The QOpenGLBuffer class provides functions for creating and managing OpenGL buffer objects. More...

#include <qopenglbuffer.h>

Collaboration diagram for QOpenGLBuffer:

Public Types
enum	Type { VertexBuffer = 0x8892 , IndexBuffer = 0x8893 , PixelPackBuffer = 0x88EB , PixelUnpackBuffer = 0x88EC }
	This enum defines the type of OpenGL buffer object to create with QOpenGLBuffer. More...

enum	UsagePattern { StreamDraw = 0x88E0 , StreamRead = 0x88E1 , StreamCopy = 0x88E2 , StaticDraw = 0x88E4 , StaticRead = 0x88E5 , StaticCopy = 0x88E6 , DynamicDraw = 0x88E8 , DynamicRead = 0x88E9 , DynamicCopy = 0x88EA }
	This enum defines the usage pattern of a QOpenGLBuffer object. More...

enum	Access { ReadOnly = 0x88B8 , WriteOnly = 0x88B9 , ReadWrite = 0x88BA }
	This enum defines the access mode for QOpenGLBuffer::map(). More...

enum	RangeAccessFlag { RangeRead = 0x0001 , RangeWrite = 0x0002 , RangeInvalidate = 0x0004 , RangeInvalidateBuffer = 0x0008 , RangeFlushExplicit = 0x0010 , RangeUnsynchronized = 0x0020 }
	This enum defines the access mode bits for QOpenGLBuffer::mapRange(). More...

Public Member Functions
	QOpenGLBuffer ()
	Constructs a new buffer object of type QOpenGLBuffer::VertexBuffer.

	QOpenGLBuffer (QOpenGLBuffer::Type type)
	Constructs a new buffer object of type.

	QOpenGLBuffer (const QOpenGLBuffer &other)
	Constructs a shallow copy of other.

	QOpenGLBuffer (QOpenGLBuffer &&other) noexcept

	~QOpenGLBuffer ()
	Destroys this buffer object, including the storage being used in the OpenGL server.

QOpenGLBuffer &	operator= (const QOpenGLBuffer &other)
	Assigns a shallow copy of other to this object.

void	swap (QOpenGLBuffer &other) noexcept

QOpenGLBuffer::Type	type () const
	Returns the type of buffer represented by this object.

QOpenGLBuffer::UsagePattern	usagePattern () const
	Returns the usage pattern for this buffer object.

void	setUsagePattern (QOpenGLBuffer::UsagePattern value)
	Sets the usage pattern for this buffer object to value.

bool	create ()
	Creates the buffer object in the OpenGL server.

bool	isCreated () const
	Returns `true` if this buffer has been created; false otherwise.

void	destroy ()
	Destroys this buffer object, including the storage being used in the OpenGL server.

bool	bind ()
	Binds the buffer associated with this object to the current OpenGL context.

void	release ()
	Releases the buffer associated with this object from the current OpenGL context.

GLuint	bufferId () const
	Returns the OpenGL identifier associated with this buffer; zero if the buffer has not been created.

int	size () const
	Returns the size of the data in this buffer, for reading operations.

bool	read (int offset, void *data, int count)
	Reads the count bytes in this buffer starting at offset into data.

void	write (int offset, const void *data, int count)
	Replaces the count bytes of this buffer starting at offset with the contents of data.

void	allocate (const void *data, int count)
	Allocates count bytes of space to the buffer, initialized to the contents of data.

void	allocate (int count)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.Allocates count bytes of space to the buffer.

void *	map (QOpenGLBuffer::Access access)
	Maps the contents of this buffer into the application's memory space and returns a pointer to it.

void *	mapRange (int offset, int count, QOpenGLBuffer::RangeAccessFlags access)
	Maps the range specified by offset and count of the contents of this buffer into the application's memory space and returns a pointer to it.

bool	unmap ()
	Unmaps the buffer after it was mapped into the application's memory space with a previous call to map().

Static Public Member Functions
static void	release (QOpenGLBuffer::Type type)
	Releases the buffer associated with type in the current QOpenGLContext.

Detailed Description

The QOpenGLBuffer class provides functions for creating and managing OpenGL buffer objects.

Since: 5.0

\inmodule QtOpenGL

Buffer objects are created in the OpenGL server so that the client application can avoid uploading vertices, indices, texture image data, etc every time they are needed.

QOpenGLBuffer objects can be copied around as a reference to the underlying OpenGL buffer object:

QOpenGLBuffer buffer1(QOpenGLBuffer::IndexBuffer);
buffer1.create();
 
QOpenGLBuffer buffer2 = buffer1;

QOpenGLBuffer performs a shallow copy when objects are copied in this manner, but does not implement copy-on-write semantics. The original object will be affected whenever the copy is modified.

Definition at line 18 of file qopenglbuffer.h.

Member Enumeration Documentation

◆ Access

enum QOpenGLBuffer::Access

This enum defines the access mode for QOpenGLBuffer::map().

\value ReadOnly The buffer will be mapped for reading only. \value WriteOnly The buffer will be mapped for writing only. \value ReadWrite The buffer will be mapped for reading and writing.

Enumerator
ReadOnly
WriteOnly
ReadWrite

Definition at line 55 of file qopenglbuffer.h.

◆ RangeAccessFlag

enum QOpenGLBuffer::RangeAccessFlag

This enum defines the access mode bits for QOpenGLBuffer::mapRange().

\value RangeRead The buffer will be mapped for reading. \value RangeWrite The buffer will be mapped for writing. \value RangeInvalidate Discard the previous contents of the specified range. \value RangeInvalidateBuffer Discard the previous contents of the entire buffer. \value RangeFlushExplicit Indicates that modifications are to be flushed explicitly via glFlushMappedBufferRange. \value RangeUnsynchronized Indicates that pending operations should not be synchronized before returning from mapRange().

Enumerator
RangeRead
RangeWrite
RangeInvalidate
RangeInvalidateBuffer
RangeFlushExplicit
RangeUnsynchronized

Definition at line 62 of file qopenglbuffer.h.

◆ Type

enum QOpenGLBuffer::Type

This enum defines the type of OpenGL buffer object to create with QOpenGLBuffer.

\value VertexBuffer Vertex buffer object for use when specifying vertex arrays. \value IndexBuffer Index buffer object for use with {glDrawElements()}. \value PixelPackBuffer Pixel pack buffer object for reading pixel data from the OpenGL server (for example, with {glReadPixels()}). Not supported under OpenGL/ES. \value PixelUnpackBuffer Pixel unpack buffer object for writing pixel data to the OpenGL server (for example, with {glTexImage2D()}). Not supported under OpenGL/ES.

Enumerator
VertexBuffer
IndexBuffer
PixelPackBuffer
PixelUnpackBuffer

Definition at line 21 of file qopenglbuffer.h.

◆ UsagePattern

enum QOpenGLBuffer::UsagePattern

This enum defines the usage pattern of a QOpenGLBuffer object.

\value StreamDraw The data will be set once and used a few times for drawing operations. Under OpenGL/ES 1.1 this is identical to StaticDraw. \value StreamRead The data will be set once and used a few times for reading data back from the OpenGL server. Not supported under OpenGL/ES. \value StreamCopy The data will be set once and used a few times for reading data back from the OpenGL server for use in further drawing operations. Not supported under OpenGL/ES. \value StaticDraw The data will be set once and used many times for drawing operations. \value StaticRead The data will be set once and used many times for reading data back from the OpenGL server. Not supported under OpenGL/ES. \value StaticCopy The data will be set once and used many times for reading data back from the OpenGL server for use in further drawing operations. Not supported under OpenGL/ES. \value DynamicDraw The data will be modified repeatedly and used many times for drawing operations. \value DynamicRead The data will be modified repeatedly and used many times for reading data back from the OpenGL server. Not supported under OpenGL/ES. \value DynamicCopy The data will be modified repeatedly and used many times for reading data back from the OpenGL server for use in further drawing operations. Not supported under OpenGL/ES.

Enumerator
StreamDraw
StreamRead
StreamCopy
StaticDraw
StaticRead
StaticCopy
DynamicDraw
DynamicRead
DynamicCopy

Definition at line 42 of file qopenglbuffer.h.

Constructor & Destructor Documentation

◆ QOpenGLBuffer() [1/4]

QOpenGLBuffer::QOpenGLBuffer ( )

Constructs a new buffer object of type QOpenGLBuffer::VertexBuffer.

Note: this constructor just creates the QOpenGLBuffer instance. The actual buffer object in the OpenGL server is not created until create() is called.

See also: create()

Definition at line 133 of file qopenglbuffer.cpp.

◆ QOpenGLBuffer() [2/4]

QOpenGLBuffer::QOpenGLBuffer ( QOpenGLBuffer::Type type )

explicit

Constructs a new buffer object of type.

Note: this constructor just creates the QOpenGLBuffer instance. The actual buffer object in the OpenGL server is not created until create() is called.

See also: create()

Definition at line 146 of file qopenglbuffer.cpp.

◆ QOpenGLBuffer() [3/4]

QOpenGLBuffer::QOpenGLBuffer ( const QOpenGLBuffer & other )

Constructs a shallow copy of other.

Note: QOpenGLBuffer does not implement copy-on-write semantics, so other will be affected whenever the copy is modified.

Definition at line 157 of file qopenglbuffer.cpp.

References QBasicAtomicInteger< T >::ref(), and QOpenGLBufferPrivate::ref.

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◆ QOpenGLBuffer() [4/4]

QOpenGLBuffer::QOpenGLBuffer ( QOpenGLBuffer && other )

inlinenoexcept

Since: 6.5

Move-constructs a new QOpenGLBuffer from other.

Note: The moved-from object other is placed in a partially-formed state, in which the only valid operations are destruction and assignment of a new value.

Definition at line 32 of file qopenglbuffer.h.

References other().

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◆ ~QOpenGLBuffer()

QOpenGLBuffer::~QOpenGLBuffer ( )

Destroys this buffer object, including the storage being used in the OpenGL server.

Definition at line 167 of file qopenglbuffer.cpp.

References QBasicAtomicInteger< T >::deref(), destroy(), and QOpenGLBufferPrivate::ref.

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Member Function Documentation

◆ allocate() [1/2]

void QOpenGLBuffer::allocate	(	const void *	data,
		int	count
	)

Allocates count bytes of space to the buffer, initialized to the contents of data.

Any previous contents will be removed.

It is assumed that create() has been called on this buffer and that it has been bound to the current context.

See also: create(), read(), write()

Definition at line 390 of file qopenglbuffer.cpp.

References d, isCreated(), and qWarning.

Referenced by QtWaylandClient::DecorationsBlitter::DecorationsBlitter(), and QOpenGLTextureGlyphCache::createTextureData().

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◆ allocate() [2/2]

void QOpenGLBuffer::allocate ( int count )

inline

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.Allocates count bytes of space to the buffer.

Any previous contents will be removed.

It is assumed that create() has been called on this buffer and that it has been bound to the current context.

See also: create(), write()

Definition at line 96 of file qopenglbuffer.h.

References allocate().

Referenced by allocate().

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◆ bind()

bool QOpenGLBuffer::bind ( )

Binds the buffer associated with this object to the current OpenGL context.

Returns false if binding was not possible, usually because type() is not supported on this OpenGL implementation.

The buffer must be bound to the same QOpenGLContext current when create() was called, or to another QOpenGLContext that is sharing with it. Otherwise, false will be returned from this function.

See also: release(), create()

Definition at line 425 of file qopenglbuffer.cpp.

References bufferId(), QOpenGLContextGroup::currentContextGroup(), d, GLuint, isCreated(), and qWarning.

Referenced by QtWaylandClient::DecorationsBlitter::DecorationsBlitter(), QOpenGLTextureGlyphCache::createTextureData(), and QOpenGLTextureBlitterPrivate::prepareProgram().

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◆ bufferId()

GLuint QOpenGLBuffer::bufferId ( ) const

Returns the OpenGL identifier associated with this buffer; zero if the buffer has not been created.

See also: isCreated()

Definition at line 491 of file qopenglbuffer.cpp.

References d.

Referenced by bind(), and create().

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◆ create()

bool QOpenGLBuffer::create ( )

Creates the buffer object in the OpenGL server.

Returns true if the object was created; false otherwise.

This function must be called with a current QOpenGLContext. The buffer will be bound to and can only be used in that context (or any other context that is shared with it).

This function will return false if the OpenGL implementation does not support buffers, or there is no current QOpenGLContext.

See also: isCreated(), allocate(), write(), destroy()

Definition at line 277 of file qopenglbuffer.cpp.

References bufferId(), QOpenGLContext::currentContext(), d, and GLuint.

Referenced by QtWaylandClient::DecorationsBlitter::DecorationsBlitter(), QOpenGLTextureGlyphCache::createTextureData(), and src_gui_opengl_qopenglbuffer::wrapper().

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◆ destroy()

void QOpenGLBuffer::destroy ( )

Destroys this buffer object, including the storage being used in the OpenGL server.

All references to the buffer will become invalid.

Definition at line 315 of file qopenglbuffer.cpp.

References d.

Referenced by QOpenGL2PaintEngineExPrivate::~QOpenGL2PaintEngineExPrivate(), ~QOpenGLBuffer(), and operator=().

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◆ isCreated()

bool QOpenGLBuffer::isCreated ( ) const

Returns true if this buffer has been created; false otherwise.

See also: create(), destroy()

Definition at line 304 of file qopenglbuffer.cpp.

References d.

Referenced by allocate(), bind(), QOpenGLTextureGlyphCache::createTextureData(), map(), mapRange(), release(), unmap(), and write().

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◆ map()

void * QOpenGLBuffer::map ( QOpenGLBuffer::Access access )

Maps the contents of this buffer into the application's memory space and returns a pointer to it.

Returns null if memory mapping is not possible. The access parameter indicates the type of access to be performed.

It is assumed that create() has been called on this buffer and that it has been bound to the current context.

Note: This function is only supported under OpenGL ES 2.0 or earlier if the GL_OES_mapbuffer extension is present.; On OpenGL ES 3.0 and newer, or, in case if desktop OpenGL, if GL_ARB_map_buffer_range is supported, this function uses glMapBufferRange instead of glMapBuffer.

See also: unmap(), create(), bind(), mapRange()

Definition at line 534 of file qopenglbuffer.cpp.

References d, isCreated(), QOpenGLExtensions::MapBufferRange, qWarning, RangeRead, RangeWrite, ReadOnly, ReadWrite, and WriteOnly.

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◆ mapRange()

void * QOpenGLBuffer::mapRange	(	int	offset,
		int	count,
		QOpenGLBuffer::RangeAccessFlags	access
	)

Maps the range specified by offset and count of the contents of this buffer into the application's memory space and returns a pointer to it.

Returns null if memory mapping is not possible. The access parameter specifies a combination of access flags.

It is assumed that create() has been called on this buffer and that it has been bound to the current context.

Note: This function is not available on OpenGL ES 2.0 and earlier.

See also: unmap(), create(), bind()

Definition at line 575 of file qopenglbuffer.cpp.

References d, isCreated(), and qWarning.

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◆ operator=()

QOpenGLBuffer & QOpenGLBuffer::operator= ( const QOpenGLBuffer & other )

Assigns a shallow copy of other to this object.

Note: QOpenGLBuffer does not implement copy-on-write semantics, so other will be affected whenever the copy is modified.

Since: 6.5

Move-assigns other to this QOpenGLBuffer instance.

Note: The moved-from object other is placed in a partially-formed state, in which the only valid operations are destruction and assignment of a new value.

Definition at line 181 of file qopenglbuffer.cpp.

References QBasicAtomicInteger< T >::deref(), destroy(), other(), and QOpenGLBufferPrivate::ref.

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◆ read()

bool QOpenGLBuffer::read	(	int	offset,
		void *	data,
		int	count
	)

Reads the count bytes in this buffer starting at offset into data.

Returns true on success; false if reading from the buffer is not supported. Buffer reading is not supported under OpenGL/ES.

It is assumed that this buffer has been bound to the current context.

See also: write(), bind()

Definition at line 336 of file qopenglbuffer.cpp.

References QOpenGLFunctions::Buffers, d, error, GL_CONTEXT_LOST, GLenum(), and Q_UNUSED.

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◆ release() [1/2]

void QOpenGLBuffer::release ( )

Releases the buffer associated with this object from the current OpenGL context.

This function must be called with the same QOpenGLContext current as when bind() was called on the buffer.

See also: bind()

Definition at line 456 of file qopenglbuffer.cpp.

References d, isCreated(), and qWarning.

Referenced by QOpenGLTextureGlyphCache::createTextureData(), QOpenGLTextureBlitterPrivate::prepareProgram(), and src_gui_opengl_qopenglbuffer::wrapper().

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◆ release() [2/2]

void QOpenGLBuffer::release ( QOpenGLBuffer::Type type )

static

Releases the buffer associated with type in the current QOpenGLContext.

This function is a direct call to {glBindBuffer(type, 0)} for use when the caller does not know which QOpenGLBuffer has been bound to the context but wants to make sure that it is released.

QOpenGLBuffer::release(QOpenGLBuffer::VertexBuffer);

QOpenGLBuffer::VertexBuffer

@ VertexBuffer

Definition qopenglbuffer.h:23

QOpenGLBuffer::release

void release()

Releases the buffer associated with this object from the current OpenGL context.

Definition qopenglbuffer.cpp:456

Definition at line 478 of file qopenglbuffer.cpp.

References QOpenGLContext::currentContext(), and GLenum().

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◆ setUsagePattern()

void QOpenGLBuffer::setUsagePattern ( QOpenGLBuffer::UsagePattern value )

Sets the usage pattern for this buffer object to value.

This function must be called before allocate() or write().

See also: usagePattern(), allocate(), write()

Definition at line 251 of file qopenglbuffer.cpp.

References d.

◆ size()

int QOpenGLBuffer::size ( ) const

Returns the size of the data in this buffer, for reading operations.

Returns -1 if fetching the buffer size is not supported, or the buffer has not been created.

It is assumed that this buffer has been bound to the current context.

See also: isCreated(), bind()

Definition at line 506 of file qopenglbuffer.cpp.

References d, GL_BUFFER_SIZE, and GLint().

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◆ swap()

QOpenGLBuffer::swap ( QOpenGLBuffer & other )

inlinenoexcept

Since: 6.5

Swaps buffer other with this buffer. This operation is very fast and never fails.

Definition at line 39 of file qopenglbuffer.h.

References other(), and qt_ptr_swap().

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◆ type()

QOpenGLBuffer::Type QOpenGLBuffer::type ( ) const

Returns the type of buffer represented by this object.

Definition at line 227 of file qopenglbuffer.cpp.

References d.

◆ unmap()

bool QOpenGLBuffer::unmap ( )

Unmaps the buffer after it was mapped into the application's memory space with a previous call to map().

Returns true if the unmap succeeded; false otherwise.

It is assumed that this buffer has been bound to the current context, and that it was previously mapped with map().

Note: This function is only supported under OpenGL ES 2.0 and earlier if the {GL_OES_mapbuffer} extension is present.

See also: map()

Definition at line 600 of file qopenglbuffer.cpp.

References d, isCreated(), and qWarning.

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◆ usagePattern()

QOpenGLBuffer::UsagePattern QOpenGLBuffer::usagePattern ( ) const

Returns the usage pattern for this buffer object.

The default value is StaticDraw.

See also: setUsagePattern()

Definition at line 239 of file qopenglbuffer.cpp.

References d.

◆ write()

void QOpenGLBuffer::write	(	int	offset,
		const void *	data,
		int	count
	)

Replaces the count bytes of this buffer starting at offset with the contents of data.

Any other bytes in the buffer will be left unmodified.

It is assumed that create() has been called on this buffer and that it has been bound to the current context.

See also: create(), read(), allocate()

Definition at line 370 of file qopenglbuffer.cpp.

References d, isCreated(), and qWarning.

Referenced by QtWaylandClient::DecorationsBlitter::DecorationsBlitter().

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The documentation for this class was generated from the following files:

qtbase/src/opengl/qopenglbuffer.h
qtbase/src/opengl/qopenglbuffer.cpp

Public Types

Public Member Functions

Static Public Member Functions

Detailed Description

Member Enumeration Documentation

◆ Access

◆ RangeAccessFlag

◆ Type

◆ UsagePattern

Constructor & Destructor Documentation

◆ QOpenGLBuffer() [1/4]

◆ QOpenGLBuffer() [2/4]

◆ QOpenGLBuffer() [3/4]

◆ QOpenGLBuffer() [4/4]

◆ ~QOpenGLBuffer()

Member Function Documentation

◆ allocate() [1/2]

◆ allocate() [2/2]

◆ bind()

◆ bufferId()

◆ create()

◆ destroy()

◆ isCreated()

◆ map()

◆ mapRange()

◆ operator=()

◆ read()

◆ release() [1/2]

◆ release() [2/2]

◆ setUsagePattern()

◆ size()

◆ swap()

◆ type()

◆ unmap()

◆ usagePattern()

◆ write()