Workspaces: Store an active view-layer per scene

Instead of storing a single active view-layer in the workspace, one is
stored for each scene the workspace showed before.
With this, some things become possible:
* Multiple windows in the same workspace but showing different scenes.
* Toggling back and forth scene keeps same active view-layer for each scene.
* Activating workspace which didn't show current scene before, the current view-layer is kept.

A necessary evil for this is that accessing view-layer and object mode
from .py can't be done via workspace directly anymore. It has to be done
through the window, so RNA can use the correct scene.
So instead of `workspace.view_layer`, it's `window.view_layer` now (same
with mode) even though it's still workspace data.

Fixes T53432.

6 files changed, 40 insertions, 31 deletions

diff --git a/source/blender/editors/include/ED_screen.h b/source/blender/editors/include/ED_screen.h
index c1655cbccc2..23e65011387 100644
--- a/source/blender/editors/include/ED_screen.h
+++ b/source/blender/editors/include/ED_screen.h
@@ -136,6 +136,7 @@ void    ED_screen_preview_render(const struct bScreen *screen, int size_x, int s
 struct WorkSpace *ED_workspace_add(
         struct Main *bmain,
         const char *name,
+        Scene *scene,
         ViewLayer *act_render_layer,
         struct ViewRender *view_render) ATTR_NONNULL();
 bool ED_workspace_change(
@@ -152,7 +153,8 @@ bool ED_workspace_delete(
 void ED_workspace_scene_data_sync(
         struct WorkSpaceInstanceHook *hook, Scene *scene) ATTR_NONNULL();
 void ED_workspace_view_layer_unset(
-        const struct Main *bmain, const ViewLayer *layer_unset, ViewLayer *layer_new) ATTR_NONNULL(1, 2);
+        const struct Main *bmain, struct Scene *scene,
+        const ViewLayer *layer_unset, ViewLayer *layer_new) ATTR_NONNULL(1, 2);
 struct WorkSpaceLayout *ED_workspace_layout_add(
         struct WorkSpace *workspace,
         struct wmWindow *win,
diff --git a/source/blender/editors/object/object_edit.c b/source/blender/editors/object/object_edit.c
index 804d0ed1f0d..5697c48d381 100644
--- a/source/blender/editors/object/object_edit.c
+++ b/source/blender/editors/object/object_edit.c
@@ -1516,15 +1516,13 @@ bool ED_object_mode_compat_set(bContext *C, Object *ob, int mode, ReportList *re
 {
 	bool ok;
 	if (!ELEM(ob->mode, mode, OB_MODE_OBJECT)) {
-		WorkSpace *workspace = CTX_wm_workspace(C);
 		const char *opstring = object_mode_op_string(ob->mode);
 
 		WM_operator_name_call(C, opstring, WM_OP_EXEC_REGION_WIN, NULL);
 #ifdef USE_WORKSPACE_MODE
-		BKE_workspace_object_mode_set(workspace, ob->mode);
-#else
-		UNUSED_VARS(workspace);
+		BKE_workspace_object_mode_set(CTX_wm_workspace(C), CTX_data_scene(C), ob->mode);
 #endif
+
 		ok = ELEM(ob->mode, mode, OB_MODE_OBJECT);
 		if (!ok) {
 			wmOperatorType *ot = WM_operatortype_find(opstring, false);
@@ -1648,7 +1646,7 @@ void ED_object_toggle_modes(bContext *C, int mode)
 #ifdef USE_WORKSPACE_MODE
 			Object *ob = CTX_data_active_object(C);
 			if (ob) {
-				BKE_workspace_object_mode_set(workspace, ob->mode);
+				BKE_workspace_object_mode_set(workspace, CTX_data_scene(C), ob->mode);
 			}
 #endif
 		}
diff --git a/source/blender/editors/object/object_select.c b/source/blender/editors/object/object_select.c
index 47e63cb43e5..552380cebdb 100644
--- a/source/blender/editors/object/object_select.c
+++ b/source/blender/editors/object/object_select.c
@@ -123,8 +123,7 @@ void ED_object_base_activate(bContext *C, Base *base)
 
 	if (base) {
 #ifdef USE_WORKSPACE_MODE
-		WorkSpace *workspace = CTX_wm_workspace(C);
-		BKE_workspace_object_mode_set(workspace, base->object->mode);
+		BKE_workspace_object_mode_set(CTX_wm_workspace(C), CTX_data_scene(C), base->object->mode);
 #endif
 		WM_event_add_notifier(C, NC_SCENE | ND_OB_ACTIVE, view_layer);
 	}
diff --git a/source/blender/editors/scene/scene_edit.c b/source/blender/editors/scene/scene_edit.c
index c7f04a0e2f9..812f9a736bf 100644
--- a/source/blender/editors/scene/scene_edit.c
+++ b/source/blender/editors/scene/scene_edit.c
@@ -118,16 +118,20 @@ void ED_scene_exit(bContext *C)
 	ED_object_editmode_exit(C, EM_FREEDATA | EM_DO_UNDO);
 }
 
+static ViewLayer *scene_change_get_new_view_layer(const WorkSpace *workspace, const Scene *scene_new)
+{
+	ViewLayer *layer_new = BKE_workspace_view_layer_get(workspace, scene_new);
+	return layer_new ? layer_new : BKE_view_layer_from_scene_get(scene_new);
+}
+
 void ED_scene_changed_update(Main *bmain, bContext *C, Scene *scene_new, const bScreen *active_screen)
 {
-	/* XXX Just using active scene render-layer for workspace when switching,
-	 * but workspace should remember the last one set. Could store render-layer
-	 * per window-workspace combination (using WorkSpaceDataRelation) */
-	ViewLayer *layer_new = BLI_findlink(&scene_new->view_layers, scene_new->active_view_layer);
+	WorkSpace *workspace = CTX_wm_workspace(C);
+	ViewLayer *layer_new = scene_change_get_new_view_layer(workspace, scene_new);
 	Depsgraph *depsgraph = BKE_scene_get_depsgraph(scene_new, layer_new, true);
 
 	CTX_data_scene_set(C, scene_new);
-	BKE_workspace_view_layer_set(CTX_wm_workspace(C), layer_new);
+	BKE_workspace_view_layer_set(workspace, layer_new, scene_new);
 	BKE_scene_set_background(bmain, scene_new);
 	DEG_graph_relations_update(depsgraph, bmain, scene_new, layer_new);
 	DEG_on_visible_update(bmain, false);
@@ -186,7 +190,8 @@ bool ED_scene_view_layer_delete(
 	BLI_assert(BLI_listbase_is_empty(&scene->view_layers) == false);
 	scene->active_view_layer = 0;
 
-	ED_workspace_view_layer_unset(bmain, layer, scene->view_layers.first);
+	ED_workspace_view_layer_unset(bmain, scene, layer, scene->view_layers.first);
+	BKE_workspace_view_layer_remove_references(bmain, layer);
 	view_layer_remove_unset_nodetrees(bmain, scene, layer);
 
 	BKE_view_layer_free(layer);
diff --git a/source/blender/editors/screen/screen_context.c b/source/blender/editors/screen/screen_context.c
index d84f256bc32..4c62253bef6 100644
--- a/source/blender/editors/screen/screen_context.c
+++ b/source/blender/editors/screen/screen_context.c
@@ -91,7 +91,7 @@ int ed_screen_context(const bContext *C, const char *member, bContextDataResult
 	WorkSpace *workspace = BKE_workspace_active_get(win->workspace_hook);
 	ViewLayer *view_layer = BKE_view_layer_from_workspace_get(scene, workspace);
 	Object *obedit = scene->obedit;
-	Object *obact = view_layer->basact ? view_layer->basact->object : NULL;
+	Object *obact = (view_layer && view_layer->basact) ? view_layer->basact->object : NULL;
 
 	if (CTX_data_dir(member)) {
 		CTX_data_dir_set(result, screen_context_dir);
diff --git a/source/blender/editors/screen/workspace_edit.c b/source/blender/editors/screen/workspace_edit.c
index 84288740df8..00dc1003121 100644
--- a/source/blender/editors/screen/workspace_edit.c
+++ b/source/blender/editors/screen/workspace_edit.c
@@ -71,15 +71,16 @@
  * \{ */
 
 WorkSpace *ED_workspace_add(
-        Main *bmain, const char *name, ViewLayer *act_view_layer, ViewRender *view_render)
+        Main *bmain, const char *name, Scene *scene,
+        ViewLayer *act_view_layer, ViewRender *view_render)
 {
 	WorkSpace *workspace = BKE_workspace_add(bmain, name);
 
-	BKE_workspace_view_layer_set(workspace, act_view_layer);
+	BKE_workspace_view_layer_set(workspace, act_view_layer, scene);
 	BKE_viewrender_copy(&workspace->view_render, view_render);
 
 #ifdef USE_WORKSPACE_MODE
-	BKE_workspace_object_mode_set(workspace, OB_MODE_OBJECT);
+	BKE_workspace_object_mode_set(workspace, scene, OB_MODE_OBJECT);
 #endif
 
 	return workspace;
@@ -94,8 +95,9 @@ static void workspace_change_update_mode(
         const WorkSpace *workspace_old, const WorkSpace *workspace_new,
         bContext *C, Object *ob_act, ReportList *reports)
 {
-	eObjectMode mode_old = BKE_workspace_object_mode_get(workspace_old);
-	eObjectMode mode_new = BKE_workspace_object_mode_get(workspace_new);
+	const Scene *scene = CTX_data_scene(C);
+	eObjectMode mode_old = BKE_workspace_object_mode_get(workspace_old, scene);
+	eObjectMode mode_new = BKE_workspace_object_mode_get(workspace_new, scene);
 
 	if (mode_old != mode_new) {
 		ED_object_mode_compat_set(C, ob_act, mode_new, reports);
@@ -105,10 +107,11 @@ static void workspace_change_update_mode(
 #endif
 
 static void workspace_change_update_view_layer(
-        WorkSpace *workspace_new, const WorkSpace *workspace_old)
+        WorkSpace *workspace_new, const WorkSpace *workspace_old,
+        Scene *scene)
 {
-	if (!BKE_workspace_view_layer_get(workspace_new)) {
-		BKE_workspace_view_layer_set(workspace_new, BKE_workspace_view_layer_get(workspace_old));
+	if (!BKE_workspace_view_layer_get(workspace_new, scene)) {
+		BKE_workspace_view_layer_set(workspace_new, BKE_workspace_view_layer_get(workspace_old, scene), scene);
 	}
 }
 
@@ -117,7 +120,7 @@ static void workspace_change_update(
         bContext *C, wmWindowManager *wm)
 {
 	/* needs to be done before changing mode! (to ensure right context) */
-	workspace_change_update_view_layer(workspace_new, workspace_old);
+	workspace_change_update_view_layer(workspace_new, workspace_old, CTX_data_scene(C));
 #ifdef USE_WORKSPACE_MODE
 	workspace_change_update_mode(workspace_old, workspace_new, C, CTX_data_active_object(C), &wm->reports);
 #else
@@ -199,7 +202,7 @@ bool ED_workspace_change(
 		screen_changed_update(C, win, screen_new);
 		workspace_change_update(workspace_new, workspace_old, C, wm);
 
-		BLI_assert(BKE_workspace_view_layer_get(workspace_new) != NULL);
+		BLI_assert(BKE_workspace_view_layer_get(workspace_new, CTX_data_scene(C)) != NULL);
 		BLI_assert(CTX_wm_workspace(C) == workspace_new);
 
 		WM_toolsystem_unlink(C, workspace_old);
@@ -220,15 +223,16 @@ WorkSpace *ED_workspace_duplicate(
 {
 	WorkSpaceLayout *layout_active_old = BKE_workspace_active_layout_get(win->workspace_hook);
 	ListBase *layouts_old = BKE_workspace_layouts_get(workspace_old);
+	Scene *scene = WM_window_get_active_scene(win);
 	WorkSpace *workspace_new = ED_workspace_add(
-	        bmain, workspace_old->id.name + 2,
-	        BKE_workspace_view_layer_get(workspace_old),
+	        bmain, workspace_old->id.name + 2, scene,
+	        BKE_workspace_view_layer_get(workspace_old, scene),
 	        &workspace_old->view_render);
 	ListBase *transform_orientations_old = BKE_workspace_transform_orientations_get(workspace_old);
 	ListBase *transform_orientations_new = BKE_workspace_transform_orientations_get(workspace_new);
 
 #ifdef USE_WORKSPACE_MODE
-	BKE_workspace_object_mode_set(workspace_new, BKE_workspace_object_mode_get(workspace_old));
+	BKE_workspace_object_mode_set(workspace_new, scene, BKE_workspace_object_mode_get(workspace_old, scene));
 #endif
 	BLI_duplicatelist(transform_orientations_new, transform_orientations_old);
 
@@ -279,11 +283,12 @@ void ED_workspace_scene_data_sync(
 }
 
 void ED_workspace_view_layer_unset(
-        const Main *bmain, const ViewLayer *layer_unset, ViewLayer *layer_new)
+        const Main *bmain, Scene *scene,
+        const ViewLayer *layer_unset, ViewLayer *layer_new)
 {
 	for (WorkSpace *workspace = bmain->workspaces.first; workspace; workspace = workspace->id.next) {
-		if (BKE_workspace_view_layer_get(workspace) == layer_unset) {
-			BKE_workspace_view_layer_set(workspace, layer_new);
+		if (BKE_workspace_view_layer_get(workspace, scene) == layer_unset) {
+			BKE_workspace_view_layer_set(workspace, layer_new, scene);
 		}
 	}
 }