More night ground lighting tweaks.

src/Main/main.cxx

@@ -1363,7 +1363,7 @@ int main( int argc, char **argv ) {
 	    << FLIGHTGEAR_VERSION << endl );
 
     // seed the random number generater
-    sg_srandom();
+    sg_srandom_time();
 
     // Allocate global data structures.  This needs to happen before
     // we parse command line options

src/Objects/obj.cxx

@@ -337,32 +337,39 @@ static void random_pt_inside_tri( float *res,
 static void gen_random_surface_points( ssgLeaf *leaf, ssgVertexArray *lights,
 				       double factor ) {
     int num = leaf->getNumTriangles();
-    short int n1, n2, n3;
-    float *p1, *p2, *p3;
-    sgVec3 result;
+    if ( num > 0 ) {
+	short int n1, n2, n3;
+	float *p1, *p2, *p3;
+	sgVec3 result;
 
-    for ( int i = 0; i < num; ++i ) {
-	leaf->getTriangle( i, &n1, &n2, &n3 );
-	p1 = leaf->getVertex(n1);
-	p2 = leaf->getVertex(n2);
-	p3 = leaf->getVertex(n3);
-	double area = sgTriArea( p1, p2, p3 );
-	double num = area / factor;
+	// generate a repeatable random seed
+	p1 = leaf->getVertex( 0 );
+	unsigned int *seed = (unsigned int *)p1;
+	sg_srandom( *seed );
 
-	// generate a light point for each unit of area
-	while ( num > 1.0 ) {
-	    random_pt_inside_tri( result, p1, p2, p3 );
-	    lights->add( result );
-	    num -= 1.0;
-	}
-	// for partial units of area, use a zombie door method to
-	// create the proper random chance of a light being created
-	// for this triangle
-	if ( num > 0.0 ) {
-	    if ( sg_random() <= num ) {
-		// a zombie made it through our door
+	for ( int i = 0; i < num; ++i ) {
+	    leaf->getTriangle( i, &n1, &n2, &n3 );
+	    p1 = leaf->getVertex(n1);
+	    p2 = leaf->getVertex(n2);
+	    p3 = leaf->getVertex(n3);
+	    double area = sgTriArea( p1, p2, p3 );
+	    double num = area / factor;
+
+	    // generate a light point for each unit of area
+	    while ( num > 1.0 ) {
 		random_pt_inside_tri( result, p1, p2, p3 );
 		lights->add( result );
+		num -= 1.0;
+	    }
+	    // for partial units of area, use a zombie door method to
+	    // create the proper random chance of a light being created
+	    // for this triangle
+	    if ( num > 0.0 ) {
+		if ( sg_random() <= num ) {
+		    // a zombie made it through our door
+		    random_pt_inside_tri( result, p1, p2, p3 );
+		    lights->add( result );
+		}
 	    }
 	}
     }

src/Scenery/newcache.cxx

@@ -134,6 +134,11 @@ static void print_refs( ssgSelector *sel, ssgTransform *trans,
 
 
 static ssgLeaf *gen_lights( ssgVertexArray *lights, int inc, float bright ) {
+    // generate a repeatable random seed
+    float *p1 = lights->get( 0 );
+    unsigned int *seed = (unsigned int *)p1;
+    sg_srandom( *seed );
+
     int size = lights->getNum() / inc;
 
     // Allocate ssg structure
@@ -143,25 +148,31 @@ static ssgLeaf *gen_lights( ssgVertexArray *lights, int inc, float bright ) {
     ssgColourArray   *cl = new ssgColourArray( size + 1 );
 
     sgVec4 color;
-    for ( int i = 0; i < lights->getNum(); i += inc ) {
-	vl->add( lights->get(i) );
-
-	// yellow = 1,1,0
+    for ( int i = 0; i < lights->getNum(); ++i ) {
+	// this loop is slightly less efficient than it otherwise
+	// could be, but we want a red light to always be red, and a
+	// yellow light to always be yellow, etc. so we are trying to
+	// preserve the random sequence.
 	float zombie = sg_random();
-	if ( zombie > 0.5 ) {
-	    // 50% chance of yellowish
-	    sgSetVec4( color, 0.9, 0.9, 0.3, bright );
-	} else if ( zombie > 0.15 ) {
-	    // 35% chance of whitish
-	    sgSetVec4( color, 0.9, 0.9, 0.6, bright );
-	} else if ( zombie > 0.05 ) {
-	    // 10% chance of orangish
-	    sgSetVec4( color, 0.9, 0.6, 0.2, bright );
-	} else {
-	    // 5% chance of redish
-	    sgSetVec4( color, 0.9, 0.2, 0.2, bright );
+	if ( i % inc == 0 ) {
+	    vl->add( lights->get(i) );
+
+	    // yellow = 1,1,0
+	    if ( zombie > 0.5 ) {
+		// 50% chance of yellowish
+		sgSetVec4( color, 0.9, 0.9, 0.3, bright );
+	    } else if ( zombie > 0.15 ) {
+		// 35% chance of whitish
+		sgSetVec4( color, 0.9, 0.9, 0.8, bright );
+	    } else if ( zombie > 0.05 ) {
+		// 10% chance of orangish
+		sgSetVec4( color, 0.9, 0.6, 0.2, bright );
+	    } else {
+		// 5% chance of redish
+		sgSetVec4( color, 0.9, 0.2, 0.2, bright );
+	    }
+	    cl->add( color );
 	}
-	cl->add( color );
     }
 
     // create ssg leaf

src/Scenery/tileentry.cxx

@@ -218,9 +218,9 @@ void FGTileEntry::prep_ssg_node( const Point3D& p, float vis) {
 
 	// select which set of lights based on sun angle
 	float sun_angle = cur_light_params.sun_angle * RAD_TO_DEG;
-	if ( sun_angle > 98 ) {
+	if ( sun_angle > 95 ) {
 	    lights_brightness->select(0x04);
-	} else if ( sun_angle > 93.5 ) {
+	} else if ( sun_angle > 92 ) {
 	    lights_brightness->select(0x02);
 	} else if ( sun_angle > 89 ) {
 	    lights_brightness->select(0x01);