bool
TileSource::hasData(const osgEarth::TileKey& key) const
{
//sematics: might have data.
//If no data extents are provided, just return true
if (_dataExtents.size() == 0)
return true;
const osgEarth::GeoExtent& keyExtent = key.getExtent();
bool intersectsData = false;
for (DataExtentList::const_iterator itr = _dataExtents.begin(); itr != _dataExtents.end(); ++itr)
{
if ((keyExtent.intersects( *itr )) &&
(!itr->minLevel().isSet() || itr->minLevel() <= key.getLOD()) &&
(!itr->maxLevel().isSet() || itr->maxLevel() >= key.getLOD()))
{
intersectsData = true;
break;
}
}
return intersectsData;
}
bool
TileSource::getBestAvailableTileKey(const osgEarth::TileKey& key,
osgEarth::TileKey& output) const
{
// trivial reject
if ( !key.valid() )
return false;
// trivial accept: no data extents = not enough info.
if (_dataExtents.size() == 0)
{
output = key;
return true;
}
// trivial reject: key doesn't intersect the union of data extents at all.
if ( !getDataExtentsUnion().intersects(key.getExtent()) )
{
return false;
}
bool intersects = false;
unsigned highestLOD = 0;
// We must use the equivalent lod b/c the key can be in any profile.
int layerLOD = getProfile()->getEquivalentLOD( key.getProfile(), key.getLOD() );
for (DataExtentList::const_iterator itr = _dataExtents.begin(); itr != _dataExtents.end(); ++itr)
{
// check for 2D intersection:
if (key.getExtent().intersects( *itr ))
{
// check that the extent isn't higher-resolution than our key:
if ( !itr->minLevel().isSet() || layerLOD >= itr->minLevel().get() )
{
// Got an intersetion; now test the LODs:
intersects = true;
// Is the high-LOD set? If not, there's not enough information
// so just assume our key might be good.
if ( itr->maxLevel().isSet() == false )
{
output = key;
return true;
}
// Is our key at a lower or equal LOD than the max key in this extent?
// If so, our key is good.
else if ( layerLOD <= itr->maxLevel().get() )
{
output = key;
return true;
}
// otherwise, record the highest encountered LOD that
// intersects our key.
else if ( itr->maxLevel().get() > highestLOD )
{
highestLOD = itr->maxLevel().get();
}
}
}
}
if ( intersects )
{
output = key.createAncestorKey( highestLOD );
return true;
}
else
{
return false;
}
}