flightgear/src/Scenery/tileentry.cxx

// tileentry.cxx -- routines to handle a scenery tile
//
// Written by Curtis Olson, started May 1998.
//
// Copyright (C) 1998 - 2001  Curtis L. Olson  - http://www.flightgear.org/~curt
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License as
// published by the Free Software Foundation; either version 2 of the
// License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
//
// $Id$


#ifdef HAVE_CONFIG_H
#  include <config.h>
#endif

#include <simgear/compiler.h>
#include <plib/ul.h>
#include <Main/main.hxx>


#include STL_STRING

#include <osg/Array>
#include <osg/Geometry>
#include <osg/Geode>
#include <osg/LOD>
#include <osg/MatrixTransform>
#include <osg/NodeCallback>
#include <osg/Switch>

#include <simgear/bucket/newbucket.hxx>
#include <simgear/debug/logstream.hxx>
#include <simgear/math/polar3d.hxx>
#include <simgear/math/sg_geodesy.hxx>
#include <simgear/math/sg_random.h>
#include <simgear/misc/sgstream.hxx>
#include <simgear/scene/material/mat.hxx>
#include <simgear/scene/material/matlib.hxx>
#include <simgear/scene/tgdb/apt_signs.hxx>
#include <simgear/scene/tgdb/obj.hxx>
#include <simgear/scene/model/placementtrans.hxx>

#include <Aircraft/aircraft.hxx>
#include <Include/general.hxx>
#include <Main/fg_props.hxx>
#include <Main/globals.hxx>
#include <Main/viewer.hxx>
#include <Scenery/scenery.hxx>
#include <Time/light.hxx>

#include "tileentry.hxx"
#include "tilemgr.hxx"

SG_USING_STD(string);


// Constructor
FGTileEntry::FGTileEntry ( const SGBucket& b )
    : center( Point3D( 0.0 ) ),
      tile_bucket( b ),
      terra_transform( new SGPlacementTransform ),
      vasi_lights_transform( new SGPlacementTransform ),
      rwy_lights_transform( new SGPlacementTransform ),
      taxi_lights_transform( new SGPlacementTransform ),
      terra_range( new osg::LOD ),
      vasi_lights_selector( new osg::Switch ),
      rwy_lights_selector( new osg::Switch ),
      taxi_lights_selector( new osg::Switch ),
      loaded(false),
      pending_models(0),
      is_inner_ring(false),
      free_tracker(0)
{
    // update the contents
    // if ( vec3_ptrs.size() || vec2_ptrs.size() || index_ptrs.size() ) {
    //     SG_LOG( SG_TERRAIN, SG_ALERT, 
    //             "Attempting to overwrite existing or"
    //             << " not properly freed leaf data." );
    //     exit(-1);
    // }
}


// Destructor
FGTileEntry::~FGTileEntry () {
    // cout << "nodes = " << nodes.size() << endl;;
    // delete[] nodes;
}

static void WorldCoordinate( osg::Matrix& obj_pos, Point3D center, double lat,
                             double lon, double elev, double hdg )
{
    double lon_rad = lon * SGD_DEGREES_TO_RADIANS;
    double lat_rad = lat * SGD_DEGREES_TO_RADIANS;
    double hdg_rad = hdg * SGD_DEGREES_TO_RADIANS;

    // setup transforms
    Point3D geod( lon_rad, lat_rad, elev );
        
    Point3D world_pos = sgGeodToCart( geod );
    Point3D offset = world_pos - center;

    sgMat4 mat;

    SGfloat sin_lat = (SGfloat)sin( lat_rad );
    SGfloat cos_lat = (SGfloat)cos( lat_rad );
    SGfloat cos_lon = (SGfloat)cos( lon_rad );
    SGfloat sin_lon = (SGfloat)sin( lon_rad );
    SGfloat sin_hdg = (SGfloat)sin( hdg_rad ) ;
    SGfloat cos_hdg = (SGfloat)cos( hdg_rad ) ;

    mat[0][0] =  cos_hdg * (SGfloat)sin_lat * (SGfloat)cos_lon - sin_hdg * (SGfloat)sin_lon;
    mat[0][1] =  cos_hdg * (SGfloat)sin_lat * (SGfloat)sin_lon + sin_hdg * (SGfloat)cos_lon;
    mat[0][2] = -cos_hdg * (SGfloat)cos_lat;
    mat[0][3] =  SG_ZERO;

    mat[1][0] = -sin_hdg * (SGfloat)sin_lat * (SGfloat)cos_lon - cos_hdg * (SGfloat)sin_lon;
    mat[1][1] = -sin_hdg * (SGfloat)sin_lat * (SGfloat)sin_lon + cos_hdg * (SGfloat)cos_lon;
    mat[1][2] =  sin_hdg * (SGfloat)cos_lat;
    mat[1][3] =  SG_ZERO;

    mat[2][0] = (SGfloat)cos_lat * (SGfloat)cos_lon;
    mat[2][1] = (SGfloat)cos_lat * (SGfloat)sin_lon;
    mat[2][2] = (SGfloat)sin_lat;
    mat[2][3] =  SG_ZERO;

    mat[3][0] = offset.x();
    mat[3][1] = offset.y();
    mat[3][2] = offset.z();
    mat[3][3] = SG_ONE ;

    for (unsigned i = 0; i < 4; ++i)
      for (unsigned j = 0; j < 4; ++j)
        obj_pos(i, j) = mat[i][j];
}


// recurse an ssg tree and call removeChild() on every node from the
// bottom up.  Leaves the original branch in existance, but empty so
// it can be removed by the calling routine.
// static void my_remove_branch( osg::Group * branch ) {
//     branch->removeChildren(0, branch->getNumChildren());
// }


// Free "n" leaf elements of an ssg tree.  returns the number of
// elements freed.  An empty branch node is considered a leaf.  This
// is intended to spread the load of freeing a complex tile out over
// several frames.
static int fgPartialFreeSSGtree( osg::Group *b, int n ) {
    int num_deletes = 0;

    b->removeChildren(0, b->getNumChildren());

//     if ( n > 0 ) {
//         // we still have some delete budget left
//         // if ( b->getNumChilds() > 100 ) {
//         //     cout << "large family = " << b->getNumChilds() << endl;
//         // }
//         // deleting in reverse would help if my plib patch get's
//         // applied, but for now it will make things slower.
//         // for ( int i = b->getNumChilds() - 1; i >= 0 ; --i ) {
//         for ( int i = 0; i < b->getNumChildren(); ++i ) {
//             ssgEntity *kid = b->getChild(i);
//             if ( kid->isAKindOf( ssgTypeBranch() ) && kid->getRef() <= 1 ) {
//                 int result = fgPartialFreeSSGtree( (osg::Group *)kid, n );
//                 num_deletes += result;
//                 n -= result;
//                 if ( n < 0 ) {
//                     break;
//                 }
//             }
//             // remove the kid if (a) it is now empty -or- (b) it's ref
//             // count is > zero at which point we don't care if it's
//             // empty, we don't want to touch it's contents.
//             if ( kid->getNumChildren() == 0 || kid->getRef() > 1 ) {
//                 b->removeChild( kid );
//                 num_deletes++;
//                 n--;
//             }
//         }
//     }

    return num_deletes;
}


// Clean up the memory used by this tile and delete the arrays used by
// ssg as well as the whole ssg branch
bool FGTileEntry::free_tile() {
    int delete_size = 100;
    SG_LOG( SG_TERRAIN, SG_DEBUG,
            "FREEING TILE = (" << tile_bucket << ")" );

    SG_LOG( SG_TERRAIN, SG_DEBUG, "(start) free_tracker = " << free_tracker );
    
    if ( !(free_tracker & NODES) ) {
        free_tracker |= NODES;
    } else if ( !(free_tracker & VEC_PTRS) ) {
        free_tracker |= VEC_PTRS;
    } else if ( !(free_tracker & TERRA_NODE) ) {
        // delete the terrain branch (this should already have been
        // disconnected from the scene graph)
        SG_LOG( SG_TERRAIN, SG_DEBUG, "FREEING terra_transform" );
        if ( fgPartialFreeSSGtree( terra_transform.get(), delete_size ) == 0 ) {
            terra_transform = 0;
            free_tracker |= TERRA_NODE;
        }
    } else if ( !(free_tracker & GROUND_LIGHTS) && gnd_lights_transform.get() ) {
        // delete the terrain lighting branch (this should already have been
        // disconnected from the scene graph)
        SG_LOG( SG_TERRAIN, SG_DEBUG, "FREEING gnd_lights_transform" );
        if ( fgPartialFreeSSGtree( gnd_lights_transform.get(), delete_size ) == 0 ) {
            gnd_lights_transform = 0;
            free_tracker |= GROUND_LIGHTS;
        }
    } else if ( !(free_tracker & VASI_LIGHTS) && vasi_lights_selector.get() ) {
        // delete the runway lighting branch (this should already have
        // been disconnected from the scene graph)
        SG_LOG( SG_TERRAIN, SG_DEBUG, "FREEING vasi_lights_selector" );
        if ( fgPartialFreeSSGtree( vasi_lights_selector.get(), delete_size ) == 0 ) {
            vasi_lights_selector = 0;
            free_tracker |= VASI_LIGHTS;
        }
    } else if ( !(free_tracker & RWY_LIGHTS) && rwy_lights_selector.get() ) {
        // delete the runway lighting branch (this should already have
        // been disconnected from the scene graph)
        SG_LOG( SG_TERRAIN, SG_DEBUG, "FREEING rwy_lights_selector" );
        if ( fgPartialFreeSSGtree( rwy_lights_selector.get(), delete_size ) == 0 ) {
            rwy_lights_selector = 0;
            free_tracker |= RWY_LIGHTS;
        }
    } else if ( !(free_tracker & TAXI_LIGHTS) && taxi_lights_selector.get() ) {
        // delete the taxi lighting branch (this should already have been
        // disconnected from the scene graph)
        SG_LOG( SG_TERRAIN, SG_DEBUG, "FREEING taxi_lights_selector" );
        if ( fgPartialFreeSSGtree( taxi_lights_selector.get(), delete_size ) == 0 ) {
            taxi_lights_selector = 0;
            free_tracker |= TAXI_LIGHTS;
        }
    } else if ( !(free_tracker & LIGHTMAPS) ) {
        free_tracker |= LIGHTMAPS;
    } else {
        return true;
    }

    SG_LOG( SG_TERRAIN, SG_DEBUG, "(end) free_tracker = " << free_tracker );

    // if we fall down to here, we still have work todo, return false
    return false;
}


// Update the ssg transform node for this tile so it can be
// properly drawn relative to our (0,0,0) point
void FGTileEntry::prep_ssg_node( const Point3D& p, sgVec3 up, float vis) {
    if ( !loaded ) return;

    // visibility can change from frame to frame so we update the
    // range selector cutoff's each time.
    terra_range->setRange( 0, 0, vis + bounding_radius );

    if ( gnd_lights_range.get() ) {
        gnd_lights_range->setRange( 0, 0, vis * 1.5 + bounding_radius );
    }

    SGVec3d lt_trans(center.x(), center.y(), center.z());

    FGLight *l = (FGLight *)(globals->get_subsystem("lighting"));
    if ( gnd_lights_transform.get() ) {
        // we need to lift the lights above the terrain to avoid
        // z-buffer fighting.  We do this based on our altitude and
        // the distance this tile is away from scenery center.

        // we expect 'up' to be a unit vector coming in, but since we
        // modify the value of lift_vec, we need to create a local
        // copy.
        SGVec3f lift_vec(up);
  
        double agl;
        agl = globals->get_current_view()->getAltitudeASL_ft()*SG_FEET_TO_METER
          - globals->get_current_view()->getSGLocation()->get_cur_elev_m();

        // Compute the distance of the scenery center from the view position.
        double dist = center.distance3D(p);

        if ( general.get_glDepthBits() > 16 ) {
            lift_vec *= 10.0 + agl / 100.0 + dist / 10000;
        } else {
            lift_vec *= 10.0 + agl / 20.0 + dist / 5000;
        }

        gnd_lights_transform->setTransform( lt_trans + toVec3d(lift_vec) );

        // select which set of lights based on sun angle
        float sun_angle = l->get_sun_angle() * SGD_RADIANS_TO_DEGREES;
        if ( sun_angle > 95 ) {
            gnd_lights_brightness->setSingleChildOn(2);
        } else if ( sun_angle > 92 ) {
            gnd_lights_brightness->setSingleChildOn(1);
        } else if ( sun_angle > 89 ) {
            gnd_lights_brightness->setSingleChildOn(0);
        } else {
            gnd_lights_brightness->setAllChildrenOff();
        }
    }

    if ( rwy_lights_transform.get() ) {
        // turn runway lights on/off based on sun angle and visibility
        float sun_angle = l->get_sun_angle() * SGD_RADIANS_TO_DEGREES;
        if ( sun_angle > 85 ||
             (fgGetDouble("/environment/visibility-m") < 5000.0) ) {
            rwy_lights_selector->setAllChildrenOn();
        } else {
            rwy_lights_selector->setAllChildrenOff();
        }
    }

    if ( taxi_lights_transform.get() ) {
        // turn taxi lights on/off based on sun angle and visibility
        float sun_angle = l->get_sun_angle() * SGD_RADIANS_TO_DEGREES;
        if ( sun_angle > 85 ||
             (fgGetDouble("/environment/visibility-m") < 5000.0) ) {
            taxi_lights_selector->setAllChildrenOn();
        } else {
            taxi_lights_selector->setAllChildrenOff();
        }
    }
}


osg::Node*
FGTileEntry::gen_lights( SGMaterialLib *matlib, osg::Vec3Array *lights,
                         int inc, float bright )
{
    // generate a repeatable random seed
    sg_srandom( (unsigned)(*lights)[0][0] );

    // Allocate ssg structure
    osg::Vec3Array *vl = new osg::Vec3Array;
    osg::Vec4Array *cl = new osg::Vec4Array;

    for ( unsigned i = 0; i < lights->size(); ++i ) {
        // this loop is slightly less efficient than it otherwise
        // could be, but we want a red light to always be red, and a
        // yellow light to always be yellow, etc. so we are trying to
        // preserve the random sequence.
        float zombie = sg_random();
        if ( i % inc == 0 ) {
            vl->push_back( (*lights)[i] );

            // factor = sg_random() ^ 2, range = 0 .. 1 concentrated towards 0
            float factor = sg_random();
            factor *= factor;

            osg::Vec4 color;
            if ( zombie > 0.5 ) {
                // 50% chance of yellowish
                color = osg::Vec4( 0.9, 0.9, 0.3, bright - factor * 0.2 );
            } else if ( zombie > 0.15 ) {
                // 35% chance of whitish
                color = osg::Vec4( 0.9, 0.9, 0.8, bright - factor * 0.2 );
            } else if ( zombie > 0.05 ) {
                // 10% chance of orangish
                color = osg::Vec4( 0.9, 0.6, 0.2, bright - factor * 0.2 );
            } else {
                // 5% chance of redish
                color = osg::Vec4( 0.9, 0.2, 0.2, bright - factor * 0.2 );
            }
            cl->push_back( color );
        }
    }

    // create ssg leaf
    osg::Geometry* geometry = new osg::Geometry;
    geometry->setVertexArray(vl);
    geometry->setColorArray(cl);
    geometry->setColorBinding(osg::Geometry::BIND_PER_VERTEX);
    geometry->addPrimitiveSet(new osg::DrawArrays(GL_POINTS, 0, vl->size()));
    osg::Geode* geode = new osg::Geode;
    geode->addDrawable(geometry);

    // assign state
    SGMaterial *mat = matlib->find( "GROUND_LIGHTS" );
    geode->setStateSet(mat->get_state());

    return geode;
}


bool FGTileEntry::obj_load( const string& path,
                            osg::Group *geometry,
                            osg::Group *vasi_lights,
                            osg::Group *rwy_lights,
                            osg::Group *taxi_lights,
                            osg::Vec3Array *ground_lights, bool is_base )
{
    Point3D c;                  // returned center point
    double br;                  // returned bounding radius

    bool use_random_objects =
        fgGetBool("/sim/rendering/random-objects", true);

    // try loading binary format
    if ( SGBinObjLoad( path, is_base,
                       &c, &br, globals->get_matlib(), use_random_objects,
                       geometry, vasi_lights, rwy_lights, taxi_lights,
                       ground_lights ) )
    {
        if ( is_base ) {
            center = c;
            bounding_radius = br;
        }
    }

    return (geometry != NULL);
}


typedef enum {
    OBJECT,
    OBJECT_SHARED,
    OBJECT_STATIC,
    OBJECT_SIGN,
    OBJECT_RUNWAY_SIGN
} object_type;


// storage class for deferred object processing in FGTileEntry::load()
struct Object {
    Object(object_type t, const string& token, const SGPath& p, istream& in)
        : type(t), path(p)
    {
        in >> name;
        if (type != OBJECT)
            in >> lon >> lat >> elev >> hdg;
        in >> ::skipeol;

        if (type == OBJECT)
            SG_LOG(SG_TERRAIN, SG_INFO, "    " << token << "  " << name);
        else
            SG_LOG(SG_TERRAIN, SG_INFO, "    " << token << "  " << name << "  lon=" <<
                    lon << "  lat=" << lat << "  elev=" << elev << "  hdg=" << hdg);
    }
    object_type type;
    string name;
    SGPath path;
    double lon, lat, elev, hdg;
};


void
FGTileEntry::load( const string_list &path_list, bool is_base )
{
    bool found_tile_base = false;

    SGPath object_base;
    vector<const Object*> objects;

    string index_str = tile_bucket.gen_index_str();
    SG_LOG( SG_TERRAIN, SG_INFO, "Loading tile " << index_str );

    // scan and parse all files and store information
    for (unsigned int i = 0; i < path_list.size(); i++) {
        // If we found a terrain tile in Terrain/, we have to process the
        // Objects/ dir in the same group, too, before we can stop scanning.
        // FGGlobals::set_fg_scenery() inserts an empty string to path_list
        // as marker.
        if (path_list[i].empty()) {
            if (found_tile_base)
                break;
            else
                continue;
        }

        bool has_base = false;

        SGPath tile_path = path_list[i];
        tile_path.append( tile_bucket.gen_base_path() );

        SGPath basename = tile_path;
        basename.append( index_str );

        SG_LOG( SG_TERRAIN, SG_INFO, "  Trying " << basename.str() );


        // Check for master .stg (scene terra gear) file
        SGPath stg_name = basename;
        stg_name.concat( ".stg" );

        sg_gzifstream in( stg_name.str() );
        if ( !in.is_open() )
            continue;

        while ( ! in.eof() ) {
            string token;
            in >> token;

            if ( token[0] == '#' ) {
               in >> ::skipeol;
               continue;
            }
                            // Load only once (first found)
            if ( token == "OBJECT_BASE" ) {
                string name;
                in >> name >> ::skipws;
                SG_LOG( SG_TERRAIN, SG_INFO, "    " << token << " " << name );

                if (!found_tile_base) {
                    found_tile_base = true;
                    has_base = true;

                    object_base = tile_path;
                    object_base.append(name);

                } else
                    SG_LOG(SG_TERRAIN, SG_INFO, "    (skipped)");

                            // Load only if base is not in another file
            } else if ( token == "OBJECT" ) {
                if (!found_tile_base || has_base)
                    objects.push_back(new Object(OBJECT, token, tile_path, in));
                else {
                    string name;
                    in >> name >> ::skipeol;
                    SG_LOG(SG_TERRAIN, SG_INFO, "    " << token << "  "
                            << name << "  (skipped)");
                }

                            // Always OK to load
            } else if ( token == "OBJECT_STATIC" ) {
                objects.push_back(new Object(OBJECT_STATIC, token, tile_path, in));

            } else if ( token == "OBJECT_SHARED" ) {
                objects.push_back(new Object(OBJECT_SHARED, token, tile_path, in));

            } else if ( token == "OBJECT_SIGN" ) {
                objects.push_back(new Object(OBJECT_SIGN, token, tile_path, in));

            } else if ( token == "OBJECT_RUNWAY_SIGN" ) {
                objects.push_back(new Object(OBJECT_RUNWAY_SIGN, token, tile_path, in));

            } else {
                SG_LOG( SG_TERRAIN, SG_DEBUG,
                        "Unknown token '" << token << "' in " << stg_name.str() );
                in >> ::skipws;
            }
        }
    }


    // obj_load() will generate ground lighting for us ...
    osg::ref_ptr<osg::Vec3Array> light_pts = new osg::Vec3Array;
    osg::Group* new_tile = new osg::Group;


    if (found_tile_base) {
        // load tile if found ...
        osg::ref_ptr<osg::Group> geometry = new osg::Group;
        if ( obj_load( object_base.str(), geometry.get(),
                       NULL, NULL, NULL, light_pts.get(), true ) ) {
            new_tile -> addChild( geometry.get() );
        }

    } else {
        // ... or generate an ocean tile on the fly
        SG_LOG(SG_TERRAIN, SG_INFO, "  Generating ocean tile");
        osg::ref_ptr<osg::Group> geometry = new osg::Group;
        Point3D c;
        double br;
        if ( SGGenTile( path_list[0], tile_bucket, &c, &br,
                        globals->get_matlib(), geometry.get() ) ) {
            center = c;
            bounding_radius = br;
            new_tile -> addChild( geometry.get() );
        } else {
            SG_LOG( SG_TERRAIN, SG_ALERT,
                    "Warning: failed to generate ocean tile!" );
        }
    }


    // now that we have a valid center, process all the objects
    for (unsigned int j = 0; j < objects.size(); j++) {
        const Object *obj = objects[j];

        if (obj->type == OBJECT) {
            SGPath custom_path = obj->path;
            custom_path.append( obj->name );

            osg::ref_ptr<osg::Group> geometry = new osg::Group;
            osg::ref_ptr<osg::Group> vasi_lights = new osg::Group;
            osg::ref_ptr<osg::Group> rwy_lights = new osg::Group;
            osg::ref_ptr<osg::Group> taxi_lights = new osg::Group;

            if ( obj_load( custom_path.str(),
                           geometry.get(), vasi_lights.get(), rwy_lights.get(),
                           taxi_lights.get(), NULL, false ) ) {

                if ( geometry -> getNumChildren() > 0 ) {
                    new_tile -> addChild( geometry.get() );
                }

                if ( vasi_lights -> getNumChildren() > 0 )
                    vasi_lights_transform -> addChild( vasi_lights.get() );

                if ( rwy_lights -> getNumChildren() > 0 )
                    rwy_lights_transform -> addChild( rwy_lights.get() );

                if ( taxi_lights -> getNumChildren() > 0 )
                    taxi_lights_transform -> addChild( taxi_lights.get() );
            }


        } else if (obj->type == OBJECT_SHARED || obj->type == OBJECT_STATIC) {
            // object loading is deferred to main render thread,
            // but lets figure out the paths right now.
            SGPath custom_path;
            if ( obj->type == OBJECT_STATIC ) {
                custom_path = obj->path;
            } else {
                custom_path = globals->get_fg_root();
            }
            custom_path.append( obj->name );

            osg::Matrix obj_pos;
            WorldCoordinate( obj_pos, center, obj->lat, obj->lon, obj->elev, obj->hdg );

            osg::MatrixTransform *obj_trans = new osg::MatrixTransform;
            obj_trans->setMatrix( obj_pos );

            // wire as much of the scene graph together as we can
            new_tile->addChild( obj_trans );
            pending_models++;

            // push an entry onto the model load queue
            FGDeferredModel *dm
                = new FGDeferredModel( custom_path.str(),
                                       obj->path.str(),
                                       tile_bucket,
                                       this, obj_trans,
                                       obj->type == OBJECT_SHARED );
            FGTileMgr::model_ready( dm );


        } else if (obj->type == OBJECT_SIGN || obj->type == OBJECT_RUNWAY_SIGN) {
            // load the object itself
            SGPath custom_path = obj->path;
            custom_path.append( obj->name );

            osg::Matrix obj_pos;
            WorldCoordinate( obj_pos, center, obj->lat, obj->lon, obj->elev, obj->hdg );

            osg::MatrixTransform *obj_trans = new osg::MatrixTransform;
            obj_trans->setMatrix( obj_pos );

            osg::Node *custom_obj = 0;
            if (obj->type == OBJECT_SIGN)
                custom_obj = SGMakeSign(globals->get_matlib(), custom_path.str(), obj->name);
            else
                custom_obj = SGMakeRunwaySign(globals->get_matlib(), custom_path.str(), obj->name);

            // wire the pieces together
            if ( custom_obj != NULL ) {
                obj_trans -> addChild( custom_obj );
            }
            new_tile->addChild( obj_trans );

        }
        delete obj;
    }


    if ( new_tile != NULL ) {
        terra_range->addChild( new_tile );
    }

    terra_transform->addChild( terra_range.get() );

    // calculate initial tile offset
    SGVec3d sgdTrans(center.x(), center.y(), center.z());
    terra_transform->setTransform( sgdTrans );

    // Add ground lights to scene graph if any exist
    gnd_lights_transform = NULL;
    gnd_lights_range = NULL;
    if ( light_pts->size() ) {
        SG_LOG( SG_TERRAIN, SG_DEBUG, "generating lights" );
        gnd_lights_transform = new SGPlacementTransform;
        gnd_lights_range = new osg::LOD;
        gnd_lights_brightness = new osg::Switch;
        osg::Node *lights;

        lights = gen_lights( globals->get_matlib(), light_pts.get(), 4, 0.7 );
        gnd_lights_brightness->addChild( lights );

        lights = gen_lights( globals->get_matlib(), light_pts.get(), 2, 0.85 );
        gnd_lights_brightness->addChild( lights );

        lights = gen_lights( globals->get_matlib(), light_pts.get(), 1, 1.0 );
        gnd_lights_brightness->addChild( lights );

        gnd_lights_range->addChild( gnd_lights_brightness.get() );
        gnd_lights_transform->addChild( gnd_lights_range.get() );
        gnd_lights_transform->setTransform( sgdTrans );
    }

    // Update vasi lights transform
    if ( vasi_lights_transform->getNumChildren() > 0 ) {
        vasi_lights_transform->setTransform( sgdTrans );
    }

    // Update runway lights transform
    if ( rwy_lights_transform->getNumChildren() > 0 ) {
        rwy_lights_transform->setTransform( sgdTrans );
    }

     // Update taxi lights transform
    if ( taxi_lights_transform->getNumChildren() > 0 ) {
        taxi_lights_transform->setTransform( sgdTrans );
    }
}

void
FGTileEntry::add_ssg_nodes( osg::Group *terrain_branch,
                            osg::Group *gnd_lights_branch,
                            osg::Group *vasi_lights_branch,
                            osg::Group *rwy_lights_branch,
                            osg::Group *taxi_lights_branch )
{
    // bump up the ref count so we can remove this later without
    // having ssg try to free the memory.
    terrain_branch->addChild( terra_transform.get() );

    SG_LOG( SG_TERRAIN, SG_DEBUG,
            "connected a tile into scene graph.  terra_transform = "
            << terra_transform.get() );
    SG_LOG( SG_TERRAIN, SG_DEBUG, "num parents now = "
            << terra_transform->getNumParents() );

    if ( gnd_lights_transform.get() != NULL ) {
        // bump up the ref count so we can remove this later without
        // having ssg try to free the memory.
        gnd_lights_branch->addChild( gnd_lights_transform.get() );
    }

    if ( vasi_lights_transform.get() != NULL ) {
        // bump up the ref count so we can remove this later without
        // having ssg try to free the memory.
        vasi_lights_selector->addChild( vasi_lights_transform.get() );
        vasi_lights_branch->addChild( vasi_lights_selector.get() );
    }

    if ( rwy_lights_transform.get() != NULL ) {
        // bump up the ref count so we can remove this later without
        // having ssg try to free the memory.
        rwy_lights_selector->addChild( rwy_lights_transform.get() );
        rwy_lights_branch->addChild( rwy_lights_selector.get() );
    }

    if ( taxi_lights_transform.get() != NULL ) {
        // bump up the ref count so we can remove this later without
        // having ssg try to free the memory.
        taxi_lights_selector->addChild( taxi_lights_transform.get() );
        taxi_lights_branch->addChild( taxi_lights_selector.get() );
    }

    loaded = true;
}


void
FGTileEntry::disconnect_ssg_nodes()
{
    SG_LOG( SG_TERRAIN, SG_DEBUG, "disconnecting ssg nodes" );

    if ( ! loaded ) {
        SG_LOG( SG_TERRAIN, SG_DEBUG, "removing a not-fully loaded tile!" );
    } else {
        SG_LOG( SG_TERRAIN, SG_DEBUG, "removing a fully loaded tile!  terra_transform = " << terra_transform.get() );
    }
        
    // find the terrain branch parent
    int pcount = terra_transform->getNumParents();
    if ( pcount > 0 ) {
        // find the first parent (should only be one)
        osg::Group *parent = terra_transform->getParent( 0 ) ;
        if( parent ) {
            // disconnect the tile (we previously ref()'d it so it
            // won't get freed now)
            parent->removeChild( terra_transform.get() );
        } else {
            SG_LOG( SG_TERRAIN, SG_ALERT,
                    "parent pointer is NULL!  Dying" );
            exit(-1);
        }
    } else {
        SG_LOG( SG_TERRAIN, SG_ALERT,
                "Parent count is zero for an ssg tile!  Dying" );
        exit(-1);
    }

    // find the ground lighting branch
    if ( gnd_lights_transform.get() ) {
        pcount = gnd_lights_transform->getNumParents();
        if ( pcount > 0 ) {
            // find the first parent (should only be one)
            osg::Group *parent = gnd_lights_transform->getParent( 0 ) ;
            if( parent ) {
                // disconnect the light branch (we previously ref()'d
                // it so it won't get freed now)
                parent->removeChild( gnd_lights_transform.get() );
            } else {
                SG_LOG( SG_TERRAIN, SG_ALERT,
                        "parent pointer is NULL!  Dying" );
                exit(-1);
            }
        } else {
            SG_LOG( SG_TERRAIN, SG_ALERT,
                    "Parent count is zero for an ssg light tile!  Dying" );
            exit(-1);
        }
    }

    // find the vasi lighting branch
    if ( vasi_lights_transform.get() ) {
        pcount = vasi_lights_transform->getNumParents();
        if ( pcount > 0 ) {
            // find the first parent (should only be one)
            osg::Group *parent = vasi_lights_transform->getParent( 0 ) ;
            if( parent ) {
                // disconnect the light branch (we previously ref()'d
                // it so it won't get freed now)
                parent->removeChild( vasi_lights_transform.get() );
            } else {
                SG_LOG( SG_TERRAIN, SG_ALERT,
                        "parent pointer is NULL!  Dying" );
                exit(-1);
            }
        } else {
            SG_LOG( SG_TERRAIN, SG_ALERT,
                    "Parent count is zero for an ssg light tile!  Dying" );
            exit(-1);
        }
    }

    // find the runway lighting branch
    if ( rwy_lights_transform.get() ) {
        pcount = rwy_lights_transform->getNumParents();
        if ( pcount > 0 ) {
            // find the first parent (should only be one)
            osg::Group *parent = rwy_lights_transform->getParent( 0 ) ;
            if( parent ) {
                // disconnect the light branch (we previously ref()'d
                // it so it won't get freed now)
                parent->removeChild( rwy_lights_transform.get() );
            } else {
                SG_LOG( SG_TERRAIN, SG_ALERT,
                        "parent pointer is NULL!  Dying" );
                exit(-1);
            }
        } else {
            SG_LOG( SG_TERRAIN, SG_ALERT,
                    "Parent count is zero for an ssg light tile!  Dying" );
            exit(-1);
        }
    }

    // find the taxi lighting branch
    if ( taxi_lights_transform.get() ) {
        pcount = taxi_lights_transform->getNumParents();
        if ( pcount > 0 ) {
            // find the first parent (should only be one)
            osg::Group *parent = taxi_lights_transform->getParent( 0 ) ;
            if( parent ) {
                // disconnect the light branch (we previously ref()'d
                // it so it won't get freed now)
                parent->removeChild( taxi_lights_transform.get() );
            } else {
                SG_LOG( SG_TERRAIN, SG_ALERT,
                        "parent pointer is NULL!  Dying" );
                exit(-1);
            }
        } else {
            SG_LOG( SG_TERRAIN, SG_ALERT,
                    "Parent count is zero for an ssg light tile!  Dying" );
            exit(-1);
        }
    }
}