From 24d5cc737f553aec9a201fedd5dbe4a315374eb1 Mon Sep 17 00:00:00 2001
From: John Mayfield <john@nextmovesoftware.com>
Date: Sat, 5 Aug 2023 12:18:08 +0100
Subject: [PATCH] For n=1 one we want bonds to be left to right and not aligned
 at 30 deg, e.g. "Cl-Ph".

---
 .../cdk/layout/StructureDiagramGenerator.java          | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/tool/sdg/src/main/java/org/openscience/cdk/layout/StructureDiagramGenerator.java b/tool/sdg/src/main/java/org/openscience/cdk/layout/StructureDiagramGenerator.java
index 5b56c37ca8..be5578ccf1 100644
--- a/tool/sdg/src/main/java/org/openscience/cdk/layout/StructureDiagramGenerator.java
+++ b/tool/sdg/src/main/java/org/openscience/cdk/layout/StructureDiagramGenerator.java
@@ -1045,6 +1045,16 @@ private void selectOrientation(IAtomContainer mol, double widthDiff, int alignDi
         Point2d pivot = new Point2d(minmax[0] + ((minmax[2] - minmax[0]) / 2),
                                     minmax[1] + ((minmax[3] - minmax[1]) / 2));
 
+        // n=1
+        if (bonds.size() == 1) {
+            IBond bond = bonds.get(0);
+            Point2d beg = bond.getBegin().getPoint2d();
+            Point2d end = bond.getEnd().getPoint2d();
+            double dx = beg.x - end.x;
+            double dy = beg.y - end.y;
+            GeometryUtil.rotate(mol, pivot, Math.atan2(dx, dy) + Math.PI/2);
+            return;
+        }
 
         int[] dirhist = new int[180];