From 3410330bb2091ca908f34a61b084a5e8133b4bfa Mon Sep 17 00:00:00 2001
From: Jeroen D Stout <jeroenstout@gmail.com>
Date: Wed, 11 Oct 2017 18:13:01 +0200
Subject: [PATCH] Add paint session memory for tracks and paths

---
 src/openrct2/paint/paint.h                    |  3 +-
 .../paint/tile_element/tile_element.c         | 36 +++++++++++++++++++
 2 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/src/openrct2/paint/paint.h b/src/openrct2/paint/paint.h
index b83759c4a6..e0110149f7 100644
--- a/src/openrct2/paint/paint.h
+++ b/src/openrct2/paint/paint.h
@@ -170,7 +170,8 @@ typedef struct paint_session
     tunnel_entry            RightTunnels[TUNNEL_MAX_COUNT];
     uint8                   RightTunnelCount;
     uint8                   VerticalTunnelHeight;
-    rct_tile_element *       SurfaceElement;
+    rct_tile_element *      PathElementOnSameHeight;
+    rct_tile_element *      TrackElementOnSameHeight;
     bool                    DidPassSurface;
     uint8                   Unk141E9DB;
     uint16                  Unk141E9DC;
diff --git a/src/openrct2/paint/tile_element/tile_element.c b/src/openrct2/paint/tile_element/tile_element.c
index 4f9d53f109..62aefb369d 100644
--- a/src/openrct2/paint/tile_element/tile_element.c
+++ b/src/openrct2/paint/tile_element/tile_element.c
@@ -234,6 +234,7 @@ static void sub_68B3FB(paint_session * session, sint32 x, sint32 y)
     session->SpritePosition.x = x;
     session->SpritePosition.y = y;
     session->DidPassSurface = false;
+    sint32 previousHeight = 0;
     do {
         // Only paint tile_elements below the clip height.
         if ((gCurrentViewportFlags & VIEWPORT_FLAG_PAINT_CLIP_TO_HEIGHT) && (tile_element->base_height > gClipHeight)) break;
@@ -241,6 +242,41 @@ static void sub_68B3FB(paint_session * session, sint32 x, sint32 y)
         sint32 direction = tile_element_get_direction_with_offset(tile_element, rotation);
         sint32 height = tile_element->base_height * 8;
 
+        // If we are on a new height level, look through elements on the
+        //  same height and store any types might be relevant to others
+        if (height != previousHeight)
+        {
+            previousHeight = height;
+            session->PathElementOnSameHeight = 0;
+            session->TrackElementOnSameHeight = 0;
+            rct_tile_element * tile_element_sub_iterator = tile_element;
+            while (!map_element_is_last_for_tile(tile_element_sub_iterator++))
+            {
+                if (tile_element_sub_iterator->base_height != tile_element->base_height)
+                {
+                    break;
+                }
+                switch (map_element_get_type(tile_element_sub_iterator))
+                {
+                case TILE_ELEMENT_TYPE_PATH:
+                    session->PathElementOnSameHeight = tile_element_sub_iterator;
+                    break;
+                case TILE_ELEMENT_TYPE_TRACK:
+                    session->TrackElementOnSameHeight = tile_element_sub_iterator;
+                    break;
+                case TILE_ELEMENT_TYPE_CORRUPT:
+                    // To preserve regular behaviour, make an element hidden by
+                    //  corruption also invisible to this method.
+                    if (tile_element_is_last_for_tile(tile_element))
+                    {
+                        break;
+                    }
+                    tile_element_sub_iterator++;
+                    break;
+                }
+            }
+        }
+
         LocationXY16 dword_9DE574 = session->MapPosition;
         session->CurrentlyDrawnItem = tile_element;
         // Setup the painting of for example: the underground, signs, rides, scenery, etc.