QOpenGLBuffer¶

PyQt5.QtGui.QOpenGLBuffer

Description¶

The QOpenGLBuffer class provides functions 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.

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.

Enums¶

Access

This enum defines the access mode for map().

Member

Value

Description
ReadOnly

0x88B8

The buffer will be mapped for reading only.
ReadWrite

0x88BA

The buffer will be mapped for reading and writing.
WriteOnly

0x88B9

The buffer will be mapped for writing only.
RangeAccessFlag

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

Member

Value

Description
RangeFlushExplicit

0x0010

Indicates that modifications are to be flushed explicitly via glFlushMappedBufferRange.
RangeInvalidate

0x0004

Discard the previous contents of the specified range.
RangeInvalidateBuffer

0x0008

Discard the previous contents of the entire buffer.
RangeRead

0x0001

The buffer will be mapped for reading.
RangeUnsynchronized

0x0020

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

0x0002

The buffer will be mapped for writing.
Type

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

Member

Value

Description
IndexBuffer

0x8893

Index buffer object for use with glDrawElements().
PixelPackBuffer

0x88EB

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

0x88EC

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

0x8892

Vertex buffer object for use when specifying vertex arrays.
UsagePattern

This enum defines the usage pattern of a QOpenGLBuffer object.

Member

Value

Description
DynamicCopy

0x88EA

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.
DynamicDraw

0x88E8

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

0x88E9

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

0x88E6

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.
StaticDraw

0x88E4

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

0x88E5

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

0x88E2

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.
StreamDraw

0x88E0

The data will be set once and used a few times for drawing operations. Under OpenGL/ES 1.1 this is identical to .
StreamRead

0x88E1

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

Methods¶

__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)

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__(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(int)

TODO

allocate(sip.voidptr, 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() → 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() → int

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

See also

isCreated().

create() → 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() → bool

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

See also

create(), destroy().

__len__() → int

TODO

map(Access) → sip.voidptr

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(), mapRange().

mapRange(int, int, Union[RangeAccessFlags, RangeAccessFlag]) → sip.voidptr

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().

read(int, sip.voidptr, int) → 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().

@staticmethod
release(Type)

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(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() → 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().

type() → Type

Returns the type of buffer represented by this object.

unmap() → 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.

See also

map().

usagePattern() → UsagePattern

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

See also

setUsagePattern().

write(int, sip.voidptr, int)

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().