Object: Enable transfer mode functionality for switching objects in Sculpt Mode

This implements the changes discussed in T87134 for including switch
object funcionality in 2.93. This includes:

- Remove the switch object operator experimental option
- Remove the option for switching objects in Edit Mode.
- Rename switch_object to transfer_mode.
- Enable the operator only in sculpt mode.
- Expose the operator in the Sculpt menu with an eyedropper modal
option.

On later releases, we could revisit enabling the operator in other mode
and object types as well as its place in the UI.

Reviewed By: JulienKaspar, JacquesLucke

Differential Revision: https://developer.blender.org/D10953

5 files changed, 104 insertions, 42 deletions

diff --git a/source/blender/editors/object/object_intern.h b/source/blender/editors/object/object_intern.h
index 00426e96a81..5b2e0e36ba9 100644
--- a/source/blender/editors/object/object_intern.h
+++ b/source/blender/editors/object/object_intern.h
@@ -90,7 +90,7 @@ void OBJECT_OT_forcefield_toggle(struct wmOperatorType *ot);
 void OBJECT_OT_move_to_collection(struct wmOperatorType *ot);
 void OBJECT_OT_link_to_collection(struct wmOperatorType *ot);
 
-void OBJECT_OT_switch_object(struct wmOperatorType *ot);
+void OBJECT_OT_transfer_mode(struct wmOperatorType *ot);
 
 /* object_select.c */
 void OBJECT_OT_select_all(struct wmOperatorType *ot);
diff --git a/source/blender/editors/object/object_modes.c b/source/blender/editors/object/object_modes.c
index 99103cf10c7..ff1855cafc5 100644
--- a/source/blender/editors/object/object_modes.c
+++ b/source/blender/editors/object/object_modes.c
@@ -30,6 +30,8 @@
 #include "BLI_math.h"
 #include "BLI_utildefines.h"
 
+#include "BLT_translation.h"
+
 #include "BKE_context.h"
 #include "BKE_gpencil_modifier.h"
 #include "BKE_layer.h"
@@ -39,11 +41,13 @@
 #include "BKE_paint.h"
 #include "BKE_report.h"
 #include "BKE_scene.h"
+#include "BKE_screen.h"
 
 #include "WM_api.h"
 #include "WM_types.h"
 
 #include "RNA_access.h"
+#include "RNA_define.h"
 
 #include "DEG_depsgraph.h"
 #include "DEG_depsgraph_query.h"
@@ -400,51 +404,59 @@ bool ED_object_mode_generic_has_data(struct Depsgraph *depsgraph, struct Object
 /** \} */
 
 /* -------------------------------------------------------------------- */
-/** \name Switch Object
+/** \name Transfer Mode
  *
  * Enters the same mode of the current active object in another object,
  * leaving the mode of the current object.
  * \{ */
 
-static bool object_switch_object_poll(bContext *C)
+static bool object_transfer_mode_poll(bContext *C)
 {
-
-  if (!U.experimental.use_switch_object_operator) {
-    return false;
-  }
-
   if (!CTX_wm_region_view3d(C)) {
     return false;
   }
   const Object *ob = CTX_data_active_object(C);
-  return ob && (ob->mode & (OB_MODE_EDIT | OB_MODE_SCULPT));
+  return ob && (ob->mode & (OB_MODE_SCULPT));
 }
 
-static int object_switch_object_invoke(bContext *C, wmOperator *op, const wmEvent *event)
+/* Update the viewport rotation origin to the mouse cursor. */
+static void object_transfer_mode_reposition_view_pivot(bContext *C, const int mval[2])
 {
   ARegion *region = CTX_wm_region(C);
   Scene *scene = CTX_data_scene(C);
-  ViewLayer *view_layer = CTX_data_view_layer(C);
 
-  Base *base_dst = ED_view3d_give_base_under_cursor(C, event->mval);
+  float global_loc[3];
+  if (!ED_view3d_autodist_simple(region, mval, global_loc, 0, NULL)) {
+    return;
+  }
+  UnifiedPaintSettings *ups = &scene->toolsettings->unified_paint_settings;
+  copy_v3_v3(ups->average_stroke_accum, global_loc);
+  ups->average_stroke_counter = 1;
+  ups->last_stroke_valid = true;
+}
+
+static bool object_transfer_mode_to_base(bContext *C, wmOperator *op, Base *base_dst)
+{
+  Scene *scene = CTX_data_scene(C);
+  ViewLayer *view_layer = CTX_data_view_layer(C);
 
   if (base_dst == NULL) {
-    return OPERATOR_CANCELLED;
+    return false;
   }
 
   Object *ob_dst = base_dst->object;
   Object *ob_src = CTX_data_active_object(C);
 
   if (ob_dst == ob_src) {
-    return OPERATOR_CANCELLED;
+    return false;
   }
 
   const eObjectMode last_mode = (eObjectMode)ob_src->mode;
   if (!ED_object_mode_compat_test(ob_dst, last_mode)) {
-    return OPERATOR_CANCELLED;
+    return false;
   }
 
-  int retval = OPERATOR_CANCELLED;
+  bool mode_transfered = false;
 
   ED_undo_group_begin(C);
 
@@ -460,42 +472,98 @@ static int object_switch_object_invoke(bContext *C, wmOperator *op, const wmEven
     ob_dst_orig = DEG_get_original_object(ob_dst);
     ED_object_mode_set_ex(C, last_mode, true, op->reports);
 
-    /* Update the viewport rotation origin to the mouse cursor. */
-    if (last_mode & OB_MODE_ALL_PAINT) {
-      float global_loc[3];
-      if (ED_view3d_autodist_simple(region, event->mval, global_loc, 0, NULL)) {
-        UnifiedPaintSettings *ups = &scene->toolsettings->unified_paint_settings;
-        copy_v3_v3(ups->average_stroke_accum, global_loc);
-        ups->average_stroke_counter = 1;
-        ups->last_stroke_valid = true;
-      }
-    }
-
     WM_event_add_notifier(C, NC_SCENE | ND_OB_SELECT, scene);
     WM_toolsystem_update_from_context_view3d(C);
-    retval = OPERATOR_FINISHED;
+    mode_transfered = true;
   }
 
   ED_undo_group_end(C);
+  return mode_transfered;
+}
 
-  return retval;
+static int object_transfer_mode_modal(bContext *C, wmOperator *op, const wmEvent *event)
+{
+  switch (event->type) {
+    case LEFTMOUSE:
+      if (event->val == KM_PRESS) {
+        WM_cursor_modal_restore(CTX_wm_window(C));
+        ED_workspace_status_text(C, NULL);
+
+        /* This ensures that the click was done in an viewport region. */
+        bScreen *screen = CTX_wm_screen(C);
+        ARegion *region = BKE_screen_find_main_region_at_xy(
+            screen, SPACE_VIEW3D, event->x, event->y);
+        if (!region) {
+          return OPERATOR_CANCELLED;
+        }
+
+        const int mval[2] = {event->x - region->winrct.xmin, event->y - region->winrct.ymin};
+        Base *base_dst = ED_view3d_give_base_under_cursor(C, mval);
+        const bool mode_transfered = object_transfer_mode_to_base(C, op, base_dst);
+        if (!mode_transfered) {
+          return OPERATOR_CANCELLED;
+        }
+
+        return OPERATOR_FINISHED;
+      }
+      break;
+    case RIGHTMOUSE: {
+      WM_cursor_modal_restore(CTX_wm_window(C));
+      ED_workspace_status_text(C, NULL);
+      return OPERATOR_CANCELLED;
+    }
+  }
+  return OPERATOR_RUNNING_MODAL;
+}
+
+static int object_transfer_mode_invoke(bContext *C, wmOperator *op, const wmEvent *event)
+{
+  const bool use_eyedropper = RNA_boolean_get(op->ptr, "use_eyedropper");
+  if (use_eyedropper) {
+    ED_workspace_status_text(C, TIP_("Click in the viewport to select an object"));
+    WM_cursor_modal_set(CTX_wm_window(C), WM_CURSOR_EYEDROPPER);
+    WM_event_add_modal_handler(C, op);
+    return OPERATOR_RUNNING_MODAL;
+  }
+
+  Object *ob_src = CTX_data_active_object(C);
+  const eObjectMode src_mode = (eObjectMode)ob_src->mode;
+
+  Base *base_dst = ED_view3d_give_base_under_cursor(C, event->mval);
+  const bool mode_transfered = object_transfer_mode_to_base(C, op, base_dst);
+  if (!mode_transfered) {
+    return OPERATOR_CANCELLED;
+  }
+
+  if (src_mode & OB_MODE_ALL_PAINT) {
+    object_transfer_mode_reposition_view_pivot(C, event->mval);
+  }
+
+  return OPERATOR_FINISHED;
 }
 
-void OBJECT_OT_switch_object(wmOperatorType *ot)
+void OBJECT_OT_transfer_mode(wmOperatorType *ot)
 {
   /* identifiers */
-  ot->name = "Switch Object";
-  ot->idname = "OBJECT_OT_switch_object";
+  ot->name = "Transfer Mode";
+  ot->idname = "OBJECT_OT_transfer_mode";
   ot->description =
       "Switches the active object and assigns the same mode to a new one under the mouse cursor, "
       "leaving the active mode in the current one";
 
   /* api callbacks */
-  ot->invoke = object_switch_object_invoke;
-  ot->poll = object_switch_object_poll;
+  ot->invoke = object_transfer_mode_invoke;
+  ot->modal = object_transfer_mode_modal;
+  ot->poll = object_transfer_mode_poll;
 
   /* Undo push is handled by the operator. */
   ot->flag = OPTYPE_REGISTER;
+
+  RNA_def_boolean(ot->srna,
+                  "use_eyedropper",
+                  false,
+                  "Use Eyedropper",
+                  "Pick the object to switch to using an eyedropper");
 }
 
 /** \} */
diff --git a/source/blender/editors/object/object_ops.c b/source/blender/editors/object/object_ops.c
index 71bea6bf9e3..b50fc3c88fd 100644
--- a/source/blender/editors/object/object_ops.c
+++ b/source/blender/editors/object/object_ops.c
@@ -65,7 +65,7 @@ void ED_operatortypes_object(void)
   WM_operatortype_append(OBJECT_OT_paths_range_update);
   WM_operatortype_append(OBJECT_OT_forcefield_toggle);
 
-  WM_operatortype_append(OBJECT_OT_switch_object);
+  WM_operatortype_append(OBJECT_OT_transfer_mode);
 
   WM_operatortype_append(OBJECT_OT_parent_set);
   WM_operatortype_append(OBJECT_OT_parent_no_inverse_set);
diff --git a/source/blender/makesdna/DNA_userdef_types.h b/source/blender/makesdna/DNA_userdef_types.h
index 334669d3433..1fed8e14bd6 100644
--- a/source/blender/makesdna/DNA_userdef_types.h
+++ b/source/blender/makesdna/DNA_userdef_types.h
@@ -643,11 +643,10 @@ typedef struct UserDef_Experimental {
   char use_new_hair_type;
   char use_new_point_cloud_type;
   char use_sculpt_vertex_colors;
-  char use_switch_object_operator;
   char use_sculpt_tools_tilt;
   char use_asset_browser;
   char use_override_templates;
-  char _pad[5];
+  char _pad[6];
   /** `makesdna` does not allow empty structs. */
 } UserDef_Experimental;
 
diff --git a/source/blender/makesrna/intern/rna_userdef.c b/source/blender/makesrna/intern/rna_userdef.c
index baf77aae87f..a20ce2d05d0 100644
--- a/source/blender/makesrna/intern/rna_userdef.c
+++ b/source/blender/makesrna/intern/rna_userdef.c
@@ -6289,11 +6289,6 @@ static void rna_def_userdef_experimental(BlenderRNA *brna)
   RNA_def_property_boolean_sdna(prop, NULL, "use_sculpt_vertex_colors", 1);
   RNA_def_property_ui_text(prop, "Sculpt Vertex Colors", "Use the new Vertex Painting system");
 
-  prop = RNA_def_property(srna, "use_switch_object_operator", PROP_BOOLEAN, PROP_NONE);
-  RNA_def_property_boolean_sdna(prop, NULL, "use_switch_object_operator", 1);
-  RNA_def_property_ui_text(
-      prop, "Switch Object Operator", "Enable the operator to switch objects by pressing D");
-
   prop = RNA_def_property(srna, "use_sculpt_tools_tilt", PROP_BOOLEAN, PROP_NONE);
   RNA_def_property_boolean_sdna(prop, NULL, "use_sculpt_tools_tilt", 1);
   RNA_def_property_ui_text(