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

@@ -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);
 	}
 

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;

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();
 

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

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);