diff --git a/Main/GLUTmain.cxx b/Main/GLUTmain.cxx
index 1a896331f..097ff62de 100644
--- a/Main/GLUTmain.cxx
+++ b/Main/GLUTmain.cxx
@@ -72,10 +72,6 @@
 // This is a record containing global housekeeping information
 fgGENERAL general;
 
-// view parameters
-static GLfloat win_ratio = 1.0;
-static GLint winWidth, winHeight;
-
 // Another hack
 int use_signals = 0;
 
@@ -233,21 +229,22 @@ static void fgUpdateViewParams( void ) {
     o = &current_options;
     v = &current_view;
 
-    fgViewUpdate(f, v, l);
+    v->Update(f);
+    v->UpdateWorldToEye(f);
 
     if (displayInstruments) {
-	xglViewport( 0, (GLint)(winHeight / 2 ) , 
-		     (GLint)winWidth, (GLint)winHeight / 2 );
+	xglViewport( 0, (GLint)((v->winHeight) / 2 ) , 
+		     (GLint)(v->winWidth), (GLint)(v->winHeight) / 2 );
 	// Tell GL we are about to modify the projection parameters
 	xglMatrixMode(GL_PROJECTION);
 	xglLoadIdentity();
-	gluPerspective(o->fov, 2.0/win_ratio, 1.0, 100000.0);
+	gluPerspective(o->fov, v->win_ratio / 2.0, 1.0, 100000.0);
     } else {
-	xglViewport(0, 0 , (GLint)winWidth, (GLint) winHeight);
+	xglViewport(0, 0 , (GLint)(v->winWidth), (GLint)(v->winHeight) );
 	// Tell GL we are about to modify the projection parameters
 	xglMatrixMode(GL_PROJECTION);
 	xglLoadIdentity();
-	gluPerspective(o->fov, 1.0/win_ratio, 10.0, 100000.0);
+	gluPerspective(o->fov, v->win_ratio, 10.0, 100000.0);
     }
 
     xglMatrixMode(GL_MODELVIEW);
@@ -288,7 +285,11 @@ static void fgUpdateViewParams( void ) {
 
 // Draw a basic instrument panel
 static void fgUpdateInstrViewParams( void ) {
-    xglViewport(0, 0 , (GLint)winWidth, (GLint)winHeight / 2);
+    fgVIEW *v;
+
+    v = &current_view;
+
+    xglViewport(0, 0 , (GLint)(v->winWidth), (GLint)(v->winHeight) / 2);
   
     xglMatrixMode(GL_PROJECTION);
     xglPushMatrix();
@@ -618,14 +619,18 @@ static void fgMainLoop( void ) {
 
 // Handle new window size or exposure
 static void fgReshape( int width, int height ) {
+    fgVIEW *v;
+
+    v = &current_view;
+
     // Do this so we can call fgReshape(0,0) ourselves without having
     // to know what the values of width & height are.
     if ( (height > 0) && (width > 0) ) {
-	win_ratio = (GLfloat) height / (GLfloat) width;
+	v->win_ratio = (GLfloat) width / (GLfloat) height;
     }
 
-    winWidth = width;
-    winHeight = height;
+    v->winWidth = width;
+    v->winHeight = height;
 
     // Inform gl of our view window size (now handled elsewhere)
     // xglViewport(0, 0, (GLint)width, (GLint)height);
@@ -768,6 +773,14 @@ extern "C" {
 
 
 // $Log$
+// Revision 1.15  1998/05/16 13:08:34  curt
+// C++ - ified views.[ch]xx
+// Shuffled some additional view parameters into the fgVIEW class.
+// Changed tile-radius to tile-diameter because it is a much better
+//   name.
+// Added a WORLD_TO_EYE transformation to views.cxx.  This allows us
+//  to transform world space to eye space for view frustum culling.
+//
 // Revision 1.14  1998/05/13 18:29:57  curt
 // Added a keyboard binding to dynamically adjust field of view.
 // Added a command line option to specify fov.
diff --git a/Main/Makefile.am b/Main/Makefile.am
index 08cc5d65b..2497c22c0 100644
--- a/Main/Makefile.am
+++ b/Main/Makefile.am
@@ -1,6 +1,6 @@
 EXTRA_DIST = runfg.in runfg.bat.in
 
-bin_PROGRAMS = fg
+bin_PROGRAMS = fg ttest
 
 bin_SCRIPTS = runfg runfg.bat
 
@@ -31,6 +31,10 @@ fg_LDADD = \
 	$(top_builddir)/Lib/Debug/libDebug.la \
 	$(top_builddir)/Lib/zlib/libz.la
 
+ttest_SOURCES = ttest.cxx
+
+ttest_LDADD = $(top_builddir)/Lib/Math/libMath.la \
+
 INCLUDES += \
 	-DGLUT \
 	-I$(top_builddir) \
diff --git a/Main/Makefile.in b/Main/Makefile.in
index 64171d5f9..07339a381 100644
--- a/Main/Makefile.in
+++ b/Main/Makefile.in
@@ -73,7 +73,7 @@ VERSION = @VERSION@
 
 EXTRA_DIST = runfg.in runfg.bat.in
 
-bin_PROGRAMS = fg
+bin_PROGRAMS = fg ttest
 
 bin_SCRIPTS = runfg runfg.bat
 
@@ -103,6 +103,8 @@ fg_LDADD = \
 	$(top_builddir)/Lib/Bucket/libBucket.la \
 	$(top_builddir)/Lib/Debug/libDebug.la \
 	$(top_builddir)/Lib/zlib/libz.la
+
+ttest_SOURCES = ttest.cxx
 mkinstalldirs = $(SHELL) $(top_srcdir)/mkinstalldirs
 CONFIG_HEADER = ../../Include/config.h
 CONFIG_CLEAN_FILES =  runfg runfg.bat
@@ -135,6 +137,10 @@ $(top_builddir)/Lib/Math/libMath.la \
 $(top_builddir)/Lib/Bucket/libBucket.la \
 $(top_builddir)/Lib/Debug/libDebug.la $(top_builddir)/Lib/zlib/libz.la
 fg_LDFLAGS = 
+ttest_OBJECTS =  ttest.o
+ttest_LDADD = $(LDADD)
+ttest_DEPENDENCIES = 
+ttest_LDFLAGS = 
 SCRIPTS =  $(bin_SCRIPTS)
 
 CXXFLAGS = @CXXFLAGS@
@@ -149,10 +155,10 @@ DISTFILES = $(DIST_COMMON) $(SOURCES) $(HEADERS) $(TEXINFOS) $(EXTRA_DIST)
 TAR = tar
 GZIP = --best
 DEP_FILES =  .deps/GLUTkey.P .deps/GLUTmain.P .deps/airports.P \
-.deps/fg_init.P .deps/options.P .deps/views.P
+.deps/fg_init.P .deps/options.P .deps/ttest.P .deps/views.P
 CXXMKDEP = $(CXX) -M $(DEFS) $(INCLUDES) $(CPPFLAGS) $(CXXFLAGS)
-SOURCES = $(fg_SOURCES)
-OBJECTS = $(fg_OBJECTS)
+SOURCES = $(fg_SOURCES) $(ttest_SOURCES)
+OBJECTS = $(fg_OBJECTS) $(ttest_OBJECTS)
 
 all: Makefile $(PROGRAMS) $(SCRIPTS)
 
@@ -231,6 +237,10 @@ fg: $(fg_OBJECTS) $(fg_DEPENDENCIES)
 	@rm -f fg
 	$(CXXLINK) $(fg_LDFLAGS) $(fg_OBJECTS) $(fg_LDADD) $(LIBS)
 
+ttest: $(ttest_OBJECTS) $(ttest_DEPENDENCIES)
+	@rm -f ttest
+	$(CXXLINK) $(ttest_LDFLAGS) $(ttest_OBJECTS) $(ttest_LDADD) $(LIBS)
+
 install-binSCRIPTS: $(bin_SCRIPTS)
 	@$(NORMAL_INSTALL)
 	$(mkinstalldirs) $(DESTDIR)$(bindir)
diff --git a/Main/fg_init.cxx b/Main/fg_init.cxx
index 133689ef7..ba9429073 100644
--- a/Main/fg_init.cxx
+++ b/Main/fg_init.cxx
@@ -133,8 +133,8 @@ int fgInitPosition( void ) {
     // Test Position
     // FG_Longitude = (  8.5 ) * DEG_TO_RAD;
     // FG_Latitude  = ( 47.5 ) * DEG_TO_RAD;
-    // FG_Runway_altitude = ( 6000 );
-    // FG_Altitude = FG_Runway_altitude + 3.758099;
+    FG_Runway_altitude = ( 6000 );
+    FG_Altitude = FG_Runway_altitude + 3.758099;
 
     if ( strlen(o->airport_id) ) {
 	fgAIRPORTS airports;
@@ -271,9 +271,9 @@ int fgInitSubsystems( void ) {
     fgTimeUpdate(f, t);
 
     // Initialize view parameters
-    // ---->
-    fgViewInit(v);
-    fgViewUpdate(f, v, l);
+    v->Init();
+    v->Update(f);
+    v->UpdateWorldToEye(f);
 
     // Initialize the orbital elements of sun, moon and mayor planets
     fgSolarSystemInit(*t);
@@ -297,11 +297,9 @@ int fgInitSubsystems( void ) {
     // fgUpdateSunPos() needs a few position and view parameters set
     // so it can calculate local relative sun angle and a few other
     // things for correctly orienting the sky.
-    // ---->
     fgUpdateSunPos();
 
     // Initialize Lighting interpolation tables
-    // ---->
     fgLightInit();
 
     // update the lighting parameters (based on sun angle)
@@ -323,7 +321,6 @@ int fgInitSubsystems( void ) {
     }
 
     // Initialize the "sky"
-    // ---->
     fgSkyInit();
 
     // Initialize the Scenery Management subsystem
@@ -384,6 +381,14 @@ int fgInitSubsystems( void ) {
 
 
 // $Log$
+// Revision 1.13  1998/05/16 13:08:35  curt
+// C++ - ified views.[ch]xx
+// Shuffled some additional view parameters into the fgVIEW class.
+// Changed tile-radius to tile-diameter because it is a much better
+//   name.
+// Added a WORLD_TO_EYE transformation to views.cxx.  This allows us
+//  to transform world space to eye space for view frustum culling.
+//
 // Revision 1.12  1998/05/13 18:29:58  curt
 // Added a keyboard binding to dynamically adjust field of view.
 // Added a command line option to specify fov.
diff --git a/Main/options.cxx b/Main/options.cxx
index 61eaf96f8..838838623 100644
--- a/Main/options.cxx
+++ b/Main/options.cxx
@@ -33,6 +33,7 @@
 #include <string.h>
 
 #include <Debug/fg_debug.h>
+#include <Include/fg_constants.h>
 #include <Include/fg_zlib.h>
 
 #include "options.hxx"
@@ -79,7 +80,7 @@ fgOPTIONS::fgOPTIONS( void ) {
     wireframe = 0;
 
     // Scenery options
-    tile_radius = 7;
+    tile_diameter = 7;
 
     // Time options
     time_offset = 0;
@@ -229,22 +230,16 @@ static int parse_time_offset(char *time_str) {
 }
 
 
-// Parse --tile-radius=n type option 
+// Parse --tile-diameter=n type option 
 
-#define FG_RADIUS_MIN 3
-#define FG_RADIUS_MAX 9
+#define FG_RADIUS_MIN 1
+#define FG_RADIUS_MAX 4
 
 static int parse_tile_radius(char *arg) {
     int radius, tmp;
 
     radius = parse_int(arg);
 
-    // radius must be odd
-    tmp = radius / 2;
-    if ( radius == ( tmp * 2 ) ) {
-	radius -= 1;
-    }
-
     if ( radius < FG_RADIUS_MIN ) { radius = FG_RADIUS_MIN; }
     if ( radius > FG_RADIUS_MAX ) { radius = FG_RADIUS_MAX; }
 
@@ -255,10 +250,6 @@ static int parse_tile_radius(char *arg) {
 
 
 // Parse --fov=x.xx type option 
-
-#define FG_FOV_MIN 0.1
-#define FG_FOV_MAX 179.9
-
 static double parse_fov(char *arg) {
     double fov;
 
@@ -318,6 +309,7 @@ int fgOPTIONS::parse_option( char *arg ) {
 	wireframe = 1;	
     } else if ( strncmp(arg, "--tile-radius=", 14) == 0 ) {
 	tile_radius = parse_tile_radius(arg);
+	tile_diameter = tile_radius * 2 + 1;
     } else if ( strncmp(arg, "--time-offset=", 14) == 0 ) {
 	time_offset = parse_time_offset(arg);
     } else {
@@ -424,7 +416,7 @@ void fgOPTIONS::usage ( void ) {
     printf("\n");
 
     printf("Scenery Options:\n");
-    printf("\t--tile-radius=n:  specify tile radius, must be odd 3, 5, or 7\n");
+    printf("\t--tile-radius=n:  specify tile radius, must be 1 - 4\n");
     printf("\n");
 
     printf("Time Options:\n");
@@ -438,6 +430,14 @@ fgOPTIONS::~fgOPTIONS( void ) {
 
 
 // $Log$
+// Revision 1.10  1998/05/16 13:08:36  curt
+// C++ - ified views.[ch]xx
+// Shuffled some additional view parameters into the fgVIEW class.
+// Changed tile-radius to tile-diameter because it is a much better
+//   name.
+// Added a WORLD_TO_EYE transformation to views.cxx.  This allows us
+//  to transform world space to eye space for view frustum culling.
+//
 // Revision 1.9  1998/05/13 18:29:59  curt
 // Added a keyboard binding to dynamically adjust field of view.
 // Added a command line option to specify fov.
diff --git a/Main/options.hxx b/Main/options.hxx
index 1ed98a66b..dc88b418c 100644
--- a/Main/options.hxx
+++ b/Main/options.hxx
@@ -59,8 +59,10 @@ public:
     int wireframe;     // Wireframe mode enabled/disabled
 
     // Scenery options
-    int tile_radius;   // Square radius of rendered tiles.  for instance
-                       // if tile_radius = 3 then a 3 x 3 grid of tiles will 
+    int tile_radius;   // Square radius of rendered tiles (around center 
+                       // square.)
+    int tile_diameter; // Diameter of rendered tiles.  for instance
+                       // if tile_diameter = 3 then a 3 x 3 grid of tiles will 
                        // be drawn.  Increase this to see terrain that is 
                        // further away.
 
@@ -95,6 +97,14 @@ extern fgOPTIONS current_options;
 
 
 // $Log$
+// Revision 1.8  1998/05/16 13:08:36  curt
+// C++ - ified views.[ch]xx
+// Shuffled some additional view parameters into the fgVIEW class.
+// Changed tile-radius to tile-diameter because it is a much better
+//   name.
+// Added a WORLD_TO_EYE transformation to views.cxx.  This allows us
+//  to transform world space to eye space for view frustum culling.
+//
 // Revision 1.7  1998/05/13 18:29:59  curt
 // Added a keyboard binding to dynamically adjust field of view.
 // Added a command line option to specify fov.
diff --git a/Main/views.cxx b/Main/views.cxx
index 8952347d9..d9ac0d6e6 100644
--- a/Main/views.cxx
+++ b/Main/views.cxx
@@ -1,5 +1,5 @@
-//
-// views.cxx -- data structures and routines for managing and view parameters.
+// views.cxx -- data structures and routines for managing and view
+//               parameters.
 //
 // Written by Curtis Olson, started August 1997.
 //
@@ -23,7 +23,6 @@
 // (Log is kept at end of this file)
 
 
-
 #ifdef HAVE_CONFIG_H
 #  include <config.h>
 #endif
@@ -37,6 +36,7 @@
 #include <Scenery/scenery.hxx>
 #include <Time/fg_time.hxx>
 
+#include "options.hxx"
 #include "views.hxx"
 
 
@@ -44,51 +44,77 @@
 fgVIEW current_view;
 
 
+// Constructor
+fgVIEW::fgVIEW( void ) {
+}
+
+
 // Initialize a view structure
-void fgViewInit(fgVIEW *v) {
+void fgVIEW::Init( void ) {
     fgPrintf( FG_VIEW, FG_INFO, "Initializing View parameters\n");
 
-    v->view_offset = 0.0;
-    v->goal_view_offset = 0.0;
+    view_offset = 0.0;
+    goal_view_offset = 0.0;
 }
 
 
 // Update the view parameters
-void fgViewUpdate(fgFLIGHT *f, fgVIEW *v, fgLIGHT *l) {
+void fgVIEW::Update( fgFLIGHT *f ) {
+    fgOPTIONS *o;
     fgPolarPoint3d p;
     MAT3vec vec, forward, v0, minus_z;
     MAT3mat R, TMP, UP, LOCAL, VIEW;
-    double ntmp;
+    double theta_x, theta_y, ntmp;
+
+    o = &current_options;
 
     scenery.center.x = scenery.next_center.x;
     scenery.center.y = scenery.next_center.y;
     scenery.center.z = scenery.next_center.z;
 
+    printf("win_ratio = %.2f\n", win_ratio);
+
+    // calculate sin() and cos() of fov / 2 in X direction;
+    theta_x = FG_PI_2 - (o->fov * win_ratio * DEG_TO_RAD) / 2.0;
+    printf("theta_x = %.2f\n", theta_x);
+    sin_fov_x = sin(theta_x);
+    cos_fov_x = cos(theta_x);
+    slope_x = sin_fov_x / cos_fov_x;
+    printf("slope_x = %.2f\n", slope_x);
+
+    // calculate sin() and cos() of fov / 2 in Y direction;
+    theta_y = FG_PI_2 - (o->fov * DEG_TO_RAD) / 2.0;
+    printf("theta_y = %.2f\n", theta_y);
+    sin_fov_y = sin(theta_y);
+    cos_fov_y = cos(theta_y);
+    slope_y = sin_fov_y / cos_fov_y;
+    printf("slope_y = %.2f\n", slope_y);
+
     // calculate the cartesion coords of the current lat/lon/0 elev
     p.lon = FG_Longitude;
     p.lat = FG_Lat_geocentric;
     p.radius = FG_Sea_level_radius * FEET_TO_METER;
 
-    v->cur_zero_elev = fgPolarToCart3d(p);
+    cur_zero_elev = fgPolarToCart3d(p);
 
-    v->cur_zero_elev.x -= scenery.center.x;
-    v->cur_zero_elev.y -= scenery.center.y;
-    v->cur_zero_elev.z -= scenery.center.z;
+    cur_zero_elev.x -= scenery.center.x;
+    cur_zero_elev.y -= scenery.center.y;
+    cur_zero_elev.z -= scenery.center.z;
 
     // calculate view position in current FG view coordinate system
     // p.lon & p.lat are already defined earlier
     p.radius = FG_Radius_to_vehicle * FEET_TO_METER + 1.0;
 
-    v->abs_view_pos = fgPolarToCart3d(p);
+    abs_view_pos = fgPolarToCart3d(p);
 
-    v->view_pos.x = v->abs_view_pos.x - scenery.center.x;
-    v->view_pos.y = v->abs_view_pos.y - scenery.center.y;
-    v->view_pos.z = v->abs_view_pos.z - scenery.center.z;
+    view_pos.x = abs_view_pos.x - scenery.center.x;
+    view_pos.y = abs_view_pos.y - scenery.center.y;
+    view_pos.z = abs_view_pos.z - scenery.center.z;
 
     fgPrintf( FG_VIEW, FG_DEBUG, "Absolute view pos = %.4f, %.4f, %.4f\n", 
-	   v->abs_view_pos.x, v->abs_view_pos.y, v->abs_view_pos.z);
+	   abs_view_pos.x, abs_view_pos.y, abs_view_pos.z);
     fgPrintf( FG_VIEW, FG_DEBUG, "Relative view pos = %.4f, %.4f, %.4f\n", 
-	   v->view_pos.x, v->view_pos.y, v->view_pos.z);
+	   view_pos.x, view_pos.y, view_pos.z);
 
     // Derive the LOCAL aircraft rotation matrix (roll, pitch, yaw)
     // from FG_T_local_to_body[3][3]
@@ -156,11 +182,11 @@ void fgViewUpdate(fgFLIGHT *f, fgVIEW *v, fgLIGHT *l) {
     // printf("Local up matrix\n");
     // MAT3print(UP, stdout);
 
-    MAT3_SET_VEC(v->local_up, 1.0, 0.0, 0.0);
-    MAT3mult_vec(v->local_up, v->local_up, UP);
+    MAT3_SET_VEC(local_up, 1.0, 0.0, 0.0);
+    MAT3mult_vec(local_up, local_up, UP);
 
     // printf( "Local Up = (%.4f, %.4f, %.4f)\n",
-    //         v->local_up[0], v->local_up[1], v->local_up[2]);
+    //         local_up[0], local_up[1], local_up[2]);
     
     // Alternative method to Derive local up vector based on
     // *geodetic* coordinates
@@ -175,39 +201,131 @@ void fgViewUpdate(fgFLIGHT *f, fgVIEW *v, fgLIGHT *l) {
 
     // generate the current up, forward, and fwrd-view vectors
     MAT3_SET_VEC(vec, 1.0, 0.0, 0.0);
-    MAT3mult_vec(v->view_up, vec, VIEW);
+    MAT3mult_vec(view_up, vec, VIEW);
 
     MAT3_SET_VEC(vec, 0.0, 0.0, 1.0);
     MAT3mult_vec(forward, vec, VIEW);
     // printf( "Forward vector is (%.2f,%.2f,%.2f)\n", forward[0], forward[1], 
     //         forward[2]);
 
-    MAT3rotate(TMP, v->view_up, v->view_offset);
-    MAT3mult_vec(v->view_forward, forward, TMP);
+    MAT3rotate(TMP, view_up, view_offset);
+    MAT3mult_vec(view_forward, forward, TMP);
 
     // make a vector to the current view position
-    MAT3_SET_VEC(v0, v->view_pos.x, v->view_pos.y, v->view_pos.z);
+    MAT3_SET_VEC(v0, view_pos.x, view_pos.y, view_pos.z);
 
     // Given a vector pointing straight down (-Z), map into onto the
     // local plane representing "horizontal".  This should give us the
     // local direction for moving "south".
     MAT3_SET_VEC(minus_z, 0.0, 0.0, -1.0);
-    map_vec_onto_cur_surface_plane(v->local_up, v0, minus_z, v->surface_south);
-    MAT3_NORMALIZE_VEC(v->surface_south, ntmp);
+    map_vec_onto_cur_surface_plane(local_up, v0, minus_z, surface_south);
+    MAT3_NORMALIZE_VEC(surface_south, ntmp);
     // printf( "Surface direction directly south %.2f %.2f %.2f\n",
-    //         v->surface_south[0], v->surface_south[1], v->surface_south[2]);
+    //         surface_south[0], surface_south[1], surface_south[2]);
 
     // now calculate the surface east vector
-    MAT3rotate(TMP, v->view_up, FG_PI_2);
-    MAT3mult_vec(v->surface_east, v->surface_south, TMP);
+    MAT3rotate(TMP, view_up, FG_PI_2);
+    MAT3mult_vec(surface_east, surface_south, TMP);
     // printf( "Surface direction directly east %.2f %.2f %.2f\n",
-    //         v->surface_east[0], v->surface_east[1], v->surface_east[2]);
+    //         surface_east[0], surface_east[1], surface_east[2]);
     // printf( "Should be close to zero = %.2f\n", 
-    //         MAT3_DOT_PRODUCT(v->surface_south, v->surface_east));
+    //         MAT3_DOT_PRODUCT(surface_south, surface_east));
+}
+
+
+// Update the "World to Eye" transformation matrix
+// This is most useful for view frustum culling
+void fgVIEW::UpdateWorldToEye( fgFLIGHT *f ) {
+    MAT3mat R_Phi, R_Theta, R_Psi, R_Lat, R_Lon, T_view;
+    MAT3mat TMP;
+    MAT3hvec vec;
+
+    // Roll Matrix
+    MAT3_SET_HVEC(vec, 0.0, 0.0, -1.0, 1.0);
+    MAT3rotate(R_Phi, vec, FG_Phi);
+    // printf("Roll matrix (Phi)\n");
+    // MAT3print(R_Phi, stdout);
+
+    // Pitch Matrix
+    MAT3_SET_HVEC(vec, 1.0, 0.0, 0.0, 1.0);
+    MAT3rotate(R_Theta, vec, FG_Theta);
+    // printf("\nPitch matrix (Theta)\n");
+    // MAT3print(R_Theta, stdout);
+
+    // Yaw Matrix
+    MAT3_SET_HVEC(vec, 0.0, -1.0, 0.0, 1.0);
+    MAT3rotate(R_Psi, vec, FG_Psi + FG_PI - view_offset );
+    // printf("\nYaw matrix (Psi)\n");
+    // MAT3print(R_Psi, stdout);
+
+    // Latitude
+    MAT3_SET_HVEC(vec, 1.0, 0.0, 0.0, 1.0);
+    // R_Lat = rotate about X axis
+    MAT3rotate(R_Lat, vec, FG_Latitude);
+    // printf("\nLatitude matrix\n");
+    // MAT3print(R_Lat, stdout);
+
+    // Longitude
+    MAT3_SET_HVEC(vec, 0.0, 0.0, 1.0, 1.0);
+    // R_Lon = rotate about Z axis
+    MAT3rotate(R_Lon, vec, FG_Longitude - FG_PI_2 );
+    // printf("\nLongitude matrix\n");
+    // MAT3print(R_Lon, stdout);
+
+    // View position in scenery centered coordinates
+    MAT3_SET_HVEC(vec, view_pos.x, view_pos.y, view_pos.z, 1.0);
+    MAT3translate(T_view, vec);
+    // printf("\nTranslation matrix\n");
+    // MAT3print(T_view, stdout);
+
+    // aircraft roll/pitch/yaw
+    MAT3mult(TMP, R_Phi, R_Theta);
+    MAT3mult(AIRCRAFT, TMP, R_Psi);
+    // printf("\naircraft roll pitch yaw\n");
+    // MAT3print(AIRCRAFT, stdout);
+
+    // lon/lat
+    MAT3mult(WORLD, R_Lat, R_Lon);
+    // printf("\nworld\n");
+    // MAT3print(WORLD, stdout);
+
+    MAT3mult(EYE_TO_WORLD, AIRCRAFT, WORLD);
+    MAT3mult(EYE_TO_WORLD, EYE_TO_WORLD, T_view);
+    // printf("\nEye to world\n");
+    // MAT3print(EYE_TO_WORLD, stdout);
+
+    MAT3invert(WORLD_TO_EYE, EYE_TO_WORLD);
+    // printf("\nWorld to eye\n");
+    // MAT3print(WORLD_TO_EYE, stdout);
+
+    // printf( "\nview_pos = %.2f %.2f %.2f\n", 
+    //         view_pos.x, view_pos.y, view_pos.z );
+
+    // MAT3_SET_HVEC(eye, 0.0, 0.0, 0.0, 1.0);
+    // MAT3mult_vec(vec, eye, EYE_TO_WORLD);
+    // printf("\neye -> world = %.2f %.2f %.2f\n", vec[0], vec[1], vec[2]);
+
+    // MAT3_SET_HVEC(vec1, view_pos.x, view_pos.y, view_pos.z, 1.0);
+    // MAT3mult_vec(vec, vec1, WORLD_TO_EYE);
+    // printf( "\nabs_view_pos -> eye = %.2f %.2f %.2f\n", 
+    //         vec[0], vec[1], vec[2]);
+}
+
+
+// Destructor
+fgVIEW::~fgVIEW( void ) {
 }
 
 
 // $Log$
+// Revision 1.9  1998/05/16 13:08:37  curt
+// C++ - ified views.[ch]xx
+// Shuffled some additional view parameters into the fgVIEW class.
+// Changed tile-radius to tile-diameter because it is a much better
+//   name.
+// Added a WORLD_TO_EYE transformation to views.cxx.  This allows us
+//  to transform world space to eye space for view frustum culling.
+//
 // Revision 1.8  1998/05/02 01:51:01  curt
 // Updated polartocart conversion routine.
 //
diff --git a/Main/views.hxx b/Main/views.hxx
index 03f0f24c1..a4c0f580d 100644
--- a/Main/views.hxx
+++ b/Main/views.hxx
@@ -1,27 +1,26 @@
-/**************************************************************************
- * views.hxx -- data structures and routines for managing and view parameters.
- *
- * Written by Curtis Olson, started August 1997.
- *
- * Copyright (C) 1997  Curtis L. Olson  - curt@infoplane.com
- *
- * 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., 675 Mass Ave, Cambridge, MA 02139, USA.
- *
- * $Id$
- * (Log is kept at end of this file)
- **************************************************************************/
+//
+// views.hxx -- data structures and routines for managing and view parameters.
+//
+// Written by Curtis Olson, started August 1997.
+//
+// Copyright (C) 1997  Curtis L. Olson  - curt@infoplane.com
+//
+// 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., 675 Mass Ave, Cambridge, MA 02139, USA.
+//
+// $Id$
+// (Log is kept at end of this file)
 
 
 #ifndef _VIEWS_HXX
@@ -40,119 +39,171 @@
 #include <Time/light.hxx>
 
 
-/* Define a structure containing view information */
-typedef struct {
-    /* absolute view position */
-    fgCartesianPoint3d abs_view_pos;
+// Define a structure containing view information
+class fgVIEW {
 
-    /* view position translated to scenery.center */
-    fgCartesianPoint3d view_pos;
+public:
 
-    /* cartesion coordinates of current lon/lat if at sea level
-     * translated to scenery.center*/
-    fgCartesianPoint3d cur_zero_elev;
-
-    /* vector in cartesian coordinates from current position to the
-     * postion on the earth's surface the sun is directly over */
-    MAT3vec to_sun;
-    
-    /* surface direction to go to head towards sun */
-    MAT3vec surface_to_sun;
-
-    /* surface vector heading south */
-    MAT3vec surface_south;
-
-    /* surface vector heading east (used to unambiguously align sky with sun) */
-    MAT3vec surface_east;
-
-    /* local up vector (normal to the plane tangent to the earth's
-     * surface at the spot we are directly above */
-    MAT3vec local_up;
-
-    /* up vector for the view (usually point straight up through the
-     * top of the aircraft */
-    MAT3vec view_up;
-
-    /* the vector pointing straight out the nose of the aircraft */
-    MAT3vec view_forward;
-
-    /* the current offset from forward for viewing */
+    // the current offset from forward for viewing
     double view_offset;
 
-    /* the goal view offset for viewing (used for smooth view changes) */
+    // the goal view offset for viewing (used for smooth view changes)
     double goal_view_offset;
-} fgVIEW;
+
+    // fov of view is specified in the y direction, win_ratio is used to
+    // calculate the fov in the X direction = width/height
+    double win_ratio;
+
+    // width & height of window
+    int winWidth, winHeight;
+
+    // sin and cos of (fov / 2) in Y axis
+    double sin_fov_y, cos_fov_y;
+
+    // slope of view frustum edge in eye space Y axis
+    double slope_y;
+
+    // sin and cos of (fov / 2) in X axis
+    double sin_fov_x, cos_fov_x;
+
+    // slope of view frustum edge in eye space X axis
+    double slope_x;
+
+    // absolute view position
+    fgCartesianPoint3d abs_view_pos;
+
+    // view position translated to scenery.center
+    fgCartesianPoint3d view_pos;
+
+    // cartesion coordinates of current lon/lat if at sea level
+    // translated to scenery.center*/
+    fgCartesianPoint3d cur_zero_elev;
+
+    // vector in cartesian coordinates from current position to the
+    // postion on the earth's surface the sun is directly over
+    MAT3vec to_sun;
+    
+    // surface direction to go to head towards sun
+    MAT3vec surface_to_sun;
+
+    // surface vector heading south
+    MAT3vec surface_south;
+
+    // surface vector heading east (used to unambiguously align sky
+    // with sun)
+    MAT3vec surface_east;
+
+    // local up vector (normal to the plane tangent to the earth's
+    // surface at the spot we are directly above
+    MAT3vec local_up;
+
+    // up vector for the view (usually point straight up through the
+    // top of the aircraft
+    MAT3vec view_up;
+
+    // the vector pointing straight out the nose of the aircraft
+    MAT3vec view_forward;
+
+    // Transformation matrix for eye coordinates to aircraft coordinates
+    MAT3mat AIRCRAFT;
+
+    // Transformation matrix for aircraft coordinates to world
+    // coordinates
+    MAT3mat WORLD;
+
+    // Combined transformation from eye coordinates to world coordinates
+    MAT3mat EYE_TO_WORLD;
+
+    // Inverse of EYE_TO_WORLD which is a transformation from world
+    // coordinates to eye coordinates
+    MAT3mat WORLD_TO_EYE;
+
+    // Constructor
+    fgVIEW( void );
+
+    // Initialize a view class
+    void Init( void );
+
+    // Update the view parameters
+    void Update( fgFLIGHT *f );
+
+    // Update the "World to Eye" transformation matrix
+    void UpdateWorldToEye(  fgFLIGHT *f );
+
+    // Destructor
+    ~fgVIEW( void );
+};
 
 
 extern fgVIEW current_view;
 
 
-/* Initialize a view structure */
-void fgViewInit(fgVIEW *v);
-
-/* Update the view parameters */
-void fgViewUpdate(fgFLIGHT *f, fgVIEW *v, fgLIGHT *l);
+#endif // _VIEWS_HXX
 
 
-#endif /* _VIEWS_HXX */
-
-
-/* $Log$
-/* Revision 1.5  1998/05/02 01:51:02  curt
-/* Updated polartocart conversion routine.
-/*
- * Revision 1.4  1998/04/28 01:20:24  curt
- * Type-ified fgTIME and fgVIEW.
- * Added a command line option to disable textures.
- *
- * Revision 1.3  1998/04/25 22:06:31  curt
- * Edited cvs log messages in source files ... bad bad bad!
- *
- * Revision 1.2  1998/04/24 00:49:22  curt
- * Wrapped "#include <config.h>" in "#ifdef HAVE_CONFIG_H"
- * Trying out some different option parsing code.
- * Some code reorganization.
- *
- * Revision 1.1  1998/04/22 13:25:46  curt
- * C++ - ifing the code.
- * Starting a bit of reorganization of lighting code.
- *
- * Revision 1.11  1998/04/21 17:02:42  curt
- * Prepairing for C++ integration.
- *
- * Revision 1.10  1998/02/07 15:29:45  curt
- * Incorporated HUD changes and struct/typedef changes from Charlie Hotchkiss
- * <chotchkiss@namg.us.anritsu.com>
- *
- * Revision 1.9  1998/01/29 00:50:29  curt
- * Added a view record field for absolute x, y, z position.
- *
- * Revision 1.8  1998/01/27 00:47:58  curt
- * Incorporated Paul Bleisch's <pbleisch@acm.org> new debug message
- * system and commandline/config file processing code.
- *
- * Revision 1.7  1998/01/22 02:59:38  curt
- * Changed #ifdef FILE_H to #ifdef _FILE_H
- *
- * Revision 1.6  1998/01/19 19:27:10  curt
- * Merged in make system changes from Bob Kuehne <rpk@sgi.com>
- * This should simplify things tremendously.
- *
- * Revision 1.5  1997/12/22 04:14:32  curt
- * Aligned sky with sun so dusk/dawn effects can be correct relative to the sun.
- *
- * Revision 1.4  1997/12/17 23:13:36  curt
- * Began working on rendering a sky.
- *
- * Revision 1.3  1997/12/15 23:54:51  curt
- * Add xgl wrappers for debugging.
- * Generate terrain normals on the fly.
- *
- * Revision 1.2  1997/12/10 22:37:48  curt
- * Prepended "fg" on the name of all global structures that didn't have it yet.
- * i.e. "struct WEATHER {}" became "struct fgWEATHER {}"
- *
- * Revision 1.1  1997/08/27 21:31:18  curt
- * Initial revision.
- *
- */
+// $Log$
+// Revision 1.6  1998/05/16 13:08:37  curt
+// C++ - ified views.[ch]xx
+// Shuffled some additional view parameters into the fgVIEW class.
+// Changed tile-radius to tile-diameter because it is a much better
+//   name.
+// Added a WORLD_TO_EYE transformation to views.cxx.  This allows us
+//  to transform world space to eye space for view frustum culling.
+//
+// Revision 1.5  1998/05/02 01:51:02  curt
+// Updated polartocart conversion routine.
+//
+// Revision 1.4  1998/04/28 01:20:24  curt
+// Type-ified fgTIME and fgVIEW.
+// Added a command line option to disable textures.
+//
+// Revision 1.3  1998/04/25 22:06:31  curt
+// Edited cvs log messages in source files ... bad bad bad!
+//
+// Revision 1.2  1998/04/24 00:49:22  curt
+// Wrapped "#include <config.h>" in "#ifdef HAVE_CONFIG_H"
+// Trying out some different option parsing code.
+// Some code reorganization.
+//
+// Revision 1.1  1998/04/22 13:25:46  curt
+// C++ - ifing the code.
+// Starting a bit of reorganization of lighting code.
+//
+// Revision 1.11  1998/04/21 17:02:42  curt
+// Prepairing for C++ integration.
+//
+// Revision 1.10  1998/02/07 15:29:45  curt
+// Incorporated HUD changes and struct/typedef changes from Charlie Hotchkiss
+// <chotchkiss@namg.us.anritsu.com>
+//
+// Revision 1.9  1998/01/29 00:50:29  curt
+// Added a view record field for absolute x, y, z position.
+//
+// Revision 1.8  1998/01/27 00:47:58  curt
+// Incorporated Paul Bleisch's <pbleisch@acm.org> new debug message
+// system and commandline/config file processing code.
+//
+// Revision 1.7  1998/01/22 02:59:38  curt
+// Changed #ifdef FILE_H to #ifdef _FILE_H
+//
+// Revision 1.6  1998/01/19 19:27:10  curt
+// Merged in make system changes from Bob Kuehne <rpk@sgi.com>
+// This should simplify things tremendously.
+//
+// Revision 1.5  1997/12/22 04:14:32  curt
+// Aligned sky with sun so dusk/dawn effects can be correct relative to the sun.
+//
+// Revision 1.4  1997/12/17 23:13:36  curt
+// Began working on rendering a sky.
+//
+// Revision 1.3  1997/12/15 23:54:51  curt
+// Add xgl wrappers for debugging.
+// Generate terrain normals on the fly.
+//
+// Revision 1.2  1997/12/10 22:37:48  curt
+// Prepended "fg" on the name of all global structures that didn't have it yet.
+// i.e. "struct WEATHER {}" became "struct fgWEATHER {}"
+//
+// Revision 1.1  1997/08/27 21:31:18  curt
+// Initial revision.
+//