Pause waypoint updates while player is touching finish line but not crossing it

- 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).

src/d_player.h

@@ -106,8 +106,9 @@ typedef enum
 
 	PF_ANALOGSTICK		= 1<<14, // This player is using an analog joystick
 	PF_TRUSTWAYPOINTS	= 1<<15, // Do not activate lap cheat prevention next time finish line distance is updated
+	PF_FREEZEWAYPOINTS	= 1<<16, // Skip the next waypoint/finish line distance update
 
-	//16-17 free, was previously itemflags stuff
+	//1<<17 free, was previously itemflags stuff
 
 	PF_DRIFTINPUT		= 1<<18, // Drifting!
 	PF_GETSPARKS		= 1<<19, // Can get sparks

src/deh_tables.c

@@ -4049,7 +4049,7 @@ const char *const PLAYERFLAG_LIST[] = {
 
 	"ANALOGSTICK", // This player is using an analog joystick
 	"TRUSTWAYPOINTS", // Do not activate lap cheat prevention next time finish line distance is updated
-	"\x01", // Free
+	"FREEZEWAYPOINTS", // Skip the next waypoint/finish line distance update
 	"\x01", // Free
 
 	"DRIFTINPUT", // Drifting!

src/k_kart.c

@@ -10013,6 +10013,12 @@ static UINT32 u32_delta(UINT32 x, UINT32 y)
 --------------------------------------------------*/
 static void K_UpdatePlayerWaypoints(player_t *const player)
 {
+	if (player->pflags & PF_FREEZEWAYPOINTS)
+	{
+		player->pflags &= ~PF_FREEZEWAYPOINTS;
+		return;
+	}
+
 	const UINT32 distance_threshold = FixedMul(32768, mapobjectscale);
 
 	waypoint_t *const old_currentwaypoint = player->currentwaypoint;

src/p_map.c

@@ -3147,6 +3147,26 @@ 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;
+			}
 		}
 
 		// Currently this just iterates all checkpoints.