I am trying to create a simple QQuickFrameBufferObject
in order to render some custom opengl textures in Qt Quick. So I decided to test it with PySide2. Here is a simple implementation:
from PySide2.QtQuick import QQuickFramebufferObject
from PySide2.QtGui import QOpenGLFramebufferObjectFormat, QOpenGLFramebufferObject
from PySide2.QtCore import QSize, Qt
class FboRenderer(QQuickFramebufferObject.Renderer):
def __init__(self, parent=None):
super().__init__(parent)
print("Creating renderer")
def createFrameBufferObject(self, size):
format = QOpenGLFramebufferObjectFormat()
format.setAttachment(QOpenGLFramebufferObject.Depth)
return QOpenGLFramebufferObject(size, format)
def synchronize(self, item):
print("Synchronizing")
def render(self):
print("Rendering")
class OpenGLCanvas(QQuickFramebufferObject):
def __init__(self, parent=None):
super().__init__(parent)
def createRenderer(self):
return FboRenderer()
Then to use this in QML I used:
qmlRegisterType(OpenGLCanvas,"OpenGLCanvas", 1, 0, "OpenGLCanvas")
import QtQuick 2.12
import QtQuick.Window 2.12
import OpenGLCanvas 1.0
Window{
id: win
visible: true
OpenGLCanvas{
anchors.fill: parent
}
}
Now the app runs and displays "Creating renderer" but then it crashes after a couple of seconds.
The problem is that FboRenderer()
is a local variable that will be destroyed instantly, and therefore it will also destroy the C++ object causing a Segmentation fault since unreserved memory is accessed.
On the other hand you have a typo in createFrameBufferObject
since it must be createFramebufferObject
, that also reveals an error similar to the initial error, for this the solution is similar.
class FboRenderer(QQuickFramebufferObject.Renderer):
def __init__(self):
super().__init__()
print("Creating renderer")
self._fbos = []
def createFramebufferObject(self, size):
fmt = QOpenGLFramebufferObjectFormat()
fmt.setAttachment(QOpenGLFramebufferObject.Depth)
fbo = QOpenGLFramebufferObject(size, fmt)
self._fbos.append(fbo)
return fbo
def synchronize(self, item):
print("Synchronizing")
def render(self):
print("Rendering")
class OpenGLCanvas(QQuickFramebufferObject):
def __init__(self, parent=None):
super().__init__(parent)
self._renderer = None
def createRenderer(self):
if self._renderer is None:
self.renderer = FboRenderer()
return self.renderer