QGLBuffer

The QGLBuffer class provides functions for creating and managing GL buffer objects. More

Inheritance diagram of PySide2.QtOpenGL.QGLBuffer

New in version 4.7.

Synopsis

Functions

Static functions

Detailed Description

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

QGLBuffer objects can be copied around as a reference to the underlying GL buffer object:

QGLBuffer buffer1(QGLBuffer::IndexBuffer);
buffer1.create();

QGLBuffer buffer2 = buffer1;

QGLBuffer 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.

Note

This class has been deprecated in favor of QOpenGLBuffer .

class QGLBuffer

QGLBuffer(type)

QGLBuffer(other)

param type

Type

param other

QGLBuffer

Constructs a new buffer object of type VertexBuffer .

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

See also

create()

Constructs a new buffer object of type .

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

See also

create()

PySide2.QtOpenGL.QGLBuffer.Type

This enum defines the type of GL buffer object to create with QGLBuffer .

Constant

Description

QGLBuffer.VertexBuffer

Vertex buffer object for use when specifying vertex arrays.

QGLBuffer.IndexBuffer

Index buffer object for use with glDrawElements().

QGLBuffer.PixelPackBuffer

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

QGLBuffer.PixelUnpackBuffer

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

New in version 4.7.

PySide2.QtOpenGL.QGLBuffer.UsagePattern

This enum defines the usage pattern of a QGLBuffer object.

Constant

Description

QGLBuffer.StreamDraw

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

QGLBuffer.StreamRead

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

QGLBuffer.StreamCopy

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

QGLBuffer.StaticDraw

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

QGLBuffer.StaticRead

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

QGLBuffer.StaticCopy

The data will be set once and used many times for reading data back from the GL server for use in further drawing operations. Not supported under OpenGL/ES.

QGLBuffer.DynamicDraw

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

QGLBuffer.DynamicRead

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

QGLBuffer.DynamicCopy

The data will be modified repeatedly and used many times for reading data back from the GL server for use in further drawing operations. Not supported under OpenGL/ES.

New in version 4.7.

PySide2.QtOpenGL.QGLBuffer.Access

This enum defines the access mode for map() .

Constant

Description

QGLBuffer.ReadOnly

The buffer will be mapped for reading only.

QGLBuffer.WriteOnly

The buffer will be mapped for writing only.

QGLBuffer.ReadWrite

The buffer will be mapped for reading and writing.

New in version 4.7.

PySide2.QtOpenGL.QGLBuffer.allocate(data[, count=-1])
Parameters
  • datavoid

  • countint

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.

PySide2.QtOpenGL.QGLBuffer.allocate(count)
Parameters

countint

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()

PySide2.QtOpenGL.QGLBuffer.bind()
Return type

bool

Binds the buffer associated with this object to the current GL context. Returns false if binding was not possible, usually because type() is not supported on this GL implementation.

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

See also

release() create()

PySide2.QtOpenGL.QGLBuffer.bufferId()
Return type

GLuint

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

See also

isCreated()

PySide2.QtOpenGL.QGLBuffer.create()
Return type

bool

Creates the buffer object in the GL server. Returns true if the object was created; false otherwise.

This function must be called with a current QGLContext . 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 GL implementation does not support buffers, or there is no current QGLContext .

PySide2.QtOpenGL.QGLBuffer.destroy()

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

PySide2.QtOpenGL.QGLBuffer.isCreated()
Return type

bool

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

See also

create() destroy()

PySide2.QtOpenGL.QGLBuffer.map(access)
Parameters

accessAccess

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.

This function is only supported under OpenGL/ES if the GL_OES_mapbuffer extension is present.

PySide2.QtOpenGL.QGLBuffer.read(offset, count)
Parameters
  • offsetint

  • countint

Return type

(retval, data)

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()

PySide2.QtOpenGL.QGLBuffer.release()

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

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

See also

bind()

static PySide2.QtOpenGL.QGLBuffer.release(type)
Parameters

typeType

Releases the buffer associated with type in the current QGLContext .

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

QGLBuffer::release(QGLBuffer::VertexBuffer);
PySide2.QtOpenGL.QGLBuffer.setUsagePattern(value)
Parameters

valueUsagePattern

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

PySide2.QtOpenGL.QGLBuffer.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()

PySide2.QtOpenGL.QGLBuffer.type()
Return type

Type

Returns the type of buffer represented by this object.

PySide2.QtOpenGL.QGLBuffer.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() .

This function is only supported under OpenGL/ES if the GL_OES_mapbuffer extension is present.

See also

map()

PySide2.QtOpenGL.QGLBuffer.usagePattern()
Return type

UsagePattern

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

PySide2.QtOpenGL.QGLBuffer.write(offset, data[, count=-1])
Parameters
  • offsetint

  • datavoid

  • countint

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.