# HG changeset patch
# User Adam Kaminski <kaminskiadam9@gmail.com>
# Date 1644163138 18000
#      Sun Feb 06 10:58:58 2022 -0500
# Node ID fab0c73eb12dceadc03474d5e352fa82e76c849c
# Parent  a81bb124128c22b8bf7b99c5dc00af0d74ab99d9
Fixed: players appeared jittery when standing on lifts moving downward in online games.

diff -r a81bb124128c -r fab0c73eb12d src/cl_main.cpp
--- a/src/cl_main.cpp	Sun Feb 06 10:38:24 2022 -0500
+++ b/src/cl_main.cpp	Sun Feb 06 10:58:58 2022 -0500
@@ -3799,6 +3799,19 @@
 	// [BB] But don't just set the position, but also properly set floorz and ceilingz, etc.
 	CLIENT_MoveThing( player->mo, x, y, z );
 
+	// [AK] Did the server tell us this player is supposed to be on the ground? If so, move
+	// them to the floor of whatever sector they're in.
+	if ( flags & PLAYER_ONGROUND )
+	{
+		// [AK] In some cases, especially when the player is standing on the edge of a moving lift,
+		// their floorz might be messed up and lower than it actually is, so we have to fix it.
+		player->mo->floorz = player->mo->Sector->floorplane.ZatPoint( player->mo->x, player->mo->y );
+		player->mo->ceilingz = player->mo->Sector->ceilingplane.ZatPoint( player->mo->x, player->mo->y );
+		P_FindFloorCeiling( player->mo, false );
+
+		player->mo->z = player->mo->floorz;
+	}
+
 	// [AK] Calculate how much this player's angle changed.
 	player->mo->AngleDelta = angle - player->mo->angle;
 
diff -r a81bb124128c -r fab0c73eb12d src/network.h
--- a/src/network.h	Sun Feb 06 10:38:24 2022 -0500
+++ b/src/network.h	Sun Feb 06 10:58:58 2022 -0500
@@ -92,6 +92,7 @@
 	PLAYER_SENDVELX		= 1 << 4,
 	PLAYER_SENDVELY		= 1 << 5,
 	PLAYER_SENDVELZ		= 1 << 6,
+	PLAYER_ONGROUND		= 1 << 7,
 };
 
 /* [BB] This is not used anywhere anymore.
diff -r a81bb124128c -r fab0c73eb12d src/sv_commands.cpp
--- a/src/sv_commands.cpp	Sun Feb 06 10:38:24 2022 -0500
+++ b/src/sv_commands.cpp	Sun Feb 06 10:58:58 2022 -0500
@@ -313,6 +313,12 @@
 	if ( players[ulPlayer].mo->velz )
 		ulPlayerFlags |= PLAYER_SENDVELZ;
 
+	// [AK] Check if the player is touching the ground. This tells clients to clamp the player onto
+	// the floor of whatever sector they end up in. This fixes players appearing jittery on lifts
+	// that are moving downward.
+	if ( players[ulPlayer].mo->z <= players[ulPlayer].mo->floorz )
+		ulPlayerFlags |= PLAYER_ONGROUND;
+
 	ServerCommands::MovePlayer fullCommand;
 	fullCommand.SetPlayer ( &players[ulPlayer] );
 	fullCommand.SetFlags( ulPlayerFlags | PLAYER_VISIBLE );