From 3f07d4e689a0db34128d7b1c2762c912bb905f80 Mon Sep 17 00:00:00 2001
From: Boondorl <boondorl@live.com>
Date: Thu, 25 Apr 2024 16:10:00 -0400
Subject: [PATCH] View fixes when predicting

View interpolation paths are now reset properly when predicting, fixing portals. Teleporters disabling view interpolation is now handled before every movement instead of only once at the start of predicting. Enabled FoV interpolation when playing online.
---
 src/playsim/p_mobj.cpp |  4 ----
 src/playsim/p_user.cpp | 21 ++++++++++++---------
 2 files changed, 12 insertions(+), 13 deletions(-)

diff --git a/src/playsim/p_mobj.cpp b/src/playsim/p_mobj.cpp
index daa19670fa..a75925996f 100644
--- a/src/playsim/p_mobj.cpp
+++ b/src/playsim/p_mobj.cpp
@@ -3662,10 +3662,6 @@ void AActor::SetViewAngle(DAngle ang, int fflags)
 
 double AActor::GetFOV(double ticFrac)
 {
-	// [B] Disable interpolation when playing online, otherwise it gets vomit inducing
-	if (netgame)
-		return player ? player->FOV : CameraFOV;
-
 	double fov;
 	if (player)
 	{
diff --git a/src/playsim/p_user.cpp b/src/playsim/p_user.cpp
index dad3a98707..e5f02b2fe8 100644
--- a/src/playsim/p_user.cpp
+++ b/src/playsim/p_user.cpp
@@ -1437,7 +1437,6 @@ void P_PredictPlayer (player_t *player)
 
 	act->flags &= ~MF_PICKUP;
 	act->flags2 &= ~MF2_PUSHWALL;
-	act->renderflags &= ~RF_NOINTERPOLATEVIEW;
 	player->cheats |= CF_PREDICTING;
 
 	BackupNodeList(act, act->touching_sectorlist, &sector_t::touching_thinglist, PredictionTouchingSectors_sprev_Backup, PredictionTouchingSectorsBackup);
@@ -1474,11 +1473,16 @@ void P_PredictPlayer (player_t *player)
 	act->BlockNode = NULL;
 
 	// Values too small to be usable for lerping can be considered "off".
-	bool CanLerp = (!(cl_predict_lerpscale < 0.01f) && (ticdup == 1)), DoLerp = false, NoInterpolateOld = R_GetViewInterpolationStatus();
+	bool CanLerp = (!(cl_predict_lerpscale < 0.01f) && (ticdup == 1)), DoLerp = false;
+	// This essentially acts like a mini P_Ticker where only the stuff relevant to the client is actually
+	// called. Call order is preserved.
 	for (int i = gametic; i < maxtic; ++i)
 	{
-		if (!NoInterpolateOld)
-			R_RebuildViewInterpolation(player);
+		// Make sure any portal paths have been cleared from the previous movement.
+		R_ClearInterpolationPath();
+		r_NoInterpolate = false;
+		// Because we're always predicting, this will get set by teleporters and then can never unset itself in the renderer properly.
+		player->mo->renderflags &= ~RF_NOINTERPOLATEVIEW;
 
 		player->cmd = localcmds[i % LOCALCMDTICS];
 		player->mo->ClearInterpolation();
@@ -1486,7 +1490,7 @@ void P_PredictPlayer (player_t *player)
 		P_PlayerThink (player);
 		player->mo->Tick ();
 
-		if (CanLerp && PredictionLast.gametic > 0 && i == PredictionLast.gametic && !NoInterpolateOld)
+		if (CanLerp && PredictionLast.gametic > 0 && i == PredictionLast.gametic)
 		{
 			// Z is not compared as lifts will alter this with no apparent change
 			// Make lerping less picky by only testing whole units
@@ -1503,12 +1507,11 @@ void P_PredictPlayer (player_t *player)
 		}
 	}
 
+	// TODO: This should be changed to a proper rubberbanding solution in the near future (only rubberband if there was
+	// a mismatch between client's last predicted pos and current predicted pos).
 	if (CanLerp)
 	{
-		if (NoInterpolateOld)
-			P_PredictionLerpReset();
-
-		else if (DoLerp)
+		if (DoLerp)
 		{
 			// If lerping is already in effect, use the previous camera postion so the view doesn't suddenly snap
 			PredictionLerpFrom = (PredictionLerptics == 0) ? PredictionLast : PredictionLerpResult;