X-Git-Url: https://git.mxchange.org/?a=blobdiff_plain;f=src%2FScenery%2Ftilemgr.cxx;h=53d2d6d4eb59e1a210e66305530fc786e1f5baec;hb=048da049f87fe3f543795f3b1b511d774caa2787;hp=6b148a629394b201cff5ead1e0af6851c8f10859;hpb=01c44cbb99691b2a38527b40721330b2b143e604;p=flightgear.git

diff --git a/src/Scenery/tilemgr.cxx b/src/Scenery/tilemgr.cxx
index 6b148a629..53d2d6d4e 100644
--- a/src/Scenery/tilemgr.cxx
+++ b/src/Scenery/tilemgr.cxx
@@ -30,7 +30,8 @@
 #endif
 
 #include <GL/glut.h>
-#include <simgear/xgl/xgl.h>
+
+#include <plib/ssg.h>
 
 #include <simgear/constants.h>
 #include <simgear/debug/logstream.hxx>
@@ -39,75 +40,81 @@
 #include <simgear/math/sg_geodesy.hxx>
 #include <simgear/math/vector.hxx>
 
-// #include <Aircraft/aircraft.hxx>
 #include <Main/globals.hxx>
+#include <Main/fg_props.hxx>
+#include <Main/viewer.hxx>
 #include <Objects/obj.hxx>
 
-#ifndef FG_OLD_WEATHER
-#  include <WeatherCM/FGLocalWeatherDatabase.h>
-#else
-#  include <Weather/weather.hxx>
-#endif
-
+#include "newcache.hxx"
 #include "scenery.hxx"
-#include "tilecache.hxx"
 #include "tilemgr.hxx"
 
 #define TEST_LAST_HIT_CACHE
 
-extern ssgRoot *scene;
-extern ssgBranch *terrain;
-
 // the tile manager
 FGTileMgr global_tile_mgr;
 
 
-// a temporary hack until we get everything rewritten with sgdVec3
-static inline Point3D operator + (const Point3D& a, const sgdVec3 b)
-{
-    return Point3D(a.x()+b[0], a.y()+b[1], a.z()+b[2]);
-}
+#ifdef ENABLE_THREADS
+SGLockedQueue<FGTileEntry *> FGTileMgr::attach_queue;
+SGLockedQueue<FGDeferredModel *> FGTileMgr::model_queue;
+#else
+queue<FGTileEntry *> FGTileMgr::attach_queue;
+queue<FGDeferredModel *> FGTileMgr::model_queue;
+#endif // ENABLE_THREADS
 
 
 // Constructor
-FGTileMgr::FGTileMgr ( void ):
-    state( Start )
+FGTileMgr::FGTileMgr():
+    state( Start ),
+    current_tile( NULL ),
+    vis( 16000 ),
+    counter_hack(0)
 {
 }
 
 
 // Destructor
-FGTileMgr::~FGTileMgr ( void ) {
+FGTileMgr::~FGTileMgr() {
 }
 
 
 // Initialize the Tile Manager subsystem
-int FGTileMgr::init( void ) {
-    FG_LOG( FG_TERRAIN, FG_INFO, "Initializing Tile Manager subsystem." );
+int FGTileMgr::init() {
+    SG_LOG( SG_TERRAIN, SG_INFO, "Initializing Tile Manager subsystem." );
 
-    if ( state != Start ) {
-	FG_LOG( FG_TERRAIN, FG_INFO,
-		"... Reinitializing." );
-	destroy_queue();
-    } else {
-	FG_LOG( FG_TERRAIN, FG_INFO,
-		"... First time through." );
+    tile_cache.init();
+
+#if 0
+
+    // instead it's just a lot easier to let any pending work flush
+    // through, rather than trying to arrest the queue and nuke all
+    // the various work at all the various stages and get everything
+    // cleaned up properly.
+
+    while ( ! attach_queue.empty() ) {
+        attach_queue.pop();
     }
 
-    global_tile_cache.init();
+    while ( ! model_queue.empty() ) {
+#ifdef ENABLE_THREADS
+	FGDeferredModel* dm = model_queue.pop();
+#else
+        FGDeferredModel* dm = model_queue.front();
+        model_queue.pop();
+#endif
+        delete dm;
+    }
+    loader.reinit();
+#endif
+
     hit_list.clear();
 
     state = Inited;
 
-    tile_diameter = globals->get_options()->get_tile_diameter();
-    FG_LOG( FG_TERRAIN, FG_INFO, "Tile Diameter = " << tile_diameter);
-    
     previous_bucket.make_bad();
     current_bucket.make_bad();
 
-    scroll_direction = SCROLL_INIT;
-    tile_index = -9999;
-
     longitude = latitude = -1000.0;
     last_longitude = last_latitude = -1000.0;
 	
@@ -116,180 +123,86 @@ int FGTileMgr::init( void ) {
 
 
 // schedule a tile for loading
-int FGTileMgr::sched_tile( const FGBucket& b ) {
+void FGTileMgr::sched_tile( const SGBucket& b ) {
     // see if tile already exists in the cache
-    int cache_index = global_tile_cache.exists( b );
-
-    if ( cache_index >= 0 ) {
-        // tile exists in cache, reenable it.
-        // cout << "REENABLING DISABLED TILE" << endl;
-        FGTileEntry *t = global_tile_cache.get_tile( cache_index );
-        t->select_ptr->select( 1 );
-        t->mark_loaded();
-    } else {
-        // find the next available cache entry and mark it as
-        // scheduled
-        cache_index = global_tile_cache.next_avail();
-        FGTileEntry *t = global_tile_cache.get_tile( cache_index );
-        t->mark_scheduled_for_use();
-
-        // register a load request
-        FGLoadRec request;
-        request.b = b;
-        request.cache_index = cache_index;
-        load_queue.push_back( request );
-    }
-
-    return cache_index;
-}
-
+    FGTileEntry *t = tile_cache.get_tile( b );
 
-// load a tile
-void FGTileMgr::load_tile( const FGBucket& b, int cache_index) {
+    if ( t == NULL ) {
+        // create a new entry
+        FGTileEntry *e = new FGTileEntry( b );
 
-    FG_LOG( FG_TERRAIN, FG_DEBUG, "Loading tile " << b );
-    global_tile_cache.fill_in(cache_index, b);
-    FG_LOG( FG_TERRAIN, FG_DEBUG, "Loaded for cache index: " << cache_index );
+        // insert the tile into the cache
+	if ( tile_cache.insert_tile( e ) ) {
+	  // Schedule tile for loading
+	  loader.add( e );
+	} else {
+	  // insert failed (cache full with no available entries to
+	  // delete.)  Try again later
+	  delete e;
+	}
+    }
 }
 
 
-// Determine scenery altitude via ssg.  Normally this just happens
-// when we render the scene, but we'd also like to be able to do this
-// explicitely.  lat & lon are in radians.  view_pos in current world
-// coordinate translated near (0,0,0) (in meters.)  Returns result in
-// meters.
-
-bool
-FGTileMgr::current_elev_ssg( const Point3D& abs_view_pos, 
-			     const Point3D& view_pos )
-{
-    sgdVec3 orig, dir;
-
-    sgdSetVec3(orig, view_pos.x(), view_pos.y(), view_pos.z() );
-    sgdSetVec3(dir, abs_view_pos.x(), abs_view_pos.y(), abs_view_pos.z() );
-
-    hit_list.Intersect( terrain, orig, dir );
-
-    int this_hit=0;
-    Point3D geoc;
-    double result = -9999;
-
-    int hitcount = hit_list.num_hits();
-    for ( int i = 0; i < hitcount; ++i ) {
-	geoc = sgCartToPolar3d( scenery.center + hit_list.get_point(i) );      
-	double lat_geod, alt, sea_level_r;
-	sgGeocToGeod(geoc.lat(), geoc.radius(), &lat_geod, 
-		     &alt, &sea_level_r);
-	if ( alt > result && alt < 10000 ) {
-	    result = alt;
-	    this_hit = i;
-	}
+// schedule a needed buckets for loading
+void FGTileMgr::schedule_needed( double vis, SGBucket curr_bucket) {
+    // sanity check (unfortunately needed!)
+    if ( longitude < -180.0 || longitude > 180.0 
+         || latitude < -90.0 || latitude > 90.0 )
+    {
+        SG_LOG( SG_TERRAIN, SG_ALERT,
+                "Attempting to schedule tiles for bogus latitude and" );
+        SG_LOG( SG_TERRAIN, SG_ALERT,
+                "longitude.  This is a FATAL error.  Exiting!" );
+        exit(-1);        
     }
 
-    if ( result > -9000 ) {
-	scenery.cur_elev = result;
-	scenery.cur_radius = geoc.radius();
-	sgVec3 tmp;
-	sgSetVec3(tmp, hit_list.get_normal(this_hit));
-	ssgState *IntersectedLeafState =
-	    ((ssgLeaf*)hit_list.get_entity(this_hit))->getState();
-	globals->get_current_view()->CurrentNormalInLocalPlane(tmp, tmp);
-	sgdSetVec3( scenery.cur_normal, tmp );
-	// cout << "NED: " << tmp[0] << " " << tmp[1] << " " << tmp[2] << endl;
-	return true;
-    } else {
-	FG_LOG( FG_TERRAIN, FG_INFO, "no terrain intersection" );
-	scenery.cur_elev = 0.0;
-	float *up = globals->get_current_view()->get_local_up();
-	sgdSetVec3(scenery.cur_normal, up[0], up[1], up[2]);
-	return false;
-    }
-}
+   SG_LOG( SG_TERRAIN, SG_INFO,
+           "scheduling needed tiles for " << longitude << " " << latitude );
 
+//   vis = fgGetDouble("/environment/visibility-m");
 
-FGBucket FGTileMgr::BucketOffset( int dx, int dy )
-{
-    double clat, clon, span;
-    if( scroll_direction == SCROLL_INIT ) {
-	// use current latitude and longitude
-	// walk dy units in the lat direction
-	clat = current_bucket.get_center_lat() + dy * FG_BUCKET_SPAN;
-
-	// find the lon span for the new latitude
-	span = bucket_span( clat );
-	
-	// walk dx units in the lon direction
-	clon = longitude + dx * span;
-    } else	{
-	// use previous latitude and longitude
-	// walk dy units in the lat direction
-	clat = previous_bucket.get_center_lat() + dy * FG_BUCKET_SPAN;
-
-	// find the lon span for the new latitude
-	span = bucket_span( clat );
-
-	// walk dx units in the lon direction
-	clon = last_longitude + dx * span;
-    }    
-	
-    while ( clon < -180.0 ) clon += 360.0;
-    while ( clon >= 180.0 ) clon -= 360.0;
-    pending.set_bucket( clon, clat );
+    double tile_width = curr_bucket.get_width_m();
+    double tile_height = curr_bucket.get_height_m();
+    // cout << "tile width = " << tile_width << "  tile_height = "
+    //      << tile_height !<< endl;
 
-    FG_LOG( FG_TERRAIN, FG_DEBUG, "    fgBucketOffset " << pending );
-    return pending;
-}
+    xrange = (int)(vis / tile_width) + 1;
+    yrange = (int)(vis / tile_height) + 1;
+    if ( xrange < 1 ) { xrange = 1; }
+    if ( yrange < 1 ) { yrange = 1; }
+    // cout << "xrange = " << xrange << "  yrange = " << yrange << endl;
 
+    // note * 2 at end doubles cache size (for fdm and viewer)
+    tile_cache.set_max_cache_size( (2*xrange + 2) * (2*yrange + 2) * 2 );
 
-// schedule a tile row(column) for loading
-void FGTileMgr::scroll( void )
-{
-    FG_LOG( FG_TERRAIN, FG_DEBUG, "schedule_row: Scrolling" );
+    SGBucket b;
 
-    int i, dw, dh;
-	
-    switch( scroll_direction ) {
-    case SCROLL_NORTH:
-	FG_LOG( FG_TERRAIN, FG_DEBUG, 
-		"  (North) Loading " << tile_diameter << " tiles" );
-	dw = tile_diameter / 2;
-	dh = dw + 1;
-	for ( i = 0; i < tile_diameter; i++ ) {
-	    sched_tile( BucketOffset( i - dw, dh ) );
-	}
-	break;
-    case SCROLL_EAST:
-	FG_LOG( FG_TERRAIN, FG_DEBUG, 
-		"  (East) Loading " << tile_diameter << " tiles" );
-	dh = tile_diameter / 2;
-	dw = dh + 1;
-	for ( i = 0; i < tile_diameter; i++ ) {
-	    sched_tile( BucketOffset( dw, i - dh ) );
-	}
-	break;
-    case SCROLL_SOUTH:
-	FG_LOG( FG_TERRAIN, FG_DEBUG, 
-		"  (South) Loading " << tile_diameter << " tiles" );
-	dw = tile_diameter / 2;
-	dh = -dw - 1;
-	for ( i = 0; i < tile_diameter; i++ ) {
-	    sched_tile( BucketOffset( i - dw, dh ) );
+    // schedule center tile first so it can be loaded first
+    b = sgBucketOffset( longitude, latitude, 0, 0 );
+    sched_tile( b );
+
+    int x, y;
+
+    // schedule next ring of 8 tiles
+    for ( x = -1; x <= 1; ++x ) {
+	for ( y = -1; y <= 1; ++y ) {
+	    if ( x != 0 || y != 0 ) {
+		b = sgBucketOffset( longitude, latitude, x, y );
+		sched_tile( b );
+	    }
 	}
-	break;
-    case SCROLL_WEST:
-	FG_LOG( FG_TERRAIN, FG_DEBUG, 
-		"  (West) Loading " << tile_diameter << " tiles" );
-	dh = tile_diameter / 2;
-	dw = -dh - 1;
-	for ( i = 0; i < tile_diameter; i++ ) {
-	    sched_tile( BucketOffset( dw, i - dh ) );
+    }
+    
+    // schedule remaining tiles
+    for ( x = -xrange; x <= xrange; ++x ) {
+	for ( y = -yrange; y <= yrange; ++y ) {
+	    if ( x < -1 || x > 1 || y < -1 || y > 1 ) {
+		SGBucket b = sgBucketOffset( longitude, latitude, x, y );
+		sched_tile( b );
+	    }
 	}
-	break;
-    default:
-	FG_LOG( FG_TERRAIN, FG_WARN, "UNKNOWN SCROLL DIRECTION in schedule_row" );
-	;
     }
-    FG_LOG( FG_TERRAIN, FG_DEBUG, "\tschedule_row returns" );
 }
 
 
@@ -298,16 +211,11 @@ void FGTileMgr::initialize_queue()
     // First time through or we have teleported, initialize the
     // system and load all relavant tiles
 
-    FG_LOG( FG_TERRAIN, FG_INFO, "Updating Tile list for " << current_bucket );
-    FG_LOG( FG_TERRAIN, FG_INFO, "  Updating Tile list for " << current_bucket );
-    FG_LOG( FG_TERRAIN, FG_INFO, "  Loading " 
-            << tile_diameter * tile_diameter << " tiles" );
-
-    int i;
-    scroll_direction = SCROLL_INIT;
+    SG_LOG( SG_TERRAIN, SG_INFO, "Updating Tile list for " << current_bucket );
+    // cout << "tile cache size = " << tile_cache.get_size() << endl;
 
     // wipe/initialize tile cache
-    global_tile_cache.init();
+    // tile_cache.init();
     previous_bucket.make_bad();
 
     // build the local area list and schedule tiles for loading
@@ -315,220 +223,237 @@ void FGTileMgr::initialize_queue()
     // start with the center tile and work out in concentric
     // "rings"
 
-    sched_tile( current_bucket );
-
-    for ( i = 3; i <= tile_diameter; i = i + 2 ) {
-        int j;
-        int span = i / 2;
-
-        // bottom row
-        for ( j = -span; j <= span; ++j ) {
-            sched_tile( BucketOffset( j, -span ) );
-        }
-
-        // top row
-        for ( j = -span; j <= span; ++j ) {
-            sched_tile( BucketOffset( j, span ) );
-        }
-
-        // middle rows
-        for ( j = -span + 1; j <= span - 1; ++j ) {
-            sched_tile( BucketOffset( -span, j ) );
-            sched_tile( BucketOffset( span, j ) );
-        }
-
-    }
+    double visibility_meters = fgGetDouble("/environment/visibility-m");
+    schedule_needed(visibility_meters, current_bucket);
 
+    // do we really want to lose this? CLO
+#if 0
     // Now force a load of the center tile and inner ring so we
     // have something to see in our first frame.
+    int i;
     for ( i = 0; i < 9; ++i ) {
         if ( load_queue.size() ) {
-            FG_LOG( FG_TERRAIN, FG_DEBUG, 
+            SG_LOG( SG_TERRAIN, SG_DEBUG, 
                     "Load queue not empty, loading a tile" );
 
-            FGLoadRec pending = load_queue.front();
+            SGBucket pending = load_queue.front();
             load_queue.pop_front();
-            load_tile( pending.b, pending.cache_index );
+            load_tile( pending );
         }
     }
-}
-
-
-// forced emptying of the queue
-// This is necessay to keep bookeeping straight for the
-// tile_cache   -- which actually handles all the
-// (de)allocations  
-void FGTileMgr::destroy_queue() {
-    while( load_queue.size() ) {
-	FG_LOG( FG_TERRAIN, FG_INFO, 
-		"Load queue not empty, popping a tile" );
-	FGLoadRec pending = load_queue.front();
-	load_queue.pop_front();
-        FGTileEntry *t = global_tile_cache.get_tile( pending.cache_index );
-	// just t->mark_unused() should be enough
-	// but a little paranoia doesn't hurt us here
-	if(t->is_scheduled_for_use())
-	    t->mark_unused();
-	else
-	    load_tile( pending.b, pending.cache_index );
-    }
+#endif
 }
 
 
 // given the current lon/lat (in degrees), fill in the array of local
 // chunks.  If the chunk isn't already in the cache, then read it from
 // disk.
-int FGTileMgr::update( double lon, double lat ) {
-    // FG_LOG( FG_TERRAIN, FG_DEBUG, "FGTileMgr::update()" );
+int FGTileMgr::update( double lon, double lat, double visibility_meters ) {
+	sgdVec3 abs_pos_vector;
+        sgdCopyVec3(abs_pos_vector , globals->get_current_view()->get_absolute_view_pos());
+        return update( lon, lat, visibility_meters, abs_pos_vector,
+                       current_bucket, previous_bucket,
+                       globals->get_scenery()->get_center() );
+}
 
-    // FGInterface *f = current_aircraft.fdm_state;
+int FGTileMgr::update( double lon, double lat, double visibility_meters,
+                       sgdVec3 abs_pos_vector, SGBucket p_current,
+                       SGBucket p_previous, Point3D center ) {
+    // SG_LOG( SG_TERRAIN, SG_DEBUG, "FGTileMgr::update() for "
+    //         << lon << " " << lat );
 
-    // lonlat for this update 
-    // longitude = f->get_Longitude() * RAD_TO_DEG;
-    // latitude = f->get_Latitude() * RAD_TO_DEG;
     longitude = lon;
     latitude = lat;
-    // FG_LOG( FG_TERRAIN, FG_DEBUG, "lon "<< lonlat[LON] <<
-    //      " lat " << lonlat[LAT] );
+    current_bucket = p_current;
+    previous_bucket = p_previous;
 
-    current_bucket.set_bucket( longitude, latitude );
-    // FG_LOG( FG_TERRAIN, FG_DEBUG, "Updating Tile list for " << current_bucket );
+    // SG_LOG( SG_TERRAIN, SG_DEBUG, "lon "<< lonlat[LON] <<
+    //      " lat " << lonlat[LAT] );
 
-    tile_index = global_tile_cache.exists(current_bucket);
-    // FG_LOG( FG_TERRAIN, FG_DEBUG, "tile index " << tile_index );
+    // SG_LOG( SG_TERRAIN, SG_DEBUG, "Updating Tile list for " << current_bucket );
 
-    if ( tile_index >= 0 ) {
-        current_tile = global_tile_cache.get_tile(tile_index);
-        scenery.next_center = current_tile->center;
-    } else {
-        FG_LOG( FG_TERRAIN, FG_WARN, "Tile not found (Ok if initializing)" );
-    }
+    setCurrentTile( longitude, latitude);
 
+    // do tile load scheduling. 
+    // Note that we need keep track of both viewer buckets and fdm buckets.
     if ( state == Running ) {
-	if( current_bucket == previous_bucket) {
-	    FG_LOG( FG_TERRAIN, FG_DEBUG, "Same bucket as last time" );
-	    scroll_direction = SCROLL_NONE;
-	} else {
-	    // We've moved to a new bucket, we need to scroll our
-	    // structures, and load in the new tiles
-	    // CURRENTLY THIS ASSUMES WE CAN ONLY MOVE TO ADJACENT TILES.
-	    // AT ULTRA HIGH SPEEDS THIS ASSUMPTION MAY NOT BE VALID IF
-	    // THE AIRCRAFT CAN SKIP A TILE IN A SINGLE ITERATION.
-
-	    if ( (current_bucket.get_lon() > previous_bucket.get_lon()) ||
-		 ( (current_bucket.get_lon() == previous_bucket.get_lon()) && 
-		   (current_bucket.get_x() > previous_bucket.get_x()) ) )
-		{
-		    scroll_direction = SCROLL_EAST;
-		}
-	    else if ( (current_bucket.get_lon() < previous_bucket.get_lon()) ||
-		      ( (current_bucket.get_lon() == previous_bucket.get_lon()) && 
-			(current_bucket.get_x() < previous_bucket.get_x()) ) )
-		{   
-		    scroll_direction = SCROLL_WEST;
-		}   
-
-	    if ( (current_bucket.get_lat() > previous_bucket.get_lat()) ||
-		 ( (current_bucket.get_lat() == previous_bucket.get_lat()) && 
-		   (current_bucket.get_y() > previous_bucket.get_y()) ) )
-		{   
-		    scroll_direction = SCROLL_NORTH;
-		}
-	    else if ( (current_bucket.get_lat() < previous_bucket.get_lat()) ||
-		      ( (current_bucket.get_lat() == previous_bucket.get_lat()) && 
-			(current_bucket.get_y() < previous_bucket.get_y()) ) )
-		{
-		    scroll_direction = SCROLL_SOUTH;
-		}
-
-	    scroll();
-	}
-
+       SG_LOG( SG_TERRAIN, SG_DEBUG, "State == Running" );
+       if (!(current_bucket == previous_bucket )) {
+	 // We've moved to a new bucket, we need to schedule any
+	 // needed tiles for loading.
+	 schedule_needed(visibility_meters, current_bucket);
+       }
     } else if ( state == Start || state == Inited ) {
+	SG_LOG( SG_TERRAIN, SG_INFO, "State == Start || Inited" );
 	initialize_queue();
 	state = Running;
+
+	// load the next tile in the load queue (or authorize the next
+	// load in the case of the threaded tile pager)
+	loader.update();
     }
 
-    if ( load_queue.size() ) {
-	FG_LOG( FG_TERRAIN, FG_DEBUG, "Load queue not empty, loading a tile" );
+    
+    // load the next model in the load queue.  Currently this must
+    // happen in the render thread because model loading can trigger
+    // texture loading which involves use of the opengl api.
+    if ( !model_queue.empty() ) {
+	// cout << "loading next model ..." << endl;
+	// load the next tile in the queue
+#ifdef ENABLE_THREADS
+	FGDeferredModel* dm = model_queue.pop();
+#else
+        FGDeferredModel* dm = model_queue.front();
+        model_queue.pop();
+#endif
+	
+	ssgTexturePath( (char *)(dm->get_texture_path().c_str()) );
+	ssgEntity *obj_model
+	    = ssgLoad( (char *)(dm->get_model_path().c_str()) );
+        if ( obj_model != NULL ) {
+            dm->get_obj_trans()->addKid( obj_model );
+        }
+        dm->get_tile()->dec_pending_models();
 
-	FGLoadRec pending = load_queue.front();
-	load_queue.pop_front();
-	load_tile( pending.b, pending.cache_index );
+	delete dm;
     }
+    
+    // cout << "current elevation (ssg) == " << scenery.get_cur_elev() << endl;
 
-    if ( scenery.center == Point3D(0.0) ) {
-	// initializing
-	// cout << "initializing ... " << endl;
-	Point3D geod_pos = Point3D( longitude * DEG_TO_RAD,
-				    latitude * DEG_TO_RAD,
-				    0.0);
-	Point3D tmp_abs_view_pos = sgGeodToCart( geod_pos );
-	scenery.center = tmp_abs_view_pos;
-	// cout << "abs_view_pos = " << tmp_abs_view_pos << endl;
-	prep_ssg_nodes();
-	current_elev_ssg( tmp_abs_view_pos,
-			  Point3D( 0.0 ) );
+
+    // save bucket...
+    previous_bucket = current_bucket;
+
+    // activate loader thread one out of every 5 frames
+    if ( counter_hack == 0 ) {
+      // Notify the tile loader that it can load another tile
+      loader.update();
     } else {
-	// cout << "abs view pos = " << current_view.abs_view_pos
-	//      << " view pos = " << current_view.view_pos << endl;
-	current_elev_ssg( globals->get_current_view()->get_abs_view_pos(),
-			  globals->get_current_view()->get_view_pos() );
+      counter_hack = (counter_hack + 1) % 5;
     }
 
-    // cout << "current elevation (ssg) == " << scenery.cur_elev << endl;
+    if ( !attach_queue.empty() ) {
+#ifdef ENABLE_THREADS
+	FGTileEntry* e = attach_queue.pop();
+#else
+	FGTileEntry* e = attach_queue.front();
+	attach_queue.pop();
+#endif
+	e->add_ssg_nodes( globals->get_scenery()->get_terrain_branch(),
+			  globals->get_scenery()->get_gnd_lights_branch(),
+			  globals->get_scenery()->get_rwy_lights_branch() );
+	// cout << "Adding ssg nodes for "
+    }
 
-    previous_bucket = current_bucket;
-    last_longitude = longitude;
-    last_latitude  = latitude;
+    // no reason to update this if we haven't moved...
+    if ( longitude != last_longitude || latitude != last_latitude ) {
+      // update current elevation... 
+      if (updateCurrentElevAtPos(abs_pos_vector, center)) {
+        last_longitude = longitude;
+        last_latitude = latitude;
+      }
+    }
+
+#if 0
+    }
+#endif
 
     return 1;
 }
 
-// Prepare the ssg nodes ... for each tile, set it's proper
-// transform and update it's range selector based on current
-// visibilty
-void FGTileMgr::prep_ssg_node( int idx ) {
+// timer event driven call to scheduler for the purpose of refreshing the tile timestamps
+void FGTileMgr::refresh_view_timestamps() {
+  SG_LOG( SG_TERRAIN, SG_INFO,
+      "Refreshing timestamps for " << current_bucket.get_center_lon() << " " << current_bucket.get_center_lat() );
+  schedule_needed(fgGetDouble("/environment/visibility-m"), current_bucket);
 }
 
-void FGTileMgr::prep_ssg_nodes( void ) {
-    FGTileEntry *t;
-    float ranges[2];
-    ranges[0] = 0.0f;
-    double vis = 0.0;
+// check and set current tile and scenery center...
+void FGTileMgr::setCurrentTile(double longitude, double latitude) {
 
-#ifndef FG_OLD_WEATHER
-    if ( WeatherDatabase != NULL ) {
-	vis = WeatherDatabase->getWeatherVisibility();
+    // check tile cache entry...
+    current_bucket.set_bucket( longitude, latitude );
+    if ( tile_cache.exists( current_bucket ) ) {
+        current_tile = tile_cache.get_tile( current_bucket );
+        globals->get_scenery()->set_next_center( current_tile->center );
     } else {
-	vis = 16000;
+        SG_LOG( SG_TERRAIN, SG_WARN, "Tile not found (Ok if initializing)" );
+        globals->get_scenery()->set_next_center( Point3D(0.0) );
+    }
+}
+
+int FGTileMgr::updateCurrentElevAtPos(sgdVec3 abs_pos_vector, Point3D center) {
+
+  sgdVec3 sc;
+
+  sgdSetVec3( sc,
+    center[0],
+    center[1],
+    center[2]);
+
+    // overridden with actual values if a terrain intersection is
+    // found
+    double hit_elev = -9999.0;
+    double hit_radius = 0.0;
+    sgdVec3 hit_normal = { 0.0, 0.0, 0.0 };
+    
+    bool hit = false;
+    if ( fabs(sc[0]) > 1.0 || fabs(sc[1]) > 1.0 || fabs(sc[2]) > 1.0 ) {
+       // scenery center has been properly defined so any hit
+       // should be valid (and not just luck)
+       hit = fgCurrentElev(abs_pos_vector,
+	  sc,
+	  current_tile->get_terra_transform(),
+	  &hit_list,
+	  &hit_elev,
+	  &hit_radius,
+          hit_normal);
     }
-#else
-    vis = current_weather.get_visibility();
-#endif
-    // cout << "visibility = " << vis << endl;
+
+    if ( hit ) {
+          globals->get_scenery()->set_cur_elev( hit_elev );
+          globals->get_scenery()->set_cur_radius( hit_radius );
+          globals->get_scenery()->set_cur_normal( hit_normal );
+    } else {
+          globals->get_scenery()->set_cur_elev( -9999.0 );
+          globals->get_scenery()->set_cur_radius( 0.0 );
+          globals->get_scenery()->set_cur_normal( hit_normal );
+    }
+    return hit;
+}
+
+void FGTileMgr::prep_ssg_nodes(float vis) {
 
     // traverse the potentially viewable tile list and update range
     // selector and transform
-    for ( int i = 0; i < (int)global_tile_cache.get_size(); i++ ) {
-        t = global_tile_cache.get_tile( i );
 
-        if ( t->is_loaded() ) {
-	    // set range selector (LOD trick) to be distance to center
-	    // of tile + bounding radius
+    // just setup and call new function...
+
+    sgVec3 up;
+    sgCopyVec3( up, globals->get_current_view()->get_world_up() );
+
+    Point3D center;
+    center = globals->get_scenery()->get_center();
+    prep_ssg_nodes( vis, up, center );
 
-            ranges[1] = vis + t->bounding_radius;
-            t->range_ptr->setRanges( ranges, 2 );
+}
+
+void FGTileMgr::prep_ssg_nodes(float vis, sgVec3 up, Point3D center) {
 
-            // calculate tile offset
-            t->SetOffset( scenery.center );
+    // traverse the potentially viewable tile list and update range
+    // selector and transform
 
-            // calculate ssg transform
-            sgCoord sgcoord;
-            sgSetCoord( &sgcoord,
-                        t->offset.x(), t->offset.y(), t->offset.z(),
-                        0.0, 0.0, 0.0 );
-            t->transform_ptr->setTransform( &sgcoord );
+    FGTileEntry *e;
+    tile_cache.reset_traversal();
+
+    while ( ! tile_cache.at_end() ) {
+        // cout << "processing a tile" << endl;
+	if ( (e = tile_cache.get_current()) ) {
+	    e->prep_ssg_node( center, up, vis);
+        } else {
+	    SG_LOG(SG_INPUT, SG_ALERT, "warning ... empty tile in cache");
         }
-    }
+	tile_cache.next();
+   }
 }
+