From 92d4ed6e90df3815c4a4ce8824313049df66dd6c Mon Sep 17 00:00:00 2001
From: Oleg Antipin <60584843+olanti-p@users.noreply.github.com>
Date: Thu, 7 May 2020 00:47:04 +0300
Subject: [PATCH] Avoid revealing hidden tiles when selecting automove
 destination on CURSES (#40194)

(cherry picked from commit 3d706f38110314577e6f55e8d89b0674ede16373)
---
 src/animation.cpp | 22 +++++++++++++++-------
 src/game.cpp      |  2 +-
 src/game.h        |  2 +-
 3 files changed, 17 insertions(+), 9 deletions(-)

diff --git a/src/animation.cpp b/src/animation.cpp
index 539e7b1cdf350..069179803949b 100644
--- a/src/animation.cpp
+++ b/src/animation.cpp
@@ -553,8 +553,8 @@ void game::draw_hit_player( const player &p, const int dam )
 /* Line drawing code, not really an animation but should be separated anyway */
 namespace
 {
-void draw_line_curses( game &g, const tripoint &/*pos*/, const tripoint &center,
-                       const std::vector<tripoint> &ret )
+void draw_line_curses( game &g, const tripoint &center, const std::vector<tripoint> &ret,
+                       bool noreveal )
 {
     for( const tripoint &p : ret ) {
         const auto critter = g.critter_at( p, true );
@@ -562,7 +562,16 @@ void draw_line_curses( game &g, const tripoint &/*pos*/, const tripoint &center,
         // NPCs and monsters get drawn with inverted colors
         if( critter && g.u.sees( *critter ) ) {
             critter->draw( g.w_terrain, center, true );
+        } else if( noreveal && !g.u.sees( p ) ) {
+            // Draw a meaningless symbol. Avoids revealing tile, but keeps feedback
+            const char sym = '?';
+            const nc_color col = c_dark_gray;
+            const catacurses::window &w = g.w_terrain;
+            const int k = p.x + getmaxx( w ) / 2 - center.x;
+            const int j = p.y + getmaxy( w ) / 2 - center.y;
+            mvwputch( w, point( k, j ), col, sym );
         } else {
+            // This function reveals tile at p and writes it to the player's memory
             g.m.drawsq( g.w_terrain, g.u, p, true, true, center );
         }
     }
@@ -571,15 +580,14 @@ void draw_line_curses( game &g, const tripoint &/*pos*/, const tripoint &center,
 
 #if defined(TILES)
 void game::draw_line( const tripoint &p, const tripoint &center,
-                      const std::vector<tripoint> &points )
+                      const std::vector<tripoint> &points, bool noreveal )
 {
     if( !u.sees( p ) ) {
         return;
     }
 
-    // TODO: needed for tiles ver too??
     if( !use_tiles ) {
-        draw_line_curses( *this, p, center, points );
+        draw_line_curses( *this, center, points, noreveal );
         return;
     }
 
@@ -587,13 +595,13 @@ void game::draw_line( const tripoint &p, const tripoint &center,
 }
 #else
 void game::draw_line( const tripoint &p, const tripoint &center,
-                      const std::vector<tripoint> &points )
+                      const std::vector<tripoint> &points, bool noreveal )
 {
     if( !u.sees( p ) ) {
         return;
     }
 
-    draw_line_curses( *this, p, center, points );
+    draw_line_curses( *this, center, points, noreveal );
 }
 #endif
 
diff --git a/src/game.cpp b/src/game.cpp
index 262c5bb2d47e0..04342029cd668 100644
--- a/src/game.cpp
+++ b/src/game.cpp
@@ -3256,7 +3256,7 @@ void game::draw_ter( const tripoint &center, const bool looking, const bool draw
         // Draw auto-move preview trail
         const tripoint &final_destination = destination_preview.back();
         tripoint line_center = u.pos() + u.view_offset;
-        draw_line( final_destination, line_center, destination_preview );
+        draw_line( final_destination, line_center, destination_preview, true );
         mvwputch( w_terrain, final_destination.xy() - u.view_offset.xy() + point( POSX - u.posx(),
                   POSY - u.posy() ), c_white, 'X' );
     }
diff --git a/src/game.h b/src/game.h
index 767ad951ee788..1def24ddea95b 100644
--- a/src/game.h
+++ b/src/game.h
@@ -643,7 +643,7 @@ class game
         void draw_hit_mon( const tripoint &p, const monster &m, bool dead = false );
         void draw_hit_player( const player &p, int dam );
         void draw_line( const tripoint &p, const tripoint &center_point,
-                        const std::vector<tripoint> &points );
+                        const std::vector<tripoint> &points, bool noreveal = false );
         void draw_line( const tripoint &p, const std::vector<tripoint> &points );
         void draw_weather( const weather_printable &wPrint );
         void draw_sct();