From: curt <curt>
Date: Tue, 29 Feb 2000 23:31:32 +0000 (+0000)
Subject: Working on skydome ... some actual progress has been made. :-)  Still
X-Git-Url: https://git.mxchange.org/?a=commitdiff_plain;h=41218272c447b7f7a93e5df39d620755022f20e2;p=simgear.git

Working on skydome ... some actual progress has been made. :-)  Still
something goofy with sunrise, sunset effects.
---

diff --git a/simgear/ephemeris/Makefile.am b/simgear/ephemeris/Makefile.am
index 0d21c976..efca10b8 100644
--- a/simgear/ephemeris/Makefile.am
+++ b/simgear/ephemeris/Makefile.am
@@ -9,7 +9,7 @@ libAstro_a_SOURCES = \
 	neptune.cxx neptune.hxx \
 	pluto.hxx \
 	saturn.cxx saturn.hxx \
-	sky.cxx sky.hxx \
+	skydome.cxx skydome.hxx \
 	solarsystem.cxx solarsystem.hxx \
 	star.cxx star.hxx \
 	stars.cxx stars.hxx \
diff --git a/simgear/ephemeris/sky.cxx b/simgear/ephemeris/sky.cxx
deleted file mode 100644
index a8d8bca7..00000000
--- a/simgear/ephemeris/sky.cxx
+++ /dev/null
@@ -1,809 +0,0 @@
-// sky.cxx -- model sky with an upside down "bowl"
-//
-// Written by Curtis Olson, started December 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.
-//
-// $Id$
-
-
-#ifdef HAVE_CONFIG_H
-#  include <config.h>
-#endif
-
-#ifdef HAVE_WINDOWS_H
-#  include <windows.h>
-#endif
-
-#include <math.h>
-
-#include <GL/glut.h>
-#include <simgear/xgl/xgl.h>
-
-#include <simgear/constants.h>
-#include <simgear/debug/logstream.hxx>
-#include <simgear/math/fg_random.h>
-
-#include <Aircraft/aircraft.hxx>
-#include <FDM/flight.hxx>
-#include <Main/views.hxx>
-#include <Time/event.hxx>
-#include <Time/fg_time.hxx>
-
-#include "sky.hxx"
-
-
-#ifdef __MWERKS__
-#  pragma global_optimizer off
-#endif
-
-
-// in meters of course
-#define CENTER_ELEV   25000.0
-
-#define UPPER_RADIUS  50000.0
-#define UPPER_ELEV    20000.0
-
-#define MIDDLE_RADIUS 70000.0
-#define MIDDLE_ELEV    8000.0
-
-#define LOWER_RADIUS  80000.0
-#define LOWER_ELEV        0.0
-
-#define BOTTOM_RADIUS 50000.0
-#define BOTTOM_ELEV   -2000.0
-
-
-static float inner_vertex[12][3];
-static float middle_vertex[12][3];
-static float outer_vertex[12][3];
-static float bottom_vertex[12][3];
-
-static GLubyte upper_color[12][4];
-static GLubyte middle_color[12][4];
-static GLubyte lower_color[12][4];
-
-
-// Defined the shared sky object here
-FGSky current_sky;
-
-
-// Constructor
-FGSky::FGSky( void ) {
-}
-
-
-// Destructor
-FGSky::~FGSky( void ) {
-}
-
-
-// initialize the sky object and connect it into the scene graph
-bool FGSky::initialize( ssgRoot *root ) {
-    sgVec3 color;
-
-    float theta;
-    int i;
-
-    // set up the state
-    sky_state = new ssgSimpleState();
-    if ( current_options.get_shading() == 1 ) {
-	sky_state->setShadeModel( GL_SMOOTH );
-    } else {
-	sky_state->setShadeModel( GL_FLAT );
-    }
-    sky_state->disable( GL_DEPTH_TEST );
-    sky_state->enable( GL_LIGHTING );
-    sky_state->disable( GL_FOG );
-    sky_state->disable( GL_CULL_FACE );
-    sky_state->disable( GL_TEXTURE_2D );
-
-    // initialize arrays
-    center_disk_vl = new ssgVertexArray( 14 );
-    center_disk_cl = new ssgColourArray( 14 );
-				       
-    upper_ring_vl = new ssgVertexArray( 26 );
-    upper_ring_cl = new ssgColourArray( 26 );
-
-    middle_ring_vl = new ssgVertexArray( 26 );
-    middle_ring_cl = new ssgColourArray( 26 );
-
-    lower_ring_vl = new ssgVertexArray( 26 );
-    lower_ring_cl = new ssgColourArray( 26 );
-
-    // initially seed to all blue
-    sgSetVec3( color, 0.0, 0.0, 1.0 );
-
-    // generate the raw vertex data
-    sgVec3 center_vertex;
-    sgVec3 upper_vertex[12];
-    sgVec3 middle_vertex[12];
-    sgVec3 lower_vertex[12];
-    sgVec3 bottom_vertex[12];
-
-    sgSetVec3( center_vertex, 0.0, 0.0, CENTER_ELEV );
-
-    for ( i = 0; i < 12; i++ ) {
-	theta = (i * 30.0) * DEG_TO_RAD;
-
-	sgSetVec3( upper_vertex[i],
-		   cos(theta) * UPPER_RADIUS,
-		   sin(theta) * UPPER_RADIUS,
-		   UPPER_ELEV );
-	
-	sgSetVec3( middle_vertex[i],
-		   cos((double)theta) * MIDDLE_RADIUS,
-		   sin((double)theta) * MIDDLE_RADIUS,
-		   MIDDLE_ELEV );
-
-	sgSetVec3( lower_vertex[i],
-		   cos((double)theta) * LOWER_RADIUS,
-		   sin((double)theta) * LOWER_RADIUS,
-		   LOWER_ELEV );
-
-	sgSetVec3( bottom_vertex[i],
-		   cos((double)theta) * BOTTOM_RADIUS,
-		   sin((double)theta) * BOTTOM_RADIUS,
-		   BOTTOM_ELEV );
-    }
-
-    // generate the center disk vertex/color arrays
-    center_disk_vl->add( center_vertex );
-    center_disk_cl->add( color );
-    for ( i = 11; i >= 0; i-- ) {
-	center_disk_vl->add( upper_vertex[i] );
-	center_disk_cl->add( color );
-    }
-    center_disk_vl->add( upper_vertex[11] );
-    center_disk_cl->add( color );
-
-    // generate the upper ring
-    for ( i = 0; i < 12; i++ ) {
-	upper_ring_vl->add( middle_vertex[i] );
-	upper_ring_cl->add( color );
-
-	upper_ring_vl->add( upper_vertex[i] );
-	upper_ring_cl->add( color );
-    }
-    upper_ring_vl->add( middle_vertex[0] );
-    upper_ring_cl->add( color );
-
-    upper_ring_vl->add( upper_vertex[0] );
-    upper_ring_cl->add( color );
-
-    // generate middle ring
-    for ( i = 0; i < 12; i++ ) {
-	middle_ring_vl->add( lower_vertex[i] );
-	middle_ring_cl->add( color );
-
-	middle_ring_vl->add( middle_vertex[i] );
-	middle_ring_cl->add( color );
-    }
-    middle_ring_vl->add( lower_vertex[0] );
-    middle_ring_cl->add( color );
-
-    middle_ring_vl->add( middle_vertex[0] );
-    middle_ring_cl->add( color );
-
-    // generate lower ring
-    for ( i = 0; i < 12; i++ ) {
-	lower_ring_vl->add( bottom_vertex[i] );
-	lower_ring_cl->add( color );
-
-	lower_ring_vl->add( lower_vertex[i] );
-	lower_ring_cl->add( color );
-    }
-    lower_ring_vl->add( bottom_vertex[0] );
-    lower_ring_cl->add( color );
-
-    lower_ring_vl->add( lower_vertex[0] );
-    lower_ring_cl->add( color );
-
-    // force a repaint of the sky colors with ugly defaults
-    sgVec3 fog_color;
-    sgSetVec3( fog_color, 1.0, 1.0, 1.0 );
-    repaint( color, fog_color, 0.0 );
-
-    // build the ssg scene graph sub tree for the sky and connected
-    // into the provide scene graph branch
-    sky_selector = new ssgSelector;
-    sky_transform = new ssgTransform;
-
-    ssgVtxTable *center_disk, *upper_ring, *middle_ring, *lower_ring;
-
-    center_disk = new ssgVtxTable( GL_TRIANGLE_FAN, 
-				   center_disk_vl, NULL, NULL, center_disk_cl );
-
-    upper_ring = new ssgVtxTable( GL_TRIANGLE_STRIP, 
-				  upper_ring_vl, NULL, NULL, upper_ring_cl );
-
-    middle_ring = new ssgVtxTable( GL_TRIANGLE_STRIP, 
-				   middle_ring_vl, NULL, NULL, middle_ring_cl );
-
-    lower_ring = new ssgVtxTable( GL_TRIANGLE_STRIP, 
-				  lower_ring_vl, NULL, NULL, lower_ring_cl );
-
-    center_disk->setState( sky_state );
-    upper_ring->setState( sky_state );
-    middle_ring->setState( sky_state );
-    lower_ring->setState( sky_state );
-
-    sky_transform->addKid( center_disk );
-    sky_transform->addKid( upper_ring );
-    sky_transform->addKid( middle_ring );
-    sky_transform->addKid( lower_ring );
-
-    sky_selector->addKid( sky_transform );
-    sky_selector->clrTraversalMaskBits( SSGTRAV_HOT );
-
-    root->addKid( sky_selector );
-
-    return true;
-}
-
-
-// repaint the sky colors based on current value of sun_angle, sky,
-// and fog colors.  This updates the color arrays for ssgVtxTable.
-// sun angle in degrees relative to verticle
-// 0 degrees = high noon
-// 90 degrees = sun rise/set
-// 180 degrees = darkest midnight
-bool FGSky::repaint( sgVec3 sky_color, sgVec3 fog_color, double sun_angle ) {
-    double diff;
-    sgVec3 outer_param, outer_amt, outer_diff;
-    sgVec3 middle_param, middle_amt, middle_diff;
-    int i, j;
-
-    // Check for sunrise/sunset condition
-    if ( (sun_angle > 80.0) && (sun_angle < 100.0) ) {
-	// 0.0 - 0.4
-	sgSetVec3( outer_param,
-		   (10.0 - fabs(90.0 - sun_angle)) / 20.0,
-		   (10.0 - fabs(90.0 - sun_angle)) / 40.0,
-		   -(10.0 - fabs(90.0 - sun_angle)) / 30.0 );
-
-	sgSetVec3( middle_param,
-		   (10.0 - fabs(90.0 - sun_angle)) / 40.0,
-		   (10.0 - fabs(90.0 - sun_angle)) / 80.0,
-		   0.0 );
-
-	sgScaleVec3( outer_diff, outer_param, 1.0 / 6.0 );
-
-	sgScaleVec3( middle_diff, middle_param, 1.0 / 6.0 );
-    } else {
-	sgSetVec3( outer_param, 0.0, 0.0, 0.0 );
-	sgSetVec3( middle_param, 0.0, 0.0, 0.0 );
-
-	sgSetVec3( outer_diff, 0.0, 0.0, 0.0 );
-	sgSetVec3( middle_diff, 0.0, 0.0, 0.0 );
-    }
-    // printf("  outer_red_param = %.2f  outer_red_diff = %.2f\n", 
-    //        outer_red_param, outer_red_diff);
-
-    // calculate transition colors between sky and fog
-    sgCopyVec3( outer_amt, outer_param );
-    sgCopyVec3( middle_amt, middle_param );
-
-    //
-    // First, recalulate the basic colors
-    //
-
-    sgVec3 center_color;
-    sgVec3 upper_color[12];
-    sgVec3 middle_color[12];
-    sgVec3 lower_color[12];
-    sgVec3 bottom_color[12];
-
-    for ( i = 0; i < 6; i++ ) {
-	for ( j = 0; j < 3; j++ ) {
-	    diff = sky_color[j] - fog_color[j];
-
-	    // printf("sky = %.2f  fog = %.2f  diff = %.2f\n", 
-	    //        l->sky_color[j], l->fog_color[j], diff);
-
-	    upper_color[i][j] = (GLubyte)((sky_color[j] - diff * 0.3) * 255);
-	    middle_color[i][j] = (GLubyte)((sky_color[j] - diff * 0.9 
-					   + middle_amt[j]) * 255);
-	    lower_color[i][j] = (GLubyte)((fog_color[j] + outer_amt[j]) 
-					  * 255);
-
-	    if ( upper_color[i][j] > 255 ) { upper_color[i][j] = 255; }
-	    if ( upper_color[i][j] < 25 ) { upper_color[i][j] = 25; }
-	    if ( middle_color[i][j] > 255 ) { middle_color[i][j] = 255; }
-	    if ( middle_color[i][j] < 25 ) { middle_color[i][j] = 25; }
-	    if ( lower_color[i][j] > 255 ) { lower_color[i][j] = 255; }
-	    if ( lower_color[i][j] < 25 ) { lower_color[i][j] = 25; }
-	}
-	// upper_color[i][3] = middle_color[i][3] = lower_color[i][3] = 
-	//                     (GLubyte)(sky_color[3] * 255);
-
-	for ( j = 0; j < 3; j++ ) {
-	    outer_amt[j] -= outer_diff[j];
-	    middle_amt[j] -= middle_diff[j];
-	}
-
-	/*
-	printf("upper_color[%d] = %.2f %.2f %.2f %.2f\n", i, upper_color[i][0],
-	       upper_color[i][1], upper_color[i][2], upper_color[i][3]);
-	printf("middle_color[%d] = %.2f %.2f %.2f %.2f\n", i, 
-	       middle_color[i][0], middle_color[i][1], middle_color[i][2], 
-	       middle_color[i][3]);
-	printf("lower_color[%d] = %.2f %.2f %.2f %.2f\n", i, 
-	       lower_color[i][0], lower_color[i][1], lower_color[i][2], 
-	       lower_color[i][3]);
-	*/
-    }
-
-    sgSetVec3( outer_amt, 0.0, 0.0, 0.0 );
-    sgSetVec3( middle_amt, 0.0, 0.0, 0.0 );
-
-    for ( i = 6; i < 12; i++ ) {
-	for ( j = 0; j < 3; j++ ) {
-	    diff = sky_color[j] - fog_color[j];
-
-	    // printf("sky = %.2f  fog = %.2f  diff = %.2f\n", 
-	    //        sky_color[j], fog_color[j], diff);
-
-	    upper_color[i][j] = (GLubyte)((sky_color[j] - diff * 0.3) * 255);
-	    middle_color[i][j] = (GLubyte)((sky_color[j] - diff * 0.9 
-					    + middle_amt[j]) * 255);
-	    lower_color[i][j] = (GLubyte)((fog_color[j] + outer_amt[j]) 
-					  * 255);
-
-	    if ( upper_color[i][j] > 255 ) { upper_color[i][j] = 255; }
-	    if ( upper_color[i][j] < 25 ) { upper_color[i][j] = 25; }
-	    if ( middle_color[i][j] > 255 ) { middle_color[i][j] = 255; }
-	    if ( middle_color[i][j] < 25 ) { middle_color[i][j] = 25; }
-	    if ( lower_color[i][j] > 255 ) { lower_color[i][j] = 255; }
-	    if ( lower_color[i][j] < 35 ) { lower_color[i][j] = 35; }
-	}
-	// upper_color[i][3] = middle_color[i][3] = lower_color[i][3] = 
-	//                     (GLubyte)(sky_color[3] * 255);
-
-	for ( j = 0; j < 3; j++ ) {
-	    outer_amt[j] += outer_diff[j];
-	    middle_amt[j] += middle_diff[j];
-	}
-
-	/*
-	printf("upper_color[%d] = %.2f %.2f %.2f %.2f\n", i, upper_color[i][0],
-	       upper_color[i][1], upper_color[i][2], upper_color[i][3]);
-	printf("middle_color[%d] = %.2f %.2f %.2f %.2f\n", i, 
-	       middle_color[i][0], middle_color[i][1], middle_color[i][2], 
-	       middle_color[i][3]);
-	printf("lower_color[%d] = %.2f %.2f %.2f %.2f\n", i, 
-	       lower_color[i][0], lower_color[i][1], lower_color[i][2], 
-	       lower_color[i][3]);
-	*/
-    }
-
-    for ( i = 0; i < 12; i++ ) {
-	sgCopyVec3( bottom_color[i], fog_color );
-    }
-
-    //
-    // Second, assign the basic colors to the object color arrays
-    //
-
-    float *slot;
-    int counter;
-
-    // update the center disk color arrays
-    counter = 0;
-    slot = center_disk_cl->get( counter++ );
-    sgCopyVec3( slot, center_color );
-    for ( i = 11; i >= 0; i-- ) {
-	slot = center_disk_cl->get( counter++ );
-	sgCopyVec3( slot, upper_color[i] );
-    }
-    slot = center_disk_cl->get( counter++ );
-    sgCopyVec3( slot, upper_color[11] );
-
-    // generate the upper ring
-    counter = 0;
-    for ( i = 0; i < 12; i++ ) {
-	slot = upper_ring_cl->get( counter++ );
-	sgCopyVec3( slot, middle_color[i] );
-
-	slot = upper_ring_cl->get( counter++ );
-	sgCopyVec3( slot, upper_color[i] );
-    }
-    slot = upper_ring_cl->get( counter++ );
-    sgCopyVec3( slot, middle_color[0] );
-
-    slot = upper_ring_cl->get( counter++ );
-    sgCopyVec3( slot, upper_color[0] );
-
-    // generate middle ring
-    counter = 0;
-    for ( i = 0; i < 12; i++ ) {
-	slot = middle_ring_cl->get( counter++ );
-	sgCopyVec3( slot, lower_color[i] );
-
-	slot = middle_ring_cl->get( counter++ );
-	sgCopyVec3( slot, middle_color[i] );
-    }
-    slot = middle_ring_cl->get( counter++ );
-    sgCopyVec3( slot, lower_color[0] );
-
-    slot = middle_ring_cl->get( counter++ );
-    sgCopyVec3( slot, middle_color[0] );
-
-    // generate lower ring
-    counter = 0;
-    for ( i = 0; i < 12; i++ ) {
-	slot = lower_ring_cl->get( counter++ );
-	sgCopyVec3( slot, bottom_color[i] );
-
-	slot = lower_ring_cl->get( counter++ );
-	sgCopyVec3( slot, lower_color[i] );
-    }
-    slot = lower_ring_cl->get( counter++ );
-    sgCopyVec3( slot, bottom_color[0] );
-
-    slot = lower_ring_cl->get( counter++ );
-    sgCopyVec3( slot, lower_color[0] );
-
-    return true;
-}
-
-
-// reposition the sky at the specified origin and orientation
-// lon specifies a rotation about the Z axis
-// lat specifies a rotation about the new Y axis
-// spin specifies a rotation about the new Z axis (and orients the
-// sunrise/set effects
-bool FGSky::reposition( sgVec3 p, double lon, double lat, double spin ) {
-    sgMat4 T, LON, LAT, SPIN;
-    sgVec3 axis;
-
-    // Translate to view position
-    // Point3D zero_elev = current_view.get_cur_zero_elev();
-    // xglTranslatef( zero_elev.x(), zero_elev.y(), zero_elev.z() );
-    sgMakeTransMat4( T, p );
-
-    // printf("  Translated to %.2f %.2f %.2f\n", 
-    //        zero_elev.x, zero_elev.y, zero_elev.z );
-
-    // Rotate to proper orientation
-    // printf("  lon = %.2f  lat = %.2f\n", FG_Longitude * RAD_TO_DEG,
-    //        FG_Latitude * RAD_TO_DEG);
-    // xglRotatef( f->get_Longitude() * RAD_TO_DEG, 0.0, 0.0, 1.0 );
-    sgSetVec3( axis, 0.0, 0.0, 1.0 );
-    sgMakeRotMat4( LON, lon * RAD_TO_DEG, axis );
-
-    // xglRotatef( 90.0 - f->get_Latitude() * RAD_TO_DEG, 0.0, 1.0, 0.0 );
-    sgSetVec3( axis, 0.0, 1.0, 0.0 );
-    sgMakeRotMat4( LAT, 90.0 - lat * RAD_TO_DEG, axis );
-
-    // xglRotatef( l->sun_rotation * RAD_TO_DEG, 0.0, 0.0, 1.0 );
-    sgSetVec3( axis, 0.0, 0.0, 1.0 );
-    sgMakeRotMat4( SPIN, spin * RAD_TO_DEG, axis );
-
-    sgMat4 TRANSFORM;
-
-    sgCopyMat4( TRANSFORM, T );
-    sgPreMultMat4( TRANSFORM, LON );
-    sgPreMultMat4( TRANSFORM, LAT );
-    sgPreMultMat4( TRANSFORM, SPIN );
-
-    sgCoord skypos;
-    sgSetCoord( &skypos, TRANSFORM );
-
-    sky_transform->setTransform( &skypos );
-
-    return true;
-}
-
-
-// Calculate the sky structure vertices
-void fgSkyVerticesInit() {
-    float theta;
-    int i;
-
-    FG_LOG(FG_ASTRO, FG_INFO, "  Generating the sky dome vertices.");
-
-    for ( i = 0; i < 12; i++ ) {
-	theta = (i * 30.0) * DEG_TO_RAD;
-	
-	inner_vertex[i][0] = cos(theta) * UPPER_RADIUS;
-	inner_vertex[i][1] = sin(theta) * UPPER_RADIUS;
-	inner_vertex[i][2] = UPPER_ELEV;
-	
-	// printf("    %.2f %.2f\n", cos(theta) * UPPER_RADIUS, 
-	//        sin(theta) * UPPER_RADIUS);
-
-	middle_vertex[i][0] = cos((double)theta) * MIDDLE_RADIUS;
-	middle_vertex[i][1] = sin((double)theta) * MIDDLE_RADIUS;
-	middle_vertex[i][2] = MIDDLE_ELEV;
-	    
-	outer_vertex[i][0] = cos((double)theta) * LOWER_RADIUS;
-	outer_vertex[i][1] = sin((double)theta) * LOWER_RADIUS;
-	outer_vertex[i][2] = LOWER_ELEV;
-	    
-	bottom_vertex[i][0] = cos((double)theta) * BOTTOM_RADIUS;
-	bottom_vertex[i][1] = sin((double)theta) * BOTTOM_RADIUS;
-	bottom_vertex[i][2] = BOTTOM_ELEV;
-    }
-}
-
-
-// (Re)calculate the sky colors at each vertex
-void fgSkyColorsInit() {
-    fgLIGHT *l;
-    double sun_angle, diff;
-    double outer_param[3], outer_amt[3], outer_diff[3];
-    double middle_param[3], middle_amt[3], middle_diff[3];
-    int i, j;
-
-    l = &cur_light_params;
-
-    FG_LOG( FG_ASTRO, FG_INFO, 
-	    "  Generating the sky colors for each vertex." );
-
-    // setup for the possibility of sunset effects
-    sun_angle = l->sun_angle * RAD_TO_DEG;
-    // fgPrintf( FG_ASTRO, FG_INFO, 
-    //           "  Sun angle in degrees = %.2f\n", sun_angle);
-
-    if ( (sun_angle > 80.0) && (sun_angle < 100.0) ) {
-	// 0.0 - 0.4
-	outer_param[0] = (10.0 - fabs(90.0 - sun_angle)) / 20.0;
-	outer_param[1] = (10.0 - fabs(90.0 - sun_angle)) / 40.0;
-	outer_param[2] = -(10.0 - fabs(90.0 - sun_angle)) / 30.0;
-	// outer_param[2] = 0.0;
-
-	middle_param[0] = (10.0 - fabs(90.0 - sun_angle)) / 40.0;
-	middle_param[1] = (10.0 - fabs(90.0 - sun_angle)) / 80.0;
-	middle_param[2] = 0.0;
-
-	outer_diff[0] = outer_param[0] / 6.0;
-	outer_diff[1] = outer_param[1] / 6.0;
-	outer_diff[2] = outer_param[2] / 6.0;
-
-	middle_diff[0] = middle_param[0] / 6.0;
-	middle_diff[1] = middle_param[1] / 6.0;
-	middle_diff[2] = middle_param[2] / 6.0;
-    } else {
-	outer_param[0] = outer_param[1] = outer_param[2] = 0.0;
-	middle_param[0] = middle_param[1] = middle_param[2] = 0.0;
-
-	outer_diff[0] = outer_diff[1] = outer_diff[2] = 0.0;
-	middle_diff[0] = middle_diff[1] = middle_diff[2] = 0.0;
-    }
-    // printf("  outer_red_param = %.2f  outer_red_diff = %.2f\n", 
-    //        outer_red_param, outer_red_diff);
-
-    // calculate transition colors between sky and fog
-    for ( j = 0; j < 3; j++ ) {
-	outer_amt[j] = outer_param[j];
-	middle_amt[j] = middle_param[j];
-    }
-
-    for ( i = 0; i < 6; i++ ) {
-	for ( j = 0; j < 3; j++ ) {
-	    diff = l->sky_color[j] - l->fog_color[j];
-
-	    // printf("sky = %.2f  fog = %.2f  diff = %.2f\n", 
-	    //        l->sky_color[j], l->fog_color[j], diff);
-
-	    upper_color[i][j] = (GLubyte)((l->sky_color[j] - diff * 0.3) * 255);
-	    middle_color[i][j] = (GLubyte)((l->sky_color[j] - diff * 0.9 
-					   + middle_amt[j]) * 255);
-	    lower_color[i][j] = (GLubyte)((l->fog_color[j] + outer_amt[j]) 
-					  * 255);
-
-	    if ( upper_color[i][j] > 255 ) { upper_color[i][j] = 255; }
-	    if ( upper_color[i][j] < 25 ) { upper_color[i][j] = 25; }
-	    if ( middle_color[i][j] > 255 ) { middle_color[i][j] = 255; }
-	    if ( middle_color[i][j] < 25 ) { middle_color[i][j] = 25; }
-	    if ( lower_color[i][j] > 255 ) { lower_color[i][j] = 255; }
-	    if ( lower_color[i][j] < 25 ) { lower_color[i][j] = 25; }
-	}
-	upper_color[i][3] = middle_color[i][3] = lower_color[i][3] = 
-	    (GLubyte)(l->sky_color[3] * 255);
-
-	for ( j = 0; j < 3; j++ ) {
-	    outer_amt[j] -= outer_diff[j];
-	    middle_amt[j] -= middle_diff[j];
-	}
-
-	/*
-	printf("upper_color[%d] = %.2f %.2f %.2f %.2f\n", i, upper_color[i][0],
-	       upper_color[i][1], upper_color[i][2], upper_color[i][3]);
-	printf("middle_color[%d] = %.2f %.2f %.2f %.2f\n", i, 
-	       middle_color[i][0], middle_color[i][1], middle_color[i][2], 
-	       middle_color[i][3]);
-	printf("lower_color[%d] = %.2f %.2f %.2f %.2f\n", i, 
-	       lower_color[i][0], lower_color[i][1], lower_color[i][2], 
-	       lower_color[i][3]);
-	*/
-    }
-
-    for ( j = 0; j < 3; j++ ) {
-	outer_amt[j] = 0.0;
-	middle_amt[j] = 0.0;
-    }
-
-    for ( i = 6; i < 12; i++ ) {
-
-	for ( j = 0; j < 3; j++ ) {
-	    diff = l->sky_color[j] - l->fog_color[j];
-
-	    // printf("sky = %.2f  fog = %.2f  diff = %.2f\n", 
-	    //        l->sky_color[j], l->fog_color[j], diff);
-
-	    upper_color[i][j] = (GLubyte)((l->sky_color[j] - diff * 0.3) * 255);
-	    middle_color[i][j] = (GLubyte)((l->sky_color[j] - diff * 0.9 
-					    + middle_amt[j]) * 255);
-	    lower_color[i][j] = (GLubyte)((l->fog_color[j] + outer_amt[j]) 
-					  * 255);
-
-	    if ( upper_color[i][j] > 255 ) { upper_color[i][j] = 255; }
-	    if ( upper_color[i][j] < 25 ) { upper_color[i][j] = 25; }
-	    if ( middle_color[i][j] > 255 ) { middle_color[i][j] = 255; }
-	    if ( middle_color[i][j] < 25 ) { middle_color[i][j] = 25; }
-	    if ( lower_color[i][j] > 255 ) { lower_color[i][j] = 255; }
-	    if ( lower_color[i][j] < 35 ) { lower_color[i][j] = 35; }
-	}
-	upper_color[i][3] = middle_color[i][3] = lower_color[i][3] = 
-	    (GLubyte)(l->sky_color[3] * 255);
-
-	for ( j = 0; j < 3; j++ ) {
-	    outer_amt[j] += outer_diff[j];
-	    middle_amt[j] += middle_diff[j];
-	}
-
-	/*
-	printf("upper_color[%d] = %.2f %.2f %.2f %.2f\n", i, upper_color[i][0],
-	       upper_color[i][1], upper_color[i][2], upper_color[i][3]);
-	printf("middle_color[%d] = %.2f %.2f %.2f %.2f\n", i, 
-	       middle_color[i][0], middle_color[i][1], middle_color[i][2], 
-	       middle_color[i][3]);
-	printf("lower_color[%d] = %.2f %.2f %.2f %.2f\n", i, 
-	       lower_color[i][0], lower_color[i][1], lower_color[i][2], 
-	       lower_color[i][3]);
-	*/
-    }
-}
-
-
-// Initialize the sky structure and colors
-void fgSkyInit() {
-    FG_LOG( FG_ASTRO, FG_INFO, "Initializing the sky" );
-
-    fgSkyVerticesInit();
-
-    // regester fgSkyColorsInit() as an event to be run periodically
-    global_events.Register( "fgSkyColorsInit()", fgSkyColorsInit, 
-		            fgEVENT::FG_EVENT_READY, 30000);
-}
-
-
-// Draw the Sky
-void fgSkyRender() {
-    FGInterface *f;
-    fgLIGHT *l;
-    GLubyte sky_color[4];
-    GLubyte upper_color[4];
-    GLubyte middle_color[4];
-    GLubyte lower_color[4];
-    double diff;
-    int i;
-
-    f = current_aircraft.fdm_state;
-    l = &cur_light_params;
-
-    // printf("Rendering the sky.\n");
-
-    // calculate the proper colors
-    for ( i = 0; i < 3; i++ ) {
-	diff = l->sky_color[i] - l->adj_fog_color[i];
-
-	// printf("sky = %.2f  fog = %.2f  diff = %.2f\n", 
-	//        l->sky_color[j], l->adj_fog_color[j], diff);
-
-	upper_color[i] = (GLubyte)((l->sky_color[i] - diff * 0.3) * 255);
-	middle_color[i] = (GLubyte)((l->sky_color[i] - diff * 0.9) * 255);
-	lower_color[i] = (GLubyte)(l->adj_fog_color[i] * 255);
-    }
-    upper_color[3] = middle_color[3] = lower_color[3] = 
-	(GLubyte)(l->adj_fog_color[3] * 255);
-
-    xglPushMatrix();
-
-    // Translate to view position
-    Point3D zero_elev = current_view.get_cur_zero_elev();
-    xglTranslatef( zero_elev.x(), zero_elev.y(), zero_elev.z() );
-    // printf("  Translated to %.2f %.2f %.2f\n", 
-    //        zero_elev.x, zero_elev.y, zero_elev.z );
-
-    // Rotate to proper orientation
-    // printf("  lon = %.2f  lat = %.2f\n", FG_Longitude * RAD_TO_DEG,
-    //        FG_Latitude * RAD_TO_DEG);
-    xglRotatef( f->get_Longitude() * RAD_TO_DEG, 0.0, 0.0, 1.0 );
-    xglRotatef( 90.0 - f->get_Latitude() * RAD_TO_DEG, 0.0, 1.0, 0.0 );
-    xglRotatef( l->sun_rotation * RAD_TO_DEG, 0.0, 0.0, 1.0 );
-
-    // Draw inner/center section of sky*/
-    xglBegin( GL_TRIANGLE_FAN );
-    for ( i = 0; i < 4; i++ ) {
-	sky_color[i] = (GLubyte)(l->sky_color[i] * 255);
-    }
-    xglColor4fv(l->sky_color);
-    xglVertex3f(0.0, 0.0, CENTER_ELEV);
-    for ( i = 11; i >= 0; i-- ) {
-	xglColor4ubv( upper_color );
-	xglVertex3fv( inner_vertex[i] );
-    }
-    xglColor4ubv( upper_color );
-    xglVertex3fv( inner_vertex[11] );
-    xglEnd();
-
-    // Draw the middle ring
-    xglBegin( GL_TRIANGLE_STRIP );
-    for ( i = 0; i < 12; i++ ) {
-	xglColor4ubv( middle_color );
-	// printf("middle_color[%d] = %.2f %.2f %.2f %.2f\n", i, 
-	//        middle_color[i][0], middle_color[i][1], middle_color[i][2], 
-	//        middle_color[i][3]);
-	// xglColor4f(1.0, 0.0, 0.0, 1.0);
-	xglVertex3fv( middle_vertex[i] );
-	xglColor4ubv( upper_color );
-	// printf("upper_color[%d] = %.2f %.2f %.2f %.2f\n", i, 
-	//        upper_color[i][0], upper_color[i][1], upper_color[i][2], 
-	//        upper_color[i][3]);
-	// xglColor4f(0.0, 0.0, 1.0, 1.0);
-	xglVertex3fv( inner_vertex[i] );
-    }
-    xglColor4ubv( middle_color );
-    // xglColor4f(1.0, 0.0, 0.0, 1.0);
-    xglVertex3fv( middle_vertex[0] );
-    xglColor4ubv( upper_color );
-    // xglColor4f(0.0, 0.0, 1.0, 1.0);
-    xglVertex3fv( inner_vertex[0] );
-    xglEnd();
-
-    // Draw the outer ring
-    xglBegin( GL_TRIANGLE_STRIP );
-    for ( i = 0; i < 12; i++ ) {
-	xglColor4ubv( lower_color );
-	xglVertex3fv( outer_vertex[i] );
-	xglColor4ubv( middle_color );
-	xglVertex3fv( middle_vertex[i] );
-    }
-    xglColor4ubv( lower_color );
-    xglVertex3fv( outer_vertex[0] );
-    xglColor4ubv( middle_color );
-    xglVertex3fv( middle_vertex[0] );
-    xglEnd();
-
-    // Draw the bottom skirt
-    xglBegin( GL_TRIANGLE_STRIP );
-    xglColor4ubv( lower_color );
-    for ( i = 0; i < 12; i++ ) {
-	xglVertex3fv( bottom_vertex[i] );
-	xglVertex3fv( outer_vertex[i] );
-    }
-    xglVertex3fv( bottom_vertex[0] );
-    xglVertex3fv( outer_vertex[0] );
-    xglEnd();
-
-    xglPopMatrix();
-}
-
-
diff --git a/simgear/ephemeris/sky.hxx b/simgear/ephemeris/sky.hxx
deleted file mode 100644
index 17cf2edb..00000000
--- a/simgear/ephemeris/sky.hxx
+++ /dev/null
@@ -1,108 +0,0 @@
-// sky.hxx -- model sky with an upside down "bowl"
-//
-// Written by Curtis Olson, started December 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.
-//
-// $Id$
-
-
-#ifndef _SKY_HXX
-#define _SKY_HXX
-
-
-#ifndef __cplusplus                                                          
-# error This library requires C++
-#endif                                   
-
-
-#include <plib/ssg.h>		// plib include
-
-
-class FGSky {
-
-    ssgSelector *sky_selector;
-    ssgTransform *sky_transform;
-    ssgSimpleState *sky_state;
-
-    ssgVertexArray *center_disk_vl;
-    ssgColourArray *center_disk_cl;
-
-    ssgVertexArray *upper_ring_vl;
-    ssgColourArray *upper_ring_cl;
-
-    ssgVertexArray *middle_ring_vl;
-    ssgColourArray *middle_ring_cl;
-
-    ssgVertexArray *lower_ring_vl;
-    ssgColourArray *lower_ring_cl;
-
-public:
-
-    // Constructor
-    FGSky( void );
-
-    // Destructor
-    ~FGSky( void );
-
-    // initialize the sky object and connect it into the scene graph
-    // as a kid to to the specified root
-    bool initialize( ssgRoot *branch );
-
-    // repaint the sky colors based on current value of sun_angle,
-    // sky, and fog colors.  This updates the color arrays for
-    // ssgVtxTable.
-    // sun angle in degrees relative to verticle
-    // 0 degrees = high noon
-    // 90 degrees = sun rise/set
-    // 180 degrees = darkest midnight
-    bool repaint( sgVec3 sky_color, sgVec3 fog_color, double sun_angle );
-
-    // reposition the sky at the specified origin and orientation
-    // lon specifies a rotation about the Z axis
-    // lat specifies a rotation about the new Y axis
-    // spin specifies a rotation about the new Z axis (and orients the
-    // sunrise/set effects
-    bool reposition( sgVec3 p, double lon, double lat, double spin );
-
-    // enable the sky in the scene graph (default)
-    void enable() { sky_selector->select( 1 ); }
-
-    // disable the sky in the scene graph.  The leaf node is still
-    // there, how ever it won't be traversed on the cullandrender
-    // phase.
-    void disable() { sky_selector->select( 0 ); }
-
-};
-
-
-extern FGSky current_sky;
-
-
-// (Re)generate the display list
-void fgSkyInit();
-
-// (Re)calculate the sky colors at each vertex
-void fgSkyColorsInit();
-
-// Draw the Sky
-void fgSkyRender();
-
-
-#endif // _SKY_HXX
-
-
diff --git a/simgear/ephemeris/skydome.cxx b/simgear/ephemeris/skydome.cxx
new file mode 100644
index 00000000..f71f98bd
--- /dev/null
+++ b/simgear/ephemeris/skydome.cxx
@@ -0,0 +1,814 @@
+// skydome.cxx -- model sky with an upside down "bowl"
+//
+// Written by Curtis Olson, started December 1997.
+// SSG-ified by Curtis Olson, February 2000.
+//
+// Copyright (C) 1997-2000  Curtis L. Olson  - curt@flightgear.org
+//
+// 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.
+//
+// $Id$
+
+
+#ifdef HAVE_CONFIG_H
+#  include <config.h>
+#endif
+
+#ifdef HAVE_WINDOWS_H
+#  include <windows.h>
+#endif
+
+#include <math.h>
+
+#include <GL/glut.h>
+#include <simgear/xgl/xgl.h>
+
+#include <simgear/constants.h>
+#include <simgear/debug/logstream.hxx>
+#include <simgear/math/fg_random.h>
+
+#include <Aircraft/aircraft.hxx>
+#include <FDM/flight.hxx>
+#include <Main/views.hxx>
+#include <Time/event.hxx>
+#include <Time/fg_time.hxx>
+
+#include "skydome.hxx"
+
+
+#ifdef __MWERKS__
+#  pragma global_optimizer off
+#endif
+
+
+// in meters of course
+#define CENTER_ELEV   25000.0
+
+#define UPPER_RADIUS  50000.0
+#define UPPER_ELEV    20000.0
+
+#define MIDDLE_RADIUS 70000.0
+#define MIDDLE_ELEV    8000.0
+
+#define LOWER_RADIUS  80000.0
+#define LOWER_ELEV        0.0
+
+#define BOTTOM_RADIUS 50000.0
+#define BOTTOM_ELEV   -2000.0
+
+
+// static float inner_vertex[12][3];
+// static float middle_vertex[12][3];
+// static float outer_vertex[12][3];
+// static float bottom_vertex[12][3];
+
+// static GLubyte upper_color[12][4];
+// static GLubyte middle_color[12][4];
+// static GLubyte lower_color[12][4];
+
+
+// Defined the shared sky object here
+FGSkyDome current_sky;
+
+
+// Constructor
+FGSkyDome::FGSkyDome( void ) {
+}
+
+
+// Destructor
+FGSkyDome::~FGSkyDome( void ) {
+}
+
+
+// initialize the sky object and connect it into the scene graph
+bool FGSkyDome::initialize( ssgRoot *root ) {
+    sgVec3 color;
+
+    float theta;
+    int i;
+
+    // set up the state
+    sky_state = new ssgSimpleState();
+    if ( current_options.get_shading() == 1 ) {
+	sky_state->setShadeModel( GL_SMOOTH );
+    } else {
+	sky_state->setShadeModel( GL_FLAT );
+    }
+    sky_state->disable( GL_LIGHTING );
+    sky_state->disable( GL_DEPTH_TEST );
+    sky_state->disable( GL_CULL_FACE );
+    sky_state->disable( GL_TEXTURE );
+    sky_state->enable( GL_COLOR_MATERIAL );
+    sky_state->setColourMaterial( GL_AMBIENT_AND_DIFFUSE );
+
+    // initialize arrays
+    center_disk_vl = new ssgVertexArray( 14 );
+    center_disk_cl = new ssgColourArray( 14 );
+				       
+    upper_ring_vl = new ssgVertexArray( 26 );
+    upper_ring_cl = new ssgColourArray( 26 );
+
+    middle_ring_vl = new ssgVertexArray( 26 );
+    middle_ring_cl = new ssgColourArray( 26 );
+
+    lower_ring_vl = new ssgVertexArray( 26 );
+    lower_ring_cl = new ssgColourArray( 26 );
+
+    // initially seed to all blue
+    sgSetVec3( color, 0.0, 0.0, 1.0 );
+
+    // generate the raw vertex data
+    sgVec3 center_vertex;
+    sgVec3 upper_vertex[12];
+    sgVec3 middle_vertex[12];
+    sgVec3 lower_vertex[12];
+    sgVec3 bottom_vertex[12];
+
+    sgSetVec3( center_vertex, 0.0, 0.0, CENTER_ELEV );
+
+    for ( i = 0; i < 12; i++ ) {
+	theta = (i * 30.0) * DEG_TO_RAD;
+
+	sgSetVec3( upper_vertex[i],
+		   cos(theta) * UPPER_RADIUS,
+		   sin(theta) * UPPER_RADIUS,
+		   UPPER_ELEV );
+	
+	sgSetVec3( middle_vertex[i],
+		   cos((double)theta) * MIDDLE_RADIUS,
+		   sin((double)theta) * MIDDLE_RADIUS,
+		   MIDDLE_ELEV );
+
+	sgSetVec3( lower_vertex[i],
+		   cos((double)theta) * LOWER_RADIUS,
+		   sin((double)theta) * LOWER_RADIUS,
+		   LOWER_ELEV );
+
+	sgSetVec3( bottom_vertex[i],
+		   cos((double)theta) * BOTTOM_RADIUS,
+		   sin((double)theta) * BOTTOM_RADIUS,
+		   BOTTOM_ELEV );
+    }
+
+    // generate the center disk vertex/color arrays
+    center_disk_vl->add( center_vertex );
+    center_disk_cl->add( color );
+    for ( i = 11; i >= 0; i-- ) {
+	center_disk_vl->add( upper_vertex[i] );
+	center_disk_cl->add( color );
+    }
+    center_disk_vl->add( upper_vertex[11] );
+    center_disk_cl->add( color );
+
+    // generate the upper ring
+    for ( i = 0; i < 12; i++ ) {
+	upper_ring_vl->add( middle_vertex[i] );
+	upper_ring_cl->add( color );
+
+	upper_ring_vl->add( upper_vertex[i] );
+	upper_ring_cl->add( color );
+    }
+    upper_ring_vl->add( middle_vertex[0] );
+    upper_ring_cl->add( color );
+
+    upper_ring_vl->add( upper_vertex[0] );
+    upper_ring_cl->add( color );
+
+    // generate middle ring
+    for ( i = 0; i < 12; i++ ) {
+	middle_ring_vl->add( lower_vertex[i] );
+	middle_ring_cl->add( color );
+
+	middle_ring_vl->add( middle_vertex[i] );
+	middle_ring_cl->add( color );
+    }
+    middle_ring_vl->add( lower_vertex[0] );
+    middle_ring_cl->add( color );
+
+    middle_ring_vl->add( middle_vertex[0] );
+    middle_ring_cl->add( color );
+
+    // generate lower ring
+    for ( i = 0; i < 12; i++ ) {
+	lower_ring_vl->add( bottom_vertex[i] );
+	lower_ring_cl->add( color );
+
+	lower_ring_vl->add( lower_vertex[i] );
+	lower_ring_cl->add( color );
+    }
+    lower_ring_vl->add( bottom_vertex[0] );
+    lower_ring_cl->add( color );
+
+    lower_ring_vl->add( lower_vertex[0] );
+    lower_ring_cl->add( color );
+
+    // force a repaint of the sky colors with ugly defaults
+    sgVec3 fog_color;
+    sgSetVec3( fog_color, 1.0, 1.0, 1.0 );
+    repaint( color, fog_color, 0.0 );
+
+    // build the ssg scene graph sub tree for the sky and connected
+    // into the provide scene graph branch
+    sky_selector = new ssgSelector;
+    sky_transform = new ssgTransform;
+
+    ssgVtxTable *center_disk, *upper_ring, *middle_ring, *lower_ring;
+
+    center_disk = new ssgVtxTable( GL_TRIANGLE_FAN, 
+				   center_disk_vl, NULL, NULL, center_disk_cl );
+
+    upper_ring = new ssgVtxTable( GL_TRIANGLE_STRIP, 
+				  upper_ring_vl, NULL, NULL, upper_ring_cl );
+
+    middle_ring = new ssgVtxTable( GL_TRIANGLE_STRIP, 
+				   middle_ring_vl, NULL, NULL, middle_ring_cl );
+
+    lower_ring = new ssgVtxTable( GL_TRIANGLE_STRIP, 
+				  lower_ring_vl, NULL, NULL, lower_ring_cl );
+
+    center_disk->setState( sky_state );
+    upper_ring->setState( sky_state );
+    middle_ring->setState( sky_state );
+    lower_ring->setState( sky_state );
+
+    sky_transform->addKid( center_disk );
+    sky_transform->addKid( upper_ring );
+    sky_transform->addKid( middle_ring );
+    sky_transform->addKid( lower_ring );
+
+    sky_selector->addKid( sky_transform );
+    sky_selector->clrTraversalMaskBits( SSGTRAV_HOT );
+
+    root->addKid( sky_selector );
+
+    return true;
+}
+
+
+// repaint the sky colors based on current value of sun_angle, sky,
+// and fog colors.  This updates the color arrays for ssgVtxTable.
+// sun angle in degrees relative to verticle
+// 0 degrees = high noon
+// 90 degrees = sun rise/set
+// 180 degrees = darkest midnight
+bool FGSkyDome::repaint( sgVec3 sky_color, sgVec3 fog_color, double sun_angle ) {
+    double diff;
+    sgVec3 outer_param, outer_amt, outer_diff;
+    sgVec3 middle_param, middle_amt, middle_diff;
+    int i, j;
+
+    // Check for sunrise/sunset condition
+    if ( (sun_angle > 80.0) && (sun_angle < 100.0) ) {
+	// 0.0 - 0.4
+	sgSetVec3( outer_param,
+		   (10.0 - fabs(90.0 - sun_angle)) / 20.0,
+		   (10.0 - fabs(90.0 - sun_angle)) / 40.0,
+		   -(10.0 - fabs(90.0 - sun_angle)) / 30.0 );
+
+	sgSetVec3( middle_param,
+		   (10.0 - fabs(90.0 - sun_angle)) / 40.0,
+		   (10.0 - fabs(90.0 - sun_angle)) / 80.0,
+		   0.0 );
+
+	sgScaleVec3( outer_diff, outer_param, 1.0 / 6.0 );
+
+	sgScaleVec3( middle_diff, middle_param, 1.0 / 6.0 );
+    } else {
+	sgSetVec3( outer_param, 0.0, 0.0, 0.0 );
+	sgSetVec3( middle_param, 0.0, 0.0, 0.0 );
+
+	sgSetVec3( outer_diff, 0.0, 0.0, 0.0 );
+	sgSetVec3( middle_diff, 0.0, 0.0, 0.0 );
+    }
+    // printf("  outer_red_param = %.2f  outer_red_diff = %.2f\n", 
+    //        outer_red_param, outer_red_diff);
+
+    // calculate transition colors between sky and fog
+    sgCopyVec3( outer_amt, outer_param );
+    sgCopyVec3( middle_amt, middle_param );
+
+    //
+    // First, recalulate the basic colors
+    //
+
+    sgVec3 upper_color[12];
+    sgVec3 middle_color[12];
+    sgVec3 lower_color[12];
+    sgVec3 bottom_color[12];
+
+    for ( i = 0; i < 6; i++ ) {
+	for ( j = 0; j < 3; j++ ) {
+	    diff = sky_color[j] - fog_color[j];
+
+	    // printf("sky = %.2f  fog = %.2f  diff = %.2f\n", 
+	    //        l->sky_color[j], l->fog_color[j], diff);
+
+	    upper_color[i][j] = sky_color[j] - diff * 0.3;
+	    middle_color[i][j] = sky_color[j] - diff * 0.9 + middle_amt[j];
+	    lower_color[i][j] = fog_color[j] + outer_amt[j];
+
+	    if ( upper_color[i][j] > 1.0 ) { upper_color[i][j] = 1.0; }
+	    if ( upper_color[i][j] < 0.1 ) { upper_color[i][j] = 0.1; }
+	    if ( middle_color[i][j] > 1.0 ) { middle_color[i][j] = 1.0; }
+	    if ( middle_color[i][j] < 0.1 ) { middle_color[i][j] = 0.1; }
+	    if ( lower_color[i][j] > 1.0 ) { lower_color[i][j] = 1.0; }
+	    if ( lower_color[i][j] < 0.1 ) { lower_color[i][j] = 0.1; }
+	}
+	// upper_color[i][3] = middle_color[i][3] = lower_color[i][3] = 
+	//                     (GLubyte)(sky_color[3] * 1.0);
+
+	for ( j = 0; j < 3; j++ ) {
+	    outer_amt[j] -= outer_diff[j];
+	    middle_amt[j] -= middle_diff[j];
+	}
+
+	/*
+	printf("upper_color[%d] = %.2f %.2f %.2f %.2f\n", i, upper_color[i][0],
+	       upper_color[i][1], upper_color[i][2], upper_color[i][3]);
+	printf("middle_color[%d] = %.2f %.2f %.2f %.2f\n", i, 
+	       middle_color[i][0], middle_color[i][1], middle_color[i][2], 
+	       middle_color[i][3]);
+	printf("lower_color[%d] = %.2f %.2f %.2f %.2f\n", i, 
+	       lower_color[i][0], lower_color[i][1], lower_color[i][2], 
+	       lower_color[i][3]);
+	*/
+    }
+
+    sgSetVec3( outer_amt, 0.0, 0.0, 0.0 );
+    sgSetVec3( middle_amt, 0.0, 0.0, 0.0 );
+
+    for ( i = 6; i < 12; i++ ) {
+	for ( j = 0; j < 3; j++ ) {
+	    diff = sky_color[j] - fog_color[j];
+
+	    // printf("sky = %.2f  fog = %.2f  diff = %.2f\n", 
+	    //        sky_color[j], fog_color[j], diff);
+
+	    upper_color[i][j] = sky_color[j] - diff * 0.3;
+	    middle_color[i][j] = sky_color[j] - diff * 0.9 + middle_amt[j];
+	    lower_color[i][j] = fog_color[j] + outer_amt[j];
+
+	    if ( upper_color[i][j] > 1.0 ) { upper_color[i][j] = 1.0; }
+	    if ( upper_color[i][j] < 0.1 ) { upper_color[i][j] = 0.1; }
+	    if ( middle_color[i][j] > 1.0 ) { middle_color[i][j] = 1.0; }
+	    if ( middle_color[i][j] < 0.1 ) { middle_color[i][j] = 0.1; }
+	    if ( lower_color[i][j] > 1.0 ) { lower_color[i][j] = 1.0; }
+	    if ( lower_color[i][j] < 35 ) { lower_color[i][j] = 35; }
+	}
+	// upper_color[i][3] = middle_color[i][3] = lower_color[i][3] = 
+	//                     (GLubyte)(sky_color[3] * 1.0);
+
+	for ( j = 0; j < 3; j++ ) {
+	    outer_amt[j] += outer_diff[j];
+	    middle_amt[j] += middle_diff[j];
+	}
+
+	/*
+	printf("upper_color[%d] = %.2f %.2f %.2f %.2f\n", i, upper_color[i][0],
+	       upper_color[i][1], upper_color[i][2], upper_color[i][3]);
+	printf("middle_color[%d] = %.2f %.2f %.2f %.2f\n", i, 
+	       middle_color[i][0], middle_color[i][1], middle_color[i][2], 
+	       middle_color[i][3]);
+	printf("lower_color[%d] = %.2f %.2f %.2f %.2f\n", i, 
+	       lower_color[i][0], lower_color[i][1], lower_color[i][2], 
+	       lower_color[i][3]);
+	*/
+    }
+
+    for ( i = 0; i < 12; i++ ) {
+	sgCopyVec3( bottom_color[i], fog_color );
+    }
+
+    //
+    // Second, assign the basic colors to the object color arrays
+    //
+
+    float *slot;
+    int counter;
+
+    // update the center disk color arrays
+    counter = 0;
+    slot = center_disk_cl->get( counter++ );
+    // sgVec3 red;
+    // sgSetVec3( red, 1.0, 0.0, 0.0 );
+    sgCopyVec3( slot, sky_color );
+    for ( i = 11; i >= 0; i-- ) {
+	slot = center_disk_cl->get( counter++ );
+	sgCopyVec3( slot, upper_color[i] );
+    }
+    slot = center_disk_cl->get( counter++ );
+    sgCopyVec3( slot, upper_color[11] );
+
+    // generate the upper ring
+    counter = 0;
+    for ( i = 0; i < 12; i++ ) {
+	slot = upper_ring_cl->get( counter++ );
+	sgCopyVec3( slot, middle_color[i] );
+
+	slot = upper_ring_cl->get( counter++ );
+	sgCopyVec3( slot, upper_color[i] );
+    }
+    slot = upper_ring_cl->get( counter++ );
+    sgCopyVec3( slot, middle_color[0] );
+
+    slot = upper_ring_cl->get( counter++ );
+    sgCopyVec3( slot, upper_color[0] );
+
+    // generate middle ring
+    counter = 0;
+    for ( i = 0; i < 12; i++ ) {
+	slot = middle_ring_cl->get( counter++ );
+	sgCopyVec3( slot, lower_color[i] );
+
+	slot = middle_ring_cl->get( counter++ );
+	sgCopyVec3( slot, middle_color[i] );
+    }
+    slot = middle_ring_cl->get( counter++ );
+    sgCopyVec3( slot, lower_color[0] );
+
+    slot = middle_ring_cl->get( counter++ );
+    sgCopyVec3( slot, middle_color[0] );
+
+    // generate lower ring
+    counter = 0;
+    for ( i = 0; i < 12; i++ ) {
+	slot = lower_ring_cl->get( counter++ );
+	sgCopyVec3( slot, bottom_color[i] );
+
+	slot = lower_ring_cl->get( counter++ );
+	sgCopyVec3( slot, lower_color[i] );
+    }
+    slot = lower_ring_cl->get( counter++ );
+    sgCopyVec3( slot, bottom_color[0] );
+
+    slot = lower_ring_cl->get( counter++ );
+    sgCopyVec3( slot, lower_color[0] );
+
+    return true;
+}
+
+
+// reposition the sky at the specified origin and orientation
+// lon specifies a rotation about the Z axis
+// lat specifies a rotation about the new Y axis
+// spin specifies a rotation about the new Z axis (and orients the
+// sunrise/set effects
+bool FGSkyDome::reposition( sgVec3 p, double lon, double lat, double spin ) {
+    sgMat4 T, LON, LAT, SPIN;
+    sgVec3 axis;
+
+    // Translate to view position
+    // Point3D zero_elev = current_view.get_cur_zero_elev();
+    // xglTranslatef( zero_elev.x(), zero_elev.y(), zero_elev.z() );
+    sgMakeTransMat4( T, p );
+
+    // printf("  Translated to %.2f %.2f %.2f\n", 
+    //        zero_elev.x, zero_elev.y, zero_elev.z );
+
+    // Rotate to proper orientation
+    // printf("  lon = %.2f  lat = %.2f\n", FG_Longitude * RAD_TO_DEG,
+    //        FG_Latitude * RAD_TO_DEG);
+    // xglRotatef( f->get_Longitude() * RAD_TO_DEG, 0.0, 0.0, 1.0 );
+    sgSetVec3( axis, 0.0, 0.0, 1.0 );
+    sgMakeRotMat4( LON, lon * RAD_TO_DEG, axis );
+
+    // xglRotatef( 90.0 - f->get_Latitude() * RAD_TO_DEG, 0.0, 1.0, 0.0 );
+    sgSetVec3( axis, 0.0, 1.0, 0.0 );
+    sgMakeRotMat4( LAT, 90.0 - lat * RAD_TO_DEG, axis );
+
+    // xglRotatef( l->sun_rotation * RAD_TO_DEG, 0.0, 0.0, 1.0 );
+    sgSetVec3( axis, 0.0, 0.0, 1.0 );
+    sgMakeRotMat4( SPIN, spin * RAD_TO_DEG, axis );
+
+    sgMat4 TRANSFORM;
+
+    sgCopyMat4( TRANSFORM, T );
+    sgPreMultMat4( TRANSFORM, LON );
+    sgPreMultMat4( TRANSFORM, LAT );
+    sgPreMultMat4( TRANSFORM, SPIN );
+
+    sgCoord skypos;
+    sgSetCoord( &skypos, TRANSFORM );
+
+    sky_transform->setTransform( &skypos );
+
+    return true;
+}
+
+
+#if 0
+
+// depricated code from here to the end 
+
+
+// Calculate the sky structure vertices
+void fgSkyVerticesInit() {
+    float theta;
+    int i;
+
+    FG_LOG(FG_ASTRO, FG_INFO, "  Generating the sky dome vertices.");
+
+    for ( i = 0; i < 12; i++ ) {
+	theta = (i * 30.0) * DEG_TO_RAD;
+	
+	inner_vertex[i][0] = cos(theta) * UPPER_RADIUS;
+	inner_vertex[i][1] = sin(theta) * UPPER_RADIUS;
+	inner_vertex[i][2] = UPPER_ELEV;
+	
+	// printf("    %.2f %.2f\n", cos(theta) * UPPER_RADIUS, 
+	//        sin(theta) * UPPER_RADIUS);
+
+	middle_vertex[i][0] = cos((double)theta) * MIDDLE_RADIUS;
+	middle_vertex[i][1] = sin((double)theta) * MIDDLE_RADIUS;
+	middle_vertex[i][2] = MIDDLE_ELEV;
+	    
+	outer_vertex[i][0] = cos((double)theta) * LOWER_RADIUS;
+	outer_vertex[i][1] = sin((double)theta) * LOWER_RADIUS;
+	outer_vertex[i][2] = LOWER_ELEV;
+	    
+	bottom_vertex[i][0] = cos((double)theta) * BOTTOM_RADIUS;
+	bottom_vertex[i][1] = sin((double)theta) * BOTTOM_RADIUS;
+	bottom_vertex[i][2] = BOTTOM_ELEV;
+    }
+}
+
+
+// (Re)calculate the sky colors at each vertex
+void fgSkyColorsInit() {
+    fgLIGHT *l;
+    double sun_angle, diff;
+    double outer_param[3], outer_amt[3], outer_diff[3];
+    double middle_param[3], middle_amt[3], middle_diff[3];
+    int i, j;
+
+    l = &cur_light_params;
+
+    FG_LOG( FG_ASTRO, FG_INFO, 
+	    "  Generating the sky colors for each vertex." );
+
+    // setup for the possibility of sunset effects
+    sun_angle = l->sun_angle * RAD_TO_DEG;
+    // fgPrintf( FG_ASTRO, FG_INFO, 
+    //           "  Sun angle in degrees = %.2f\n", sun_angle);
+
+    if ( (sun_angle > 80.0) && (sun_angle < 100.0) ) {
+	// 0.0 - 0.4
+	outer_param[0] = (10.0 - fabs(90.0 - sun_angle)) / 20.0;
+	outer_param[1] = (10.0 - fabs(90.0 - sun_angle)) / 40.0;
+	outer_param[2] = -(10.0 - fabs(90.0 - sun_angle)) / 30.0;
+	// outer_param[2] = 0.0;
+
+	middle_param[0] = (10.0 - fabs(90.0 - sun_angle)) / 40.0;
+	middle_param[1] = (10.0 - fabs(90.0 - sun_angle)) / 80.0;
+	middle_param[2] = 0.0;
+
+	outer_diff[0] = outer_param[0] / 6.0;
+	outer_diff[1] = outer_param[1] / 6.0;
+	outer_diff[2] = outer_param[2] / 6.0;
+
+	middle_diff[0] = middle_param[0] / 6.0;
+	middle_diff[1] = middle_param[1] / 6.0;
+	middle_diff[2] = middle_param[2] / 6.0;
+    } else {
+	outer_param[0] = outer_param[1] = outer_param[2] = 0.0;
+	middle_param[0] = middle_param[1] = middle_param[2] = 0.0;
+
+	outer_diff[0] = outer_diff[1] = outer_diff[2] = 0.0;
+	middle_diff[0] = middle_diff[1] = middle_diff[2] = 0.0;
+    }
+    // printf("  outer_red_param = %.2f  outer_red_diff = %.2f\n", 
+    //        outer_red_param, outer_red_diff);
+
+    // calculate transition colors between sky and fog
+    for ( j = 0; j < 3; j++ ) {
+	outer_amt[j] = outer_param[j];
+	middle_amt[j] = middle_param[j];
+    }
+
+    for ( i = 0; i < 6; i++ ) {
+	for ( j = 0; j < 3; j++ ) {
+	    diff = l->sky_color[j] - l->fog_color[j];
+
+	    // printf("sky = %.2f  fog = %.2f  diff = %.2f\n", 
+	    //        l->sky_color[j], l->fog_color[j], diff);
+
+	    upper_color[i][j] = (GLubyte)((l->sky_color[j] - diff * 0.3) * 255);
+	    middle_color[i][j] = (GLubyte)((l->sky_color[j] - diff * 0.9 
+					   + middle_amt[j]) * 255);
+	    lower_color[i][j] = (GLubyte)((l->fog_color[j] + outer_amt[j]) 
+					  * 255);
+
+	    if ( upper_color[i][j] > 255 ) { upper_color[i][j] = 255; }
+	    if ( upper_color[i][j] < 25 ) { upper_color[i][j] = 25; }
+	    if ( middle_color[i][j] > 255 ) { middle_color[i][j] = 255; }
+	    if ( middle_color[i][j] < 25 ) { middle_color[i][j] = 25; }
+	    if ( lower_color[i][j] > 255 ) { lower_color[i][j] = 255; }
+	    if ( lower_color[i][j] < 25 ) { lower_color[i][j] = 25; }
+	}
+	upper_color[i][3] = middle_color[i][3] = lower_color[i][3] = 
+	    (GLubyte)(l->sky_color[3] * 255);
+
+	for ( j = 0; j < 3; j++ ) {
+	    outer_amt[j] -= outer_diff[j];
+	    middle_amt[j] -= middle_diff[j];
+	}
+
+	/*
+	printf("upper_color[%d] = %.2f %.2f %.2f %.2f\n", i, upper_color[i][0],
+	       upper_color[i][1], upper_color[i][2], upper_color[i][3]);
+	printf("middle_color[%d] = %.2f %.2f %.2f %.2f\n", i, 
+	       middle_color[i][0], middle_color[i][1], middle_color[i][2], 
+	       middle_color[i][3]);
+	printf("lower_color[%d] = %.2f %.2f %.2f %.2f\n", i, 
+	       lower_color[i][0], lower_color[i][1], lower_color[i][2], 
+	       lower_color[i][3]);
+	*/
+    }
+
+    for ( j = 0; j < 3; j++ ) {
+	outer_amt[j] = 0.0;
+	middle_amt[j] = 0.0;
+    }
+
+    for ( i = 6; i < 12; i++ ) {
+
+	for ( j = 0; j < 3; j++ ) {
+	    diff = l->sky_color[j] - l->fog_color[j];
+
+	    // printf("sky = %.2f  fog = %.2f  diff = %.2f\n", 
+	    //        l->sky_color[j], l->fog_color[j], diff);
+
+	    upper_color[i][j] = (GLubyte)((l->sky_color[j] - diff * 0.3) * 255);
+	    middle_color[i][j] = (GLubyte)((l->sky_color[j] - diff * 0.9 
+					    + middle_amt[j]) * 255);
+	    lower_color[i][j] = (GLubyte)((l->fog_color[j] + outer_amt[j]) 
+					  * 255);
+
+	    if ( upper_color[i][j] > 255 ) { upper_color[i][j] = 255; }
+	    if ( upper_color[i][j] < 25 ) { upper_color[i][j] = 25; }
+	    if ( middle_color[i][j] > 255 ) { middle_color[i][j] = 255; }
+	    if ( middle_color[i][j] < 25 ) { middle_color[i][j] = 25; }
+	    if ( lower_color[i][j] > 255 ) { lower_color[i][j] = 255; }
+	    if ( lower_color[i][j] < 35 ) { lower_color[i][j] = 35; }
+	}
+	upper_color[i][3] = middle_color[i][3] = lower_color[i][3] = 
+	    (GLubyte)(l->sky_color[3] * 255);
+
+	for ( j = 0; j < 3; j++ ) {
+	    outer_amt[j] += outer_diff[j];
+	    middle_amt[j] += middle_diff[j];
+	}
+
+	/*
+	printf("upper_color[%d] = %.2f %.2f %.2f %.2f\n", i, upper_color[i][0],
+	       upper_color[i][1], upper_color[i][2], upper_color[i][3]);
+	printf("middle_color[%d] = %.2f %.2f %.2f %.2f\n", i, 
+	       middle_color[i][0], middle_color[i][1], middle_color[i][2], 
+	       middle_color[i][3]);
+	printf("lower_color[%d] = %.2f %.2f %.2f %.2f\n", i, 
+	       lower_color[i][0], lower_color[i][1], lower_color[i][2], 
+	       lower_color[i][3]);
+	*/
+    }
+}
+
+
+// Initialize the sky structure and colors
+void fgSkyInit() {
+    FG_LOG( FG_ASTRO, FG_INFO, "Initializing the sky" );
+
+    fgSkyVerticesInit();
+
+    // regester fgSkyColorsInit() as an event to be run periodically
+    global_events.Register( "fgSkyColorsInit()", fgSkyColorsInit, 
+		            fgEVENT::FG_EVENT_READY, 30000);
+}
+
+
+// Draw the Sky
+void fgSkyRender() {
+    FGInterface *f;
+    fgLIGHT *l;
+    GLubyte sky_color[4];
+    GLubyte upper_color[4];
+    GLubyte middle_color[4];
+    GLubyte lower_color[4];
+    double diff;
+    int i;
+
+    f = current_aircraft.fdm_state;
+    l = &cur_light_params;
+
+    // printf("Rendering the sky.\n");
+
+    // calculate the proper colors
+    for ( i = 0; i < 3; i++ ) {
+	diff = l->sky_color[i] - l->adj_fog_color[i];
+
+	// printf("sky = %.2f  fog = %.2f  diff = %.2f\n", 
+	//        l->sky_color[j], l->adj_fog_color[j], diff);
+
+	upper_color[i] = (GLubyte)((l->sky_color[i] - diff * 0.3) * 255);
+	middle_color[i] = (GLubyte)((l->sky_color[i] - diff * 0.9) * 255);
+	lower_color[i] = (GLubyte)(l->adj_fog_color[i] * 255);
+    }
+    upper_color[3] = middle_color[3] = lower_color[3] = 
+	(GLubyte)(l->adj_fog_color[3] * 255);
+
+    xglPushMatrix();
+
+    // Translate to view position
+    Point3D zero_elev = current_view.get_cur_zero_elev();
+    xglTranslatef( zero_elev.x(), zero_elev.y(), zero_elev.z() );
+    // printf("  Translated to %.2f %.2f %.2f\n", 
+    //        zero_elev.x, zero_elev.y, zero_elev.z );
+
+    // Rotate to proper orientation
+    // printf("  lon = %.2f  lat = %.2f\n", FG_Longitude * RAD_TO_DEG,
+    //        FG_Latitude * RAD_TO_DEG);
+    xglRotatef( f->get_Longitude() * RAD_TO_DEG, 0.0, 0.0, 1.0 );
+    xglRotatef( 90.0 - f->get_Latitude() * RAD_TO_DEG, 0.0, 1.0, 0.0 );
+    xglRotatef( l->sun_rotation * RAD_TO_DEG, 0.0, 0.0, 1.0 );
+
+    // Draw inner/center section of sky*/
+    xglBegin( GL_TRIANGLE_FAN );
+    for ( i = 0; i < 4; i++ ) {
+	sky_color[i] = (GLubyte)(l->sky_color[i] * 255);
+    }
+    xglColor4fv(l->sky_color);
+    xglVertex3f(0.0, 0.0, CENTER_ELEV);
+    for ( i = 11; i >= 0; i-- ) {
+	xglColor4ubv( upper_color );
+	xglVertex3fv( inner_vertex[i] );
+    }
+    xglColor4ubv( upper_color );
+    xglVertex3fv( inner_vertex[11] );
+    xglEnd();
+
+    // Draw the middle ring
+    xglBegin( GL_TRIANGLE_STRIP );
+    for ( i = 0; i < 12; i++ ) {
+	xglColor4ubv( middle_color );
+	// printf("middle_color[%d] = %.2f %.2f %.2f %.2f\n", i, 
+	//        middle_color[i][0], middle_color[i][1], middle_color[i][2], 
+	//        middle_color[i][3]);
+	// xglColor4f(1.0, 0.0, 0.0, 1.0);
+	xglVertex3fv( middle_vertex[i] );
+	xglColor4ubv( upper_color );
+	// printf("upper_color[%d] = %.2f %.2f %.2f %.2f\n", i, 
+	//        upper_color[i][0], upper_color[i][1], upper_color[i][2], 
+	//        upper_color[i][3]);
+	// xglColor4f(0.0, 0.0, 1.0, 1.0);
+	xglVertex3fv( inner_vertex[i] );
+    }
+    xglColor4ubv( middle_color );
+    // xglColor4f(1.0, 0.0, 0.0, 1.0);
+    xglVertex3fv( middle_vertex[0] );
+    xglColor4ubv( upper_color );
+    // xglColor4f(0.0, 0.0, 1.0, 1.0);
+    xglVertex3fv( inner_vertex[0] );
+    xglEnd();
+
+    // Draw the outer ring
+    xglBegin( GL_TRIANGLE_STRIP );
+    for ( i = 0; i < 12; i++ ) {
+	xglColor4ubv( lower_color );
+	xglVertex3fv( outer_vertex[i] );
+	xglColor4ubv( middle_color );
+	xglVertex3fv( middle_vertex[i] );
+    }
+    xglColor4ubv( lower_color );
+    xglVertex3fv( outer_vertex[0] );
+    xglColor4ubv( middle_color );
+    xglVertex3fv( middle_vertex[0] );
+    xglEnd();
+
+    // Draw the bottom skirt
+    xglBegin( GL_TRIANGLE_STRIP );
+    xglColor4ubv( lower_color );
+    for ( i = 0; i < 12; i++ ) {
+	xglVertex3fv( bottom_vertex[i] );
+	xglVertex3fv( outer_vertex[i] );
+    }
+    xglVertex3fv( bottom_vertex[0] );
+    xglVertex3fv( outer_vertex[0] );
+    xglEnd();
+
+    xglPopMatrix();
+}
+
+
+#endif
diff --git a/simgear/ephemeris/skydome.hxx b/simgear/ephemeris/skydome.hxx
new file mode 100644
index 00000000..7d9b159f
--- /dev/null
+++ b/simgear/ephemeris/skydome.hxx
@@ -0,0 +1,109 @@
+// skydome.hxx -- model sky with an upside down "bowl"
+//
+// Written by Curtis Olson, started December 1997.
+// SSG-ified by Curtis Olson, February 2000.
+//
+// Copyright (C) 1997-2000  Curtis L. Olson  - curt@flightgear.org
+//
+// 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.
+//
+// $Id$
+
+
+#ifndef _SKYDOME_HXX
+#define _SKYDOME_HXX
+
+
+#ifndef __cplusplus                                                          
+# error This library requires C++
+#endif                                   
+
+
+#include <plib/ssg.h>		// plib include
+
+
+class FGSkyDome {
+
+    ssgSelector *sky_selector;
+    ssgTransform *sky_transform;
+    ssgSimpleState *sky_state;
+
+    ssgVertexArray *center_disk_vl;
+    ssgColourArray *center_disk_cl;
+
+    ssgVertexArray *upper_ring_vl;
+    ssgColourArray *upper_ring_cl;
+
+    ssgVertexArray *middle_ring_vl;
+    ssgColourArray *middle_ring_cl;
+
+    ssgVertexArray *lower_ring_vl;
+    ssgColourArray *lower_ring_cl;
+
+public:
+
+    // Constructor
+    FGSkyDome( void );
+
+    // Destructor
+    ~FGSkyDome( void );
+
+    // initialize the sky object and connect it into the scene graph
+    // as a kid to to the specified root
+    bool initialize( ssgRoot *branch );
+
+    // repaint the sky colors based on current value of sun_angle,
+    // sky, and fog colors.  This updates the color arrays for
+    // ssgVtxTable.
+    // sun angle in degrees relative to verticle
+    // 0 degrees = high noon
+    // 90 degrees = sun rise/set
+    // 180 degrees = darkest midnight
+    bool repaint( sgVec3 sky_color, sgVec3 fog_color, double sun_angle );
+
+    // reposition the sky at the specified origin and orientation
+    // lon specifies a rotation about the Z axis
+    // lat specifies a rotation about the new Y axis
+    // spin specifies a rotation about the new Z axis (and orients the
+    // sunrise/set effects
+    bool reposition( sgVec3 p, double lon, double lat, double spin );
+
+    // enable the sky in the scene graph (default)
+    void enable() { sky_selector->select( 1 ); }
+
+    // disable the sky in the scene graph.  The leaf node is still
+    // there, how ever it won't be traversed on the cullandrender
+    // phase.
+    void disable() { sky_selector->select( 0 ); }
+
+};
+
+
+extern FGSkyDome current_sky;
+
+
+// (Re)generate the display list
+// void fgSkyInit();
+
+// (Re)calculate the sky colors at each vertex
+// void fgSkyColorsInit();
+
+// Draw the Sky
+// void fgSkyRender();
+
+
+#endif // _SKYDOM_HXX
+
+