QtQuick3D scene node geometry

AlricDoRei

Using QtQuick3D/Qt3D module, got one problem with getting geometry data from scene nodes.
I am creating a simple scene with one scene node(cube mesh in this example):
@ QGLBuilder builder;
builder << QGLCube();
sceneNode = builder.finalizedSceneNode();@

I am trying to use this for vertices, but it doesn't work. It is an infinite loop, which provides wrong data (example: Iter->x() = 4.2039e-44, Iter->y() = 2.27723e-39 and Iter->z() = 861307000.0).
@ QVector3DArray::iterator Iter;
for(Iter=sceneNode->geometry().vertices().begin(); Iter!=sceneNode->geometry().vertices().begin(); Iter=Iter.Next())
{
//Taking coordinates from each vertex
}@
How I can get all data from scene node(vertices,normals,texture coordinates, etc)?
I need to get every x,y,z coordinate and write all collected data to file.

Chris H

If you've copied and pasted that code verbatim, you've got a typo in there: you mean to say .end() for the second clause in the for statement, and instead you've repeated begin().
e.g. @Iter!=sceneNode->geometry().vertices().begin()@ should be
@Iter!=sceneNode->geometry().vertices().end()@
(I assume).

kmedghaith

Hi,
I think that when you do a
@builder.finalizedSceneNode()@
the data is uploaded to the card and
@sceneNode->geometry()@
is empty.

Try to use nested nodes to build your scene like this documentation example :
@
QGLBuilder builder;
builder << CarWheel(5.0f); // some car wheel geometry
QGLSceneNode * wheel = builder.finalizedSceneNode();
QGLSceneNode * frontLeft = new QGLSceneNode(m_sceneRoot);
frontLeft->addNode(wheel);
frontLeft->setPosition(QVector3D(1.0f, 2.0f, 0.0f));
QGLSceneNode * frontRight = new QGLSceneNode(m_sceneRoot);
frontRight->addNode(wheel);
frontRight->setPosition(QVector3D(-1.0f, 2.0f, 0.0f));
QGLSceneNode * backLeft = new QGLSceneNode(m_sceneRoot);
backLeft->addNode(wheel);
backLeft->setPosition(QVector3D(1.0f, -2.0f, 0.0f));
QGLSceneNode * backRight = new QGLSceneNode(m_sceneRoot);
backRight->addNode(wheel);
backRight->setPosition(QVector3D(-1.0f, -2.0f, 0.0f));
@

Regards.
G.

AlricDoRei

[quote author="kmedghaith" date="1323764400"]Hi,
I think that when you do a
@builder.finalizedSceneNode()@
the data is uploaded to the card and
@sceneNode->geometry()@
is empty.

Try to use nested nodes to build your scene like this documentation example :
@
QGLBuilder builder;
builder << CarWheel(5.0f); // some car wheel geometry
QGLSceneNode * wheel = builder.finalizedSceneNode();
QGLSceneNode * frontLeft = new QGLSceneNode(m_sceneRoot);
frontLeft->addNode(wheel);
frontLeft->setPosition(QVector3D(1.0f, 2.0f, 0.0f));
QGLSceneNode * frontRight = new QGLSceneNode(m_sceneRoot);
frontRight->addNode(wheel);
frontRight->setPosition(QVector3D(-1.0f, 2.0f, 0.0f));
QGLSceneNode * backLeft = new QGLSceneNode(m_sceneRoot);
backLeft->addNode(wheel);
backLeft->setPosition(QVector3D(1.0f, -2.0f, 0.0f));
QGLSceneNode * backRight = new QGLSceneNode(m_sceneRoot);
backRight->addNode(wheel);
backRight->setPosition(QVector3D(-1.0f, -2.0f, 0.0f));
@

Regards.
G.[/quote]

Using this:
@ QGeometryData m_sceneRoot;
QGLBuilder builder;
builder << QGLCube(5.0f); // some car wheel geometry
QGLSceneNode * wheel = builder.finalizedSceneNode();
QGLSceneNode * frontLeft = new QGLSceneNode(m_sceneRoot);
frontLeft->addNode(wheel);
frontLeft->setPosition(QVector3D(1.0f, 2.0f, 0.0f));
QGLSceneNode * frontRight = new QGLSceneNode(m_sceneRoot);
frontRight->addNode(wheel);
frontRight->setPosition(QVector3D(-1.0f, 2.0f, 0.0f));
QGLSceneNode * backLeft = new QGLSceneNode(m_sceneRoot);
backLeft->addNode(wheel);
backLeft->setPosition(QVector3D(1.0f, -2.0f, 0.0f));
QGLSceneNode * backRight = new QGLSceneNode(m_sceneRoot);
backRight->addNode(wheel);
backRight->setPosition(QVector3D(-1.0f, -2.0f, 0.0f));
if(!wheel->geometry().vertices().isEmpty())
QMessageBox::information(this,"Info","Not Empty",QMessageBox::Ok);@

Geometry data is still empty.

It is not empty when I use:
@ QGLBuilder builder;
QGeometryData triangle;
QVector3D a(2, 2, 0);
QVector3D b(-2, 2, 0);
QVector3D c(0, -2, 0);
triangle.appendVertex(a, b, c);

// When adding geometry, QGLBuilder automatically creates lighting normals
builder << triangle;

// obtain the scene from the builder
sceneNode = builder.finalizedSceneNode();
if(!triangle.vertices().isEmpty())
        QMessageBox::information(this,"Info","Not Empty",QMessageBox::Ok);@

How I can draw the number of vertices and normals when loading 3d model from .obj or .3ds file?
I am using
@QGLAbstractScene *abstr = QGLAbstractScene::loadScene(...);@
then:
@sceneNode = abstr->mainNode();@
3D model is loading without any problems, but sceneNode->geometry is still empty.

voondo

I know this post is a bit old but I'm encountering the same problem, did you find a solution ?

voondo

Replying to myself : as explained here http://permalink.gmane.org/gmane.comp.lib.qt.3d/126 :

bq. Very often when you build an object it has more than one scene node in it, hence the builder returns always a single root node, under which are the other nodes containing the actual geometry.