Added cloud puffs as we pass through the cloud layer.

diff --git a/src/Main/main.cxx b/src/Main/main.cxx
index 21202736e4baf433487f3798f4568bda935ad8e7..98ed38e7e1834b6ed0fc95c3be14c4952b3ffb4d 100644 (file)
--- a/src/Main/main.cxx
+++ b/src/Main/main.cxx
@@ -122,6 +122,7 @@ FGGeneral general;
 // our initializations out of the glutIdleLoop() so that we can get a
 // splash screen up and running right away.
 static int idle_state = 0;
+static int global_multi_loop;
 
 // Another hack
 int use_signals = 0;
@@ -231,6 +232,11 @@ void fgRenderFrame( void ) {
     FGTime *t = FGTime::cur_time_params;
     // FGView *v = &current_view;
     static double last_visibility = -9999;
+    static bool in_puff = false;
+    static double puff_length = 0;
+    static double puff_progression = 0;
+    const double ramp_up = 0.15;
+    const double ramp_down = 0.15;
 
     double angle;
     // GLfloat black[4] = { 0.0, 0.0, 0.0, 1.0 };
@@ -353,8 +359,60 @@ void fgRenderFrame( void ) {
            double diff = fabs( cur_fdm_state->get_Altitude() * FEET_TO_METER -
                                current_options.get_clouds_asl() );
            // cout << "altitude diff = " << diff << endl;
-           if ( diff < 125 ) {
-               actual_visibility = cur_visibility * (diff - 25) / 100.0;
+           if ( diff < 75 ) {
+               if ( ! in_puff ) {
+                   // calc chance of entering cloud puff
+                   double rnd = fg_random();
+                   double chance = rnd * rnd * rnd;
+                   if ( chance > 0.95 /* * (diff - 25) / 50.0 */ ) {
+                       in_puff = true;
+                       do {
+                           puff_length = fg_random() * 2.0; // up to 2 seconds
+                       } while ( puff_length <= 0.0 );
+                       puff_progression = 0.0;
+                   }
+               }
+
+               actual_visibility = cur_visibility * (diff - 25) / 50.0;
+
+               if ( in_puff ) {
+                   // modify actual_visibility based on puff envelope
+
+                   if ( puff_progression <= ramp_up ) {
+                       double x = FG_PI_2 * puff_progression / ramp_up;
+                       double factor = 1.0 - sin( x );
+                       actual_visibility = actual_visibility * factor;
+                   } else if ( puff_progression >= ramp_up + puff_length ) {
+                       double x = FG_PI_2 * 
+                           (puff_progression - (ramp_up + puff_length)) /
+                           ramp_down;
+                       double factor = sin( x );
+                       actual_visibility = actual_visibility * factor;
+                   } else {
+                       actual_visibility = 0.0;
+                   }
+
+                   /* cout << "len = " << puff_length
+                        << "  x = " << x 
+                        << "  factor = " << factor
+                        << "  actual_visibility = " << actual_visibility 
+                        << endl; */
+
+                   puff_progression += ( global_multi_loop * 
+                                         current_options.get_speed_up() ) /
+                       (double)current_options.get_model_hz();
+
+                   /* cout << "gml = " << global_multi_loop 
+                        << "  speed up = " << current_options.get_speed_up()
+                        << "  hz = " << current_options.get_model_hz() << endl;
+                        */ 
+
+                   if ( puff_progression > puff_length + ramp_up + ramp_down) {
+                       in_puff = false; 
+                   }
+               }
+
+               // never let visibility drop below zero
                if ( actual_visibility < 0 ) {
                    actual_visibility = 0;
                }
@@ -622,7 +680,7 @@ static const double alt_adjust_m = alt_adjust_ft * FEET_TO_METER;
 static void fgMainLoop( void ) {
     FGTime *t;
     static long remainder = 0;
-    long elapsed, multi_loop;
+    long elapsed;
 #ifdef FANCY_FRAME_COUNTER
     int i;
     double accum;
@@ -727,17 +785,17 @@ static void fgMainLoop( void ) {
        // Calculate model iterations needed for next frame
        elapsed += remainder;
 
-       multi_loop = (int)(((double)elapsed * 0.000001) * 
+       global_multi_loop = (int)(((double)elapsed * 0.000001) * 
                           current_options.get_model_hz());
-       remainder = elapsed - ( (multi_loop*1000000) / 
+       remainder = elapsed - ( (global_multi_loop*1000000) / 
                                current_options.get_model_hz() );
        FG_LOG( FG_ALL, FG_DEBUG, 
-               "Model iterations needed = " << multi_loop
+               "Model iterations needed = " << global_multi_loop
                << ", new remainder = " << remainder );
        
        // flight model
-       if ( multi_loop > 0 ) {
-           fgUpdateTimeDepCalcs(multi_loop, remainder);
+       if ( global_multi_loop > 0 ) {
+           fgUpdateTimeDepCalcs(global_multi_loop, remainder);
        } else {
            FG_LOG( FG_ALL, FG_DEBUG, 
                    "Elapsed time is zero ... we're zinging" );