QWaitFence

FrameGraphNode used to wait for a fence in the graphics command stream to become signaled. More

New in version 5.13.

Synopsis

Functions

Signals

Detailed Description

Fence allow to synchronosize GPU and CPU workloads. GPU commands usually are non-blocking. When issued, commands are inserted in command buffers which will be read at a later time by the GPU. In some cases, you want to continue processing or issue specific command only when you are sure a command has been executed by the hardware. Fences are a way to do so. This is especially important when using 3rd party engines with Qt3D, Qt3D should only access shared resources when we know the other engine command are done modifying the resource.

QWaitFence is a FrameGraph node that will force to wait for it to become signaled before subsequent commands are inserted into the command stream. It can then be used in conjunction with QSetFence and contains properties to configure how long it should wait and whether it should block on the CPU side.

Note

Qt 3D uploads GPU resources (Texture, Shaders, Buffers) before issuing draw calls.

class PySide2.Qt3DRender.QWaitFence([parent=None])
Parameters

parentPySide2.Qt3DCore.QNode

PySide2.Qt3DRender.QWaitFence.HandleType
PySide2.Qt3DRender.QWaitFence.handle()
Return type

object

Holds the underlying fence handle wrapped in a QVariant .

PySide2.Qt3DRender.QWaitFence.handleChanged(handle)
Parameters

handle – object

PySide2.Qt3DRender.QWaitFence.handleType()
Return type

HandleType

Specifies the type of handle being used. Currently only OpenGL Fence ids are supported.

PySide2.Qt3DRender.QWaitFence.handleTypeChanged(handleType)
Parameters

handleTypeHandleType

PySide2.Qt3DRender.QWaitFence.setHandle(handle)
Parameters

handle – object

Holds the underlying fence handle wrapped in a QVariant .

PySide2.Qt3DRender.QWaitFence.setHandleType(type)
Parameters

typeHandleType

Specifies the type of handle being used. Currently only OpenGL Fence ids are supported.

PySide2.Qt3DRender.QWaitFence.setTimeout(timeout)
Parameters

timeout – int

Specifies the maximum amount of time in nanoseconds to wait for the fence to become signaled.

PySide2.Qt3DRender.QWaitFence.setWaitOnCPU(waitOnCPU)
Parameters

waitOnCPU – bool

Specifies whether the CPU should be block while waiting for the fence to become signaled. This is false by default.

PySide2.Qt3DRender.QWaitFence.timeout()
Return type

int

Specifies the maximum amount of time in nanoseconds to wait for the fence to become signaled.

PySide2.Qt3DRender.QWaitFence.timeoutChanged(timeoutChanged)
Parameters

timeoutChanged – int

PySide2.Qt3DRender.QWaitFence.waitOnCPU()
Return type

bool

Specifies whether the CPU should be block while waiting for the fence to become signaled. This is false by default.

PySide2.Qt3DRender.QWaitFence.waitOnCPUChanged(waitOnCPU)
Parameters

waitOnCPU – bool