Fix OpenRCT2#10477. Fix upper max height limit being very low for lar…

…ge scenery

Mistake made while improving mouse control when zoomed out caused the upper limit for multi tile scenery to be limited by the sum of all clearance z values instead of the greatest clearance z value.

distribution/changelog.txt

@@ -8,6 +8,7 @@
 - Fix: [#10228] Can't import RCT1 Deluxe from Steam.
 - Fix: [#10325] Crash when banners have no text.
 - Fix: [#10420] Money effect causing false positive desync.
+- Fix: [#10477] Large Scenery cannot be placed higher using SHIFT.
 
 0.2.4 (2019-10-28)
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src/openrct2-ui/windows/TopToolbar.cpp

@@ -1250,13 +1250,12 @@ static void sub_6E1F34(
         rct_scenery_entry* scenery_entry = get_large_scenery_entry(selected_scenery);
         if (scenery_entry)
         {
-            int16_t tileZ = 0;
+            int16_t maxClearZ = 0;
             for (int32_t i = 0; scenery_entry->large_scenery.tiles[i].x_offset != -1; ++i)
             {
-                assert(i < MAXIMUM_MAP_SIZE_TECHNICAL);
-                tileZ += scenery_entry->large_scenery.tiles[i].z_clearance;
+                maxClearZ = std::max<int16_t>(maxClearZ, scenery_entry->large_scenery.tiles[i].z_clearance);
             }
-            maxPossibleHeight = std::max(0, maxPossibleHeight - tileZ);
+            maxPossibleHeight = std::max(0, maxPossibleHeight - maxClearZ);
         }
         can_raise_item = true;
     }