help on QSGGeometry

[joko]

Hi,

I would like to know some advise on creating a custom geometry using scene graph.
My problem is I don't know how to fill the custom geometry with color.
And how to add text on geometry node without using QPainter, is it possible?

Below is my code:

QSGNode *TabBar::updatePaintNode(QSGNode *oldNode, UpdatePaintNodeData *)
{
    QSGNode *root = static_cast<QSGNode *>(oldNode);
    if(!root) root = new QSGNode;
    root->removeAllChildNodes();
 
    QSGGeometry *geometry;
 
    geometry = new QSGGeometry(QSGGeometry::defaultAttributes_Point2D(), 6);
    geometry->setDrawingMode(GL_TRIANGLE_FAN);
    geometry->vertexDataAsPoint2D()[0].set(20, 40);
    geometry->vertexDataAsPoint2D()[1].set(0, 0);
    geometry->vertexDataAsPoint2D()[2].set(100, 0);
    geometry->vertexDataAsPoint2D()[3].set(120, 40);
    geometry->vertexDataAsPoint2D()[4].set(100, 80);
    geometry->vertexDataAsPoint2D()[5].set(0, 80);
    node = drawPolygon(geometry, Qt::red);
    root->appendChildNode(node);
}
QSGNode *TabBar::drawPolygon(QSGGeometry *geometry, const QColor &color)
{
    QSGFlatColorMaterial *material = new QSGFlatColorMaterial;
    material->setColor(color);
 
    QSGGeometryNode *node = new QSGGeometryNode;
    node->setGeometry(geometry);
    node->setFlag(QSGNode::OwnsGeometry);
    node->setMaterial(material);
    node->setFlag(QSGNode::OwnsMaterial);
    return node;
}

QSGNode *TabBar::updatePaintNode(QSGNode *oldNode, UpdatePaintNodeData *)
{
    QSGNode *root = static_cast<QSGNode *>(oldNode);
    if(!root) root = new QSGNode;
    root->removeAllChildNodes();

    QSGGeometry *geometry;

    geometry = new QSGGeometry(QSGGeometry::defaultAttributes_Point2D(), 6);
    geometry->setDrawingMode(GL_TRIANGLE_FAN);
    geometry->vertexDataAsPoint2D()[0].set(20, 40);
    geometry->vertexDataAsPoint2D()[1].set(0, 0);
    geometry->vertexDataAsPoint2D()[2].set(100, 0);
    geometry->vertexDataAsPoint2D()[3].set(120, 40);
    geometry->vertexDataAsPoint2D()[4].set(100, 80);
    geometry->vertexDataAsPoint2D()[5].set(0, 80);
    node = drawPolygon(geometry, Qt::red);
    root->appendChildNode(node);
}
QSGNode *TabBar::drawPolygon(QSGGeometry *geometry, const QColor &color)
{
    QSGFlatColorMaterial *material = new QSGFlatColorMaterial;
    material->setColor(color);

    QSGGeometryNode *node = new QSGGeometryNode;
    node->setGeometry(geometry);
    node->setFlag(QSGNode::OwnsGeometry);
    node->setMaterial(material);
    node->setFlag(QSGNode::OwnsMaterial);
    return node;
}

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Update:
I managed to fill the geometry using GL_TRIANGLE_FAN drawingMode and by modifying the vertices which will start on the vertex which will create a triangle without intersecting each other.

The problem now is how to draw a text on the geometry.

Please advise. TIA.