[Development] QSGNode::markDirty no longer works?

[Sletta Gunnar]

I'm afraid this is your bug :)

QSGNode::DirtyForceUpdate is an internal undocumented property used for internal reasons. The right thing to do is to the scene graph exactly what you changed, which is also cheaper for the scene graph to handle. QSGNode::DirtyGeometry in this case. 

cheers,
Gunnar
________________________________________
Fra: development-bounces+gunnar.sletta=digia.com at qt-project.org [development-bounces+gunnar.sletta=digia.com at qt-project.org] på vegne av achartier at fastmail.fm [achartier at fastmail.fm]
Sendt: 5. desember 2013 02:04
To: development at qt-project.org
Emne: Re: [Development] QSGNode::markDirty no longer works?

It looks like using QSGNode::DirtyGeometry did the trick. I would have
expected QSGNode::DirtyForceUpdate to work though. Is this a bug?

On Wed, Dec 4, 2013, at 02:14 PM, achartier at fastmail.fm wrote:
> Hi,
>
> I had a QQuickItem-based 2D linegraph working fine in prior versions of
> Qt 5. This code does not seem to work with Qt 5.2 RC 1. Below is the
> relevant code of my QQuickItem-based linegraph:
>
> QSGNode* Linegraph::updatePaintNode(QSGNode* oldNode,
> UpdatePaintNodeData* updatePaintNodeData)
> {
>     Q_UNUSED(updatePaintNodeData);
>
>     QSGGeometryNode* node = nullptr;
>     QSGGeometry* geometry = nullptr;
>     QSGFlatColorMaterial* material = nullptr;
>
>     if (!oldNode)
>     {
>         node = new QSGGeometryNode();
>         geometry = new
>         QSGGeometry(QSGGeometry::defaultAttributes_Point2D(), 1000);
>         geometry->setLineWidth(1);
>         geometry->setDrawingMode(GL_LINE_STRIP);
>         geometry->allocate(1000);
>         node->setGeometry(geometry);
>         node->setFlag(QSGNode::OwnsGeometry);
>         material = new QSGFlatColorMaterial();
>         node->setMaterial(material);
>         node->setFlag(QSGNode::OwnsMaterial);
>     }
>     else
>     {
>         node = static_cast<QSGGeometryNode*>(oldNode);
>         geometry = node->geometry();
>         material = static_cast<QSGFlatColorMaterial*>(node->material());
>     }
>
>     const QRectF bounds = boundingRect();
>     const float horizontalPointSpacing = (float)bounds.width() / (1000 -
>     1.0f);
>     QSGGeometry::Point2D* vertices = geometry->vertexDataAsPoint2D();
>
>     float currentX = 0.0f;
>     float currentY = 0.0f;
>
>     for (quint32 pointIndex = 0; pointIndex < m_numOfTracePoints;
>     ++pointIndex)
>     {
>         currentX = 1.0f + pointIndex * horizontalPointSpacing;
>         currentY = qBound(0.0f, (m_data[pointIndex] * (-1)) / 100000.0f,
>         1.0f) * (float)bounds.height();
>
>         vertices[pointIndex].set(currentX, currentY);
>     }
>
>     node->markDirty(QSGNode::DirtyForceUpdate);
>
>     return node;
> }
>
> In prior versions of Qt, the second to last line
> (node->markDirty(QSGNode::DirtyForceUpdate)) was needed, otherwise
> updates to the "vertices" point array would not be reflected in what
> gets drawn. Now, with Qt 5.2 RC 1, changes made to the points stored in
> the "vertices" point array are never reflected in what is drawn:
> whatever the array is initialized with is what is drawn in all
> subsequent updates.
>
> Is this a user error on my part? Should I be using something other than
> QSGNode::markDirty to force the "vertices" point array changes to take
> effect? Or is this perhaps a bug in Qt 5.2 RC 1?
>
> Any help is greatly appreciated.
>
> Thanks.
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