QOpenGLBuffer — PyQt Documentation v6.9.0 (original) (raw)

PyQt6.QtOpenGL.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().

RangeAccessFlag

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

Type

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

UsagePattern

This enum defines the usage pattern of a QOpenGLBuffer object.

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.

__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.

__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)

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(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.

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.

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) → 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, RangeAccessFlag) → 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, 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.

@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().

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().

swap(QOpenGLBuffer)

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

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.

usagePattern() → UsagePattern

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

See also

setUsagePattern().

write(int, 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().