From 28eef7cfdd7f73ea39580c60b8399bcb64dd124a Mon Sep 17 00:00:00 2001
From: "J. Tyne" <jt_coding@verizon.net>
Date: Tue, 5 Feb 2013 21:22:34 +0000
Subject: [PATCH] A tweak to the way fog/shroud is cleared during a [teleport]
 action:

Clear the destination hex before the teleport animation (so it can be
seen), and clear the remaining hexes after the animation (when it
looks like the unit can see them).
---
 src/actions/vision.cpp | 39 +++++++++++++++++++++++++++++++++++++++
 src/actions/vision.hpp |  3 +++
 src/game_events.cpp    | 14 ++++++++++----
 3 files changed, 52 insertions(+), 4 deletions(-)

diff --git a/src/actions/vision.cpp b/src/actions/vision.cpp
index 8c599212504..cf00c92e962 100644
--- a/src/actions/vision.cpp
+++ b/src/actions/vision.cpp
@@ -374,6 +374,45 @@ bool shroud_clearer::clear_unit(const map_location &view_loc, const unit &viewer
 }
 
 
+/**
+ * Clears shroud (and fog) at the provided location and it immediate neighbors.
+ * This is an aid for the [teleport] action, allowing the destination to be
+ * cleared before teleporting, while the unit's full visual range gets cleared
+ * after.
+ * The @a viewer is needed for correct firing of sighted events.
+ *
+ * @return whether or not information was uncovered (i.e. returns true if the
+ *         locations in question were fogged/shrouded under shared vision/maps).
+ */
+bool shroud_clearer::clear_dest(const map_location &dest, const unit &viewer)
+{
+	team & viewing_team = (*resources::teams)[viewer.side()-1];
+	// A pair of dummy variables needed to simplify some logic.
+	size_t enemies, friends;
+
+	// Abort if there is nothing to clear.
+	if ( !viewing_team.fog_or_shroud() )
+		return false;
+
+	// Clear the destination.
+	bool cleared_something = clear_loc(viewing_team, dest, viewer, dest, true,
+	                                   enemies, friends);
+
+	// Clear the adjacent hexes (will be seen even if vision is 0, and the
+	// graphics do not work so well for an isolated cleared hex).
+	map_location adjacent[6];
+	get_adjacent_tiles(dest, adjacent);
+	for ( int i = 0; i != 6; ++i )
+		cleared_something = clear_loc(viewing_team, adjacent[i], viewer, dest,
+		                              true, enemies, friends);
+
+	if ( cleared_something )
+		invalidate_after_clear();
+
+	return cleared_something;
+}
+
+
 /**
  * Clears the record of sighted events from earlier fog/shroud clearing.
  * This should be called if the events are to be ignored and not fired.
diff --git a/src/actions/vision.hpp b/src/actions/vision.hpp
index 4d100f04cef..858fe3e9ac7 100644
--- a/src/actions/vision.hpp
+++ b/src/actions/vision.hpp
@@ -74,6 +74,9 @@ public:
 	                bool can_delay = false, bool invalidate = true,
 	                bool instant = false);
 
+	/// Clears shroud (and fog) at the provided location and it immediate neighbors.
+	bool clear_dest(const map_location &dest, const unit &viewer);
+
 	/// Erases the record of sighted events from earlier fog/shroud clearing.
 	void drop_events();
 
diff --git a/src/game_events.cpp b/src/game_events.cpp
index 0edccae0b3e..89085fb2cb2 100644
--- a/src/game_events.cpp
+++ b/src/game_events.cpp
@@ -878,9 +878,11 @@ WML_HANDLER_FUNCTION(teleport, event_info, cfg)
 	const map_location vacant_dst = find_vacant_tile(dst, pathfind::VACANT_ANY, pass_check);
 	if (!resources::game_map->on_board(vacant_dst)) return;
 
+	// Clear the destination hex before the move (so the animation can be seen).
+	bool clear_shroud = cfg["clear_shroud"].to_bool(true);
 	actions::shroud_clearer clearer;
-	if (cfg["clear_shroud"].to_bool(true)) {
-		clearer.clear_unit(vacant_dst, *u);
+	if ( clear_shroud ) {
+		clearer.clear_dest(vacant_dst, *u);
 	}
 
 	map_location src_loc = u->get_location();
@@ -897,12 +899,16 @@ WML_HANDLER_FUNCTION(teleport, event_info, cfg)
 	u = resources::units->find(vacant_dst);
 	u->set_standing();
 
+	if ( clear_shroud ) {
+		// Now that the unit is visibly in position, clear the shroud.
+		clearer.clear_unit(vacant_dst, *u);
+	}
+
 	if (resources::game_map->is_village(vacant_dst)) {
 		actions::get_village(vacant_dst, u->side());
 	}
 
-	resources::screen->invalidate_unit_after_move(src_loc, dst);
-
+	resources::screen->invalidate_unit_after_move(src_loc, vacant_dst);
 	resources::screen->draw();
 
 	// Sighted events.