From e8a8064da95d95353177dcf80b7b379874d2f59a Mon Sep 17 00:00:00 2001
From: James R <justsomejames2@gmail.com>
Date: Sat, 22 Apr 2023 20:40:35 -0700
Subject: [PATCH 1/2] P_Ticker: update view interpolation at the start of a tic

This lets R_ResetViewInterpolation only need to be called
once from game logic.
---
 src/g_game.c    | 2 --
 src/g_party.cpp | 1 -
 src/p_setup.c   | 1 -
 src/p_tick.c    | 8 +++++++-
 src/p_user.c    | 1 -
 5 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/src/g_game.c b/src/g_game.c
index 5791fc7db..faade2de5 100644
--- a/src/g_game.c
+++ b/src/g_game.c
@@ -2090,8 +2090,6 @@ void G_ResetView(UINT8 viewnum, INT32 playernum, boolean onlyactive)
 		camerap = &camera[viewnum-1];
 		P_ResetCamera(&players[(*displayplayerp)], camerap);
 
-		// Why does it need to be done twice?
-		R_ResetViewInterpolation(viewnum);
 		R_ResetViewInterpolation(viewnum);
 	}
 
diff --git a/src/g_party.cpp b/src/g_party.cpp
index 7d2d57e34..1c82a2d1d 100644
--- a/src/g_party.cpp
+++ b/src/g_party.cpp
@@ -150,7 +150,6 @@ public:
 			// all into its new position -- just snap
 			// instantly into place.
 			R_ResetViewInterpolation(1 + i);
-			R_ResetViewInterpolation(1 + i); // (Why does it need to be called twice?)
 		}
 
 		r_splitscreen = size() - 1;
diff --git a/src/p_setup.c b/src/p_setup.c
index 32f0766eb..e1fbaf15f 100644
--- a/src/p_setup.c
+++ b/src/p_setup.c
@@ -8093,7 +8093,6 @@ boolean P_LoadLevel(boolean fromnetsave, boolean reloadinggamestate)
 
 	if (rendermode != render_none && reloadinggamestate == false)
 	{
-		R_ResetViewInterpolation(0);
 		R_ResetViewInterpolation(0);
 		R_UpdateMobjInterpolators();
 
diff --git a/src/p_tick.c b/src/p_tick.c
index b7e907e6b..54ce0a21f 100644
--- a/src/p_tick.c
+++ b/src/p_tick.c
@@ -646,6 +646,13 @@ void P_Ticker(boolean run)
 		}
 	}
 
+	if (run)
+	{
+		// Update old view state BEFORE ticking so resetting
+		// the old interpolation state from game logic works.
+		R_UpdateViewInterpolation();
+	}
+
 	if (objectplacing)
 	{
 		if (OP_FreezeObjectplace())
@@ -982,7 +989,6 @@ void P_Ticker(boolean run)
 	if (run)
 	{
 		R_UpdateLevelInterpolators();
-		R_UpdateViewInterpolation();
 
 		// Hack: ensure newview is assigned every tic.
 		// Ensures view interpolation is T-1 to T in poor network conditions
diff --git a/src/p_user.c b/src/p_user.c
index 80afd5aaf..fe15573c4 100644
--- a/src/p_user.c
+++ b/src/p_user.c
@@ -3606,7 +3606,6 @@ boolean P_MoveChaseCamera(player_t *player, camera_t *thiscam, boolean resetcall
 	{
 		P_MoveChaseCamera(player, thiscam, false);
 		R_ResetViewInterpolation(num + 1);
-		R_ResetViewInterpolation(num + 1);
 	}
 
 	return (x == thiscam->x && y == thiscam->y && z == thiscam->z && angle == thiscam->aiming);

From 11242527ed7a2cf79adf2210442a13e35573b832 Mon Sep 17 00:00:00 2001
From: James R <justsomejames2@gmail.com>
Date: Sat, 22 Apr 2023 20:49:01 -0700
Subject: [PATCH 2/2] 412 teleport: correctly update interpolation state

- Fixes relative teleport not updating floorz/ceilingz,
  causing camera to potentially get clipped by old
  position

- Fixes absolute teleport not resetting viewpoint
  interpolation
---
 src/p_spec.c   | 6 +-----
 src/p_telept.c | 2 ++
 2 files changed, 3 insertions(+), 5 deletions(-)

diff --git a/src/p_spec.c b/src/p_spec.c
index 3c462c4d7..5adad0c23 100644
--- a/src/p_spec.c
+++ b/src/p_spec.c
@@ -2853,11 +2853,7 @@ boolean P_ProcessSpecial(activator_t *activator, INT16 special, INT32 *args, cha
 					y = args[3] << FRACBITS;
 					z = args[4] << FRACBITS;
 
-					P_UnsetThingPosition(mo);
-					mo->x += x;
-					mo->y += y;
-					mo->z += z;
-					P_SetThingPosition(mo);
+					P_SetOrigin(mo, mo->x + x, mo->y + y, mo->z + z);
 
 					if (mo->player)
 					{
diff --git a/src/p_telept.c b/src/p_telept.c
index 9d3f792a3..a3a38a84f 100644
--- a/src/p_telept.c
+++ b/src/p_telept.c
@@ -169,6 +169,8 @@ boolean P_Teleport(mobj_t *thing, fixed_t x, fixed_t y, fixed_t z, angle_t angle
 					P_ResetCamera(thing->player, &camera[i]);
 				}
 
+				R_ResetViewInterpolation(1 + i);
+
 				break;
 			}
 		}