Add an index to RequiresMeshUV, allows require UV1 to UV3

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

             if (uvSlot == null)
                 return;
 
-            var uvName = string.Format("{0}.xy", ShaderGeneratorNames.UV0);
+            var uvName = string.Format("{0}.xy", ShaderGeneratorNames.UV[0]);
             var edges = owner.GetEdges(uvSlot.slotReference).ToList();
 
             if (edges.Count > 0)
 
         public override PropertyType propertyType { get { return PropertyType.Texture2D; } }
 
-        public bool RequiresMeshUV()
+        public bool RequiresMeshUV(int index)
+            if (index != 0)
+            {
+                return false;
+            }
+
             var uvSlot = FindInputSlot<MaterialSlot>(UvSlotId);
             if (uvSlot == null)
                 return true;

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

 {
     interface IMayRequireMeshUV
     {
-        bool RequiresMeshUV();
+        bool RequiresMeshUV(int index);
     }
 
     [Title("Input/UV Node")]
 
         public void GenerateNodeCode(ShaderGenerator visitor, GenerationMode generationMode)
         {
-            visitor.AddShaderChunk(precision + "4 " + GetVariableNameForSlot(OutputSlotId) + " = " + ShaderGeneratorNames.UV0 + ";", true);
+            visitor.AddShaderChunk(precision + "4 " + GetVariableNameForSlot(OutputSlotId) + " = " + ShaderGeneratorNames.UV[0] + ";", true);
-        public bool RequiresMeshUV()
+        public bool RequiresMeshUV(int index)
-            return true;
+            return index == 0;
         }
     }
 }

MaterialGraphProject/Assets/UnityShaderEditor/Runtime/SubGraph/SubGraphNode.cs

             return subGraph.activeNodes.OfType<IMayRequireNormal>().Any(x => x.RequiresNormal());
         }
 
-        public bool RequiresMeshUV()
+        public bool RequiresMeshUV(int index)
-            return subGraph.activeNodes.OfType<IMayRequireMeshUV>().Any(x => x.RequiresMeshUV());
+            return subGraph.activeNodes.OfType<IMayRequireMeshUV>().Any(x => x.RequiresMeshUV(index));
         }
 
         public bool RequiresScreenPosition()

MaterialGraphProject/Assets/UnityShaderEditor/Runtime/SurfaceModel/AbstractSurfaceMasterNode.cs

             // always add color because why not.
             shaderInputVisitor.AddShaderChunk("float4 color : COLOR;", true);
 
-            if (activeNodeList.OfType<IMayRequireMeshUV>().Any(x => x.RequiresMeshUV()))
+            for (int uvIndex = 0; uvIndex < ShaderGeneratorNames.UV.Length; ++uvIndex)
-                shaderInputVisitor.AddShaderChunk("half4 meshUV0;", true);
-                vertexShaderBlock.AddShaderChunk("o.meshUV0 = v.texcoord;", true);
-                shaderBody.AddShaderChunk("half4 " + ShaderGeneratorNames.UV0 + " = IN.meshUV0;", true);
+                if (activeNodeList.OfType<IMayRequireMeshUV>().Any(x => x.RequiresMeshUV(uvIndex)))
+                {
+                    shaderInputVisitor.AddShaderChunk(string.Format("half4 meshUV{0};", uvIndex), true);
+                    vertexShaderBlock.AddShaderChunk(string.Format("o.meshUV{0} = v.texcoord{1};", uvIndex, uvIndex == 0 ? "" : uvIndex.ToString()), true);
+                    shaderBody.AddShaderChunk(string.Format("half4 {0} = IN.meshUV{1};", ShaderGeneratorNames.UV[uvIndex], uvIndex), true);
+                }
             }
 
             if (activeNodeList.OfType<IMayRequireViewDirection>().Any(x => x.RequiresViewDirection()))

MaterialGraphProject/Assets/UnityShaderEditor/Runtime/Util/ShaderGenerator.cs

         public const string WorldSpaceViewDirection = "worldSpaceViewDirection";
         public const string ScreenPosition = "screenPosition";
         public const string VertexColor = "vertexColor";
-        public const string UV0 = "uv0";
+        public static string[] UV = { "uv0", "uv1", "uv2", "uv3" };
     }
 
     public class ShaderGenerator
                 shaderBodyVisitor.AddShaderChunk("float3 " + ShaderGeneratorNames.WorldSpaceNormal + " = normalize(IN.worldNormal);", true);
             }
 
-            if (activeNodeList.OfType<IMayRequireMeshUV>().Any(x => x.RequiresMeshUV()))
+            for (int uvIndex = 0; uvIndex < ShaderGeneratorNames.UV.Length; ++uvIndex)
-                shaderInputVisitor.AddShaderChunk("half4 meshUV0 : TEXCOORD2;", true);
-                vertexShaderBlock.AddShaderChunk("o.meshUV0 = v.texcoord;", true);
-                shaderBodyVisitor.AddShaderChunk("half4 " + ShaderGeneratorNames.UV0 + " = IN.meshUV0;", true);
+                if (activeNodeList.OfType<IMayRequireMeshUV>().Any(x => x.RequiresMeshUV(uvIndex)))
+                {
+                    shaderInputVisitor.AddShaderChunk(string.Format("half4 meshUV{0} : TEXCOORD{1};", uvIndex, (uvIndex + 5)), true);
+                    vertexShaderBlock.AddShaderChunk(string.Format("o.meshUV{0} = v.texcoord{1};", uvIndex, uvIndex == 0 ? "" : uvIndex.ToString()), true);
+                    shaderBodyVisitor.AddShaderChunk(string.Format("half4 {0} = IN.meshUV{1};", ShaderGeneratorNames.UV[uvIndex], uvIndex), true);
+                }
             }
 
             if (activeNodeList.OfType<IMayRequireViewDirection>().Any(x => x.RequiresViewDirection()))