From 2269c3aa76d327004cfb94d799672cc38da9ad94 Mon Sep 17 00:00:00 2001
From: lisyarus <lisyarus@gmail.com>
Date: Tue, 20 Aug 2024 19:02:14 +0300
Subject: [PATCH] Preserve belts when placing zoomer

---
 source/application.cpp | 74 ++++++++++++++++++++++++++++++++++++++----
 1 file changed, 67 insertions(+), 7 deletions(-)

diff --git a/source/application.cpp b/source/application.cpp
index 2c768d5..0ca2883 100644
--- a/source/application.cpp
+++ b/source/application.cpp
@@ -492,10 +492,13 @@ namespace gmtk
 	using index = index_base<vertex, util::make_uuid("vertex_index")>;
 	using path_index = index_base<path_vertex, util::make_uuid("path_vertex_index")>;
 
-	void sink_belt(ecs::container & world, location m)
+	//  1 - from center to m
+	// -1 - from m to center
+	//  0 - no belt
+	int sink_belt(ecs::container & world, location m)
 	{
 		if (auto entity = world.index<index>().find(m.up()); !entity || !world.get(*entity).contains<zoomer>())
-			return;
+			return 0;
 
 		auto & index = world.index<path_index>();
 
@@ -526,6 +529,8 @@ namespace gmtk
 			add_belt(world, mde, ne);
 
 			sink_belt(world, md);
+
+			return 1;
 		}
 		else if (cv.belts_from.contains(me))
 		{
@@ -545,7 +550,11 @@ namespace gmtk
 			add_belt(world, mde, cde);
 
 			sink_belt(world, md);
+
+			return -1;
 		}
+		else
+			return 0;
 	}
 
 	void sink(ecs::container & world, location & c, location & m)
@@ -687,12 +696,63 @@ namespace gmtk
 				zoomer{}
 			);
 
-			auto c = l.down();
+			auto & index = map.world->index<path_index>();
 
-			sink_belt(*map.world, c.left());
-			sink_belt(*map.world, c.right());
-			sink_belt(*map.world, c.bottom());
-			sink_belt(*map.world, c.top());
+			auto c = l.down();
+			auto cd = c.down();
+
+			if (int d = sink_belt(*map.world, c.left()))
+			{
+				for (int i = 0; i < 3; ++i)
+				{
+					auto e0 = index.get(cd.moved({-i, 0}));
+					auto e1 = index.get(cd.moved({-i-1, 0}));
+
+					if (d == 1)
+						add_belt(*map.world, e0, e1);
+					else
+						add_belt(*map.world, e1, e0);
+				}
+			}
+			if (int d = sink_belt(*map.world, c.right()))
+			{
+				for (int i = 0; i < 3; ++i)
+				{
+					auto e0 = index.get(cd.moved({i, 0}));
+					auto e1 = index.get(cd.moved({i+1, 0}));
+
+					if (d == 1)
+						add_belt(*map.world, e0, e1);
+					else
+						add_belt(*map.world, e1, e0);
+				}
+			}
+			if (int d = sink_belt(*map.world, c.bottom()))
+			{
+				for (int i = 0; i < 3; ++i)
+				{
+					auto e0 = index.get(cd.moved({0, -i}));
+					auto e1 = index.get(cd.moved({0, -i-1}));
+
+					if (d == 1)
+						add_belt(*map.world, e0, e1);
+					else
+						add_belt(*map.world, e1, e0);
+				}
+			}
+			if (int d = sink_belt(*map.world, c.top()))
+			{
+				for (int i = 0; i < 3; ++i)
+				{
+					auto e0 = index.get(cd.moved({0, i}));
+					auto e1 = index.get(cd.moved({0, i+1}));
+
+					if (d == 1)
+						add_belt(*map.world, e0, e1);
+					else
+						add_belt(*map.world, e1, e0);
+				}
+			}
 			return true;
 		}
 			break;