Unable to perform translation using QSGTransformNode

? Offline

Hello,

I am a newbie to qml and scene graph so kindly pardon me if my question is too trivial. I am trying to write a very simple toy program. In this program I am generating a line graph and I want this line graph to appear at the center of my rectangular window. Now, I realize, that I can adjust my y value of each pixel that is getting plot on the rectangle but I do not want to do so, I assumed that since scene graph uses opengl it will have some viewport kind of functionality to do the translation for me... because eventually i will be using this prototype to plot charts, bar graphs, etc

More specifically,
I am using QSGTransformNode object to perform my translation but I do not know how do I convey this change to QSGNode,

I would really appreciate any help on this matter,

following is my code ...

@
QSGNode*
LineGraph::
updatePaintNode(QSGNode *node, UpdatePaintNodeData *updatePaintNodeData)
{
QSGGeometryNode *geomNode =0;
QSGGeometry *geom =0;
QSGVertexColorMaterial *material=0;
QSGTransformNode *transNode=0;

if (!node)
{
    geom = new QSGGeometry( QSGGeometry::defaultAttributes_ColoredPoint2D(), m_numPoints);
    geom->setLineWidth(1.0);
    geom->setDrawingMode(GL_LINE_STRIP);
    geom->allocate(m_numPoints);

    geomNode = new QSGGeometryNode();
    geomNode->setGeometry(geom);
    geomNode->setFlag(QSGNode::OwnsGeometry);

    material = new QSGVertexColorMaterial();
    geomNode->setMaterial(material);
    geomNode->setFlag(QSGNode::OwnsMaterial);
}
else
{
    geomNode = static_cast<QSGGeometryNode*> (node);
    geom = geomNode->geometry();
    material = static_cast<QSGVertexColorMaterial*>(geomNode->material());
}

const QRectF bounds = boundingRect();

float hh = bounds.height();
float ww = bounds.width();

// translating along yy axis by height/2
QMatrix4x4 mat1(0.0,0.0,0.0,0.0,
                0.0,0.0,0.0,300,  // hh/2
                0.0,0.0,0.0,0.0,
                0.0,0.0,0.0,0.0);


mat1.optimize();

transNode = new QSGTransformNode();
transNode->setMatrix(mat1);
transNode->markDirty(QSGNode::DirtyNodeAdded);

QSGGeometry::ColoredPoint2D *vertices = geom->vertexDataAsColoredPoint2D(); // get hold of vertices

// generating sample data -- y values in range of -130 to 100
QVector <int> yyVals;

for(quint32 yy=0; yy < m_numPoints; ++yy)
{
    if (yy > m_numPoints/2)
        yyVals.push_back( -10 );
    else
        yyVals.push_back( 10 );
}


for(quint32 ii=0; ii < m_numPoints; ++ii)
{
    vertices[ii].set(ii , yyVals[ii], ii%5 ,128,0,255); // testing --  drawing randon data on yAxis
}

geomNode->markDirty(QSGNode::DirtyForceUpdate);
geomNode->appendChildNode(transNode);

return geomNode;

}@

seyed

If you found solution, please share your knowledge.