Added input/output checking

MaterialGraphProject/Assets/UnityShaderEditor/Editor/Drawing/Presenters/MaterialGraphPresenter.cs

 using UnityEditor.Graphing.Drawing;
 using UnityEngine.MaterialGraph;
+using System.Collections.Generic;
+using System.Linq;
+using RMGUI.GraphView;
 
 namespace UnityEditor.MaterialGraph.Drawing
 {
 			typeMapper[typeof(BlendModeNode)] = typeof(BlendModeNodePresenter);
             typeMapper[typeof(AddManyNode)] = typeof(AddManyNodePresenter);
             typeMapper[typeof(IfNode)] = typeof(IfNodePresenter);
+        }
+
+		public override List<NodeAnchorPresenter> GetCompatibleAnchors(NodeAnchorPresenter startAnchor, NodeAdapter nodeAdapter)
+        {
+			return allChildren.OfType<NodeAnchorPresenter>()
+                              .Where(nap => nap.IsConnectable() &&
+                                     nap.orientation == startAnchor.orientation &&
+                                     nap.direction != startAnchor.direction &&
+                                     nodeAdapter.GetAdapter(nap.source, startAnchor.source) != null && 
+									(startAnchor is GraphAnchorPresenter && ((GraphAnchorPresenter)nap).slot is MaterialSlot && 
+									((MaterialSlot)((GraphAnchorPresenter)startAnchor).slot).IsCompatibleWithInputSlotType(((MaterialSlot)((GraphAnchorPresenter)nap).slot).valueType)))
+                              .ToList();
         }
     }
 }

MaterialGraphProject/Assets/UnityShaderEditor/Runtime/Nodes/MaterialSlot.cs

             visitor.AddShaderChunk(matOwner.precision + AbstractMaterialNode.ConvertConcreteSlotValueTypeToString(concreteValueType) + " " + matOwner.GetVariableNameForSlot(id) + ";", true);
         }
 
+		public bool IsCompatibleWithInputSlotType(SlotValueType inputType)
+		{
+			return (inputType == SlotValueType.Dynamic || valueType == SlotValueType.Vector1 || valueType <= inputType);
+		}
+
         public string GetDefaultValue(GenerationMode generationMode)
         {
             var matOwner = owner as AbstractMaterialNode;