[fix]Fix preview blending when you have alpha

MaterialGraphProject/Assets/UnityShaderEditor/Editor/Drawing/PreviewManager.cs

             m_PreviewPropertyBlock.SetFloat(m_OutputIdName, renderData.shaderData.node.tempId.index);
             if (m_PreviewMaterial.shader != renderData.shaderData.shader)
                 m_PreviewMaterial.shader = renderData.shaderData.shader;
-            m_SceneResources.camera.targetTexture = renderData.renderTexture;
-            RenderTexture.active = renderData.renderTexture;
+
+
+            //Temp workaround for alpha previews...
+            var temp = RenderTexture.GetTemporary(renderData.renderTexture.descriptor);
+            RenderTexture.active = temp;
-            Graphics.Blit(Texture2D.whiteTexture, renderData.renderTexture, m_SceneResources.checkerboardMaterial);
+            Graphics.Blit(Texture2D.whiteTexture, temp, m_SceneResources.checkerboardMaterial);
-            Graphics.DrawMesh(mesh, transform, m_PreviewMaterial, 1, m_SceneResources.camera, 0, m_PreviewPropertyBlock, ShadowCastingMode.Off, false, null, false);
+            m_SceneResources.camera.targetTexture = temp;
+             Graphics.DrawMesh(mesh, transform, m_PreviewMaterial, 1, m_SceneResources.camera, 0, m_PreviewPropertyBlock, ShadowCastingMode.Off, false, null, false);
-            var previousUseSRP = Unsupported.useScriptableRenderPipeline;
-            Unsupported.useScriptableRenderPipeline = renderData.shaderData.node is IMasterNode;
-            m_SceneResources.camera.Render();
-            Unsupported.useScriptableRenderPipeline = previousUseSRP;
+             var previousUseSRP = Unsupported.useScriptableRenderPipeline;
+             Unsupported.useScriptableRenderPipeline = renderData.shaderData.node is IMasterNode;
+             m_SceneResources.camera.Render();
+             Unsupported.useScriptableRenderPipeline = previousUseSRP;
+
+            Graphics.Blit(temp, renderData.renderTexture, m_SceneResources.blitNoAlphaMaterial);
+            RenderTexture.ReleaseTemporary(temp);
+
             RenderTexture.active = previousRenderTexure;
             renderData.texture = renderData.renderTexture;
         }

MaterialGraphProject/Assets/UnityShaderEditor/Editor/Drawing/Views/PreviewSceneResources.cs

         public Light light1 { get; private set; }
 
         Material m_CheckerboardMaterial;
+        Material m_BlitNoAlphaMaterial;
 
         static readonly Mesh[] s_Meshes = { null, null, null, null, null };
         static readonly GUIContent[] s_MeshIcons = { null, null, null, null, null };
             light1.color = new Color(.4f, .4f, .45f, 0f) * .7f;
 
             m_CheckerboardMaterial = new Material(Shader.Find("Hidden/Checkerboard"));
+            m_BlitNoAlphaMaterial = new Material(Shader.Find("Hidden/BlitNoAlpha"));
+            blitNoAlphaMaterial.hideFlags = HideFlags.HideAndDontSave;
 
             if (s_Meshes[0] == null)
             {
         public Material checkerboardMaterial
         {
             get { return m_CheckerboardMaterial; }
+        }
+
+        public Material blitNoAlphaMaterial
+        {
+            get { return m_BlitNoAlphaMaterial; }
         }
 
         public Camera camera

MaterialGraphProject/Assets/UnityShaderEditor/Editor/Templates/lightweightPBRForwardPass.template

 		// Computes fog factor per-vertex
     	ApplyFog(color.rgb, IN.fogFactorAndVertexLight.x);
 
-#if _AlphaOut
-		color.a = Alpha;
-#else
-		color.a = 1;
-#endif
-
 #if _AlphaClip
 		clip(Alpha - AlphaClipThreshold);
 #endif

MaterialGraphProject/Assets/UnityShaderEditor/Editor/Resources/Shaders/BlitNoAlpha.shader

+Shader "Hidden/BlitNoAlpha"
+{
+    Properties
+    {
+        _MainTex ("Texture", any) = "" {}
+    }
+    SubShader {
+        Pass {
+            ZTest Always Cull Off ZWrite Off
+
+            CGPROGRAM
+            #pragma vertex vert
+            #pragma fragment frag
+            #include "UnityCG.cginc"
+
+            UNITY_DECLARE_SCREENSPACE_TEXTURE(_MainTex);
+            uniform float4 _MainTex_ST;
+
+            struct appdata_t {
+                float4 vertex : POSITION;
+                float2 texcoord : TEXCOORD0;
+                UNITY_VERTEX_INPUT_INSTANCE_ID
+            };
+
+            struct v2f {
+                float4 vertex : SV_POSITION;
+                float2 texcoord : TEXCOORD0;
+                UNITY_VERTEX_OUTPUT_STEREO
+            };
+
+            v2f vert (appdata_t v)
+            {
+                v2f o;
+                UNITY_SETUP_INSTANCE_ID(v);
+                UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(o);
+                o.vertex = UnityObjectToClipPos(v.vertex);
+                o.texcoord = TRANSFORM_TEX(v.texcoord.xy, _MainTex);
+                return o;
+            }
+
+            fixed4 frag (v2f i) : SV_Target
+            {
+                UNITY_SETUP_STEREO_EYE_INDEX_POST_VERTEX(i);
+                return half4(UNITY_SAMPLE_SCREENSPACE_TEXTURE(_MainTex, i.texcoord).xyz, 1.0);
+            }
+            ENDCG
+
+        }
+    }
+    Fallback Off
+}

MaterialGraphProject/Assets/UnityShaderEditor/Editor/Resources/Shaders/BlitNoAlpha.shader.meta

+fileFormatVersion: 2
+guid: 50b406436c6214c49aaaa6011b71dde8
+timeCreated: 1502007198
+licenseType: Pro
+ShaderImporter:
+  externalObjects: {}
+  defaultTextures: []
+  nonModifiableTextures: []
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: