QGLFormat

PyQt5.QtOpenGL.QGLFormat

Description

The QGLFormat class specifies the display format of an OpenGL rendering context.

A display format has several characteristics:

• setDoubleBuffer()

• setDepth()

• setRgba()

• setAlpha()

• setAccum()

• setStencil()

• setStereo()

• setDirectRendering()

• setOverlay()

• setPlane()

• setSampleBuffers()

You can also specify preferred bit depths for the color buffer, depth buffer, alpha buffer, accumulation buffer and the stencil buffer with the functions: setRedBufferSize(), setGreenBufferSize(), setBlueBufferSize(), 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;
# 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;
# 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;
# fmt.setOverlay(true);
# fmt.setStereo(true);
# MyGLWidget* myWidget = new MyGLWidget(fmt, ...);
# if (!myWidget->format().stereo()) {
#     // ok, goggles off
#     if (!myWidget->format().hasOverlay()) {
#         qFatal("Cool hardware required");
#     }
# }

OpenGL is a trademark of Silicon Graphics, Inc. in the United States and other countries.

See also

QGLContext, QGLWidget.

Classes

OpenGLVersionFlags

Enums

OpenGLContextProfile

This enum describes the OpenGL context profiles that can be specified for contexts implementing OpenGL version 3.2 or higher. These profiles are different from OpenGL ES profiles.

Member	Value	Description
CompatibilityProfile	2	Functionality from earlier OpenGL versions is available.
CoreProfile	1	Functionality deprecated in OpenGL version 3.0 is not available.
NoProfile	0	OpenGL version is lower than 3.2.

---

OpenGLVersionFlag

This enum describes the various OpenGL versions that are recognized by Qt. Use the openGLVersionFlags() function to identify which versions that are supported at runtime.

See also http://www.opengl.org for more information about the different revisions of OpenGL.

See also

openGLVersionFlags().

Member	Value	Description
OpenGL_ES_Common_Version_1_0	0x00000080	OpenGL ES version 1.0 Common or higher is present. The Common profile supports all the features of Common Lite.
OpenGL_ES_Common_Version_1_1	0x00000200	OpenGL ES version 1.1 Common or higher is present. The Common profile supports all the features of Common Lite.
OpenGL_ES_CommonLite_Version_1_0	0x00000100	OpenGL ES version 1.0 Common Lite or higher is present.
OpenGL_ES_CommonLite_Version_1_1	0x00000400	OpenGL ES version 1.1 Common Lite or higher is present.
OpenGL_ES_Version_2_0	0x00000800	OpenGL ES version 2.0 or higher is present. Note that OpenGL ES version 2.0 does not support all the features of OpenGL ES 1.x. So if is returned, none of the ES 1.x flags are returned.
OpenGL_Version_1_1	0x00000001	OpenGL version 1.1 or higher is present.
OpenGL_Version_1_2	0x00000002	OpenGL version 1.2 or higher is present.
OpenGL_Version_1_3	0x00000004	OpenGL version 1.3 or higher is present.
OpenGL_Version_1_4	0x00000008	OpenGL version 1.4 or higher is present.
OpenGL_Version_1_5	0x00000010	OpenGL version 1.5 or higher is present.
OpenGL_Version_2_0	0x00000020	OpenGL version 2.0 or higher is present. Note that version 2.0 supports all the functionality of version 1.5.
OpenGL_Version_2_1	0x00000040	OpenGL version 2.1 or higher is present.
OpenGL_Version_3_0	0x00001000	OpenGL version 3.0 or higher is present.
OpenGL_Version_3_1	0x00002000	OpenGL version 3.1 or higher is present. Note that OpenGL version 3.1 or higher does not necessarily support all the features of version 3.0 and lower.
OpenGL_Version_3_2	0x00004000	OpenGL version 3.2 or higher is present.
OpenGL_Version_3_3	0x00008000	OpenGL version 3.3 or higher is present.
OpenGL_Version_4_0	0x00010000	OpenGL version 4.0 or higher is present.
OpenGL_Version_4_1	TODO	OpenGL version 4.1 or higher is present.
OpenGL_Version_4_2	TODO	OpenGL version 4.2 or higher is present.
OpenGL_Version_4_3	TODO	OpenGL version 4.3 or higher is present.
OpenGL_Version_None	0x00000000	If no OpenGL is present or if no OpenGL context is current.

Methods

__init__()

Constructs a QGLFormat object with the following default settings:

• setDoubleBuffer() Enabled.

• setDepth() Enabled.

• setRgba() Enabled (i.e., color index disabled).

• setAlpha() Disabled.

• setAccum() Disabled.

• setStencil() Enabled.

• setStereo() Disabled.

• setDirectRendering() Enabled.

• setOverlay() Disabled.

• setPlane() 0 (i.e., normal plane).

• setSampleBuffers() Disabled.

---

__init__(QGLFormat)

Constructs a copy of other.

---

__init__(Union[FormatOptions, FormatOption], plane: int = 0)

Creates a QGLFormat object that is a copy of the current defaultFormat().

If options is not 0, the default format is modified by the specified 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
# MyGLWidget::MyGLWidget(QWidget* parent)
#     : QGLWidget(QGLFormat(QGL::StencilBuffer | QGL::AlphaChannel), parent)
# {
#     if (!format().stencil())
#         qWarning("Could not get stencil buffer; results will be suboptimal");
#     if (!format().alpha())
#         qWarning("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(), setOption(), setPlane().

---

accum() → bool

See also

setAccum().

---

accumBufferSize() → int

Returns the accumulation buffer size.

See also

setAccumBufferSize(), accum(), setAccum().

---

alpha() → bool

See also

setAlpha().

---

alphaBufferSize() → int

Returns the alpha buffer size.

See also

alpha(), setAlpha(), setAlphaBufferSize().

---

blueBufferSize() → int

Returns the blue buffer size.

See also

setBlueBufferSize().

---

@staticmethod
defaultFormat() → QGLFormat

Returns the default QGLFormat for the application. All QGLWidget objects 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().

---

@staticmethod
defaultOverlayFormat() → QGLFormat

Returns the default QGLFormat for overlay contexts.

The default overlay format is:

• setDoubleBuffer() Disabled.

• setDepth() Disabled.

• setRgba() Disabled (i.e., color index enabled).

• setAlpha() Disabled.

• setAccum() Disabled.

• setStencil() Disabled.

• setStereo() Disabled.

• setDirectRendering() Enabled.

• setOverlay() Disabled.

• setSampleBuffers() Disabled.

• setPlane() 1 (i.e., first overlay plane).

See also

setDefaultOverlayFormat(), setDefaultFormat().

---

depth() → bool

See also

setDepth().

---

depthBufferSize() → int

Returns the depth buffer size.

See also

depth(), setDepth(), setDepthBufferSize().

---

directRendering() → bool

See also

setDirectRendering().

---

doubleBuffer() → bool

See also

setDoubleBuffer().

---

__eq__(QGLFormat) → bool

TODO

---

greenBufferSize() → int

Returns the green buffer size.

See also

setGreenBufferSize().

---

@staticmethod
hasOpenGL() → bool

TODO

---

@staticmethod
hasOpenGLOverlays() → bool

TODO

---

hasOverlay() → bool

TODO

---

majorVersion() → int

Returns the OpenGL major version.

See also

setVersion(), minorVersion().

---

minorVersion() → int

Returns the OpenGL minor version.

See also

setVersion(), majorVersion().

---

__ne__(QGLFormat) → bool

TODO

---

@staticmethod
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(), hasOpenGLOverlays().

---

plane() → int

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(), defaultOverlayFormat().

---

profile() → OpenGLContextProfile

Returns the OpenGL context profile.

See also

setProfile().

---

redBufferSize() → int

Returns the red buffer size.

See also

setRedBufferSize().

---

rgba() → bool

See also

setRgba().

---

sampleBuffers() → bool

See also

setSampleBuffers().

---

samples() → int

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(), setSamples().

---

setAccum(bool)

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(), setAccumBufferSize().

---

setAccumBufferSize(int)

Set the preferred accumulation buffer size, where size is the bit depth for each RGBA component.

See also

accum(), setAccum(), accumBufferSize().

---

setAlpha(bool)

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(), setAlphaBufferSize().

---

setAlphaBufferSize(int)

Set the preferred alpha buffer size to size. This function implicitly enables the alpha channel.

See also

setRedBufferSize(), setGreenBufferSize(), alphaBufferSize().

---

setBlueBufferSize(int)

Set the preferred blue buffer size to size.

See also

blueBufferSize(), setRedBufferSize(), setGreenBufferSize(), setAlphaBufferSize().

---

@staticmethod
setDefaultFormat(QGLFormat)

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 a(argc, argv);
# QGLFormat f;
# f.setDoubleBuffer(false);
# QGLFormat::setDefaultFormat(f);

See also

defaultFormat().

---

@staticmethod
setDefaultOverlayFormat(QGLFormat)

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(QGLFormat(QGL::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().

---

setDepth(bool)

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(), setDepthBufferSize().

---

setDepthBufferSize(int)

Set the minimum depth buffer size to size.

See also

depthBufferSize(), setDepth(), depth().

---

setDirectRendering(bool)

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(bool)

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.

Note that single buffered contexts are currently not supported with EGL.

See also

doubleBuffer(), swapBuffers(), swapBuffers().

---

setGreenBufferSize(int)

Set the preferred green buffer size to size.

See also

greenBufferSize(), setRedBufferSize(), setBlueBufferSize(), setAlphaBufferSize().

---

setOption(Union[FormatOptions, FormatOption])

Sets the format option to opt.

See also

testOption().

---

setOverlay(bool)

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(int)

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 isValid() QGLWidget will be created.

See also

plane().

---

setProfile(OpenGLContextProfile)

Set the OpenGL context profile to profile. The profile is ignored if the requested OpenGL version is less than 3.2.

See also

profile().

---

setRedBufferSize(int)

Set the preferred red buffer size to size.

See also

redBufferSize(), setGreenBufferSize(), setBlueBufferSize(), setAlphaBufferSize().

---

setRgba(bool)

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(bool)

If enable is true, a GL context with multisample buffer support is picked; otherwise ignored.

See also

sampleBuffers(), setSamples(), samples().

---

setSamples(int)

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(), samples().

---

setStencil(bool)

If enable is true enables the stencil buffer; otherwise disables the stencil buffer.

The stencil buffer is enabled by default.

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

See also

stencil(), setStencilBufferSize().

---

setStencilBufferSize(int)

Set the preferred stencil buffer size to size.

See also

stencilBufferSize(), setStencil(), stencil().

---

setStereo(bool)

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(int)

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().

---

setVersion(int, int)

Set the OpenGL version to the major and minor numbers. If a context compatible with the requested OpenGL version cannot be created, a context compatible with version 1.x is created instead.

See also

majorVersion(), minorVersion().

---

stencil() → bool

See also

setStencil().

---

stencilBufferSize() → int

Returns the stencil buffer size.

See also

stencil(), setStencil(), setStencilBufferSize().

---

stereo() → bool

See also

setStereo().

---

swapInterval() → int

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(Union[FormatOptions, FormatOption]) → bool

Returns true if format option opt is set; otherwise returns false.

See also

setOption().