Create BoundingBoxes dynamically, by creating global Geode and attaching children later

[Martin Steinborn]

Hello,

I want to display my own BoundingBoxes (BBs) using osg. The way I am trying to do it is the following:

1) create a Geode and set it as Child of the overall scene. Create a global pointer to be able to add children to this Geode.

2) for every BoundingBox I find, create a new Geometry with a LINE_LOOP PrimitiveSet and add the draw-able as Child to the geode

3) after every iteration, multiple BBs could be generated and need to be deleted, because the objects in the BBs or the camera may have moved

I managed to show one BB in my scene by directly creating the Geode and the Box as child, but I cant get it working, using the above described method. I think that the Problem is with rerendering the previously created Geode, but I may be wrong. The other think, that may prevent stuff from rendering, is that I delete the BBs in the next "iteration".

Scene creation and Vertex positions are "correct", I've used the same code in my working example where I created Geode and DrawArray at once.

OSG Version: 3.0.1 due to framework

Here is a part of my Code, ill try to add some explanation:

Visual.h
...

/** Create scene object for all the Bounding Boxes to be drawn into **/

osg::ref_ptr<osg::Geode> myGeode;

...

--------------------------------------------------
Visual.cpp

// called on plug-in load
void Visual::load()
{
    ...
    createBoundingBoxScene();
}

// called with 60fps
void Visual::update()
{
// remove old BBs and create new one

myGeode->removeDrawables(0, myGeode->getNumDrawables());

     createBoundingBox();

}

/*

* \brief   Visual create BoundingBox as Child to Geode

* creates a BoundingBox via DrawArray and lines over (later given) vertices, and adds them as child to the global Geode

*/

void Visual::createBoundingBox()

{

osg::Geometry* geo = new osg::Geometry;

osg::ref_ptr<osg::Vec3dArray> myBBPoints = new osg::Vec3dArray; // array of BB cordinates

osg::ref_ptr<osg::Vec4dArray> color = new osg::Vec4dArray;

color->push_back(osg::Vec4d(1.0, 0.0, 0.0, 1.0)); // create color: red

osg::DrawArrays* da = new osg::DrawArrays(osg::PrimitiveSet::LINE_LOOP, 0, myBBPoints->size()); // LINE_LOOP, because BBs are a loop for sure

myBBPoints->push_back(osg::Vec3d(754.0, 3860.0, 11.0)); // 4 corner vertices, TODO: if working, pass Global Points as parameters in function

myBBPoints->push_back(osg::Vec3d(760.0, 3860.0, 11.0));

myBBPoints->push_back(osg::Vec3d(760.0, 3860.0, 13.0));

myBBPoints->push_back(osg::Vec3d(754.0, 3860.0, 13.0));

geo->setVertexArray(myBBPoints);

geo->addPrimitiveSet(da);

geo->setColorArray(color);

geo->setColorBinding(osg::Geometry::BIND_PER_PRIMITIVE);

geo->setDataVariance(osg::Object::DYNAMIC);

        // add geometry to geode to be drawn

myGeode->addDrawable(geo);

        // force scene / Geode to be redrawn ? all necessary, all useless?

geo->dirtyDisplayList();

geo->dirtyBound();

da->dirty();

myGeode->dirtyBound();

}

/*

* \brief   Visual create global Geode as child to scene

* get 3D scene of environment, create a (global) geode and add it as child to scene.

*/

void Visual::createBoundingBoxScene()

{

osg::Group * scene = findScene3D(dynamic_cast<osg::Group*>(myGraphicalContext->getScene())); //works

if (scene)

{

myGeode = new osg::Geode;

myGeode->setDataVariance(osg::Object::DYNAMIC);

myGeode->setName("Geode");

osg::MatrixTransform* mat = new osg::MatrixTransform;

mat->setReferenceFrame(osg::Transform::ABSOLUTE_RF); // (?) use global coordinate system, not local

osg::StateSet *stateset = myGeode->getOrCreateStateSet();

stateset->setMode(GL_LIGHTING, osg::StateAttribute::ON);

           stateset->setRenderBinDetails(INT_MAX, "RenderBin"); // make sure to print at last possible time

                // add global Geode as child to scene

scene->addChild(mat);

mat->addChild(myGeode);

std::cout << "Scene created successfully, name: " << scene->getName() << " with " << scene->getNumChildren() << " children." << std::endl;

}

else mySimulationContext->printErrorMessage("Failed to get scene node.");

}

I hope the code is not too long, but because I'm new to osg, I dont know what is important and what not.

Have a nice Day and thanks for your responses

[Martin Steinborn]

After reading the "short" OSG documentation over at http://syntheractive.com/developer/downloads/OSGQSG.pdf , I figured it out on my own :)

Things that helped me: (obvious if you know what you are doing...)

• geodes can't have unlimited children, just use a global group, where you attach a new geode for every bounding box.
• dont use * pointers, use osg::Ref_ptr<>, and if you use iosg::ref_ptr<X> use X.get() to get the object
• just remove lighting, or set normals
• if you want the object to have one color, use BIND_OVERALL
• no need to update or set anything dirty
• you don't need a state set / matrix at all (in my case, because all is in global coordinates)

Maybe if someone like me stumbles across this thread, this Info helps