commit c7a98f94714cf4c4cb44f62fe21feffd7b46b574
Author: Leszek Koltunski <leszek@koltunski.pl>
Date:   Fri Sep 17 15:57:39 2021 +0200

    Minor

diff --git a/src/main/java/org/distorted/objects/Movement12.java b/src/main/java/org/distorted/objects/Movement12.java
index 0ceec30e..6fc6c809 100644
--- a/src/main/java/org/distorted/objects/Movement12.java
+++ b/src/main/java/org/distorted/objects/Movement12.java
@@ -28,6 +28,7 @@ import static org.distorted.objects.TwistyObject.SQ5;
 import org.distorted.library.type.Static3D;
 
 ///////////////////////////////////////////////////////////////////////////////////////////////////
+// Dodecahedral objects: map the 2D swipes of user's fingers to 3D rotations
 
 abstract class Movement12 extends Movement
 {
diff --git a/src/main/java/org/distorted/objects/Movement4.java b/src/main/java/org/distorted/objects/Movement4.java
index 23fdbc0a..0c8f756c 100644
--- a/src/main/java/org/distorted/objects/Movement4.java
+++ b/src/main/java/org/distorted/objects/Movement4.java
@@ -22,6 +22,7 @@ package org.distorted.objects;
 import org.distorted.library.type.Static3D;
 
 ///////////////////////////////////////////////////////////////////////////////////////////////////
+// Tetrahedral objects: map the 2D swipes of user's fingers to 3D rotations
 
 abstract class Movement4 extends Movement
 {
@@ -44,10 +45,11 @@ abstract class Movement4 extends Movement
     }
 
 ///////////////////////////////////////////////////////////////////////////////////////////////////
+// Jing has nL=2
 
   public float returnRotationFactor(int numLayers, int row)
     {
-    return ((float)numLayers)/(numLayers-row);
+    return numLayers==2 ? 1.0f : ((float)numLayers)/(numLayers-row);
     }
 
 ///////////////////////////////////////////////////////////////////////////////////////////////////
diff --git a/src/main/java/org/distorted/objects/Movement6.java b/src/main/java/org/distorted/objects/Movement6.java
index 2b06ebf4..e96780c2 100644
--- a/src/main/java/org/distorted/objects/Movement6.java
+++ b/src/main/java/org/distorted/objects/Movement6.java
@@ -22,6 +22,7 @@ package org.distorted.objects;
 import org.distorted.library.type.Static3D;
 
 ///////////////////////////////////////////////////////////////////////////////////////////////////
+// Hexahedral objects: map the 2D swipes of user's fingers to 3D rotations
 
 abstract class Movement6 extends Movement
 {
diff --git a/src/main/java/org/distorted/objects/Movement8.java b/src/main/java/org/distorted/objects/Movement8.java
index c4327133..9eec9c77 100644
--- a/src/main/java/org/distorted/objects/Movement8.java
+++ b/src/main/java/org/distorted/objects/Movement8.java
@@ -22,6 +22,7 @@ package org.distorted.objects;
 import org.distorted.library.type.Static3D;
 
 ///////////////////////////////////////////////////////////////////////////////////////////////////
+// Octahedral objects: map the 2D swipes of user's fingers to 3D rotations
 
 abstract class Movement8 extends Movement
 {