(), QGLContext::swapBuffers(), and QGLWidget::swapBuffers().


setGreenBufferSize

public final void setGreenBufferSize(int size)
Set the preferred green buffer size to size.

See also:
greenBufferSize(), setRedBufferSize(), setBlueBufferSize(), and setAlphaBufferSize().


setOption

public final void setOption(QGL.FormatOption[] opt)
This is an overloaded method provided for convenience.


setOption

public final void setOption(QGL.FormatOptions opt)
Sets the format option to opt.

See also:
testOption().


setOverlay

public final void setOverlay(boolean enable)
If enable is true enables an overlay plane; otherwise disables the overlay plane.

Enabling the overlay plane will cause QGLWidget to create an additional context in an overlay plane. See the QGLWidget documentation for further information.

See also:
hasOverlay().


setPlane

public final void setPlane(int plane)
Sets the requested plane to plane. 0 is the normal plane, 1 is the first overlay plane, 2 is the second overlay plane, etc.; -1, -2, etc. are underlay planes.

Note that in contrast to other format specifications, the plane specifications will be matched exactly. This means that if you specify a plane that the underlying OpenGL system cannot provide, an invalidQGLWidget will be created.

See also:
plane().


setRedBufferSize

public final void setRedBufferSize(int size)
Set the preferred red buffer size to size.

See also:
redBufferSize(), setGreenBufferSize(), setBlueBufferSize(), and setAlphaBufferSize().


setRgba

public final void setRgba(boolean enable)
If enable is true sets RGBA mode. If enable is false sets color index mode.

The default color mode is RGBA.

RGBA is the preferred mode for most OpenGL applications. In RGBA color mode you specify colors as red + green + blue + alpha quadruplets.

In color index mode you specify an index into a color lookup table.

See also:
rgba().


setSampleBuffers

public final void setSampleBuffers(boolean enable)
If enable is true, a GL context with multisample buffer support is picked; otherwise ignored.

See also:
sampleBuffers(), setSamples(), and samples().


setSamples

public final void setSamples(int numSamples)
Set the preferred number of samples per pixel when multisampling is enabled to numSamples. By default, the highest number of samples available is used.

See also:
setSampleBuffers(), sampleBuffers(), and samples().


setStencil

public final void setStencil(boolean enable)
If enable is true enables the stencil buffer; otherwise disables the stencil buffer.

The stencil buffer is disabled by default.

The stencil buffer masks certain parts of the drawing area so that masked parts are not drawn on.

See also:
stencil(), and setStencilBufferSize().


setStencilBufferSize

public final void setStencilBufferSize(int size)
Set the preferred stencil buffer size to size.

See also:
stencilBufferSize(), setStencil(), and stencil().


setStereo

public final void setStereo(boolean enable)
If enable is true enables stereo buffering; otherwise disables stereo buffering.

Stereo buffering is disabled by default.

Stereo buffering provides extra color buffers to generate left-eye and right-eye images.

See also:
stereo().


setSwapInterval

public final void setSwapInterval(int interval)
Set the preferred swap interval. This can be used to sync the GL drawing into a system window to the vertical refresh of the screen. Setting an interval value of 0 will turn the vertical refresh syncing off, any value higher than 0 will turn the vertical syncing on.

Under Windows and under X11, where the WGL_EXT_swap_control and GLX_SGI_video_sync extensions are used, the interval parameter can be used to set the minimum number of video frames that are displayed before a buffer swap will occur. In effect, setting the interval to 10, means there will be 10 vertical retraces between every buffer swap.

Under Windows the WGL_EXT_swap_control extension has to be present, and under X11 the GLX_SGI_video_sync extension has to be present.

See also:
swapInterval().


stencil

public final boolean stencil()
Returns true if the stencil buffer is enabled; otherwise returns false. The stencil buffer is disabled by default.

See also:
setStencil(), and setStencilBufferSize().


stencilBufferSize

public final int stencilBufferSize()
Returns the stencil buffer size.

See also:
stencil(), setStencil(), and setStencilBufferSize().


stereo

public final boolean stereo()
Returns true if stereo buffering is enabled; otherwise returns false. Stereo buffering is disabled by default.

See also:
setStereo().


swapInterval

public final int swapInterval()
Returns the currently set swap interval. -1 is returned if setting the swap interval isn't supported in the system GL implementation.

See also:
setSwapInterval().


testOption

public final boolean testOption(QGL.FormatOption[] opt)
This is an overloaded method provided for convenience.


testOption

public final boolean testOption(QGL.FormatOptions opt)
Returns true if format option opt is set; otherwise returns false.

See also:
setOption().


defaultFormat

public static QGLFormat defaultFormat()
Returns the default QGLFormat for the application. All QGLWidgets that are created use this format unless another format is specified, e.g. when they are constructed.

If no special default format has been set using setDefaultFormat(), the default format is the same as that created with QGLFormat().

See also:
setDefaultFormat().


defaultOverlayFormat

public static QGLFormat defaultOverlayFormat()
Returns the default QGLFormat for overlay contexts.

The factory default overlay format is:

See also:
setDefaultOverlayFormat(), and setDefaultFormat().


hasOpenGL

public static boolean hasOpenGL()
Returns true if the window system has any OpenGL support; otherwise returns false.

Warning: This function must not be called until the QApplication object has been created.


hasOpenGLOverlays

public static boolean hasOpenGLOverlays()
Returns true if the window system supports OpenGL overlays; otherwise returns false.

Warning: This function must not be called until the QApplication object has been created.


openGLVersionFlags

public static QGLFormat.OpenGLVersionFlags openGLVersionFlags()
Identifies, at runtime, which OpenGL versions that are supported by the current platform.

Note that if OpenGL version 1.5 is supported, its predecessors (i.e., version 1.4 and lower) are also supported. To identify the support of a particular feature, like multi texturing, test for the version in which the feature was first introduced (i.e., version 1.3 in the case of multi texturing) to adapt to the largest possible group of runtime platforms.

This function needs a valid current OpenGL context to work; otherwise it will return OpenGL_Version_None .

See also:
hasOpenGL(), and hasOpenGLOverlays().


setDefaultFormat

public static void setDefaultFormat(QGLFormat f)
Sets a new default QGLFormat for the application to f. For example, to set single buffering as the default instead of double buffering, your main() might contain code like this:
    QApplication.initialize(args);
    QGLFormat f = new QGLFormat();
    f.setDoubleBuffer(false);
    QGLFormat.setDefaultFormat(f);

See also:
defaultFormat().


setDefaultOverlayFormat

public static void setDefaultOverlayFormat(QGLFormat f)
Sets a new default QGLFormat for overlay contexts to f. This format is used whenever a QGLWidget is created with a format that hasOverlay() enabled.

For example, to get a double buffered overlay context (if available), use code like this:

    QGLFormat f = QGLFormat.defaultOverlayFormat();
    f.setDoubleBuffer(true);
    QGLFormat.setDefaultOverlayFormat(f);
As usual, you can find out after widget creation whether the underlying OpenGL system was able to provide the requested specification:
    // ...continued from above
    MyGLWidget myWidget = new MyGLWidget(new QGLFormat(new QGL.FormatOptions(QGL.FormatOption.HasOverlay)));
    if (myWidget.format().hasOverlay()) {
        // Yes, we got an overlay, let's check _its_ format:
        QGLContext olContext = myWidget.overlayContext();
        if (olContext.format().doubleBuffer())
        ; // yes, we got a double buffered overlay
        else
        ; // no, only single buffered overlays are available
    }

See also:
defaultOverlayFormat().


clone

public QGLFormat clone()
This method is reimplemented for internal reasons

Overrides:
clone in class java.lang.Object