From 9ec91d4b8ebdecde404459c584e7f57e6fcb247b Mon Sep 17 00:00:00 2001
From: Valentino Zegna <valentino.zegna@gmail.com>
Date: Sat, 21 Mar 2026 11:42:15 -0700
Subject: [PATCH] fix: add collinearity check to pointOnSegment() for diagonal
 wires

Bounding-box-only containment falsely merged nets when diagonal wire
bounding boxes overlapped. Add cross-product collinearity check with
2-unit perpendicular distance tolerance to handle Altium coordinate
rounding. Also clean up undefined mpn/description keys in component
output.

Closes #54
---
 src/parsers/altium/connectivity.ts |  7 +++++++
 src/parsers/altium/index.test.ts   | 22 ++++++++++++++++++++++
 src/parsers/altium/index.ts        | 10 ++++++++--
 3 files changed, 37 insertions(+), 2 deletions(-)

diff --git a/src/parsers/altium/connectivity.ts b/src/parsers/altium/connectivity.ts
index d27d4c2..14853a3 100644
--- a/src/parsers/altium/connectivity.ts
+++ b/src/parsers/altium/connectivity.ts
@@ -180,6 +180,13 @@ const pointOnSegment = (point: Coordinate, segment: LineSegment): boolean => {
   const [p1, p2] = segment;
   const [px, py] = point;
 
+  // Cross product collinearity check: perpendicular distance must be within tolerance.
+  // Altium coordinates (10000 units/mil) can have small rounding errors (~2 units),
+  // so we use tolerance of 2 units (0.0002 mil). Squared form avoids sqrt.
+  const cross = (p2[0] - p1[0]) * (py - p1[1]) - (p2[1] - p1[1]) * (px - p1[0]);
+  const segLenSq = (p2[0] - p1[0]) ** 2 + (p2[1] - p1[1]) ** 2;
+  if (segLenSq > 0 && cross * cross > 4 * segLenSq) return false;
+
   const minX = Math.min(p1[0], p2[0]);
   const maxX = Math.max(p1[0], p2[0]);
   const minY = Math.min(p1[1], p2[1]);
diff --git a/src/parsers/altium/index.test.ts b/src/parsers/altium/index.test.ts
index 468add0..55b5c7c 100644
--- a/src/parsers/altium/index.test.ts
+++ b/src/parsers/altium/index.test.ts
@@ -323,6 +323,28 @@ describe("Connectivity", () => {
       expect(isConnected(wireA, wireB)).toBe(false);
     });
 
+    it("should detect disconnected wires with overlapping bounding boxes", () => {
+      const wireA: AltiumRecord = {
+        index: 0,
+        RECORD: RECORD_TYPES.WIRE,
+        coords: [
+          [0, 0],
+          [100, 100],
+        ],
+      };
+
+      const wireB: AltiumRecord = {
+        index: 1,
+        RECORD: RECORD_TYPES.WIRE,
+        coords: [
+          [100, 0],
+          [0, 100],
+        ],
+      };
+
+      expect(isConnected(wireA, wireB)).toBe(false);
+    });
+
     it("should detect pin connected to wire", () => {
       const wire: AltiumRecord = {
         index: 0,
diff --git a/src/parsers/altium/index.ts b/src/parsers/altium/index.ts
index eaf0665..629ad67 100644
--- a/src/parsers/altium/index.ts
+++ b/src/parsers/altium/index.ts
@@ -333,11 +333,17 @@ export const extractComponents = (schematic: AltiumSchematic): ComponentDetails
     }
 
     const component: ComponentDetails[string] = {
-      mpn,
-      description: extractedDescription,
       pins,
     };
 
+    if (mpn !== undefined) {
+      component.mpn = mpn;
+    }
+
+    if (extractedDescription !== undefined) {
+      component.description = extractedDescription;
+    }
+
     if (comment !== undefined) {
       component.comment = comment;
     }