From e388d2353c42ffab97ce630bb92a62d4c0e6283d Mon Sep 17 00:00:00 2001
From: redbirdly <155550833+redbirdly@users.noreply.github.com>
Date: Wed, 14 Jan 2026 12:46:46 +0800
Subject: [PATCH] Create junction.js

---
 mods/junction.js | 50 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 50 insertions(+)
 create mode 100644 mods/junction.js

diff --git a/mods/junction.js b/mods/junction.js
new file mode 100644
index 00000000..35cf40a7
--- /dev/null
+++ b/mods/junction.js
@@ -0,0 +1,50 @@
+// Junction.js
+
+const connectedPairs = [
+	[[-1, 0], [1, 0]], // Horizontal
+	[[0, -1], [0, 1]]  // Vertical
+];
+
+let isRisingEdge = (current, prev) => current === 2 && prev !== 2;
+let isFallingEdge = (current, prev) => current !== 2 && prev === 2;
+
+elements.junction = {
+	color: "#9db8b5",
+	category: "logic",
+	state: "solid",
+	behavior: behaviors.WALL,
+	tick: function (pixel) {
+		if (pixel.start === pixelTicks)
+			pixel.prevStateMap = {};
+
+		for (const pair of connectedPairs) {
+			let pixelA = pixelMap[pixel.x + pair[0][0]]?.[pixel.y + pair[0][1]];
+			let pixelB = pixelMap[pixel.x + pair[1][0]]?.[pixel.y + pair[1][1]];
+
+			if (!pixelA) continue;
+			if (!pixelB) continue;
+			if (pixelA.element !== "logic_wire") continue;
+			if (pixelB.element !== "logic_wire") continue;
+
+			let stateA = pixelA.lstate;
+			let stateB = pixelB.lstate;
+			let prevStateA = pixel.prevStateMap[[pixelA.x, pixelA.y]];
+			let prevStateB = pixel.prevStateMap[[pixelB.x, pixelB.y]];
+
+			// console.log("A:", stateA, "->", prevStateA);
+			// console.log("B:", stateB, "->", prevStateB);
+
+			// Set previous lstate to current lstate
+			pixel.prevStateMap[[pixelA.x, pixelA.y]] = pixelA.lstate;
+			pixel.prevStateMap[[pixelB.x, pixelB.y]] = pixelB.lstate;
+
+			// Rising edge
+			if (isRisingEdge(stateA, prevStateA)) pixelB.lstate = 2;
+			if (isRisingEdge(stateB, prevStateB)) pixelA.lstate = 2;
+
+			// Falling edge
+			if (isFallingEdge(stateA, prevStateA)) pixelB.lstate = -2;
+			if (isFallingEdge(stateB, prevStateB)) pixelA.lstate = -2;
+		}
+	}
+};