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Internal/Contributor docs for the Qt SDK. <b>Note:</b> These are NOT official API docs; those are found <a href='https://doc.qt.io/'>here</a>.
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QNullBuffer Struct Reference

#include <qrhinull_p.h>

+ Inheritance diagram for QNullBuffer:
+ Collaboration diagram for QNullBuffer:

Public Member Functions

 QNullBuffer (QRhiImplementation *rhi, Type type, UsageFlags usage, quint32 size)
 
 ~QNullBuffer ()
 
void destroy () override
 Releases (or requests deferred releasing of) the underlying native graphics resources.
 
bool create () override
 Creates the corresponding native graphics resources.
 
char * beginFullDynamicBufferUpdateForCurrentFrame () override
 
- Public Member Functions inherited from QRhiBuffer
QRhiResource::Type resourceType () const override
 
Type type () const
 
void setType (Type t)
 Sets the buffer's type to t.
 
UsageFlags usage () const
 
void setUsage (UsageFlags u)
 Sets the buffer's usage flags to u.
 
quint32 size () const
 
void setSize (quint32 sz)
 Sets the size of the buffer in bytes.
 
virtual NativeBuffer nativeBuffer ()
 
virtual void endFullDynamicBufferUpdateForCurrentFrame ()
 To be called when the entire contents of the buffer data has been updated in the memory block returned from beginFullDynamicBufferUpdateForCurrentFrame().
 
- Public Member Functions inherited from QRhiResource
virtual ~QRhiResource ()
 Destructor.
 
void deleteLater ()
 When called without a frame being recorded, this function is equivalent to deleting the object.
 
QByteArray name () const
 
void setName (const QByteArray &name)
 Sets a name for the object.
 
quint64 globalResourceId () const
 
QRhirhi () const
 

Public Attributes

char * data = nullptr
 

Additional Inherited Members

- Public Types inherited from QRhiBuffer
enum  Type { Immutable , Static , Dynamic }
 Specifies storage type of buffer resource. More...
 
enum  UsageFlag { VertexBuffer = 1 << 0 , IndexBuffer = 1 << 1 , UniformBuffer = 1 << 2 , StorageBuffer = 1 << 3 }
 Flag values to specify how the buffer is going to be used. More...
 
- Public Types inherited from QRhiResource
enum  Type {
  Buffer , Texture , Sampler , RenderBuffer ,
  RenderPassDescriptor , SwapChainRenderTarget , TextureRenderTarget , ShaderResourceBindings ,
  GraphicsPipeline , SwapChain , ComputePipeline , CommandBuffer
}
 Specifies type of the resource. More...
 
- Protected Member Functions inherited from QRhiBuffer
 QRhiBuffer (QRhiImplementation *rhi, Type type_, UsageFlags usage_, quint32 size_)
 \variable QRhiBuffer::NativeBuffer::objects
 
- Protected Member Functions inherited from QRhiResource
 QRhiResource (QRhiImplementation *rhi)
 
- Protected Attributes inherited from QRhiBuffer
Type m_type
 
UsageFlags m_usage
 
quint32 m_size
 
- Protected Attributes inherited from QRhiResource
QRhiImplementationm_rhi = nullptr
 
quint64 m_id
 
QByteArray m_objectName
 

Detailed Description

Definition at line 22 of file qrhinull_p.h.

Constructor & Destructor Documentation

◆ QNullBuffer()

QNullBuffer::QNullBuffer ( QRhiImplementation * rhi,
Type type,
UsageFlags usage,
quint32 size )

Definition at line 564 of file qrhinull.cpp.

◆ ~QNullBuffer()

QNullBuffer::~QNullBuffer ( )

Definition at line 569 of file qrhinull.cpp.

References destroy().

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Member Function Documentation

◆ beginFullDynamicBufferUpdateForCurrentFrame()

char * QNullBuffer::beginFullDynamicBufferUpdateForCurrentFrame ( )
overridevirtual
Returns
a pointer to a memory block with the host visible buffer data.

This is a shortcut for medium-to-large dynamic uniform buffers that have their entire contents (or at least all regions that are read by the shaders in the current frame) changed {in every frame} and the QRhiResourceUpdateBatch-based update mechanism is seen too heavy due to the amount of data copying involved.

The call to this function must be eventually followed by a call to endFullDynamicUniformBufferUpdateForCurrentFrame(), before recording any render or compute pass that relies on this buffer.

Warning
Updating data via this method is not compatible with QRhiResourceUpdateBatch-based updates and readbacks. Unexpected behavior may occur when attempting to combine the two update models for the same buffer. Similarly, the data updated this direct way may not be visible to \l{QRhiResourceUpdateBatch::readBackBuffer()}{readBackBuffer operations}, depending on the backend.
When updating buffer data via this method, the update must be done in every frame, otherwise backends that perform double or triple buffering of resources may end up in unexpected behavior.
Partial updates are not possible with this approach since some backends may choose a strategy where the previous contents of the buffer is lost upon calling this function. Data must be written to all regions that are read by shaders in the frame currently being prepared.
This function can only be called when recording a frame, so between QRhi::beginFrame() and QRhi::endFrame().
This function can only be called on Dynamic buffers.

Reimplemented from QRhiBuffer.

Definition at line 598 of file qrhinull.cpp.

References data, QRhiBuffer::Dynamic, QRhiBuffer::m_type, and Q_ASSERT.

◆ create()

bool QNullBuffer::create ( )
overridevirtual

Creates the corresponding native graphics resources.

If there are already resources present due to an earlier create() with no corresponding destroy(), then destroy() is called implicitly first.

Returns
true when successful, false when a graphics operation failed. Regardless of the return value, calling destroy() is always safe.

Implements QRhiBuffer.

Definition at line 584 of file qrhinull.cpp.

References destroy(), QRhiBuffer::m_size, and QRHI_RES_RHI.

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◆ destroy()

void QNullBuffer::destroy ( )
overridevirtual

Releases (or requests deferred releasing of) the underlying native graphics resources.

Safe to call multiple times, subsequent invocations will be a no-op then.

Once destroy() is called, the QRhiResource instance can be reused, by calling create() again. That will then result in creating new native graphics resources underneath.

Note
Resources referenced by commands for the current frame should not be released until the frame is submitted by QRhi::endFrame().

The QRhiResource destructor also performs the same task, so calling this function is not necessary before deleting a QRhiResource.

See also
deleteLater()

Implements QRhiResource.

Definition at line 574 of file qrhinull.cpp.

References data, and QRHI_RES_RHI.

Referenced by ~QNullBuffer(), and create().

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Member Data Documentation

◆ data

char* QNullBuffer::data = nullptr

Definition at line 30 of file qrhinull_p.h.

Referenced by beginFullDynamicBufferUpdateForCurrentFrame(), and destroy().


The documentation for this struct was generated from the following files: