Begin adding directed conduit pieces

deps/zig-ldtk

@@ -1 +1 @@
-Subproject commit 1c85773b680b25d690b95e5c88b2e5bfe9ba534a
+Subproject commit d1ace5b48eaf1caa3bce44add0d14e4fb2f10061

flake.lock

@@ -32,11 +32,11 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1660017629,
+        "lastModified": 1660137652,
-        "narHash": "sha256-Koz6/k7c6hx4qVz/bboxdR2QsBdkxjRWpNmsOWJtXZE=",
+        "narHash": "sha256-L92gcG6Ya4bqjJmStl/HTENhc0PR9lmVgTmeVpk13Os=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "9f15d6c3a74d2778c6e1af67947c95f100dc6fd2",
+        "rev": "a7f89ddd6313ef88fc9c6534ac2511ba9da85fdb",
         "type": "github"
       },
       "original": {
@@ -70,11 +70,11 @@
     },
     "unstable": {
       "locked": {
-        "lastModified": 1659981942,
+        "lastModified": 1660071133,
-        "narHash": "sha256-uCFiP/B/NXOWzhN6TKfMbSxtVMk1bVnCrnJRjCF6RmU=",
+        "narHash": "sha256-XX6T9wcvEZIVWY4TO5O1d2MgFyFrF2v4TpCFs7fjdn8=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "39d7f929fbcb1446ad7aa7441b04fb30625a4190",
+        "rev": "36cc29d837e7232e3176e4651e8e117a6f231793",
         "type": "github"
       },
       "original": {
@@ -89,11 +89,11 @@
         "nixpkgs": "nixpkgs_2"
       },
       "locked": {
-        "lastModified": 1659919434,
+        "lastModified": 1660096418,
-        "narHash": "sha256-U6QsM5FbFpEkqPfXwe/QvNdCWwBIXW9A3fhXo3hFps8=",
+        "narHash": "sha256-+NewKwnerjOe5e65y0xwlRzoQ6JoKP2EaZLR+72d8wU=",
         "owner": "arqv",
         "repo": "zig-overlay",
-        "rev": "db9604e7fff0a41f06302d61dd4f320c4e23b81e",
+        "rev": "f7f0dd5bc40290187c70245d11b61c2305e4f114",
         "type": "github"
       },
       "original": {

src/extract.zig

@@ -46,7 +46,7 @@ pub fn extractLevel(opt: Options) !void {
     circuit.map_size = .{ level.width, height };
 
     w4.tracef("%d", @src().line);
-    var auto_map = try alloc.alloc(bool, size);
+    var auto_map = try alloc.alloc(world.SolidType, size);
     defer alloc.free(auto_map);
 
     var circuit_map = try alloc.alloc(CircuitType, size);
@@ -56,7 +56,7 @@ pub fn extractLevel(opt: Options) !void {
     for (tiles) |data, i| {
         switch (data) {
             .tile => |tile| {
-                auto_map[i] = false;
+                auto_map[i] = .Empty;
                 map.tiles[i] = tile;
                 circuit_map[i] = .None;
             },
@@ -79,7 +79,7 @@ pub fn extractLevel(opt: Options) !void {
             const y = @divTrunc(i, width);
             const stride = width;
 
-            if (!auto_map[i]) {
+            if (auto_map[i] == .Empty) {
                 autotiles[i] = null;
                 continue;
             }
@@ -93,25 +93,25 @@ pub fn extractLevel(opt: Options) !void {
             // Check horizontal neighbors
             if (x == 0) {
                 west = out_of_bounds;
-                east = auto_map[i + 1];
+                east = auto_map[i + 1] == .Solid;
             } else if (x == width - 1) {
-                west = auto_map[i - 1];
+                west = auto_map[i - 1] == .Solid;
                 east = out_of_bounds;
             } else {
-                west = auto_map[i - 1];
+                west = auto_map[i - 1] == .Solid;
-                east = auto_map[i + 1];
+                east = auto_map[i + 1] == .Solid;
             }
 
             // Check vertical neighbours
             if (y == 0) {
                 north = out_of_bounds;
-                south = auto_map[i + stride];
+                south = auto_map[i + stride] == .Solid;
             } else if (y == height - 1) {
-                north = auto_map[i - stride];
+                north = auto_map[i - stride] == .Solid;
                 south = out_of_bounds;
             } else {
-                north = auto_map[i - stride];
+                north = auto_map[i - stride] == .Solid;
-                south = auto_map[i + stride];
+                south = auto_map[i + stride] == .Solid;
             }
 
             autotiles[i] = AutoTile{
@@ -203,12 +203,18 @@ pub fn extractLevel(opt: Options) !void {
     for (autotiles) |autotile_opt, i| {
         if (autotile_opt) |autotile| {
             const tile = switch (circuit_map[i]) {
-                .Conduit, .Source, .Join => opt.conduit.find(autotile),
+                .Conduit,
+                .Conduit_Vertical,
+                .Conduit_Horizontal,
+                .Source,
+                .Join,
+                => opt.conduit.find(autotile),
                 .Switch_On => opt.switch_on.find(autotile),
                 .Switch_Off => opt.switch_off.find(autotile),
                 .Plug, .Socket => opt.plug.find(autotile),
                 .And => world.Tiles.LogicAnd,
                 .Xor => world.Tiles.LogicXor,
+                .Diode => world.Tiles.LogicDiode,
                 .None, .Outlet => 0,
             };
             circuit.map[i] = tile;

src/world.zig

@@ -2,22 +2,6 @@
 
 const std = @import("std");
 
-/// The CircuitType of a tile modifies how the tile responds to
-/// electricity
-pub const CircuitType = enum(u4) {
-    None = 0,
-    Conduit = 1,
-    Plug = 2,
-    Switch_Off = 3,
-    Switch_On = 4,
-    Join = 5,
-    And = 6,
-    Xor = 7,
-    Outlet = 8,
-    Source = 9,
-    Socket = 10,
-};
-
 /// This lists the most important tiles so I don't have to keep rewriting things
 pub const Tiles = struct {
     // Switches
@@ -50,9 +34,10 @@ pub const Tiles = struct {
     pub const LogicAnd = 20;
     pub const LogicNot = 21;
     pub const LogicXor = 22;
+    pub const LogicDiode = 23;
 
     pub fn is_logic(tile: u8) bool {
-        return tile >= 21 and tile <= 24;
+        return tile >= LogicAnd and tile <= LogicDiode;
     }
 
     pub const ConduitCross = 96;
@@ -109,29 +94,52 @@ pub const Tiles = struct {
     }, 2);
 };
 
+pub const SolidType = enum(u2) {
+    Empty = 0,
+    Solid = 1,
+    Oneway = 2,
+};
+
+/// The CircuitType of a tile modifies how the tile responds to
+/// electricity
+pub const CircuitType = enum(u5) {
+    None = 0,
+    Conduit = 1,
+    Plug = 2,
+    Switch_Off = 3,
+    Switch_On = 4,
+    Join = 5,
+    And = 6,
+    Xor = 7,
+    Outlet = 8,
+    Source = 9,
+    Socket = 10,
+    Diode = 11,
+    Conduit_Vertical = 12,
+    Conduit_Horizontal = 13,
+};
+
 pub const TileData = union(enum) {
     tile: u7,
     flags: struct {
-        solid: bool,
+        solid: SolidType,
         circuit: CircuitType,
     },
 
     pub fn getCircuit(data: TileData) ?CircuitType {
-        switch (data) {
+        if (data == .flags) {
-            .tile => |_| return null,
+            return data.flags.circuit;
-            .flags => |flags| {
-                if (flags.circuit == .None) return null;
-                return flags.circuit;
-            },
         }
+        return null;
     }
 
     pub fn toByte(data: TileData) u8 {
         switch (data) {
             .tile => |int| return 0b1000_0000 | @intCast(u8, int),
             .flags => |flags| {
+                const solid = @enumToInt(flags.solid);
                 const circuit = @enumToInt(flags.circuit);
-                return (@intCast(u7, @boolToInt(flags.solid))) | (@intCast(u7, circuit) << 1);
+                return 0b0111_1111 & ((@intCast(u7, solid)) | (@intCast(u7, circuit) << 2));
             },
         }
     }
@@ -139,13 +147,13 @@ pub const TileData = union(enum) {
     pub fn fromByte(byte: u8) TileData {
         const is_tile = (0b1000_0000 & byte) > 0;
         if (is_tile) {
-            const tile = @intCast(u7, (0b0111_1111 & byte));
+            const tile = @intCast(u7, (0b0000_0011 & byte));
             return TileData{ .tile = tile };
         } else {
-            const is_solid = (0b0000_0001 & byte) > 0;
+            const solid = (0b0000_0011 & byte);
-            const circuit = @intCast(u4, (0b0001_1110 & byte) >> 1);
+            const circuit = @intCast(u5, (0b0111_1100 & byte) >> 2);
             return TileData{ .flags = .{
-                .solid = is_solid,
+                .solid = @intToEnum(SolidType, solid),
                 .circuit = @intToEnum(CircuitType, circuit),
             } };
         }
@@ -257,12 +265,12 @@ pub const Level = struct {
     size: u16,
     tiles: ?[]TileData,
 
-    pub fn init(x: u8, y: u8, width: u16, buf: []TileData) Level {
+    pub fn init(x: i8, y: i8, width: u16, buf: []TileData) Level {
         return Level{
             .world_x = x,
             .world_y = y,
             .width = width,
-            .size = buf.len,
+            .size = @intCast(u16, buf.len),
             .tiles = buf,
         };
     }
@@ -310,9 +318,11 @@ pub const Level = struct {
     pub fn getTile(level: Level, globalc: Coord) ?TileData {
         const tiles = level.tiles orelse return null;
         const worldc = globalc.toLevelTopLeft();
+        const se = worldc.add(.{ 20, 20 });
+        if (!globalc.within(worldc, se)) return null;
         const x = globalc.val[0] - worldc.val[0];
         const y = globalc.val[1] - worldc.val[1];
-        const w = @intCast(i16, level.width);
+        const w = @intCast(i32, level.width);
         const i = @intCast(usize, x + y * w);
         return tiles[i];
     }
@@ -817,25 +827,30 @@ pub const Database = struct {
         if (visited[i]) return db.circuit_info[i].energized;
         visited[i] = true;
         const node = db.circuit_info[i];
+        const w4 = @import("wasm4.zig");
         switch (node.kind) {
             .And => |And| {
+                w4.tracef("[updateCircuitFragment] %d And %d %d", i, And[0], And[1]);
                 const input1 = db.updateCircuitFragment(And[0], visited);
                 const input2 = db.updateCircuitFragment(And[1], visited);
                 db.circuit_info[i].energized = (input1 and input2);
             },
             .Xor => |Xor| {
+                w4.tracef("[updateCircuitFragment] %d Xor", i);
                 const input1 = db.updateCircuitFragment(Xor[0], visited);
                 const input2 = db.updateCircuitFragment(Xor[1], visited);
                 db.circuit_info[i].energized = (input1 and !input2) or (input2 and !input1);
             },
             .Source => db.circuit_info[i].energized = true,
             .Conduit => |Conduit| {
+                w4.tracef("[updateCircuitFragment] %d Conduit", i);
                 const input1 = db.updateCircuitFragment(Conduit[0], visited);
                 const input2 = db.updateCircuitFragment(Conduit[1], visited);
                 db.circuit_info[i].energized = (input1 or input2);
             },
             // TODO: Sockets may come before the plug they are connected to
             .Socket => |socket_opt| {
+                w4.tracef("[updateCircuitFragment] %d Socket", i);
                 if (socket_opt) |input| {
                     db.circuit_info[i].energized = db.updateCircuitFragment(input, visited);
                 } else {
@@ -843,12 +858,15 @@ pub const Database = struct {
                 }
             },
             .Plug => |Plug| {
+                w4.tracef("[updateCircuitFragment] %d Plug", i);
                 db.circuit_info[i].energized = db.updateCircuitFragment(Plug, visited);
             },
             .Switch => |_Switch| {
+                w4.tracef("[updateCircuitFragment] %d Switch %d", i, _Switch.source);
                 db.circuit_info[i].energized = db.updateCircuitFragment(_Switch.source, visited);
             },
             .SwitchOutlet => |_Switch| {
+                w4.tracef("[updateCircuitFragment] %d Switch Outlet", i);
                 const is_energized = db.updateCircuitFragment(_Switch.source, visited);
                 const _switch = db.circuit_info[_Switch.source].kind.Switch;
                 const _outlet = db.circuit_info[i].kind.SwitchOutlet;
@@ -858,12 +876,15 @@ pub const Database = struct {
                 db.circuit_info[i].energized = _outlet.which == _switch.state;
             },
             .Join => |Join| {
+                w4.tracef("[updateCircuitFragment] %d Join", i);
                 db.circuit_info[i].energized = db.updateCircuitFragment(Join, visited);
             },
             .Outlet => |Outlet| {
+                w4.tracef("[updateCircuitFragment] %d Outlet", i);
                 db.circuit_info[i].energized = db.updateCircuitFragment(Outlet, visited);
             },
         }
+                w4.tracef("[updateCircuitFragment] %d end", i);
         return db.circuit_info[i].energized;
     }
 
@@ -872,6 +893,8 @@ pub const Database = struct {
         defer alloc.free(visited);
         std.mem.set(bool, visited, false);
         var i: usize = db.circuit_info.len - 1;
+        const w4 = @import("wasm4.zig");
+        w4.tracef("[updateCircuit] circuit info len %d", db.circuit_info.len);
         while (i > 0) : (i -|= 1) {
             _ = db.updateCircuitFragment(i, visited);
             if (i == 0) break;

tools/LDtkImport.zig

@@ -152,8 +152,8 @@ fn parseLevel(opt: struct {
 
     const layers = level.layerInstances orelse return error.NoLayers;
 
-    const world_x: i8 = @intCast(i8, @divExact(level.worldX, (ldtk.worldGridWidth orelse 160)));
+    const world_x: i8 = @intCast(i8, @divFloor(level.worldX, (ldtk.worldGridWidth orelse 160)));
-    const world_y: i8 = @intCast(i8, @divExact(level.worldY, (ldtk.worldGridHeight orelse 160)));
+    const world_y: i8 = @intCast(i8, @divFloor(level.worldY, (ldtk.worldGridHeight orelse 160)));
 
     var circuit_layer: ?LDtk.LayerInstance = null;
     var collision_layer: ?LDtk.LayerInstance = null;
@@ -285,14 +285,22 @@ fn parseLevel(opt: struct {
 
     // Add circuit tiles
     for (circuit.intGridCsv) |cir64, i| {
-        const cir = @intCast(u4, cir64);
+        const cir = @intToEnum(world.CircuitType, @intCast(u5, cir64));
         const col = collision.intGridCsv[i];
-        if (col == 0 or col == 1) {
+        if (cir != .None and col == 2) return error.DebrisAndCircuitOverlapped;
-            tiles[i] = world.TileData{ .flags = .{
+        if (cir == .None) continue;
-                .solid = col == 1,
+        const solid: world.SolidType = switch (col) {
-                .circuit = @intToEnum(world.CircuitType, cir),
+            0 => .Empty,
-            } };
+            1 => .Solid,
-        }
+            3 => .Oneway,
+            else => return error.DebrisAndCircuitOverlapped,
+        };
+        if (cir == .Socket)
+            std.log.warn("[parseLevel] {}: {}", .{ i, cir });
+        tiles[i] = world.TileData{ .flags = .{
+            .solid = solid,
+            .circuit = cir,
+        } };
     }
 
     return parsed_level;
@@ -313,22 +321,15 @@ pub fn buildCircuit(alloc: std.mem.Allocator, levels: []world.Level) !std.ArrayL
     var sources = Queue{};
     var sockets = Queue{};
 
-    var level_hashmap = std.AutoHashMap(u16, world.Level).init(alloc);
-    defer level_hashmap.deinit();
-
     for (levels) |level| {
-        const id: u16 = @bitCast(u8, level.world_x) | @intCast(u16, @bitCast(u8, level.world_y)) << 8;
-        // So we can quickly find levels
-        try level_hashmap.put(id, level);
-
         // Use a global coordinate system for our algorithm
         const global_x = @intCast(i16, level.world_x) * 20;
         const global_y = @intCast(i16, level.world_y) * 20;
         for (level.tiles orelse continue) |tileData, i| {
             const x = global_x + @intCast(i16, @mod(i, level.width));
             const y = global_y + @intCast(i16, @divTrunc(i, level.width));
-            const coordinate = try alloc.create(Node);
+            const search_item = try alloc.create(Node);
-            coordinate.* = .{ .data = .{
+            search_item.* = .{ .data = .{
                 .last_node = @intCast(world.NodeID, nodes.items.len),
                 .coord = Coord.init(.{ x, y }),
             } };
@@ -340,12 +341,11 @@ pub fn buildCircuit(alloc: std.mem.Allocator, levels: []world.Level) !std.ArrayL
                     switch (flags.circuit) {
                         .Source => {
                             try nodes.append(.{ .kind = .Source, .coord = Coord.init(.{ x, y }) });
-                            sources.append(coordinate);
+                            sources.append(search_item);
                         },
                         .Socket => {
-                            // try nodes.append(.{ .kind = .{ .Plug = null } });
+                            search_item.data.last_node = std.math.maxInt(world.NodeID);
-                            coordinate.data.last_node = std.math.maxInt(world.NodeID);
+                            sockets.append(search_item);
-                            sockets.append(coordinate);
                         },
                         else => {
                             // Do nothing
@@ -367,24 +367,22 @@ pub fn buildCircuit(alloc: std.mem.Allocator, levels: []world.Level) !std.ArrayL
     while (run < 2) : (run += 1) {
         if (run == 0) bfs_queue.concatByMoving(&sources);
         if (run == 1) bfs_queue.concatByMoving(&sockets);
-        // bfs_queue.concatByMoving(&outlets);
 
         while (bfs_queue.popFirst()) |node| {
             // Make sure we clean up the node's memory
             defer alloc.destroy(node);
             const coord = node.data.coord;
             if (visited.contains(coord)) continue;
-            try visited.put(coord, .{});
+            try visited.put(coord, {});
-            // TODO remove magic numbers
+
             const worldc = coord.toWorld();
-            const id: u16 = @bitCast(u8, worldc[0]) | @intCast(u16, @bitCast(u8, worldc[1])) << 8;
+            // const level = getLevel(levels, worldc[0], worldc[1]);
-            // const level_opt: ?world.Level = level_hashmap.get(.{ world_x, world_y });
+            if (getLevel(levels, worldc[0], worldc[1])) |level| {
-            if (level_hashmap.getPtr(id) != null) {
-                const level = level_hashmap.getPtr(id);
                 const last_node = node.data.last_node;
                 var next_node = last_node;
 
-                const tile = level.?.getTile(coord).?;
+                const tile = level.getTile(coord) orelse continue;
+                std.log.warn("[buildCircuit] {} [{}] {}", .{ coord, node.data.last_node, tile });
 
                 if (tile != .flags) continue;
                 const flags = tile.flags;
@@ -397,6 +395,56 @@ pub fn buildCircuit(alloc: std.mem.Allocator, levels: []world.Level) !std.ArrayL
                         // previous nodes to point to the conduit
                         // TODO
                     },
+                    .Conduit_Horizontal => {
+                        // Skip vertical inputs
+                        const last_coord = node.data.last_coord.?;
+                        const input_dir: Dir = getInputDirection(coord, last_coord);
+                        if (input_dir == .North or input_dir == .South) {
+                            _ = visited.remove(coord);
+                            continue;
+                        }
+                        const left = try alloc.create(Node);
+                        left.* = Node{ .data = .{
+                            .last_node = last_node,
+                            .coord = coord.add(.{ -1, 0 }),
+                            .last_coord = coord,
+                        } };
+                        bfs_queue.append(left);
+
+                        const right = try alloc.create(Node);
+                        right.* = Node{ .data = .{
+                            .last_node = last_node,
+                            .coord = coord.add(.{ 1, 0 }),
+                            .last_coord = coord,
+                        } };
+                        bfs_queue.append(right);
+                        continue;
+                    },
+                    .Conduit_Vertical => {
+                        // Skip horizontal inputs
+                        const last_coord = node.data.last_coord.?;
+                        const input_dir: Dir = getInputDirection(coord, last_coord);
+                        if (input_dir == .West or input_dir == .East) {
+                            _ = visited.remove(coord);
+                            continue;
+                        }
+                        const up = try alloc.create(Node);
+                        up.* = Node{ .data = .{
+                            .last_node = last_node,
+                            .coord = coord.add(.{ 0, -1 }),
+                            .last_coord = coord,
+                        } };
+                        bfs_queue.append(up);
+
+                        const down = try alloc.create(Node);
+                        down.* = Node{ .data = .{
+                            .last_node = last_node,
+                            .coord = coord.add(.{ 0, 1 }),
+                            .last_coord = coord,
+                        } };
+                        bfs_queue.append(down);
+                        continue;
+                    },
                     .Socket => {
                         next_node = @intCast(world.NodeID, nodes.items.len);
                         try nodes.append(.{
@@ -423,28 +471,39 @@ pub fn buildCircuit(alloc: std.mem.Allocator, levels: []world.Level) !std.ArrayL
                     .Switch_Off, .Switch_On => {
                         // Identify input side
                         const last_coord = node.data.last_coord.?;
-                        const Dir = enum { North, West, East, South };
+                        const input_dir: Dir = getInputDirection(coord, last_coord);
-                        const input_dir: Dir = dir: {
-                            if (last_coord.eq(coord.add(.{ 0, -1 }))) {
-                                break :dir .North;
-                            } else if (last_coord.eq(coord.add(.{ -1, 0 }))) {
-                                break :dir .West;
-                            } else if (last_coord.eq(coord.add(.{ 1, 0 }))) {
-                                break :dir .East;
-                            } else {
-                                break :dir .South;
-                            }
-                        };
                         // Find outlets
-                        const north_opt = level.?.getTile(coord.add(.{ 0, -1 })).?.getCircuit();
+                        const ncoord = coord.add(.{ 0, -1 });
-                        const west_opt = level.?.getTile(coord.add(.{ -1, 0 })).?.getCircuit();
+                        const wcoord = coord.add(.{ -1, 0 });
-                        const east_opt = level.?.getTile(coord.add(.{ 1, 0 })).?.getCircuit();
+                        const ecoord = coord.add(.{ 1, 0 });
-                        const south_opt = level.?.getTile(coord.add(.{ 0, 1 })).?.getCircuit();
+                        const scoord = coord.add(.{ 0, 1 });
 
-                        const north = (north_opt orelse world.CircuitType.None) != .None;
+                        const north_opt = if (level.getTile(ncoord)) |t| t.getCircuit() else @panic("AAAAA");
-                        const west = (west_opt orelse world.CircuitType.None) != .None;
+                        const west_opt = if (level.getTile(wcoord)) |t| t.getCircuit() else @panic("AAAAA");
-                        const east = (east_opt orelse world.CircuitType.None) != .None;
+                        const east_opt = if (level.getTile(ecoord)) |t| t.getCircuit() else @panic("AAAAA");
-                        const south = (south_opt orelse world.CircuitType.None) != .None;
+                        const south_opt = if (level.getTile(scoord)) |t| t.getCircuit() else @panic("AAAAA");
+
+                        const north_tile = north_opt orelse world.CircuitType.None;
+                        const west_tile = west_opt orelse world.CircuitType.None;
+                        const east_tile = east_opt orelse world.CircuitType.None;
+                        const south_tile = south_opt orelse world.CircuitType.None;
+
+                        const north = north_tile != .None and north_tile != .Conduit_Horizontal;
+                        const west = west_tile != .None and west_tile != .Conduit_Vertical;
+                        const east = east_tile != .None and east_tile != .Conduit_Vertical;
+                        const south = south_tile != .None and south_tile != .Conduit_Horizontal;
+
+                        std.log.warn("[buildCircuit] {}: {} {},\n\t{} {},\n\t{} {},\n\t{} {}", .{
+                            coord,
+                            north_tile,
+                            ncoord,
+                            west_tile,
+                            wcoord,
+                            east_tile,
+                            ecoord,
+                            south_tile,
+                            scoord,
+                        });
 
                         // We don't have four way switches, don't allow them
                         std.debug.assert(west != true or east != true);
@@ -480,7 +539,7 @@ pub fn buildCircuit(alloc: std.mem.Allocator, levels: []world.Level) !std.ArrayL
                         // Add switch outlets
                         if (input_dir != .West and west) {
                             const out_node = @intCast(world.NodeID, nodes.items.len);
-                            const new_coord = coord.add(.{-1, 0});
+                            const new_coord = coord.add(.{ -1, 0 });
                             try nodes.append(.{
                                 .kind = .{ .SwitchOutlet = .{
                                     .source = next_node,
@@ -499,7 +558,7 @@ pub fn buildCircuit(alloc: std.mem.Allocator, levels: []world.Level) !std.ArrayL
 
                         if (input_dir != .East and east) {
                             const out_node = @intCast(world.NodeID, nodes.items.len);
-                            const new_coord = coord.add(.{1, 0});
+                            const new_coord = coord.add(.{ 1, 0 });
                             try nodes.append(.{
                                 .kind = .{ .SwitchOutlet = .{
                                     .source = next_node,
@@ -518,7 +577,7 @@ pub fn buildCircuit(alloc: std.mem.Allocator, levels: []world.Level) !std.ArrayL
 
                         if (input_dir != .South and south) {
                             const out_node = @intCast(world.NodeID, nodes.items.len);
-                            const new_coord = coord.add(.{0, 1});
+                            const new_coord = coord.add(.{ 0, 1 });
                             try nodes.append(.{
                                 .kind = .{ .SwitchOutlet = .{
                                     .source = next_node,
@@ -537,7 +596,7 @@ pub fn buildCircuit(alloc: std.mem.Allocator, levels: []world.Level) !std.ArrayL
 
                         if (input_dir != .North and north) {
                             const out_node = @intCast(world.NodeID, nodes.items.len);
-                            const new_coord = coord.add(.{0, -1});
+                            const new_coord = coord.add(.{ 0, -1 });
                             try nodes.append(.{
                                 .kind = .{ .SwitchOutlet = .{
                                     .source = next_node,
@@ -596,10 +655,34 @@ pub fn buildCircuit(alloc: std.mem.Allocator, levels: []world.Level) !std.ArrayL
                             }
                         } else {
                             _ = visited.remove(coord);
-                            if (side == .O) {
+                            if (side != .O) {
                                 // TODO: reverse the path, since the search path
                                 // may have come from a plug
-                                return error.OutputToSource;
+                                next_node = @intCast(world.NodeID, nodes.items.len);
+                                try nodes.append(.{
+                                    .kind = .{ .And = .{ last_node, std.math.maxInt(world.NodeID) } },
+                                    .coord = coord,
+                                });
+                                std.log.warn("{}", .{nodes.items[last_node]});
+                                switch (nodes.items[last_node].kind) {
+                                    .And => |_and| {
+                                        if (_and[0] == std.math.maxInt(world.NodeID)) {
+                                            nodes.items[last_node].kind.And[0] = next_node;
+                                        } else if (_and[1] == std.math.maxInt(world.NodeID)) {
+                                            nodes.items[last_node].kind.And[1] = next_node;
+                                        } else {
+                                            return error.AndGateFilled;
+                                        }
+                                    },
+                                    .SwitchOutlet => |_switch| {
+                                        _ = _switch;
+                                        std.log.warn("{}", .{nodes.items[last_node].coord});
+                                    },
+                                    .Socket => |socket| {
+                                        _ = socket;
+                                    },
+                                    else => return error.Unimplemented,
+                                }
                             } else if (side == .L) {
                                 next_node = @intCast(world.NodeID, nodes.items.len);
                                 try nodes.append(.{
@@ -625,7 +708,7 @@ pub fn buildCircuit(alloc: std.mem.Allocator, levels: []world.Level) !std.ArrayL
                         }
                     },
                     .Xor => {
-                        std.log.warn("XOR XOR XOR",.{});
+                        std.log.warn("XOR XOR XOR", .{});
                         // TODO: verify Xor gate is properly connected
                         const last_coord = node.data.last_coord.?;
                         const Side = enum { O, L, R };
@@ -679,6 +762,9 @@ pub fn buildCircuit(alloc: std.mem.Allocator, levels: []world.Level) !std.ArrayL
                             continue;
                         }
                     },
+                    .Diode => {
+                        // TODO
+                    },
                     .None => continue,
                 }
 
@@ -712,10 +798,30 @@ pub fn buildCircuit(alloc: std.mem.Allocator, levels: []world.Level) !std.ArrayL
                 bfs_queue.append(left);
                 bfs_queue.append(down);
                 bfs_queue.append(up);
-
             }
         }
     }
 
     return nodes;
 }
+
+const Dir = enum { North, West, East, South };
+
+fn getInputDirection(coord: world.Coordinate, last_coord: world.Coordinate) Dir {
+    if (last_coord.eq(coord.add(.{ 0, -1 }))) {
+        return .North;
+    } else if (last_coord.eq(coord.add(.{ -1, 0 }))) {
+        return .West;
+    } else if (last_coord.eq(coord.add(.{ 1, 0 }))) {
+        return .East;
+    } else {
+        return .South;
+    }
+}
+
+fn getLevel(levels: []world.Level, x: i8, y: i8) ?world.Level {
+    for (levels) |level| {
+        if (level.world_x == x and level.world_y == y) return level;
+    }
+    return null;
+}