Added a spherize node and fixed a bug in the checkerboatd node.

MaterialGraphProject/Assets/UnityShaderEditor/Runtime/Nodes/Procedural/CheckerboardNode.cs

             outputString.AddShaderChunk(GetFunctionPrototype("uv", "horizontalTileScale", "verticalTileScale"), false);
             outputString.AddShaderChunk("{", false);
             outputString.Indent();
-            outputString.AddShaderChunk("return floor(fmod(floor(uv.x * horizontalTileScale) + floor(uv.y * verticalTileScale), 2.0)) * float4(1.0, 1.0, 1.0, 1.0);", false);
+            outputString.AddShaderChunk("return abs(floor(fmod(floor(uv.x * horizontalTileScale) + floor(uv.y * verticalTileScale), 2.0)));", false);
             outputString.Deindent();
             outputString.AddShaderChunk("}", false);
 

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

+namespace UnityEngine.MaterialGraph
+{
+    [Title("UV/Spherize")]
+    public class SpherizeNode : Function3Input, IGeneratesFunction
+    {
+        public SpherizeNode()
+        {
+            name = "Spherize";
+        }
+
+        protected override string GetFunctionName()
+        {
+            return "unity_spherize_" + precision;
+        }
+
+        protected override string GetInputSlot1Name()
+        {
+            return "UV";
+        }
+
+        protected override MaterialSlot GetInputSlot1()
+        {
+            return new MaterialSlot(InputSlot1Id, GetInputSlot1Name(), kInputSlot1ShaderName, UnityEngine.Graphing.SlotType.Input, SlotValueType.Vector2, Vector2.zero);
+        }
+
+        protected override string GetInputSlot2Name()
+        {
+            return "Position";
+        }
+
+        protected override MaterialSlot GetInputSlot2()
+        {
+            return new MaterialSlot(InputSlot2Id, GetInputSlot2Name(), kInputSlot2ShaderName, UnityEngine.Graphing.SlotType.Input, SlotValueType.Vector2, Vector2.zero);
+        }
+
+        protected override string GetInputSlot3Name()
+        {
+            return "RadiusAndStrength";
+        }
+
+        protected override MaterialSlot GetInputSlot3()
+        {
+            return new MaterialSlot(InputSlot3Id, GetInputSlot3Name(), kInputSlot3ShaderName, UnityEngine.Graphing.SlotType.Input, SlotValueType.Vector2, Vector3.zero);
+        }
+
+        protected override MaterialSlot GetOutputSlot()
+        {
+            return new MaterialSlot(OutputSlotId, GetOutputSlotName(), kOutputSlotShaderName, UnityEngine.Graphing.SlotType.Output, SlotValueType.Vector2, Vector2.zero);
+        }
+
+        public void GenerateNodeFunction(ShaderGenerator visitor, GenerationMode generationMode)
+        {
+            var outputString = new ShaderGenerator();
+            outputString.AddShaderChunk(GetFunctionPrototype("uv", "position", "radiusAndStrength"), false);
+            outputString.AddShaderChunk("{", false);
+            outputString.Indent();
+
+            //vec2 fromUVToPoint = pos - uv;
+            //dist = length(fromUVToPoint);
+
+            //float mag = (1.0 - (dist / radius)) * strength;
+            //mag *= step(dist, radius);
+
+            //return uv + (mag * fromUVToPoint);
+
+            outputString.AddShaderChunk("float2 fromUVToPoint = position - uv;", false);
+            outputString.AddShaderChunk("float dist = length(fromUVToPoint);", false);
+            outputString.AddShaderChunk("float mag = (1.0 - (dist / radiusAndStrength.x)) * radiusAndStrength.y * step(dist, radiusAndStrength.x);", false);
+            outputString.AddShaderChunk("return uv + (mag * fromUVToPoint);", false);
+
+            outputString.Deindent();
+            outputString.AddShaderChunk("}", false);
+
+            visitor.AddShaderChunk(outputString.GetShaderString(0), true);
+        }
+    }
+}

MaterialGraphProject/Assets/UnityShaderEditor/Runtime/Nodes/UV/SpherizeNode.cs.meta

+fileFormatVersion: 2
+guid: 249d9b9165bdf234e84a85cdb8aca2aa
+timeCreated: 1495555169
+licenseType: Pro
+MonoImporter:
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: