A custom lighting node example for Shader Graph and Lightweight Render Pipeline

MainLightNode.cs

using UnityEngine;
using UnityEditor.Graphing;

namespace UnityEditor.ShaderGraph
{
   [Title("Input", "Lighting", "Main Light")]
   public class MainLightNode : AbstractMaterialNode, IGeneratesBodyCode
   {
        public MainLightNode()
        {
            name = "Main Light";
            UpdateNodeAfterDeserialization();
        }

        public override bool hasPreview { get { return false; } }

        const string kPositionSlotName = "Position";
        const string kDirectionSlotName = "Direction";
        const string kAttenuationSlotName = "Attenuation";
        const string kColorSlotName = "Color";

        public const int PositionSlotId = 0;
        public const int DirectionSlotId = 1;
        public const int AttenuationSlotId = 2;
        public const int ColorSlotId = 3;

        public sealed override void UpdateNodeAfterDeserialization()
        {
            AddSlot(new Vector3MaterialSlot(PositionSlotId, kPositionSlotName, kPositionSlotName, SlotType.Input, Vector3.zero));
            AddSlot(new Vector3MaterialSlot(DirectionSlotId, kDirectionSlotName, kDirectionSlotName, SlotType.Output, Vector3.zero));
            AddSlot(new Vector1MaterialSlot(AttenuationSlotId, kAttenuationSlotName, kAttenuationSlotName, SlotType.Output, 0));
            AddSlot(new Vector3MaterialSlot(ColorSlotId, kColorSlotName, kColorSlotName, SlotType.Output, Vector3.zero));
            RemoveSlotsNameNotMatching(new[] { PositionSlotId, DirectionSlotId, AttenuationSlotId, ColorSlotId });
        }

        public void GenerateNodeCode(ShaderGenerator visitor, GenerationMode generationMode)
        {
            ShaderStringBuilder sb = new ShaderStringBuilder();
            if(generationMode != GenerationMode.Preview)
            {
                sb.AppendLine("Light {0}_Light = GetMainLight({1});", GetVariableNameForNode(), GetSlotValue(PositionSlotId, generationMode));
                sb.AppendLine("{0} {1} = {2}_Light.direction;"
                    , FindOutputSlot<MaterialSlot>(DirectionSlotId).concreteValueType.ToString(precision)
                    , GetVariableNameForSlot(DirectionSlotId)
                    , GetVariableNameForNode());
                sb.AppendLine("{0} {1} = {2}_Light.attenuation;"
                    , FindOutputSlot<MaterialSlot>(AttenuationSlotId).concreteValueType.ToString(precision)
                    , GetVariableNameForSlot(AttenuationSlotId)
                    , GetVariableNameForNode());
                sb.AppendLine("{0} {1} = {2}_Light.color;"
                    , FindOutputSlot<MaterialSlot>(ColorSlotId).concreteValueType.ToString(precision)
                    , GetVariableNameForSlot(ColorSlotId)
                    , GetVariableNameForNode());
            }
            else
            {
                sb.AppendLine("{0} {1} = {2}3 (0.5, 0.5, -0.25);"
                    , FindOutputSlot<MaterialSlot>(DirectionSlotId).concreteValueType.ToString(precision)
                    , GetVariableNameForSlot(DirectionSlotId)
                    , precision);
                sb.AppendLine("{0} {1} = 1;"
                    , FindOutputSlot<MaterialSlot>(AttenuationSlotId).concreteValueType.ToString(precision)
                    , GetVariableNameForSlot(AttenuationSlotId));
                sb.AppendLine("{0} {1} = {2}3 (1, 1, 1);"
                    , FindOutputSlot<MaterialSlot>(ColorSlotId).concreteValueType.ToString(precision)
                    , GetVariableNameForSlot(ColorSlotId)
                    , precision);
            }
            visitor.AddShaderChunk(sb.ToString(), true);
        }
   }
}