Move actual preview rendering into PreviewManager

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

 using UnityEngine;
 using UnityEditor.Graphing;
 using UnityEditor.ShaderGraph;
+using UnityEngine.Rendering;
 using Object = UnityEngine.Object;
 
 namespace UnityEditor.ShaderGraph.Drawing
         HashSet<Guid> m_TimeDependentPreviews = new HashSet<Guid>();
         Material m_PreviewMaterial;
         MaterialPropertyBlock m_PreviewPropertyBlock;
-        MaterialGraphPreviewGenerator m_PreviewGenerator = new MaterialGraphPreviewGenerator();
+        PreviewSceneResources m_SceneResources;
         Texture2D m_ErrorTexture;
         DateTime m_LastUpdate;
 
             m_ErrorTexture.SetPixel(1, 1, Color.magenta);
             m_ErrorTexture.filterMode = FilterMode.Point;
             m_ErrorTexture.Apply();
+            m_SceneResources = new PreviewSceneResources();
 
             foreach (var node in m_Graph.GetNodes<INode>())
                 AddPreview(node);
                 }
                 var node = m_Graph.GetNodeFromGuid(nodeGuid);
                 m_PreviewMaterial.shader = previewData.shader;
-                m_PreviewGenerator.DoRenderPreview(previewData.renderTexture, m_PreviewMaterial, previewData.mesh, previewData.previewMode, node is IMasterNode, time, m_PreviewPropertyBlock);
+
+                if (previewData.previewMode == PreviewMode.Preview3D)
+                {
+                    m_SceneResources.camera.transform.position = -Vector3.forward * 5;
+                    m_SceneResources.camera.transform.rotation = Quaternion.identity;
+                    m_SceneResources.camera.orthographic = false;
+                }
+                else
+                {
+                    m_SceneResources.camera.transform.position = -Vector3.forward * 2;
+                    m_SceneResources.camera.transform.rotation = Quaternion.identity;
+                    m_SceneResources.camera.orthographicSize = 1;
+                    m_SceneResources.camera.orthographic = true;
+                }
+
+                m_SceneResources.camera.targetTexture = previewData.renderTexture;
+                var previousRenderTexure = RenderTexture.active;
+                RenderTexture.active = previewData.renderTexture;
+
+                GL.Clear(true, true, Color.black);
+                Graphics.Blit(Texture2D.whiteTexture, previewData.renderTexture, m_SceneResources.checkerboardMaterial);
+
+                EditorUtility.SetCameraAnimateMaterialsTime(m_SceneResources.camera, time);
+                m_SceneResources.light0.enabled = true;
+                m_SceneResources.light0.intensity = 1.0f;
+                m_SceneResources.light0.transform.rotation = Quaternion.Euler(50f, 50f, 0);
+                m_SceneResources.light1.enabled = true;
+                m_SceneResources.light1.intensity = 1.0f;
+                m_SceneResources.camera.clearFlags = CameraClearFlags.Depth;
+
+                Mesh mesh = previewData.previewMode == PreviewMode.Preview2D ? m_SceneResources.quad : (previewData.mesh ?? m_SceneResources.sphere);
+                Graphics.DrawMesh(
+                    mesh,
+                    previewData.previewMode == PreviewMode.Preview3D ? Matrix4x4.TRS(-mesh.bounds.center, Quaternion.identity, Vector3.one) : Matrix4x4.identity,
+                    m_PreviewMaterial,
+                    1,
+                    m_SceneResources.camera,
+                    0,
+                    m_PreviewPropertyBlock,
+                    ShadowCastingMode.Off,
+                    false,
+                    null,
+                    false);
+
+                var previousUseSRP = Unsupported.useScriptableRenderPipeline;
+                Unsupported.useScriptableRenderPipeline = node is IMasterNode;
+                m_SceneResources.camera.Render();
+                Unsupported.useScriptableRenderPipeline = previousUseSRP;
+                RenderTexture.active = previousRenderTexure;
+                m_SceneResources.light0.enabled = false;
+                m_SceneResources.light1.enabled = false;
+
                 previewData.texture = previewData.renderTexture;
             }
 
             if (m_PreviewMaterial != null)
                 Object.DestroyImmediate(m_PreviewMaterial, true);
             m_PreviewMaterial = null;
-            if (m_PreviewGenerator != null)
-                m_PreviewGenerator.Dispose();
-            m_PreviewGenerator = null;
+            if (m_SceneResources != null)
+                m_SceneResources.Dispose();
+            m_SceneResources = null;
             var previews = m_Previews.ToList();
             foreach (var kvp in previews)
                 DestroyPreview(kvp.Key, kvp.Value);

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

+using System;
+using UnityEditor.SceneManagement;
+using UnityEngine;
+using UnityEngine.SceneManagement;
+
+namespace UnityEditor.ShaderGraph.Drawing
+{
+    public class PreviewSceneResources : IDisposable
+    {
+        readonly Scene m_Scene;
+        static Mesh s_Quad;
+        Camera m_Camera;
+        public Light light0 { get; private set; }
+        public Light light1 { get; private set; }
+
+        Material m_CheckerboardMaterial;
+
+        static readonly Mesh[] s_Meshes = { null, null, null, null, null };
+        static readonly GUIContent[] s_MeshIcons = { null, null, null, null, null };
+        static readonly GUIContent[] s_LightIcons = { null, null };
+        static readonly GUIContent[] s_TimeIcons = { null, null };
+
+        static GameObject CreateLight()
+        {
+            GameObject lightGO = EditorUtility.CreateGameObjectWithHideFlags("PreRenderLight", HideFlags.HideAndDontSave, typeof(Light));
+            var light = lightGO.GetComponent<Light>();
+            light.type = LightType.Directional;
+            light.intensity = 1.0f;
+            light.enabled = false;
+            return lightGO;
+        }
+
+        public PreviewSceneResources()
+        {
+            m_Scene = EditorSceneManager.NewPreviewScene();
+            var camGO = EditorUtility.CreateGameObjectWithHideFlags("Preview Scene Camera", HideFlags.HideAndDontSave, typeof(Camera));
+            SceneManager.MoveGameObjectToScene(camGO, m_Scene);
+
+            m_Camera = camGO.GetComponent<Camera>();
+            EditorUtility.SetCameraAnimateMaterials(camera, true);
+
+            camera.cameraType = CameraType.Preview;
+            camera.enabled = false;
+            camera.clearFlags = CameraClearFlags.Depth;
+            camera.fieldOfView = 15;
+            camera.farClipPlane = 10.0f;
+            camera.nearClipPlane = 2.0f;
+            camera.backgroundColor = new Color(49.0f / 255.0f, 49.0f / 255.0f, 49.0f / 255.0f, 1.0f);
+
+            // Explicitly use forward rendering for all previews
+            // (deferred fails when generating some static previews at editor launch; and we never want
+            // vertex lit previews if that is chosen in the player settings)
+            camera.renderingPath = RenderingPath.Forward;
+            camera.useOcclusionCulling = false;
+            camera.scene = m_Scene;
+
+            var l0 = CreateLight();
+            SceneManager.MoveGameObjectToScene(l0, m_Scene);
+
+            //previewScene.AddGameObject(l0);
+            light0 = l0.GetComponent<Light>();
+
+            var l1 = CreateLight();
+            SceneManager.MoveGameObjectToScene(l1, m_Scene);
+
+            //previewScene.AddGameObject(l1);
+            light1 = l1.GetComponent<Light>();
+
+            light0.color = new Color(0.769f, 0.769f, 0.769f, 1); // SceneView.kSceneViewFrontLight
+            light1.transform.rotation = Quaternion.Euler(340, 218, 177);
+            light1.color = new Color(.4f, .4f, .45f, 0f) * .7f;
+
+            m_CheckerboardMaterial = new Material(Shader.Find("Hidden/Checkerboard"));
+            checkerboardMaterial.shader.hideFlags = HideFlags.HideAndDontSave;
+            checkerboardMaterial.hideFlags = HideFlags.HideAndDontSave;
+
+            if (s_Meshes[0] == null)
+            {
+                var handleGo = (GameObject)EditorGUIUtility.LoadRequired("Previews/PreviewMaterials.fbx");
+
+                // @TODO: temp workaround to make it not render in the scene
+                handleGo.SetActive(false);
+                foreach (Transform t in handleGo.transform)
+                {
+                    var meshFilter = t.GetComponent<MeshFilter>();
+                    switch (t.name)
+                    {
+                        case "sphere":
+                            s_Meshes[0] = meshFilter.sharedMesh;
+                            break;
+                        case "cube":
+                            s_Meshes[1] = meshFilter.sharedMesh;
+                            break;
+                        case "cylinder":
+                            s_Meshes[2] = meshFilter.sharedMesh;
+                            break;
+                        case "torus":
+                            s_Meshes[3] = meshFilter.sharedMesh;
+                            break;
+                        default:
+                            Debug.Log("Something is wrong, weird object found: " + t.name);
+                            break;
+                    }
+                }
+
+                s_MeshIcons[0] = EditorGUIUtility.IconContent("PreMatSphere");
+                s_MeshIcons[1] = EditorGUIUtility.IconContent("PreMatCube");
+                s_MeshIcons[2] = EditorGUIUtility.IconContent("PreMatCylinder");
+                s_MeshIcons[3] = EditorGUIUtility.IconContent("PreMatTorus");
+                s_MeshIcons[4] = EditorGUIUtility.IconContent("PreMatQuad");
+
+                s_LightIcons[0] = EditorGUIUtility.IconContent("PreMatLight0");
+                s_LightIcons[1] = EditorGUIUtility.IconContent("PreMatLight1");
+
+                s_TimeIcons[0] = EditorGUIUtility.IconContent("PlayButton");
+                s_TimeIcons[1] = EditorGUIUtility.IconContent("PauseButton");
+
+                Mesh quadMesh = Resources.GetBuiltinResource(typeof(Mesh), "Quad.fbx") as Mesh;
+                s_Meshes[4] = quadMesh;
+            }
+
+            if (s_Quad == null)
+            {
+                var vertices = new[]
+                {
+                    new Vector3(-1f, -1f, 0f),
+                    new Vector3(1f, 1f, 0f),
+                    new Vector3(1f, -1f, 0f),
+                    new Vector3(-1f, 1f, 0f)
+                };
+
+                var uvs = new[]
+                {
+                    new Vector2(0f, 0f),
+                    new Vector2(1f, 1f),
+                    new Vector2(1f, 0f),
+                    new Vector2(0f, 1f)
+                };
+
+                var indices = new[] { 0, 1, 2, 1, 0, 3 };
+
+                s_Quad = new Mesh
+                {
+                    vertices = vertices,
+                    uv = uvs,
+                    triangles = indices
+                };
+                s_Quad.RecalculateNormals();
+                s_Quad.RecalculateBounds();
+            }
+        }
+
+        public Mesh sphere
+        {
+            get { return s_Meshes[0]; }
+        }
+
+        public Mesh quad
+        {
+            get { return s_Quad; }
+        }
+
+        public Material checkerboardMaterial
+        {
+            get { return m_CheckerboardMaterial; }
+        }
+
+        public Camera camera
+        {
+            get { return m_Camera; }
+        }
+
+        public void Dispose()
+        {
+            if (light0 != null)
+            {
+                UnityEngine.Object.DestroyImmediate(light0.gameObject);
+                light0 = null;
+            }
+
+            if (light1 != null)
+            {
+                UnityEngine.Object.DestroyImmediate(light1.gameObject);
+                light1 = null;
+            }
+
+            if (camera != null)
+            {
+                UnityEngine.Object.DestroyImmediate(camera.gameObject);
+                m_Camera = null;
+            }
+
+            if (checkerboardMaterial != null)
+            {
+                UnityEngine.Object.DestroyImmediate(checkerboardMaterial);
+                m_CheckerboardMaterial = null;
+            }
+
+            EditorSceneManager.ClosePreviewScene(m_Scene);
+        }
+    }
+}

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

+fileFormatVersion: 2
+guid: 37873c3b010e40d1ac1e6aace3c0fb10
+timeCreated: 1510662606