From da226e75a53935e0e4ea81b1a1a20ccb42d12db2 Mon Sep 17 00:00:00 2001
From: GenericHeroGuy <genericheroguy@noreply.codeberg.org>
Date: Tue, 20 May 2025 00:06:12 +0200
Subject: [PATCH] More robust(?) finish line handling

---
 src/k_waypoint.cpp |  4 +++
 src/p_map.c        | 20 -------------
 src/p_spec.c       | 72 +++++++++++++++++++++++++++++++++++++++++++++-
 3 files changed, 75 insertions(+), 21 deletions(-)

diff --git a/src/k_waypoint.cpp b/src/k_waypoint.cpp
index 83a0096f9..f3a1196da 100644
--- a/src/k_waypoint.cpp
+++ b/src/k_waypoint.cpp
@@ -409,6 +409,10 @@ waypoint_t *K_GetBestWaypointForMobj(mobj_t *const mobj, waypoint_t *const hint)
 				return;
 			}
 
+			// do not path over the finish line. just don't.
+			if (checkwaypoint == finishline)
+				return;
+
 			checkdist = P_AproxDistance(
 				(mobj->x / FRACUNIT) - (checkwaypoint->mobj->x / FRACUNIT),
 				(mobj->y / FRACUNIT) - (checkwaypoint->mobj->y / FRACUNIT));
diff --git a/src/p_map.c b/src/p_map.c
index 2d653d9af..270df41e8 100644
--- a/src/p_map.c
+++ b/src/p_map.c
@@ -2837,26 +2837,6 @@ boolean P_TryMove(mobj_t *thing, fixed_t x, fixed_t y, boolean allowdropoff, Try
 			{
 				P_CrossSpecialLine(ld, oldside, thing);
 			}
-			else if (ld->special == 2001 && thing->player) // Finish Line
-			{
-				// ~~ WAYPOINT BULLSHIT ~~
-				// Right on the line, P_PointOnLineSide may
-				// disagree with P_TraceWaypointTraversal.
-				// If this happens, nextwaypoint may update
-				// ahead of the finish line before the player
-				// crosses it.
-				// This bloats the finish line distance and
-				// triggers lap cheat prevention, preventing
-				// the player from gaining a lap.
-				// Since this only seems like it can happen
-				// very near to the line, simply don't update
-				// waypoints if the player is touching the
-				// line but hasn't crossed it.
-				// This will cause distancetofinish to jump
-				// but only for a very short distance (the
-				// radius of the player).
-				thing->player->pflags |= PF_FREEZEWAYPOINTS;
-			}
 		}
 	}
 
diff --git a/src/p_spec.c b/src/p_spec.c
index dacb5b66f..e65425fe6 100644
--- a/src/p_spec.c
+++ b/src/p_spec.c
@@ -1971,6 +1971,73 @@ void P_SwitchWeather(preciptype_t newWeather)
 		P_SpawnPrecipitation();
 }
 
+static boolean isfinish(waypoint_t *check)
+{
+	size_t i;
+	waypoint_t *finish = K_GetFinishLineWaypoint();
+
+	if (check == NULL)
+		return false;
+	if (check == finish)
+		return true;
+
+	for (i = 0; i < check->numnextwaypoints; i++)
+	{
+		if (check->nextwaypoints[i] == finish)
+			return true;
+	}
+	for (i = 0; i < check->numprevwaypoints; i++)
+	{
+		if (check->prevwaypoints[i] == finish)
+			return true;
+	}
+
+	return false;
+}
+
+// fix the player's current waypoint after crossing the finish line
+// get them off the finish line waypoint ASAP!
+static void K_FixupFinishWaypoint(player_t *player, boolean reverse)
+{
+	size_t i;
+	fixed_t closest = INT32_MAX;
+	waypoint_t *finish = K_GetFinishLineWaypoint(), *snapto = NULL;
+
+	// now did we actually cross the REAL finish line?
+	// this is important for sprint maps
+	if (!isfinish(player->currentwaypoint) && !isfinish(player->nextwaypoint))
+		return;
+
+	//CONS_Printf("fixed up %td\n", player - players);
+
+	if (reverse)
+	{
+		for (i = 0; i < finish->numprevwaypoints; i++)
+		{
+			waypoint_t *check = finish->prevwaypoints[i];
+			fixed_t dist = R_PointToDist2(player->mo->x, player->mo->y, check->mobj->x, check->mobj->y);
+			if (dist < closest)
+				closest = dist, snapto = check;
+		}
+	}
+	else
+	{
+		for (i = 0; i < finish->numnextwaypoints; i++)
+		{
+			waypoint_t *check = finish->nextwaypoints[i];
+			fixed_t dist = R_PointToDist2(player->mo->x, player->mo->y, check->mobj->x, check->mobj->y);
+			if (dist < closest)
+				closest = dist, snapto = check;
+		}
+	}
+
+	if (snapto)
+	{
+		player->currentwaypoint = snapto;
+		player->nextwaypoint = NULL; // don't forget to update position after this :^)
+	}
+}
+
 static boolean K_IgnoreFinishLine(player_t *player)
 {
 	// If potential lap cheating has been detected, do not
@@ -2027,9 +2094,11 @@ static void K_HandleLapIncrement(player_t *player)
 			}
 
 			if (!cv_kartdebuglap.value && player->laps == 1)
-					player->pflags |= PF_TRUSTWAYPOINTS;
+				player->pflags |= PF_TRUSTWAYPOINTS;
+			K_FixupFinishWaypoint(player, false);
 			K_UpdateAllPlayerPositions();
 
+
 			// Set up lap animation vars
 			if (player->laps > 1)
 			{
@@ -2139,6 +2208,7 @@ static void K_HandleLapDecrement(player_t *player)
 			return;
 		if (player->laps > 0)
 		{
+			K_FixupFinishWaypoint(player, true);
 			player->starpostnum = numstarposts;
 			player->laps--;
 			K_UpdateAllPlayerPositions();