QOpenGLBuffer ¶

概要 ¶

详细描述 ¶

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.

class QOpenGLBuffer ¶

QOpenGLBuffer(type)

QOpenGLBuffer(other)

param type

Type

param other

QOpenGLBuffer

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() 被调用。

另请参阅

create()

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() 被调用。

另请参阅

create()

PySide2.QtGui.QOpenGLBuffer. Type ¶

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

常量	描述
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.

PySide2.QtGui.QOpenGLBuffer. UsagePattern ¶

This enum defines the usage pattern of a QOpenGLBuffer 对象。

常量	描述
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 .
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.

PySide2.QtGui.QOpenGLBuffer. Access ¶

This enum defines the access mode for map() .

常量	描述
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.

PySide2.QtGui.QOpenGLBuffer. RangeAccessFlag ¶

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

常量	描述
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() .

PySide2.QtGui.QOpenGLBuffer. allocate ( data , count ) ¶

参数

• 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.

另请参阅

create() read() write()

PySide2.QtGui.QOpenGLBuffer. allocate ( count ) ¶

参数

count – int

这是重载函数。

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.

另请参阅

create() write()

PySide2.QtGui.QOpenGLBuffer. bind ( ) ¶

返回类型

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.

另请参阅

release() create()

PySide2.QtGui.QOpenGLBuffer. bufferId ( ) ¶

返回类型

GLuint

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

另请参阅

isCreated()

PySide2.QtGui.QOpenGLBuffer. create ( ) ¶

返回类型

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 .

另请参阅

isCreated() allocate() write() destroy()

PySide2.QtGui.QOpenGLBuffer. destroy ( ) ¶

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

PySide2.QtGui.QOpenGLBuffer. isCreated ( ) ¶

返回类型

bool

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

另请参阅

create() destroy()

PySide2.QtGui.QOpenGLBuffer. map ( access ) ¶

参数

access – Access

返回类型

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.

注意

This function is only supported under OpenGL ES 2.0 or earlier if the GL_OES_mapbuffer extension is present.

注意

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 而不是 glMapBuffer .

另请参阅

unmap() create() bind() mapRange()

PySide2.QtGui.QOpenGLBuffer. mapRange ( offset , count , access ) ¶

参数

• offset – int

• count – int

• access – RangeAccessFlags

返回类型

void

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.

注意

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

另请参阅

unmap() create() bind()

PySide2.QtGui.QOpenGLBuffer. read ( offset , data , count ) ¶

参数

• offset – int

• data – void

• count – int

返回类型

bool

读取 count bytes in this buffer starting at offset into data 。返回 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.

另请参阅

write() bind()

PySide2.QtGui.QOpenGLBuffer. 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.

另请参阅

bind()

static PySide2.QtGui.QOpenGLBuffer. release ( type ) ¶

参数

type – 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);
											

PySide2.QtGui.QOpenGLBuffer. setUsagePattern ( value ) ¶

参数

value – UsagePattern

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

另请参阅

usagePattern() allocate() write()

PySide2.QtGui.QOpenGLBuffer. size ( ) ¶

返回类型

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.

另请参阅

isCreated() bind()

PySide2.QtGui.QOpenGLBuffer. type ( ) ¶

返回类型

Type

Returns the type of buffer represented by this object.

PySide2.QtGui.QOpenGLBuffer. unmap ( ) ¶

返回类型

bool

Unmaps the buffer after it was mapped into the application’s memory space with a previous call to map() 。返回 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() .

注意

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

另请参阅

map()

PySide2.QtGui.QOpenGLBuffer. usagePattern ( ) ¶

返回类型

UsagePattern

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

另请参阅

setUsagePattern()

PySide2.QtGui.QOpenGLBuffer. write ( offset , data , count ) ¶

参数

• offset – int

• data – void

• count – 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.

另请参阅

create() read() allocate()