From 32bab8aa1063b836ee955ffc0b308a46427f5289 Mon Sep 17 00:00:00 2001
From: curt <curt>
Date: Wed, 1 Sep 1999 20:24:54 +0000
Subject: [PATCH] Setup a user definable model hertz.

---
 src/FDM/flight.cxx         |  3 ++-
 src/Include/fg_constants.h |  4 +---
 src/Main/fg_init.cxx       |  4 ++--
 src/Main/main.cxx          | 16 +++++++++++-----
 src/Main/options.cxx       |  5 +++++
 src/Main/options.hxx       |  2 ++
 6 files changed, 23 insertions(+), 11 deletions(-)

diff --git a/src/FDM/flight.cxx b/src/FDM/flight.cxx
index ccc3f908c..6bb94eec4 100644
--- a/src/FDM/flight.cxx
+++ b/src/FDM/flight.cxx
@@ -27,6 +27,7 @@
 #include <FDM/External/external.hxx>
 #include <FDM/LaRCsim/ls_interface.h>
 #include <Include/fg_constants.h>
+#include <Main/options.hxx>
 #include <Math/fg_geodesy.hxx>
 #include <Time/timestamp.hxx>
 
@@ -137,7 +138,7 @@ int fgFDMUpdate(int model, FGInterface& f, int multiloop, int time_offset) {
     // set valid time for this record
     base_fdm_state.stamp_time();
 
-    time_step = (1.0 / DEFAULT_MODEL_HZ) * multiloop;
+    time_step = (1.0 / current_options.get_model_hz()) * multiloop;
     start_elev = base_fdm_state.get_Altitude();
 
     if ( model == FGInterface::FG_SLEW ) {
diff --git a/src/Include/fg_constants.h b/src/Include/fg_constants.h
index c925c7843..ad8ee5dbd 100644
--- a/src/Include/fg_constants.h
+++ b/src/Include/fg_constants.h
@@ -153,9 +153,7 @@
 
 
 // Timing constants for Flight Model updates
-#define DEFAULT_TIMER_HZ 20
-#define DEFAULT_MULTILOOP 6
-#define DEFAULT_MODEL_HZ (DEFAULT_TIMER_HZ * DEFAULT_MULTILOOP)
+#define NEW_DEFAULT_MODEL_HZ 120
 
 
 // Field of view limits
diff --git a/src/Main/fg_init.cxx b/src/Main/fg_init.cxx
index 78418ce72..82842d392 100644
--- a/src/Main/fg_init.cxx
+++ b/src/Main/fg_init.cxx
@@ -444,7 +444,7 @@ bool fgInitSubsystems( void ) {
     // above values
 
     fgFDMInit( current_options.get_flight_model(), cur_fdm_state,
-	       1.0 / DEFAULT_MODEL_HZ );
+	       1.0 / current_options.get_model_hz() );
 
     // I'm just sticking this here for now, it should probably move
     // eventually
@@ -562,7 +562,7 @@ void fgReInitSubsystems( void )
     // v->UpdateWorldToEye(f);
 
     fgFDMInit( current_options.get_flight_model(), cur_fdm_state, 
-	       1.0 / DEFAULT_MODEL_HZ );
+	       1.0 / current_options.get_model_hz() );
 
     scenery.cur_elev = f->get_Runway_altitude() * FEET_TO_METER;
 
diff --git a/src/Main/main.cxx b/src/Main/main.cxx
index 8820f7f6d..fae72031e 100644
--- a/src/Main/main.cxx
+++ b/src/Main/main.cxx
@@ -463,7 +463,7 @@ void fgUpdateTimeDepCalcs(int multi_loop, int remainder) {
 
     // update the flight model
     if ( multi_loop < 0 ) {
-	multi_loop = DEFAULT_MULTILOOP;
+	multi_loop = 1;
     }
 
     if ( !t->getPause() ) {
@@ -527,13 +527,16 @@ void fgInitTimeDepCalcs( void ) {
     // initialize timer
 
     // #ifdef HAVE_SETITIMER
-    //   fgTimerInit( 1.0 / DEFAULT_TIMER_HZ, fgUpdateTimeDepCalcs );
+    //   fgTimerInit( 1.0 / current_options.get_model_hz(), 
+    //                fgUpdateTimeDepCalcs );
     // #endif HAVE_SETITIMER
 }
 
+
 static const double alt_adjust_ft = 3.758099;
 static const double alt_adjust_m = alt_adjust_ft * FEET_TO_METER;
 
+
 // What should we do when we have nothing else to do?  Let's get ready
 // for the next move and update the display?
 static void fgMainLoop( void ) {
@@ -646,8 +649,10 @@ static void fgMainLoop( void ) {
 	// Calculate model iterations needed for next frame
 	elapsed += remainder;
 
-	multi_loop = (int)(((double)elapsed * 0.000001) * DEFAULT_MODEL_HZ);
-	remainder = elapsed - ((multi_loop*1000000) / DEFAULT_MODEL_HZ);
+	multi_loop = (int)(((double)elapsed * 0.000001) * 
+			   current_options.get_model_hz());
+	remainder = elapsed - ( (multi_loop*1000000) / 
+				current_options.get_model_hz() );
 	FG_LOG( FG_ALL, FG_DEBUG, 
 		"Model iterations needed = " << multi_loop
 		<< ", new remainder = " << remainder );
@@ -656,7 +661,8 @@ static void fgMainLoop( void ) {
 	if ( multi_loop > 0 ) {
 	    fgUpdateTimeDepCalcs(multi_loop, remainder);
 	} else {
-	    FG_LOG( FG_ALL, FG_INFO, "Elapsed time is zero ... we're zinging" );
+	    FG_LOG( FG_ALL, FG_DEBUG, 
+		    "Elapsed time is zero ... we're zinging" );
 	}
     }
 
diff --git a/src/Main/options.cxx b/src/Main/options.cxx
index 8e9470973..13832655c 100644
--- a/src/Main/options.cxx
+++ b/src/Main/options.cxx
@@ -161,6 +161,7 @@ fgOPTIONS::fgOPTIONS() :
 
     // Flight Model options
     flight_model( FGInterface::FG_LARCSIM ),
+    model_hz( NEW_DEFAULT_MODEL_HZ ),
     speed_up( 1 ),
 
     // Rendering options
@@ -639,6 +640,9 @@ int fgOPTIONS::parse_option( const string& arg ) {
 	fg_root = arg.substr( 10 );
     } else if ( arg.find( "--fdm=" ) != string::npos ) {
 	flight_model = parse_fdm( arg.substr(6) );
+    } else if ( arg.find( "--model-hz=" ) != string::npos ) {
+	model_hz = atoi( arg.substr(11) );
+	cout << "model hz = " << model_hz << endl;
     } else if ( arg.find( "--speed=" ) != string::npos ) {
 	speed_up = atoi( arg.substr(8) );
     } else if ( arg == "--fog-disable" ) {
@@ -819,6 +823,7 @@ void fgOPTIONS::usage ( void ) {
  
     printf("Flight Model:\n");
     printf("\t--fdm=abcd:  one of slew, jsb, larcsim, or external\n");
+    printf("\t--model-hz=n:  run the FDM this rate (iterations per second)\n");
     printf("\t--speed=n:  run the FDM this much faster than real time\n");
     printf("\n");
 
diff --git a/src/Main/options.hxx b/src/Main/options.hxx
index 671d40837..919e49ce9 100644
--- a/src/Main/options.hxx
+++ b/src/Main/options.hxx
@@ -126,6 +126,7 @@ private:
 
     // Flight Model options
     int flight_model;   // Flight Model:  FG_SLEW, FG_LARCSIM, etc.
+    int model_hz;       // number of FDM iterations per second
     int speed_up;       // Sim mechanics run this much faster than normal speed
 
     // Rendering options
@@ -207,6 +208,7 @@ public:
     inline bool get_panel_status() const { return panel_status; }
     inline bool get_sound() const { return sound; }
     inline int get_flight_model() const { return flight_model; }
+    inline int get_model_hz() const { return model_hz; }
     inline int get_speed_up() const { return speed_up; }
     inline void set_speed_up( int speed ) { speed_up = speed; }
     inline bool fog_enabled() const { return fog != FG_FOG_DISABLED; }
-- 
2.39.5