Add Transparent (premultiply alpha) blend mode

com.unity.shadergraph/Editor/Data/LightweightPipeline/LightWeightPBRSubShader.cs

             if (masterNode.IsSlotConnected(PBRMasterNode.AlphaThresholdSlotId))
                 defines.AddShaderChunk("#define _AlphaClip 1", true);
 
+            if(masterNode.alphaMode == AlphaMode.Transparent)
+                defines.AddShaderChunk("#define _ALPHAPREMULTIPLY_ON 1", true);
+
             var templateLocation = ShaderGenerator.GetTemplatePath(template);
 
             foreach (var slot in usedSlots)

com.unity.shadergraph/Editor/Data/LightweightPipeline/LightWeightUnlitSubShader.cs

             if (masterNode.IsSlotConnected(UnlitMasterNode.AlphaThresholdSlotId))
                 defines.AddShaderChunk("#define _AlphaClip 1", true);
 
+            if(masterNode.alphaMode == AlphaMode.Transparent)
+                defines.AddShaderChunk("#define _ALPHAPREMULTIPLY_ON 1", true);
+
             var templateLocation = ShaderGenerator.GetTemplatePath(template);
 
             foreach (var slot in usedSlots)

com.unity.shadergraph/Editor/Data/MasterNodes/AlphaMode.cs

     {
         Opaque,
         Fade,
+        Transparent,
         Additive,
         Multiply
     }

com.unity.shadergraph/Editor/Data/Util/ShaderGenerator.cs

                     materialOptions.renderQueue = SurfaceMaterialOptions.RenderQueue.Transparent;
                     materialOptions.renderType = SurfaceMaterialOptions.RenderType.Transparent;
                     break;
+                case AlphaMode.Transparent:
+                    materialOptions.srcBlend = SurfaceMaterialOptions.BlendMode.One;
+                    materialOptions.dstBlend = SurfaceMaterialOptions.BlendMode.OneMinusSrcAlpha;
+                    materialOptions.cullMode = twoSided ? SurfaceMaterialOptions.CullMode.Off : SurfaceMaterialOptions.CullMode.Back;
+                    materialOptions.zTest = SurfaceMaterialOptions.ZTest.LEqual;
+                    materialOptions.zWrite = SurfaceMaterialOptions.ZWrite.Off;
+                    materialOptions.renderQueue = SurfaceMaterialOptions.RenderQueue.Transparent;
+                    materialOptions.renderType = SurfaceMaterialOptions.RenderType.Transparent;
+                    break;
                 case AlphaMode.Additive:
                     materialOptions.srcBlend = SurfaceMaterialOptions.BlendMode.One;
                     materialOptions.dstBlend = SurfaceMaterialOptions.BlendMode.One;