class QOpenGLBuffer¶

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

Synopsis¶

Methods¶

def __init__()
def allocate()
def bind()
def bufferId()
def create()
def destroy()
def isCreated()
def map()
def mapRange()
def read()
def release()
def setUsagePattern()
def size()
def swap()
def type()
def unmap()
def usagePattern()
def write()

Static functions¶

def release()

Note

This documentation may contain snippets that were automatically translated from C++ to Python. We always welcome contributions to the snippet translation. If you see an issue with the translation, you can also let us know by creating a ticket on https:/bugreports.qt.io/projects/PYSIDE

Detailed Description¶

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

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:

buffer1 = QOpenGLBuffer(QOpenGLBuffer.IndexBuffer)
buffer1.create()
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.

class Type¶

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

Constant

Description

QOpenGLBuffer.VertexBuffer

Vertex buffer object for use when specifying vertex arrays.

QOpenGLBuffer.IndexBuffer

Index buffer object for use with glDrawElements().

QOpenGLBuffer.PixelPackBuffer

Pixel pack buffer object for reading pixel data from the OpenGL server (for example, with glReadPixels()). Not supported under OpenGL/ES.

QOpenGLBuffer.PixelUnpackBuffer

Pixel unpack buffer object for writing pixel data to the OpenGL server (for example, with glTexImage2D()). Not supported under OpenGL/ES.

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

class UsagePattern¶

This enum defines the usage pattern of a QOpenGLBuffer object.

Constant

Description

QOpenGLBuffer.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.

QOpenGLBuffer.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.

QOpenGLBuffer.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.

QOpenGLBuffer.StaticDraw

The data will be set once and used many times for drawing operations.

QOpenGLBuffer.StaticRead

The data will be set once and used many times for reading data back from the OpenGL server. Not supported under OpenGL/ES.

QOpenGLBuffer.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.

QOpenGLBuffer.DynamicDraw

The data will be modified repeatedly and used many times for drawing operations.

QOpenGLBuffer.DynamicRead

The data will be modified repeatedly and used many times for reading data back from the OpenGL server. Not supported under OpenGL/ES.

QOpenGLBuffer.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.

Constant	Description
QOpenGLBuffer.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.
QOpenGLBuffer.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.
QOpenGLBuffer.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.
QOpenGLBuffer.StaticDraw	The data will be set once and used many times for drawing operations.
QOpenGLBuffer.StaticRead	The data will be set once and used many times for reading data back from the OpenGL server. Not supported under OpenGL/ES.
QOpenGLBuffer.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.
QOpenGLBuffer.DynamicDraw	The data will be modified repeatedly and used many times for drawing operations.
QOpenGLBuffer.DynamicRead	The data will be modified repeatedly and used many times for reading data back from the OpenGL server. Not supported under OpenGL/ES.
QOpenGLBuffer.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.

class Access¶

This enum defines the access mode for map() .

Constant

Description

QOpenGLBuffer.ReadOnly

The buffer will be mapped for reading only.

QOpenGLBuffer.WriteOnly

The buffer will be mapped for writing only.

QOpenGLBuffer.ReadWrite

The buffer will be mapped for reading and writing.

Constant	Description
QOpenGLBuffer.ReadOnly	The buffer will be mapped for reading only.
QOpenGLBuffer.WriteOnly	The buffer will be mapped for writing only.
QOpenGLBuffer.ReadWrite	The buffer will be mapped for reading and writing.

class RangeAccessFlag¶

(inherits enum.Flag) This enum defines the access mode bits for mapRange() .

Constant

Description

QOpenGLBuffer.RangeRead

The buffer will be mapped for reading.

QOpenGLBuffer.RangeWrite

The buffer will be mapped for writing.

QOpenGLBuffer.RangeInvalidate

Discard the previous contents of the specified range.

QOpenGLBuffer.RangeInvalidateBuffer

Discard the previous contents of the entire buffer.

QOpenGLBuffer.RangeFlushExplicit

Indicates that modifications are to be flushed explicitly via glFlushMappedBufferRange.

QOpenGLBuffer.RangeUnsynchronized

Indicates that pending operations should not be synchronized before returning from mapRange() .

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

__init__()¶

Constructs a new buffer object of type 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()

__init__(type)

Parameters:: type – Type

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()

__init__(other)

Parameters:: other – QOpenGLBuffer

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.

allocate(count)¶

Parameters:: count – int

This is an overloaded function.

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()

allocate(data, count)

Parameters:

data – void
count – int

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()

bind()¶

Return type:: bool

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()

bufferId()¶

Return type:: int

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

See also

isCreated()

create()¶

Return type:: bool

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()

destroy()¶

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

isCreated()¶

Return type:: bool

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

See also

create() destroy()

map(access)¶

Parameters:: access – Access
Return type:: void

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.

Note

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()

read(offset, data, count)¶

Parameters:

offset – int
data – void
count – int

Return type:

bool

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()

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()

static release(type)

Parameters:: type – Type

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

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)

setUsagePattern(value)¶

Parameters:: value – UsagePattern

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

See also

usagePattern() allocate() write()

size()¶

Return type:: int

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()

swap(other)¶

Parameters:: other – QOpenGLBuffer

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

type()¶

Return type:: Type

Returns the type of buffer represented by this object.

unmap()¶

Return type:: bool

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.