- make `cl_syncinput` work for Duke.

* Current setup was broken and unusable.
* Fixed interpolation issues.
* Only call `GetInput()` at frame-rate when `cl_syncinput` is 0.
* Create `oq16look_ang` and interpolate it for enhanced smoothness.
* Always reset `horizAngleAdjust` and `horizSkew` in `processinput_d()`.
* Don't pre-scale `sb_avel` in `processinput_d()` and `processinput_r()`.
* Promote `p->angvel` from short to fixed_t.
* Don't descale `sync[snum].q16horz` in `processinput_d()` and `processinput_r()`.
* Ensure `false` bool is provided to `sethorizon()` call  in `processinput_d()` and `processinput_r()`.
* Reset `p->q16angvel` in `resetplayerstats()`.

source/games/duke/src/actors.cpp

@@ -442,13 +442,6 @@ void moveplayers(void) //Players
 
 				execute(i, s->yvel, otherx);
 
-				//thisPlayer.smoothcamera = false;
-				//p->q16angvel = G_GetQ16AngleDelta(pPlayer->oq16ang, pPlayer->q16ang);
-				p->oq16ang = p->q16ang;
-				p->oq16horiz = p->q16horiz;
-				p->oq16horizoff = p->q16horizoff;
-
-
 				if (ud.multimode > 1)
 					if (sprite[ps[otherp].i].extra > 0)
 					{

source/games/duke/src/gameloop.cpp

@@ -352,8 +352,10 @@ bool GameTicker()
 		exitlevel();
 	}
 
-
-	GetInput();
+	if (!cl_syncinput)
+	{
+		GetInput();
+	}
 
 	int const smoothRatio = calc_smoothratio(totalclock, ototalclock);
 

source/games/duke/src/player.cpp

@@ -880,6 +880,7 @@ void checklook(int snum, int sb_snum)
 		}
 	}
 	p->oq16ang = p->q16ang;
+	p->oq16look_ang = p->q16look_ang;
 
 	if (cl_syncinput)
 		applylook(snum, 1);

source/games/duke/src/player_d.cpp

@@ -2596,11 +2596,8 @@ void processinput_d(int snum)
 	pi = p->i;
 	s = &sprite[pi];
 
-	if (!cl_syncinput)
-	{
-		p->horizAngleAdjust = 0;
-		p->horizSkew = 0;
-	}
+	p->horizAngleAdjust = 0;
+	p->horizSkew = 0;
 
 	sb_snum = PlayerInputBits(snum, SKB_ALL);
 
@@ -2794,21 +2791,23 @@ void processinput_d(int snum)
 		p->posxv = 0;
 		p->posyv = 0;
 	}
-	else if (sb_avel)          //p->ang += syncangvel * constant
-	{                         //ENGINE calculates angvel for you
-		if (cl_syncinput)
+	else if (sb_avel && cl_syncinput)
+	{
+		//p->ang += syncangvel * constant
+		//ENGINE calculates angvel for you
+		// may still be needed later for demo recording
+
+		if (psectlotag == ST_2_UNDERWATER)
 		{
-			// may still be needed later for demo recording
-			int tempang;
-
-			tempang = sb_avel << 1; // this is fixed point!
-
-			if (psectlotag == ST_2_UNDERWATER) p->angvel = (tempang - (tempang >> 3)) * sgn(doubvel);
-			else p->angvel = tempang * sgn(doubvel);
-
-			p->addang(p->angvel);
-			p->q16ang &= (2048 << FRACBITS) - 1;
+			p->q16angvel = (sb_avel - (sb_avel >> 3)) * sgn(doubvel);
 		}
+		else
+		{
+			p->q16angvel = sb_avel * sgn(doubvel);
+		}
+
+		p->q16ang += p->q16angvel;
+		p->q16ang &= 0x7FFFFFF;
 		p->crack_time = 777;
 	}
 
@@ -3053,8 +3052,8 @@ HORIZONLY:
 
 	if (cl_syncinput)
 	{
-		p->q16horiz += (sync[snum].q16horz >> 1);
-		sethorizon(snum, sb_snum, 1);
+		p->q16horiz += sync[snum].q16horz;
+		sethorizon(snum, sb_snum, 1, false);
 	}
 
 	//Shooting code/changes

source/games/duke/src/player_r.cpp

@@ -3702,21 +3702,23 @@ void processinput_r(int snum)
 		p->posxv = 0;
 		p->posyv = 0;
 	}
-	else if (sb_avel)          //p->ang += syncangvel * constant
-	{                         //ENGINE calculates angvel for you
-		if (cl_syncinput)
+	else if (sb_avel && cl_syncinput)
+	{
+		//p->ang += syncangvel * constant
+		//ENGINE calculates angvel for you
+		// may still be needed later for demo recording
+
+		if (psectlotag == ST_2_UNDERWATER)
 		{
-			// may still be needed later for demo recording
-			int tempang;
-
-			tempang = sb_avel << 1; // this is fixed point!
-
-			if (psectlotag == 2) p->angvel = (tempang - (tempang >> 3)) * sgn(doubvel);
-			else p->angvel = tempang * sgn(doubvel);
-
-			p->addang(p->angvel);
-			p->q16ang &= (2048 << FRACBITS) - 1;
+			p->q16angvel = (sb_avel - (sb_avel >> 3)) * sgn(doubvel);
 		}
+		else
+		{
+			p->q16angvel = sb_avel * sgn(doubvel);
+		}
+
+		p->q16ang += p->q16angvel;
+		p->q16ang &= 0x7FFFFFF;
 		p->crack_time = 777;
 	}
 
@@ -4080,8 +4082,8 @@ HORIZONLY:
 
 	if (cl_syncinput)
 	{
-		p->q16horiz += (sync[snum].q16horz >> 1);
-		sethorizon(snum, sb_snum, 1);
+		p->q16horiz += sync[snum].q16horz;
+		sethorizon(snum, sb_snum, 1, false);
 	}
 
 	//Shooting code/changes

source/games/duke/src/premap.cpp

@@ -94,7 +94,7 @@ void resetplayerstats(int snum)
     p->pyoff            = 0;
     p->opyoff           = 0;
     p->loogcnt          = 0;
-    //p->angvel           = 0;
+    p->q16angvel        = 0;
     p->weapon_sway      = 0;
 //    p->select_dir       = 0;
     p->extra_extra8     = 0;

source/games/duke/src/render.cpp

@@ -551,10 +551,10 @@ void displayrooms(int snum, int smoothratio)
 			cposz = omyz + mulscale16((int)(myz - omyz), smoothratio);
 			if (cl_syncinput)
 			{
-				cang.interpolate(q16ang(oq16myang), q16ang(q16myang), smoothratio);
-				fix16_t osum = (oq16myhoriz + oq16myhorizoff);
-				fix16_t sum = (q16myhoriz + q16myhorizoff);
+				fixed_t osum = (oq16myhoriz + oq16myhorizoff);
+				fixed_t sum = (q16myhoriz + q16myhorizoff);
 				choriz = q16horiz(osum + mulscale16(sum - osum, smoothratio));
+				cang = q16ang(oq16myang + mulscale16(((q16myang + (1024 << FRACBITS) - oq16myang) & 0x7FFFFFF) - (1024 << FRACBITS), smoothratio));
 			}
 			else
 			{
@@ -571,19 +571,21 @@ void displayrooms(int snum, int smoothratio)
 			if (cl_syncinput /*|| smoothcamera*/)
 			{
 				// Original code for when the values are passed through the sync struct
-				cang.interpolate(q16ang(p->oq16ang), q16ang(p->q16ang), smoothratio);
-				fix16_t osum = (p->oq16horiz + p->oq16horizoff);
-				fix16_t sum = (p->q16horiz + p->q16horizoff);
-				choriz = q16horiz(osum + mulscale16(sum - osum, smoothratio));
+				fixed_t ohorz = (p->oq16horiz + p->oq16horizoff);
+				fixed_t horz = (p->q16horiz + p->q16horizoff);
+				choriz = q16horiz(ohorz + mulscale16(horz - ohorz, smoothratio));
+
+				fixed_t oang = (p->oq16ang + p->oq16look_ang);
+				fixed_t ang = (p->q16ang + p->q16look_ang);
+				cang = q16ang(oang + mulscale16(((ang + (1024 << FRACBITS) - oang) & 0x7FFFFFF) - (1024 << FRACBITS), smoothratio));
 			}
 			else
 			{
 				// This is for real time updating of the view direction.
-				cang = q16ang(p->q16ang);
+				cang = q16ang(p->q16ang + p->q16look_ang);
 				choriz = q16horiz(p->q16horiz + p->q16horizoff);
 			}
 		}
-		cang += q16ang(p->q16look_ang);
 
 		if (p->newowner >= 0)
 		{

source/games/duke/src/savegame.cpp

@@ -149,7 +149,7 @@ FSerializer& Serialize(FSerializer& arc, const char* keyname, player_struct& w,
 			("crack_time", w.crack_time)
 			("aim.mode", w.aim_mode)
 			("auto_aim", w.auto_aim)
-			("angvel", w.angvel)
+			("q16angvel", w.q16angvel)
 			("cursectnum", w.cursectnum)
 			("last_extra", w.last_extra)
 			("subweapon", w.subweapon)

source/games/duke/src/types.h

@@ -101,8 +101,8 @@ struct player_struct
 	};
 
 	// input handles angle and horizon as fixed16 numbers. We need to account for that as well.
-	fixed_t q16ang, q16horiz, q16horizoff, q16rotscrnang, q16look_ang;
-	fixed_t oq16ang, oq16horiz, oq16horizoff, oq16rotscrnang; // These are only needed with synchronous mouse input.
+	fixed_t q16ang, q16horiz, q16horizoff, q16rotscrnang, q16look_ang, q16angvel;
+	fixed_t oq16ang, oq16horiz, oq16horizoff, oq16rotscrnang, oq16look_ang; // These are only needed with synchronous mouse input.
 	fixed_t one_eighty_count;
 
 	// using a bit field for this to save a bit of space.
@@ -126,7 +126,7 @@ struct player_struct
 
 	int aim_mode, auto_aim;
 
-	short angvel, cursectnum, last_extra, subweapon;
+	short cursectnum, last_extra, subweapon;
 	short ammo_amount[MAX_WEAPONS], wackedbyactor, frag, fraggedself;
 
 	short curr_weapon, last_weapon, tipincs, wantweaponfire;