Cycles: Fix missing viewport updates after recent changes

We can not access ensured-to-be-evaluated dependency graph from the
render API: some of it is running from within evaluation which makes
it possible for engines to access list of evaluated IDs.

Solved by passing dependency graph to viewport functions, similar to
the final render functions.

doc/python_api/examples/bpy.types.RenderEngine.py

@@ -55,10 +55,9 @@ class CustomRenderEngine(bpy.types.RenderEngine):
     # whenever the scene or 3D viewport changes. This method is where data
     # should be read from Blender in the same thread. Typically a render
     # thread will be started to do the work while keeping Blender responsive.
-    def view_update(self, context):
+    def view_update(self, context, depsgraph):
         region = context.region
         view3d = context.space_data
-        depsgraph = context.depsgraph
         scene = depsgraph.scene
 
         # Get viewport dimensions
@@ -93,9 +92,8 @@ class CustomRenderEngine(bpy.types.RenderEngine):
     # with OpenGL, and not perform other expensive work.
     # Blender will draw overlays for selection and editing on top of the
     # rendered image automatically.
-    def view_draw(self, context):
+    def view_draw(self, context, depsgraph):
         region = context.region
-        depsgraph = context.depsgraph
         scene = depsgraph.scene
 
         # Get viewport dimensions

intern/cycles/blender/addon/__init__.py

@@ -87,8 +87,7 @@ class CyclesRender(bpy.types.RenderEngine):
         engine.bake(self, depsgraph, obj, pass_type, pass_filter, object_id, pixel_array, num_pixels, depth, result)
 
     # viewport render
-    def view_update(self, context):
-        depsgraph = context.evaluated_depsgraph_get()
+    def view_update(self, context, depsgraph):
         if not self.session:
             engine.create(self, context.blend_data,
                           context.region, context.space_data, context.region_data)
@@ -96,8 +95,7 @@ class CyclesRender(bpy.types.RenderEngine):
         engine.reset(self, context.blend_data, depsgraph)
         engine.sync(self, depsgraph, context.blend_data)
 
-    def view_draw(self, context):
-        depsgraph = context.evaluated_depsgraph_get()
+    def view_draw(self, context, depsgraph):
         engine.draw(self, depsgraph, context.region, context.space_data, context.region_data)
 
     def update_script_node(self, node):

source/blender/draw/engines/external/external_engine.c

@@ -221,7 +221,7 @@ static void external_draw_scene_do(void *vedata)
     RenderEngine *engine = RE_engine_create_ex(engine_type, true);
     engine->tile_x = scene->r.tilex;
     engine->tile_y = scene->r.tiley;
-    engine_type->view_update(engine, draw_ctx->evil_C);
+    engine_type->view_update(engine, draw_ctx->evil_C, draw_ctx->depsgraph);
     rv3d->render_engine = engine;
   }
 
@@ -231,7 +231,7 @@ static void external_draw_scene_do(void *vedata)
 
   /* Render result draw. */
   type = rv3d->render_engine->type;
-  type->view_draw(rv3d->render_engine, draw_ctx->evil_C);
+  type->view_draw(rv3d->render_engine, draw_ctx->evil_C, draw_ctx->depsgraph);
 
   GPU_matrix_pop_projection();
 

source/blender/editors/render/render_update.c

@@ -132,7 +132,10 @@ void ED_render_scene_update(const DEGEditorUpdateContext *update_ctx, int update
           CTX_wm_region_set(C, ar);
 
           engine->flag &= ~RE_ENGINE_DO_UPDATE;
-          engine->type->view_update(engine, C);
+          /* NOTE: Important to pass non-updated depsgraph, This is because this function is called
+           * from inside dependency graph evaluation. Additionally, if we pass fully evaluated one
+           * we will loose updates stored in the graph. */
+          engine->type->view_update(engine, C, CTX_data_depsgraph(C));
         }
         else {
           RenderEngineType *engine_type = ED_view3d_engine_type(scene, v3d->shading.type);

source/blender/makesrna/intern/rna_render.c

@@ -206,7 +206,9 @@ static void engine_bake(RenderEngine *engine,
   RNA_parameter_list_free(&list);
 }
 
-static void engine_view_update(RenderEngine *engine, const struct bContext *context)
+static void engine_view_update(RenderEngine *engine,
+                               const struct bContext *context,
+                               Depsgraph *depsgraph)
 {
   extern FunctionRNA rna_RenderEngine_view_update_func;
   PointerRNA ptr;
@@ -218,12 +220,15 @@ static void engine_view_update(RenderEngine *engine, const struct bContext *cont
 
   RNA_parameter_list_create(&list, &ptr, func);
   RNA_parameter_set_lookup(&list, "context", &context);
+  RNA_parameter_set_lookup(&list, "depsgraph", &depsgraph);
   engine->type->ext.call(NULL, &ptr, func, &list);
 
   RNA_parameter_list_free(&list);
 }
 
-static void engine_view_draw(RenderEngine *engine, const struct bContext *context)
+static void engine_view_draw(RenderEngine *engine,
+                             const struct bContext *context,
+                             Depsgraph *depsgraph)
 {
   extern FunctionRNA rna_RenderEngine_view_draw_func;
   PointerRNA ptr;
@@ -235,6 +240,7 @@ static void engine_view_draw(RenderEngine *engine, const struct bContext *contex
 
   RNA_parameter_list_create(&list, &ptr, func);
   RNA_parameter_set_lookup(&list, "context", &context);
+  RNA_parameter_set_lookup(&list, "depsgraph", &depsgraph);
   engine->type->ext.call(NULL, &ptr, func, &list);
 
   RNA_parameter_list_free(&list);
@@ -554,12 +560,18 @@ static void rna_def_render_engine(BlenderRNA *brna)
   func = RNA_def_function(srna, "view_update", NULL);
   RNA_def_function_ui_description(func, "Update on data changes for viewport render");
   RNA_def_function_flag(func, FUNC_REGISTER_OPTIONAL | FUNC_ALLOW_WRITE);
-  RNA_def_pointer(func, "context", "Context", "", "");
+  parm = RNA_def_pointer(func, "context", "Context", "", "");
+  RNA_def_parameter_flags(parm, 0, PARM_REQUIRED);
+  parm = RNA_def_pointer(func, "depsgraph", "Depsgraph", "", "");
+  RNA_def_parameter_flags(parm, 0, PARM_REQUIRED);
 
   func = RNA_def_function(srna, "view_draw", NULL);
   RNA_def_function_ui_description(func, "Draw viewport render");
   RNA_def_function_flag(func, FUNC_REGISTER_OPTIONAL);
-  RNA_def_pointer(func, "context", "Context", "", "");
+  parm = RNA_def_pointer(func, "context", "Context", "", "");
+  RNA_def_parameter_flags(parm, 0, PARM_REQUIRED);
+  parm = RNA_def_pointer(func, "depsgraph", "Depsgraph", "", "");
+  RNA_def_parameter_flags(parm, 0, PARM_REQUIRED);
 
   /* shader script callbacks */
   func = RNA_def_function(srna, "update_script_node", NULL);

source/blender/render/extern/include/RE_engine.h

@@ -93,8 +93,12 @@ typedef struct RenderEngineType {
                const int depth,
                void *result);
 
-  void (*view_update)(struct RenderEngine *engine, const struct bContext *context);
-  void (*view_draw)(struct RenderEngine *engine, const struct bContext *context);
+  void (*view_update)(struct RenderEngine *engine,
+                      const struct bContext *context,
+                      struct Depsgraph *depsgraph);
+  void (*view_draw)(struct RenderEngine *engine,
+                    const struct bContext *context,
+                    struct Depsgraph *depsgraph);
 
   void (*update_script_node)(struct RenderEngine *engine,
                              struct bNodeTree *ntree,