Do NOT busy wait for a new game tick inside doom, return control to b…

…rowser sooner.

This improves the following:
* the Animation frames per second went up from the ~35 to the target of 60!
* my CPU fan stops spinning at full speed when playing doom in the browser, since the browser is better at controlling animations than busy waiting for time to progress.
* The chrome developer console shows almost no more dropped frames.
* the gameplay feels smoother, since there are no longer any hiccups. Do we give the browser more room for GC?
* Firefox performance debugger now says: most "expensive function" with over 70% of time consumed is the browser's idle function! \m/

doom/linuxdoom-1.10/d_main.c

@@ -387,7 +387,10 @@ void D_DoomLoop_loop (void) {
 	}
 	else
 	{
-	    TryRunTics (); // will run at least one tic
+	    if (TryRunTics() == 0){
+			return; // web modification: do NOT busy wait for a new tick, return control to browser.
+		};
+		// we did run at least one tic.
 	}
 
 	S_UpdateSounds (players[consoleplayer].mo);// move positional sounds

doom/linuxdoom-1.10/d_net.c

@@ -363,7 +363,7 @@ void GetPackets (void)
 // Builds ticcmds for console player,
 // sends out a packet
 //
-int      gametime;
+int      gametime = 0;
 
 void NetUpdate (void)
 {
@@ -633,7 +633,7 @@ int	oldnettics;
 
 extern	boolean	advancedemo;
 
-void TryRunTics (void)
+int TryRunTics (void)
 {
     int		i;
     int		lowtic;
@@ -643,6 +643,11 @@ void TryRunTics (void)
     int		availabletics;
     int		counts;
     int		numplaying;
+
+	// web modification: do NOT busy wait for a new tick, return control to browser.
+	if (I_GetTime()/ticdup <= gametime){
+		return 0; // no new tics available.
+	}
 
     // get real tics		
     entertic = I_GetTime ()/ticdup;
@@ -728,7 +733,7 @@ void TryRunTics (void)
 	if (I_GetTime ()/ticdup - entertic >= 20)
 	{
 	    M_Ticker ();
-	    return;
+	    return 1;
 	} 
     }
 
@@ -764,4 +769,7 @@ void TryRunTics (void)
 	}
 	NetUpdate ();	// check for new console commands
     }
+
+
+	return 1;
 }

doom/linuxdoom-1.10/d_net.h

@@ -136,7 +136,7 @@ void NetUpdate (void);
 void D_QuitNetGame (void);
 
 //? how many ticks to run?
-void TryRunTics (void);
+int TryRunTics (void);
 
 
 #endif