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

Public Typedefs
using	RangeAccessFlags = QFlags< RangeAccessFlag >

Public Types
enum	Access

enum	RangeAccessFlag

enum	Type

enum	UsagePattern

Public Methods
	QOpenGLBuffer ()

	QOpenGLBuffer (const QOpenGLBuffer &other)

	QOpenGLBuffer (QOpenGLBuffer::Type type)

	~QOpenGLBuffer ()

void	allocate (const void *data, int count)

void	allocate (int count)

bool	bind ()

GLuint	bufferId () const

bool	create ()

void	destroy ()

bool	isCreated () const

void *	map (QOpenGLBuffer::Access access)

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

QOpenGLBuffer &	operator= (const QOpenGLBuffer &other)

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

void	release ()

void	setUsagePattern (QOpenGLBuffer::UsagePattern value)

int	size () const

QOpenGLBuffer::Type	type () const

bool	unmap ()

QOpenGLBuffer::UsagePattern	usagePattern () const

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

Static Public Methods
static void	release (QOpenGLBuffer::Type type)

Detailed Description

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

Example

QOpenGLBuffer objects can be copied as a reference to the underlying OpenGL buffer object. A shallow copy will be done when objects are copied. The original object will be affected if the copy is modified.

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

Member Typedef Documentation

QOpenGLBuffer::RangeAccessFlags

Typedef for QFlags<RangeAccessFlag> which contains an OR combination of RangeAccessFlag values.

Refer to QOpenGLBuffer::RangeAccessFlag for the enum documentation.

Member Enumeration Documentation

enum QOpenGLBuffer::Access

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

Constant	Value	Description
QOpenGLBuffer::ReadOnly	0x88B8	Mapped for reading only
QOpenGLBuffer::WriteOnly	0x88B9	Mapped for writing only
QOpenGLBuffer::ReadWrite	0x88BA	Mapped for reading and writing

enum QOpenGLBuffer::RangeAccessFlag

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

Constant	Value	Description
QOpenGLBuffer::RangeRead	0x0001	Buffer will be mapped for reading
QOpenGLBuffer::RangeWrite	0x0002	Buffer will be mapped for writing
QOpenGLBuffer::RangeInvalidate	0x0004	Discard the previous contents of the specified range
QOpenGLBuffer::RangeInvalidateBuffer	0x0008	Discard the previous contents of the entire buffer
QOpenGLBuffer::RangeFlushExplicit	0x0010	Indicates modifications are to be flushed explicitly via glFlushMappedBufferRange
QOpenGLBuffer::RangeUnsynchronized	0x0020	Indicates pending operations should not be synchronized before returning from mapRange()

enum QOpenGLBuffer::Type

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

Constant	Value	Description
QOpenGLBuffer::VertexBuffer	0x8892	Vertex buffer object for use when specifying vertex arrays
QOpenGLBuffer::IndexBuffer	0x8893	Index buffer object for use with glDrawElements()
QOpenGLBuffer::PixelPackBuffer	0x88EB	Pixel pack buffer object for reading pixel data, used with glReadPixels(). Not supported under OpenGL/ES.
QOpenGLBuffer::PixelUnpackBuffer	0x88EC	Pixel unpack buffer object for writing pixel data, used with glTexImage2D(). Not supported under OpenGL/ES.

enum QOpenGLBuffer::UsagePattern

This enum defines the usage pattern of a QOpenGLBuffer object.

Constant	Value	Description
QOpenGLBuffer::StreamDraw	0x88E0	Data set once and used a few times for drawing. In OpenGL/ES 1.1 identical to QOpenGLBuffer::StaticDraw.
QOpenGLBuffer::StreamRead	0x88E1	Data set once and used a few times for reading. Not supported with OpenGL/ES.
QOpenGLBuffer::StreamCopy	0x88E2	Data set once and used a few times for reading data for use in later drawing. Not supported with OpenGL/ES.
QOpenGLBuffer::StaticDraw	0x88E4	Data set once and used many times for drawing
QOpenGLBuffer::StaticRead	0x88E5	Data set once and used many times for reading. Not supported with OpenGL/ES.
QOpenGLBuffer::StaticCopy	0x88E6	Data set once and used many times for reading data for use in later drawing. Not supported with OpenGL/ES.
QOpenGLBuffer::DynamicDraw	0x88E8	Data modified repeatedly and used many times for drawing
QOpenGLBuffer::DynamicRead	0x88E9	Data modified repeatedly and used many times for reading data. Not supported with OpenGL/ES.
QOpenGLBuffer::DynamicCopy	0x88EA	Data modified repeatedly and used many times for reading data for use in later drawing. Not supported under OpenGL/ES.

Constructor & Destructor Documentation

QOpenGLBuffer::QOpenGLBuffer ( )

Constructs a new buffer object of type QOpenGLBuffer::VertexBuffer and creates the QOpenGLBuffer instance. The actual buffer object in the OpenGL server is not created until create() is called.

See also: create()

QOpenGLBuffer::QOpenGLBuffer ( QOpenGLBuffer::Type type )

explicit

Constructs a new buffer object using type and creates the QOpenGLBuffer instance. The actual buffer object in the OpenGL server is not created until create() is called.

See also: create()

QOpenGLBuffer::QOpenGLBuffer ( const QOpenGLBuffer & other )

Constructs a shallow copy of other.

QOpenGLBuffer::~QOpenGLBuffer ( )

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

Method Documentation

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

Allocates count bytes of space to the buffer and initializes the buffer contents using data. Any previous contents will be removed. The create() method must be called before calling allocate() and the buffer must be bound to the current context.

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

void QOpenGLBuffer::allocate ( int count )

inline

Allocates count bytes of space to the buffer. Any previous contents will be removed. The create() method must be called before calling allocate() and the buffer must be bound to the current context.

See also: create(), write()

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.

See also: create(), release()

GLuint QOpenGLBuffer::bufferId ( ) const

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

See also: isCreated()

bool QOpenGLBuffer::create ( )

Creates the buffer object in the OpenGL server. Returns true if the object was created, otherwise false is returned. This method will also return false if the OpenGL implementation does not support buffers or there is no current QOpenGLContext.

This method 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 which is shared with it.

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

void QOpenGLBuffer::destroy ( )

Destroys this buffer object including the storage being used in the OpenGL server. All references to the buffer will become invalid.

bool QOpenGLBuffer::isCreated ( ) const

Returns true if this buffer has been created, otherwise returns false.

See also: create(), destroy()

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

Maps the contents of this buffer into host memory and returns a pointer to the mapped buffer. Returns a nullptr if memory mapping is not possible. The access parameter indicates the type of access to be performed.

The create() method must be called before calling map() and the buffer must be bound to the current context.

This method is only supported under OpenGL ES 2.0 or earlier if the GL_OES_mapbuffer extension is present. When possible this method uses glMapBufferRange instead of glMapBuffer.

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

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 host memory and returns a pointer to the mapped buffer. Returns a nullptr if memory mapping is not possible. The access parameter specifies a combination of access flags.

The create() method must be called before calling mapRange() and the buffer must be bound to the current context.

This method is not available on OpenGL ES 2.0 and earlier.

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

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

Assigns a shallow copy of other to this object.

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

Reads the count number of bytes in this buffer starting at offset into data. Returns true on success. Returns false if reading from the buffer is not supported. Buffer reading is not supported under OpenGL/ES.

The create() method must be called before calling read() and the buffer must be bound to the current context.

See also: bind(), write()

void QOpenGLBuffer::release ( )

Releases the buffer associated with this object from the current OpenGL context. This method must be called with the same QOpenGLContext current as when bind() was called on the buffer.

See also: bind()

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

static

Releases the buffer associated with type in the current QOpenGLContext. This method 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);

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

Sets the usage pattern for this buffer object to value. This method must be called before allocate() or write().

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

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 this buffer has been bound to the current context.

See also: bind(), isCreated()

QOpenGLBuffer::Type QOpenGLBuffer::type ( ) const

Returns the type of buffer represented by this object.

bool QOpenGLBuffer::unmap ( )

Unmaps the buffer after it was mapped into host memory with a previous call to map(). Returns true if this method succeeded, otherwise false is returned. The map() method must be called before calling unmap() and the buffer must be bound to the current context.

This method is only supported under OpenGL ES 2.0 and earlier if the GL_OES_mapbuffer extension is present.

See also: map()

QOpenGLBuffer::UsagePattern QOpenGLBuffer::usagePattern ( ) const

Returns the usage pattern for this buffer object. The default value is QOpenGLBuffer::StaticDraw.

See also: setUsagePattern()

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. The create() method must be called before calling write() and the buffer must be bound to the current context.

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

Public Typedefs

Public Types