Made rotation node default to mesh UVs if no UV input is specified.

MaterialGraphProject/Assets/UnityShaderEditor/Runtime/Nodes/UV/UVRotatorNode.cs

 using UnityEngine.Graphing;
+using System.Collections.Generic;
+using System.Linq;
-    public class UVRotatorNode : Function2Input, IGeneratesFunction
+    public class UVRotatorNode : Function2Input, IGeneratesFunction, IMayRequireMeshUV
     {
         private const string kUVSlotName = "UV";
         private const string kRotationSlotName = "Rotation";
             return new MaterialSlot(OutputSlotId, kUVSlotName, kUVSlotName, SlotType.Output, SlotValueType.Vector4, Vector4.zero);
         }
 
+        protected override string GetFunctionCallBody(string input1Value, string input2Value)
+        {
+            //get input UV slot
+            var uvName = string.Format("{0}", UVChannel.uv0.GetUVName());
+            bool isConnected = false;
+
+            var uvSlot = FindInputSlot<MaterialSlot>(InputSlot1Id);
+            if (uvSlot != null)
+            {
+                var edges = owner.GetEdges(uvSlot.slotReference).ToList();
+
+                if (edges.Count > 0)
+                {
+                    var edge = edges[0];
+                    var fromNode = owner.GetNodeFromGuid<AbstractMaterialNode>(edge.outputSlot.nodeGuid);
+                    uvName = ShaderGenerator.AdaptNodeOutput(fromNode, edge.outputSlot.slotId, ConcreteSlotValueType.Vector4, true);
+                    isConnected = true;
+                }
+            }
+
+
+            if (isConnected)
+                return GetFunctionName() + " (" + input1Value + ", " + input2Value + ")";
+            else
+                return GetFunctionName() + " (" + uvName + ", " + input2Value + ")";
+        }
+
+
             outputString.AddShaderChunk(GetFunctionPrototype("arg1", "arg2"), false);
             outputString.AddShaderChunk("{", false);
             outputString.Indent();
             outputString.AddShaderChunk("}", false);
 
             visitor.AddShaderChunk(outputString.GetShaderString(0), true);
+        }
+
+        public bool RequiresMeshUV(UVChannel channel)
+        {
+            if (channel != UVChannel.uv0)
+            {
+                return false;
+            }
+
+            var uvSlot = FindInputSlot<MaterialSlot>(InputSlot1Id);
+            if (uvSlot == null)
+                return true;
+
+            var edges = owner.GetEdges(uvSlot.slotReference).ToList();
+            return edges.Count == 0;
         }
     }
 }