X-Git-Url: https://git.mxchange.org/?a=blobdiff_plain;f=src%2FScenery%2Ftilemgr.cxx;h=53d2d6d4eb59e1a210e66305530fc786e1f5baec;hb=048da049f87fe3f543795f3b1b511d774caa2787;hp=88bf6eb83dc10fe0489360b1d61441b0ab9e9fd9;hpb=8b2e57a93dafd3e8a3e42559fdb2ddb8e284e1c7;p=flightgear.git

diff --git a/src/Scenery/tilemgr.cxx b/src/Scenery/tilemgr.cxx
index 88bf6eb83..53d2d6d4e 100644
--- a/src/Scenery/tilemgr.cxx
+++ b/src/Scenery/tilemgr.cxx
@@ -30,681 +30,430 @@
 #endif
 
 #include <GL/glut.h>
-#include <XGL/xgl.h>
-
-#include <Aircraft/aircraft.hxx>
-
-#include <Debug/logstream.hxx>
-// #include <Bucket/bucketutils.hxx>
-#include <Include/fg_constants.h>
-#include <Main/options.hxx>
-#include <Main/views.hxx>
-#include <Math/fg_geodesy.hxx>
-#include <Math/mat3.h>
-#include <Math/point3d.hxx>
-#include <Math/polar3d.hxx>
-#include <Math/vector.hxx>
-#include <Objects/materialmgr.hxx>
-#include <Objects/obj.hxx>
-// #include <Weather/weather.hxx>
-#include <WeatherCM/FGLocalWeatherDatabase.h>
-
-#include "scenery.hxx"
-#include "tilecache.hxx"
-#include "tileentry.hxx"
-#include "tilemgr.hxx"
 
+#include <plib/ssg.h>
 
-// to test clipping speedup in fgTileMgrRender()
-#if defined ( USE_FAST_FOV_CLIP )
-// #define TEST_FOV_CLIP
-// #define TEST_ELEV
-#endif
+#include <simgear/constants.h>
+#include <simgear/debug/logstream.hxx>
+#include <simgear/math/point3d.hxx>
+#include <simgear/math/polar3d.hxx>
+#include <simgear/math/sg_geodesy.hxx>
+#include <simgear/math/vector.hxx>
 
+#include <Main/globals.hxx>
+#include <Main/fg_props.hxx>
+#include <Main/viewer.hxx>
+#include <Objects/obj.hxx>
 
-extern ssgRoot *scene;
+#include "newcache.hxx"
+#include "scenery.hxx"
+#include "tilemgr.hxx"
 
+#define TEST_LAST_HIT_CACHE
 
 // the tile manager
 FGTileMgr global_tile_mgr;
 
 
+#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." );
+
+    tile_cache.init();
+
+#if 0
 
-    // load default material library
-    if ( ! material_mgr.loaded() ) {
-	material_mgr.load_lib();
+    // 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();
     }
 
-    state = Inited;
+    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
 
-    return 1;
-}
+    hit_list.clear();
+
+    state = Inited;
 
+    previous_bucket.make_bad();
+    current_bucket.make_bad();
 
-// schedule a tile for loading
-static void disable_tile( int cache_index ) {
-    // see if tile already exists in the cache
-    cout << "DISABLING CACHE ENTRY = " << cache_index << endl;
-    FGTileEntry *t = global_tile_cache.get_tile( cache_index );
-    t->ssg_disable();
+    longitude = latitude = -1000.0;
+    last_longitude = last_latitude = -1000.0;
+	
+    return 1;
 }
 
 
 // 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 );
+    FGTileEntry *t = tile_cache.get_tile( b );
+
+    if ( t == NULL ) {
+        // create a new entry
+        FGTileEntry *e = new FGTileEntry( b );
+
+        // 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;
+	}
     }
-
-    return cache_index;
 }
 
 
-// load a tile
-void FGTileMgr::load_tile( const FGBucket& b, int cache_index) {
-
-    FG_LOG( FG_TERRAIN, FG_DEBUG, "Loading tile " << b );
-    
-    global_tile_cache.fill_in(cache_index, b);
+// 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);        
+    }
 
-    FG_LOG( FG_TERRAIN, FG_DEBUG, "Loaded for cache index: " << cache_index );
-}
+   SG_LOG( SG_TERRAIN, SG_INFO,
+           "scheduling needed tiles for " << longitude << " " << latitude );
 
+//   vis = fgGetDouble("/environment/visibility-m");
 
-// Calculate shortest distance from point to line
-static double point_line_dist_squared( const Point3D& tc, const Point3D& vp, 
-				       MAT3vec d )
-{
-    MAT3vec p, p0;
+    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;
 
-    p[0] = tc.x(); p[1] = tc.y(); p[2] = tc.z();
-    p0[0] = vp.x(); p0[1] = vp.y(); p0[2] = vp.z();
+    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;
 
-    return fgPointLineSquared(p, p0, d);
-}
+    // note * 2 at end doubles cache size (for fdm and viewer)
+    tile_cache.set_max_cache_size( (2*xrange + 2) * (2*yrange + 2) * 2 );
 
+    SGBucket b;
 
-// Determine scenery altitude.  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.  abs_view_pos in meters.
-// Returns result in meters.
-double
-FGTileMgr::current_elev_new( const FGBucket& p ) {
-    FGTileEntry *t;
-    fgFRAGMENT *frag_ptr;
-    Point3D abs_view_pos = current_view.get_abs_view_pos();
-    Point3D earth_center(0.0);
-    Point3D result;
-    MAT3vec local_up;
-    double dist, lat_geod, alt, sea_level_r;
-    int index;
-
-    local_up[0] = abs_view_pos.x();
-    local_up[1] = abs_view_pos.y();
-    local_up[2] = abs_view_pos.z();
-
-    // Find current translation offset
-    // fgBucketFind(lon * RAD_TO_DEG, lat * RAD_TO_DEG, &p);
-    index = global_tile_cache.exists(p);
-    if ( index < 0 ) {
-	FG_LOG( FG_TERRAIN, FG_WARN, "Tile not found" );
-	return 0.0;
-    }
+    // schedule center tile first so it can be loaded first
+    b = sgBucketOffset( longitude, latitude, 0, 0 );
+    sched_tile( b );
 
-    t = global_tile_cache.get_tile(index);
+    int x, y;
 
-    scenery.next_center = t->center;
-    
-    FG_LOG( FG_TERRAIN, FG_DEBUG, 
-	    "Current bucket = " << p << "  Index = " << p.gen_index_str() );
-    FG_LOG( FG_TERRAIN, FG_DEBUG,
-	    "abs_view_pos = " << abs_view_pos );
-
-    // calculate tile offset
-    // x = (t->offset.x = t->center.x - scenery.center.x);
-    // y = (t->offset.y = t->center.y - scenery.center.y);
-    // z = (t->offset.z = t->center.z - scenery.center.z);
-    
-    // calc current terrain elevation calculate distance from
-    // vertical tangent line at current position to center of
-    // tile.
-	
-    /* printf("distance squared = %.2f, bounding radius = %.2f\n", 
-       point_line_dist_squared(&(t->offset), &(v->view_pos), 
-       v->local_up), t->bounding_radius); */
-
-    dist = point_line_dist_squared( t->center, abs_view_pos, local_up );
-    if ( dist < FG_SQUARE(t->bounding_radius) ) {
-
-	// traverse fragment list for tile
-        FGTileEntry::FragmentIterator current = t->begin();
-        FGTileEntry::FragmentIterator last = t->end();
-
-	for ( ; current != last; ++current ) {
-	    frag_ptr = &(*current);
-	    /* printf("distance squared = %.2f, bounding radius = %.2f\n", 
-	       point_line_dist_squared( &(frag_ptr->center), 
-	       &abs_view_pos), local_up),
-	       frag_ptr->bounding_radius); */
-
-	    dist = point_line_dist_squared( frag_ptr->center,
-					    abs_view_pos,
-					    local_up);
-	    if ( dist <= FG_SQUARE(frag_ptr->bounding_radius) ) {
-		if ( frag_ptr->intersect( abs_view_pos, 
-					  earth_center, 0, result ) ) {
-		    FG_LOG( FG_TERRAIN, FG_DEBUG, "intersection point " <<
-			    result );
-		    // compute geocentric coordinates of tile center
-		    Point3D pp = fgCartToPolar3d(result);
-		    FG_LOG( FG_TERRAIN, FG_DEBUG, "  polar form = " << pp );
-		    // convert to geodetic coordinates
-		    fgGeocToGeod(pp.lat(), pp.radius(), &lat_geod, 
-				 &alt, &sea_level_r);
-
-		    // printf("alt = %.2f\n", alt);
-		    // exit since we found an intersection
-		    if ( alt > -9999.0 ) {
-			// printf("returning alt\n");
-			return alt;
-		    } else {
-			// printf("returning 0\n");
-			return 0.0;
-		    }
-		}
+    // 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 );
 	    }
 	}
     }
-
-    FG_LOG( FG_TERRAIN, FG_INFO, "(new) no terrain intersection found" );
-
-    return 0.0;
-}
-
-
-// Determine scenery altitude.  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.  abs_view_pos in meters.
-// Returns result in meters.
-double
-FGTileMgr::current_elev( double lon, double lat, const Point3D& abs_view_pos ) {
-    FGTileCache *c;
-    FGTileEntry *t;
-    fgFRAGMENT *frag_ptr;
-    Point3D earth_center(0.0);
-    Point3D result;
-    MAT3vec local_up;
-    double dist, lat_geod, alt, sea_level_r;
-    int index;
-
-    c = &global_tile_cache;
-
-    local_up[0] = abs_view_pos.x();
-    local_up[1] = abs_view_pos.y();
-    local_up[2] = abs_view_pos.z();
-
-    FG_LOG( FG_TERRAIN, FG_DEBUG, "Absolute view pos = " << abs_view_pos );
-
-    // Find current translation offset
-    FGBucket p( lon * RAD_TO_DEG, lat * RAD_TO_DEG );
-    index = c->exists(p);
-    if ( index < 0 ) {
-	FG_LOG( FG_TERRAIN, FG_WARN, "Tile not found" );
-	return 0.0;
-    }
-
-    t = c->get_tile(index);
-
-    scenery.next_center = t->center;
-    
-    FG_LOG( FG_TERRAIN, FG_DEBUG, 
-	    "Pos = (" << lon * RAD_TO_DEG << ", " << lat * RAD_TO_DEG
-	    << ")  Current bucket = " << p 
-	    << "  Index = " << p.gen_index_str() );
-
-    FG_LOG( FG_TERRAIN, FG_DEBUG, "Tile center " << t->center 
-	    << "  bounding radius = " << t->bounding_radius );
-
-    // calculate tile offset
-    // x = (t->offset.x = t->center.x - scenery.center.x);
-    // y = (t->offset.y = t->center.y - scenery.center.y);
-    // z = (t->offset.z = t->center.z - scenery.center.z);
     
-    // calc current terrain elevation calculate distance from
-    // vertical tangent line at current position to center of
-    // tile.
-	
-    /* printf("distance squared = %.2f, bounding radius = %.2f\n", 
-       point_line_dist_squared(&(t->offset), &(v->view_pos), 
-       v->local_up), t->bounding_radius); */
-
-    dist = point_line_dist_squared( t->center, abs_view_pos, local_up );
-    FG_LOG( FG_TERRAIN, FG_DEBUG, "(gross check) dist squared = " << dist );
-
-    if ( dist < FG_SQUARE(t->bounding_radius) ) {
-
-	// traverse fragment list for tile
-        FGTileEntry::FragmentIterator current = t->begin();
-        FGTileEntry::FragmentIterator last = t->end();
-
-	for ( ; current != last; ++current ) {
-	    frag_ptr = &(*current);
-	    /* printf("distance squared = %.2f, bounding radius = %.2f\n", 
-	       point_line_dist_squared( &(frag_ptr->center), 
-	       &abs_view_pos), local_up),
-	       frag_ptr->bounding_radius); */
-
-	    dist = point_line_dist_squared( frag_ptr->center,
-					    abs_view_pos,
-					    local_up);
-	    if ( dist <= FG_SQUARE(frag_ptr->bounding_radius) ) {
-		if ( frag_ptr->intersect( abs_view_pos, 
-					  earth_center, 0, result ) ) {
-		    FG_LOG( FG_TERRAIN, FG_DEBUG, "intersection point " <<
-			    result );
-		    // compute geocentric coordinates of tile center
-		    Point3D pp = fgCartToPolar3d(result);
-		    FG_LOG( FG_TERRAIN, FG_DEBUG, "  polar form = " << pp );
-		    // convert to geodetic coordinates
-		    fgGeocToGeod(pp.lat(), pp.radius(), &lat_geod, 
-				 &alt, &sea_level_r);
-
-		    // printf("alt = %.2f\n", alt);
-		    // exit since we found an intersection
-		    if ( alt > -9999.0 ) {
-			// printf("returning alt\n");
-			return alt;
-		    } else {
-			// printf("returning 0\n");
-			return 0.0;
-		    }
-		}
+    // 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 );
 	    }
 	}
     }
-
-    FG_LOG( FG_TERRAIN, FG_INFO, "(old) no terrain intersection found" );
-
-    return 0.0;
 }
 
 
-// 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.
-double
-FGTileMgr::current_elev_ssg( const Point3D& abs_view_pos, 
-			     const Point3D& view_pos )
+void FGTileMgr::initialize_queue()
 {
-    ssgHit *results ;
-
-    // cout << "view pos = " << view_pos << endl;
-    // cout << "abs view pos = " << abs_view_pos << endl;
-
-    sgMat4 m;
-    sgMakeTransMat4( m, view_pos.x(), view_pos.y(), view_pos.z() );
-
-    sgVec3 s;
-    sgSetVec3(s, -abs_view_pos.x(), -abs_view_pos.y(), -abs_view_pos.z() );
-
-    int num_hits = ssgLOS ( scene, s, m, &results ) ;
-
-    for ( int i = 0 ; i < num_hits ; i++ ) {
-	ssgHit *h = &(results [ i ]) ;
-	cout << "got a hit!" << endl;
-	/* Do something with 'h' */
+    // First time through or we have teleported, initialize the
+    // system and load all relavant tiles
+
+    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
+    // tile_cache.init();
+    previous_bucket.make_bad();
+
+    // build the local area list and schedule tiles for loading
+
+    // start with the center tile and work out in concentric
+    // "rings"
+
+    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() ) {
+            SG_LOG( SG_TERRAIN, SG_DEBUG, 
+                    "Load queue not empty, loading a tile" );
+
+            SGBucket pending = load_queue.front();
+            load_queue.pop_front();
+            load_tile( pending );
+        }
     }
+#endif
+}
 
-    FG_LOG( FG_TERRAIN, FG_INFO, "(ssg) no terrain intersection found" );
 
-    return 0.0;
+// 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, 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() );
 }
 
-
-// given the current lon/lat, fill in the array of local chunks.  If
-// the chunk isn't already in the cache, then read it from disk.
-int FGTileMgr::update( void ) {
-    FGTileCache *c;
-    FGInterface *f;
-    FGBucket p2;
-    static FGBucket p_last(false);
-    static double last_lon = -1000.0;  // in degrees
-    static double last_lat = -1000.0;  // in degrees
-    int tile_diameter;
-    int i, j, dw, dh;
-
-    c = &global_tile_cache;
-    f = current_aircraft.fdm_state;
-
-    tile_diameter = current_options.get_tile_diameter();
-
-    FGBucket p1( f->get_Longitude() * RAD_TO_DEG,
-		 f->get_Latitude() * RAD_TO_DEG );
-    dw = tile_diameter / 2;
-    dh = tile_diameter / 2;
-
-    if ( (p1 == p_last) && (state == Running) ) {
-	// same bucket as last time
-	FG_LOG( FG_TERRAIN, FG_DEBUG, "Same bucket as last time" );
-    } else if ( (state == Start) || (state == Inited) ) {
+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 );
+
+    longitude = lon;
+    latitude = lat;
+    current_bucket = p_current;
+    previous_bucket = p_previous;
+
+    // SG_LOG( SG_TERRAIN, SG_DEBUG, "lon "<< lonlat[LON] <<
+    //      " lat " << lonlat[LAT] );
+
+    // SG_LOG( SG_TERRAIN, SG_DEBUG, "Updating Tile list for " << current_bucket );
+
+    setCurrentTile( longitude, latitude);
+
+    // do tile load scheduling. 
+    // Note that we need keep track of both viewer buckets and fdm buckets.
+    if ( state == Running ) {
+       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;
 
-	// 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 " << p1 );
-	FG_LOG( FG_TERRAIN, FG_INFO, "  First time through ... " );
-	FG_LOG( FG_TERRAIN, FG_INFO, "  Updating Tile list for " << p1 );
-	FG_LOG( FG_TERRAIN, FG_INFO, "  Loading " 
-		<< tile_diameter * tile_diameter << " tiles" );
-
-	// wipe/initialize tile cache
-	c->init();
-	p_last.make_bad();
-
-	// build the local area list and schedule tiles for loading
-
-	// start with the center tile and work out in concentric
-	// "rings"
-
-	p2 = fgBucketOffset( f->get_Longitude() * RAD_TO_DEG,
-			     f->get_Latitude() * RAD_TO_DEG,
-			     0, 0 );
-	sched_tile( p2 );
-
-	for ( i = 3; i <= tile_diameter; i = i + 2 ) {
-	    int span = i / 2;
-
-	    // bottom row
-	    for ( j = -span; j <= span; ++j ) {
-		p2 = fgBucketOffset( f->get_Longitude() * RAD_TO_DEG,
-				     f->get_Latitude() * RAD_TO_DEG,
-				     j, -span );
-		sched_tile( p2 );
-	    }
+	// load the next tile in the load queue (or authorize the next
+	// load in the case of the threaded tile pager)
+	loader.update();
+    }
 
-	    // top row
-	    for ( j = -span; j <= span; ++j ) {
-		p2 = fgBucketOffset( f->get_Longitude() * RAD_TO_DEG,
-				     f->get_Latitude() * RAD_TO_DEG,
-				     j, span );
-		sched_tile( p2 );
-	    }
+    
+    // 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();
+
+	delete dm;
+    }
+    
+    // cout << "current elevation (ssg) == " << scenery.get_cur_elev() << endl;
 
-	    // middle rows
-	    for ( j = -span + 1; j <= span - 1; ++j ) {
-		p2 = fgBucketOffset( f->get_Longitude() * RAD_TO_DEG,
-				     f->get_Latitude() * RAD_TO_DEG,
-				     -span, j );
-		sched_tile( p2 );
-		p2 = fgBucketOffset( f->get_Longitude() * RAD_TO_DEG,
-				     f->get_Latitude() * RAD_TO_DEG,
-				     span, j );
-		sched_tile( p2 );
-	    }
 
-	}
-
-	/* for ( j = 0; j < tile_diameter; j++ ) {
-	    for ( i = 0; i < tile_diameter; i++ ) {
-		// fgBucketOffset(&p1, &p2, i - dw, j - dh);
-		p2 = fgBucketOffset( f->get_Longitude() * RAD_TO_DEG,
-				     f->get_Latitude() * RAD_TO_DEG,
-				     i - dw, j -dh );
-		sched_tile( p2 );
-	    }
-	} */
-
-	// Now force a load of the center tile and inner ring so we
-	// have something to see in our first frame.
-	for ( i = 0; i < 9; ++i ) {
-	    if ( load_queue.size() ) {
-		FG_LOG( FG_TERRAIN, FG_INFO, 
-			"Load queue not empty, loading a tile" );
-	    
-		FGLoadRec pending = load_queue.front();
-		load_queue.pop_front();
-		load_tile( pending.b, pending.cache_index );
-	    }
-	}
+    // 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 {
-	// We've moved to a new bucket, we need to scroll our
-        // structures, and load in the new tiles
-
-#if 0 
-	// make sure load queue is flushed before doing shift
-	while ( load_queue.size() ) {
-	    FG_LOG( FG_TERRAIN, FG_INFO, 
-		    "Load queue not empty, flushing queue before tile shift." );
-	    
-	    FGLoadRec pending = load_queue.front();
-	    load_queue.pop_front();
-	    load_tile( pending.b, pending.index );
-	}
-#endif
-
-	// 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.
-
-	FG_LOG( FG_TERRAIN, FG_INFO, "Updating Tile list for " << p1 );
-
-	if ( (p1.get_lon() > p_last.get_lon()) ||
-	     ( (p1.get_lon() == p_last.get_lon()) && 
-	       (p1.get_x() > p_last.get_x()) ) ) {
-	    FG_LOG( FG_TERRAIN, FG_INFO, 
-		    "  (East) Loading " << tile_diameter << " tiles" );
-	    for ( j = 0; j < tile_diameter; j++ ) {
-		// scrolling East
-		// schedule new column
-		p2 = fgBucketOffset( last_lon, last_lat, dw + 1, j - dh );
-		sched_tile( p2 );
-	    }
-	} else if ( (p1.get_lon() < p_last.get_lon()) ||
-		    ( (p1.get_lon() == p_last.get_lon()) && 
-		      (p1.get_x() < p_last.get_x()) ) ) {
-	    FG_LOG( FG_TERRAIN, FG_INFO, 
-		    "  (West) Loading " << tile_diameter << " tiles" );
-	    for ( j = 0; j < tile_diameter; j++ ) {
-		// scrolling West
-		// schedule new column
-		p2 = fgBucketOffset( last_lon, last_lat, -dw - 1, j - dh );
-		sched_tile( p2 );
-	    }
-	}
+      counter_hack = (counter_hack + 1) % 5;
+    }
 
-	if ( (p1.get_lat() > p_last.get_lat()) ||
-	     ( (p1.get_lat() == p_last.get_lat()) && 
-	       (p1.get_y() > p_last.get_y()) ) ) {
-	    FG_LOG( FG_TERRAIN, FG_INFO, 
-		    "  (North) Loading " << tile_diameter << " tiles" );
-	    for ( i = 0; i < tile_diameter; i++ ) {
-		// scrolling North
-		// schedule new row
-		p2 = fgBucketOffset( last_lon, last_lat, i - dw, dh + 1);
-		sched_tile( p2 );
-	    }
-	} else if ( (p1.get_lat() < p_last.get_lat()) ||
-		    ( (p1.get_lat() == p_last.get_lat()) && 
-		      (p1.get_y() < p_last.get_y()) ) ) {
-	    FG_LOG( FG_TERRAIN, FG_INFO, 
-		    "  (South) Loading " << tile_diameter << " tiles" );
-	    for ( i = 0; i < tile_diameter; i++ ) {
-		// scrolling South
-		// schedule new row
-		p2 = fgBucketOffset( last_lon, last_lat, i - dw, -dh - 1);
-		sched_tile( p2 );
-	    }
-	}
+    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 "
     }
 
-    if ( load_queue.size() ) {
-	FG_LOG( FG_TERRAIN, FG_INFO, "Load queue not empty, loading a tile" );
+    // 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;
+      }
+    }
 
-	FGLoadRec pending = load_queue.front();
-	load_queue.pop_front();
-	load_tile( pending.b, pending.cache_index );
+#if 0
     }
+#endif
 
-    // find our current elevation (feed in the current bucket to save work)
-    Point3D geod_pos = Point3D( f->get_Longitude(), f->get_Latitude(), 0.0);
-    Point3D tmp_abs_view_pos = fgGeodToCart(geod_pos);
+    return 1;
+}
 
-    scenery.cur_elev = 
-	current_elev( f->get_Longitude(), f->get_Latitude(), tmp_abs_view_pos );
-    // cout << "current elevation == " << scenery.cur_elev << endl;
-    // double junk = current_elev_ssg( current_view.abs_view_pos,
-    //                                 current_view.view_pos );
-    // cout << "current elevation (ssg) == " << 
-	
-    p_last = p1;
-    last_lon = f->get_Longitude() * RAD_TO_DEG;
-    last_lat = f->get_Latitude() * RAD_TO_DEG;
+// 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);
+}
 
-    return 1;
+// check and set current tile and scenery center...
+void FGTileMgr::setCurrentTile(double longitude, double latitude) {
+
+    // 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 {
+        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) {
 
-// NEW 
+  sgdVec3 sc;
 
-// inrange() IS THIS POINT WITHIN POSSIBLE VIEWING RANGE ?
-//	calculate distance from vertical tangent line at
-//	current position to center of object.
-//	this is equivalent to
-//	dist = point_line_dist_squared( &(t->center), &(v->abs_view_pos), 
-//				        v->local_up );
-//	if ( dist < FG_SQUARE(t->bounding_radius) ) {
-//
-// the compiler should inline this for us
+  sgdSetVec3( sc,
+    center[0],
+    center[1],
+    center[2]);
 
-static int
-inrange( const double radius, const Point3D& center, const Point3D& vp,
-	 const MAT3vec up)
-{
-    MAT3vec u, u1, v;
-    //	double tmp;
-	
-    // u = p - p0
-    u[0] = center.x() - vp.x();
-    u[1] = center.y() - vp.y();
-    u[2] = center.z() - vp.z();
-	
-    // calculate the projection, u1, of u along d.
-    // u1 = ( dot_prod(u, d) / dot_prod(d, d) ) * d;
-	
-    MAT3_SCALE_VEC(u1, up,
-		   (MAT3_DOT_PRODUCT(u, up) / MAT3_DOT_PRODUCT(up, up)) );
+    // 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 };
     
-    // v = u - u1 = vector from closest point on line, p1, to the
-    // original point, p.
-    MAT3_SUB_VEC(v, u, u1);
-	
-    return( FG_SQUARE(radius) >= MAT3_DOT_PRODUCT(v, v));
+    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);
+    }
+
+    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) {
 
-// NEW for legibility
+    // traverse the potentially viewable tile list and update range
+    // selector and transform
 
-// update this tile's geometry for current view
-// The Compiler should inline this
-static void
-update_tile_geometry( FGTileEntry *t, GLdouble *MODEL_VIEW)
-{
-    GLfloat *m;
-    double x, y, z;
-	
-    // calculate tile offset
-    t->offset = t->center - scenery.center;
+    // just setup and call new function...
 
-    x = t->offset.x();
-    y = t->offset.y();
-    z = t->offset.z();
-	
-    m = t->model_view;
-	
-    // Calculate the model_view transformation matrix for this tile
-    FG_MEM_COPY( m, MODEL_VIEW, 16*sizeof(GLdouble) );
-    
-    // This is equivalent to doing a glTranslatef(x, y, z);
-    m[12] += (m[0]*x + m[4]*y + m[8] *z);
-    m[13] += (m[1]*x + m[5]*y + m[9] *z);
-    m[14] += (m[2]*x + m[6]*y + m[10]*z);
-    // m[15] += (m[3]*x + m[7]*y + m[11]*z);
-    // m[3] m7[] m[11] are 0.0 see LookAt() in views.cxx
-    // so m[15] is unchanged
-}
+    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 );
 
-// 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_nodes( void ) {
-    FGTileEntry *t;
+}
 
-    float ranges[2];
-    ranges[0] = 0.0f;
+void FGTileMgr::prep_ssg_nodes(float vis, sgVec3 up, Point3D center) {
 
     // 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
-	    /*
-	     * ranges[1] = current_weather.get_visibility()+t->bounding_radius;
-	     */
-	    ranges[1] = WeatherDatabase->getWeatherVisibility()
-		+ t->bounding_radius;
-	    t->range_ptr->setRanges( ranges, 2 );
-
-	    // calculate tile offset
-	    t->SetOffset( scenery.center );
-
-	    // 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();
+   }
 }
+