PreviewTarget.cs

using System;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Rendering;
using UnityEngine.UIElements;

namespace UnityEditor.ShaderGraph
{
    sealed class PreviewTarget : Target
    {
        static readonly GUID kSourceCodeGuid = new GUID("7464b9fcde08e5645a16b9b8ae1e573c"); // PreviewTarget.cs

        private bool isUITKPreview = false;

        public PreviewTarget() : this(false)
        {
        }

        public PreviewTarget(bool isUITKPreview)
        {
            displayName = "Preview";
            isHidden = true;
            this.isUITKPreview = isUITKPreview;
        }

        public override bool IsActive() => false;
        internal override bool ignoreCustomInterpolators => false;

        public override void Setup(ref TargetSetupContext context)
        {
            context.AddAssetDependency(kSourceCodeGuid, AssetCollection.Flags.SourceDependency);
            context.AddSubShader(SubShaders.GetPreview(isUITKPreview));
        }

        public override void GetFields(ref TargetFieldContext context)
        {
        }

        public override void GetActiveBlocks(ref TargetActiveBlockContext context)
        {
        }

        public override void GetPropertiesGUI(ref TargetPropertyGUIContext context, Action onChange, Action<String> registerUndo)
        {
        }

        public override bool WorksWithSRP(RenderPipelineAsset scriptableRenderPipeline) => true;

        static class SubShaders
        {
            public static SubShaderDescriptor GetPreview(bool isUITKPreview)
            {
                var preview = new SubShaderDescriptor()
                {
                    renderQueue = "Geometry",
                    renderType = "Opaque",
                    generatesPreview = true,
                    passes = new PassCollection { Passes.GetPreview(isUITKPreview) },
                };

                return preview;
            }
        }

        static class Passes
        {
            public static PassDescriptor GetPreview(bool isUITKPreview)
            {
                var pass = new PassDescriptor()
                {
                    // Definition
                    referenceName = "SHADERPASS_PREVIEW",
                    useInPreview = true,

                    // Templates
                    passTemplatePath = GenerationUtils.GetDefaultTemplatePath("PassMesh.template"),
                    sharedTemplateDirectories = GenerationUtils.GetDefaultSharedTemplateDirectories(),

                    // Collections
                    structs = new StructCollection
                    {
                        { Structs.Attributes },
                        { StructDescriptors.PreviewVaryings },
                        { Structs.SurfaceDescriptionInputs },
                        { Structs.VertexDescriptionInputs },
                    },
                    fieldDependencies = FieldDependencies.Default,
                    pragmas = new PragmaCollection
                    {
                        { Pragma.Vertex("vert") },
                        { Pragma.Fragment("frag") },
                    },
                    defines = new DefineCollection
                    {
                        { KeywordDescriptors.PreviewKeyword, 1 },
                        { KeywordDescriptors.UITKPreviewKeyword, isUITKPreview ? 1 : 0 }
                    },
                    includes = new IncludeCollection
                    {
                        // Pre-graph
                        { "Packages/com.unity.render-pipelines.core/ShaderLibrary/Common.hlsl", IncludeLocation.Pregraph },
                        { "Packages/com.unity.render-pipelines.core/ShaderLibrary/Packing.hlsl", IncludeLocation.Pregraph },
                        { "Packages/com.unity.render-pipelines.core/ShaderLibrary/TextureStack.hlsl", IncludeLocation.Pregraph },       // TODO: put this on a conditional
                        { "Packages/com.unity.render-pipelines.core/ShaderLibrary/NormalSurfaceGradient.hlsl", IncludeLocation.Pregraph },
                        { "Packages/com.unity.render-pipelines.core/ShaderLibrary/Color.hlsl", IncludeLocation.Pregraph },
                        { "Packages/com.unity.render-pipelines.core/ShaderLibrary/Texture.hlsl", IncludeLocation.Pregraph },
                        { "Packages/com.unity.render-pipelines.core/ShaderLibrary/UnityInstancing.hlsl", IncludeLocation.Pregraph },
                        { "Packages/com.unity.render-pipelines.core/ShaderLibrary/EntityLighting.hlsl", IncludeLocation.Pregraph },
                        { "Packages/com.unity.shadergraph/ShaderGraphLibrary/ShaderVariables.hlsl", IncludeLocation.Pregraph },
                        { "Packages/com.unity.shadergraph/ShaderGraphLibrary/ShaderVariablesFunctions.hlsl", IncludeLocation.Pregraph },
                        { "Packages/com.unity.shadergraph/ShaderGraphLibrary/Functions.hlsl", IncludeLocation.Pregraph },
                        { "Packages/com.unity.shadergraph/Editor/Generation/Targets/BuiltIn/ShaderLibrary/Shim/UIShimPreview.hlsl", IncludeLocation.Pregraph },

                        // Post-graph
                        { "Packages/com.unity.shadergraph/ShaderGraphLibrary/PreviewVaryings.hlsl", IncludeLocation.Postgraph },
                        { "Packages/com.unity.shadergraph/ShaderGraphLibrary/PreviewPass.hlsl", IncludeLocation.Postgraph },
                    }
                };

                return pass;
            }
        }

        static class StructDescriptors
        {
            public static StructDescriptor PreviewVaryings = new StructDescriptor()
            {
                name = "Varyings",
                packFields = true,
                fields = new[]
                {
                    StructFields.Varyings.positionCS,
                    StructFields.Varyings.positionWS,
                    StructFields.Varyings.positionPredisplacementWS,
                    StructFields.Varyings.normalWS,
                    StructFields.Varyings.tangentWS,
                    StructFields.Varyings.texCoord0,
                    StructFields.Varyings.texCoord1,
                    StructFields.Varyings.texCoord2,
                    StructFields.Varyings.texCoord3,
                    StructFields.Varyings.texCoord4,
                    StructFields.Varyings.texCoord5,
                    StructFields.Varyings.texCoord6,
                    StructFields.Varyings.texCoord7,
                    StructFields.Varyings.color,
                    StructFields.Varyings.screenPosition,
                    StructFields.Varyings.instanceID,
                    StructFields.Varyings.vertexID,
                    StructFields.Varyings.cullFace,
                }
            };
        }

        static class KeywordDescriptors
        {
            public static KeywordDescriptor PreviewKeyword = new KeywordDescriptor()
            {
                displayName = "Preview",
                referenceName = "SHADERGRAPH_PREVIEW",
                type = KeywordType.Boolean,
                definition = KeywordDefinition.MultiCompile,
                scope = KeywordScope.Global,
                stages = KeywordShaderStage.All,
            };
            public static KeywordDescriptor UITKPreviewKeyword = new KeywordDescriptor()
            {
                displayName = "UITK Preview",
                referenceName = "UITK_PREVIEW",
                type = KeywordType.Boolean,
                definition = KeywordDefinition.MultiCompile,
                scope = KeywordScope.Global,
                stages = KeywordShaderStage.All,
            };
        }
    }
}