Hide the polygon outlines

[pks23]

osgEarth Version (required): 3.7

Description of the problem: Not able to the polygon outlines

What you have tried: Added custom shader for hiding the polygon by objectid.

I am working with osgEarth’s C++ API and have loaded a shapefile as a FeatureModelLayer. I need to hide the polygons upon selection, which I have achieved using shaders (making the polygon transparent) and objectid. However, the polygon outlines are still visible because they are rendered by LineDrawable.

To hide the outlines, I attempted to find the corresponding geode using nodeIntersector to get the LineGroup containing the outlines. I then used the following code to identify the LineDrawable:

osgEarth::LineGroup group = findAllNodesByTypeosgEarth::LineGroup(lyrNode).at(0);

Despite enabling feature indexing for the FeatureSource, the LineDrawable objects are not tagged with objectid.

Upon debugging, I found that in the BuildGeometryFilter class, the processLines function uses this line for tagging:

if (context.featureIndex())

{

context.featureIndex()->tagDrawable(drawable, input); 

}

However, the tagDrawable function only tags geometry class objects and does not tag the node, which prevents me from hiding the outlines effectively.

Could you please help identify a solution to hide the polygon outlines?

[gwaldron]

Ok, I am a little confused here.

Are you saying that LineDrawables are not getting an object id?

Is all this stuff about LineGroups and nodes just your attempt at a workaround?

I added some polygon outlines to feature_polygons.earth and they are tagged just fine according to the picker.

[pks23]

I wrote a custom shader to hide a polygon using its ObjectID, and it works fine. But the polygon's outline is still visible. I tried to find the drawable for the outline, but it doesn’t have an ObjectID, so I couldn’t identify it.

[gwaldron]

Object IDs are not stored in the scene graph, but rather in the ObjectIndex so you need to call

std::set<ObjectID> object_ids;
ObjectIndex::getObjectIDs(drawable, object_ids);

[pks23]

I used ObjectIndex to find the ID:

auto group = findAllNodesByTypeosgEarth::LineGroup(lyrNode).at(0);
auto drawable = dynamic_castosgEarth::LineDrawable* (group->getChild(0)->asDrawable());
std::set object_ids;
obi->getObjectIDs(drawable, object_ids);

But getObjectIDs function returns while attempting to cast drawable as geometry.

bool ObjectIndex::getObjectIDs(const osg::Drawable* drawable, std::set& output) const
{
if (!drawable) return false;

// It returns from this line
const osg::Geometry* geometry = drawable->asGeometry();
if (!geometry) return false;

const ObjectIDArray* oids = dynamic_cast<const ObjectIDArray*>(geometry->getVertexAttribArray(_attribLocation));
if ( !oids ) return false;
if (oids->empty()) return false;
for (ObjectIDArray::const_iterator i = oids->begin(); i != oids->end(); ++i)
    output.insert( *i );
return true;

}

The same issue occurs when ObjectIndex attempts to tag the drawable, the function returns after the asGeometry() call.

[gwaldron]

Hey, now we are getting somewhere! Thanks for tracking down this bug. I have pushed a fix for this - please test and report back.