Point Cloud: Implement join operator

Similar to !134691.

Pull Request: https://projects.blender.org/blender/blender/pulls/134702

source/blender/editors/include/ED_point_cloud.hh

@@ -24,6 +24,7 @@ struct PointCloud;
 struct rcti;
 struct UndoType;
 struct wmKeyConfig;
+struct wmOperator;
 struct wmOperatorType;
 namespace blender::bke {
 struct GSpanAttributeWriter;
@@ -143,6 +144,8 @@ void POINT_CLOUD_OT_attribute_set(wmOperatorType *ot);
 void POINT_CLOUD_OT_duplicate(wmOperatorType *ot);
 void POINT_CLOUD_OT_separate(wmOperatorType *ot);
 
+int join_objects(bContext *C, wmOperator *op);
+
 /** \} */
 
 }  // namespace blender::ed::point_cloud

source/blender/editors/object/object_add.cc

@@ -121,6 +121,7 @@
 #include "ED_object.hh"
 #include "ED_outliner.hh"
 #include "ED_physics.hh"
+#include "ED_point_cloud.hh"
 #include "ED_render.hh"
 #include "ED_screen.hh"
 #include "ED_select_utils.hh"
@@ -4714,7 +4715,14 @@ static bool object_join_poll(bContext *C)
     return false;
   }
 
-  if (ELEM(ob->type, OB_MESH, OB_CURVES_LEGACY, OB_SURF, OB_ARMATURE, OB_GREASE_PENCIL, OB_CURVES))
+  if (ELEM(ob->type,
+           OB_MESH,
+           OB_CURVES_LEGACY,
+           OB_SURF,
+           OB_ARMATURE,
+           OB_CURVES,
+           OB_GREASE_PENCIL,
+           OB_POINTCLOUD))
   {
     return true;
   }
@@ -4752,6 +4760,9 @@ static int object_join_exec(bContext *C, wmOperator *op)
   else if (ob->type == OB_ARMATURE) {
     ret = ED_armature_join_objects_exec(C, op);
   }
+  else if (ob->type == OB_POINTCLOUD) {
+    ret = point_cloud::join_objects(C, op);
+  }
   else if (ob->type == OB_CURVES) {
     ret = curves::join_objects(C, op);
   }

source/blender/editors/point_cloud/CMakeLists.txt

@@ -16,6 +16,7 @@ set(INC_SYS
 set(SRC
   intern/attribute_set.cc
   intern/duplicate.cc
+  intern/join.cc
   intern/point_cloud_edit.cc
   intern/point_cloud_ops.cc
   intern/point_cloud_selection.cc
@@ -28,6 +29,7 @@ set(LIB
   PRIVATE bf::blenlib
   PRIVATE bf::depsgraph
   PRIVATE bf::dna
+  PRIVATE bf::geometry
   PRIVATE bf::functions
   PRIVATE bf::intern::clog
   PRIVATE bf::intern::guardedalloc

source/blender/editors/point_cloud/intern/join.cc

@@ -0,0 +1,91 @@
+/* SPDX-FileCopyrightText: 2025 Blender Authors
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include "BLI_map.hh"
+
+#include "DNA_scene_types.h"
+
+#include "BKE_context.hh"
+#include "BKE_instances.hh"
+#include "BKE_pointcloud.hh"
+#include "BKE_report.hh"
+
+#include "DEG_depsgraph.hh"
+#include "DEG_depsgraph_build.hh"
+
+#include "WM_api.hh"
+#include "WM_types.hh"
+
+#include "ED_object.hh"
+#include "ED_point_cloud.hh"
+
+#include "GEO_realize_instances.hh"
+
+namespace blender::ed::point_cloud {
+
+int join_objects(bContext *C, wmOperator *op)
+{
+  Main *bmain = CTX_data_main(C);
+  Scene *scene = CTX_data_scene(C);
+  Object *active_object = CTX_data_active_object(C);
+  BLI_assert(active_object);
+  BLI_assert(active_object->type == OB_POINTCLOUD);
+  PointCloud &active_pointcloud = *static_cast<PointCloud *>(active_object->data);
+  const float4x4 &world_to_active = active_object->world_to_object();
+
+  Vector<Object *> objects{active_object};
+  bool active_object_selected = false;
+  CTX_DATA_BEGIN (C, Object *, object, selected_editable_objects) {
+    if (object == active_object) {
+      active_object_selected = true;
+      continue;
+    }
+    if (object->type != OB_POINTCLOUD) {
+      continue;
+    }
+    objects.append(object);
+  }
+  CTX_DATA_END;
+
+  if (!active_object_selected) {
+    BKE_report(op->reports, RPT_WARNING, "Active object is not a selected point cloud object");
+    return OPERATOR_CANCELLED;
+  }
+
+  bke::Instances instances;
+  instances.resize(objects.size());
+  MutableSpan<float4x4> transforms = instances.transforms_for_write();
+  MutableSpan<int> references = instances.reference_handles_for_write();
+  Map<const PointCloud *, int> reference_by_orig_points;
+  for (const int i : objects.index_range()) {
+    transforms[i] = world_to_active * objects[i]->object_to_world();
+    const PointCloud *orig_points = static_cast<const PointCloud *>(objects[i]->data);
+    references[i] = reference_by_orig_points.lookup_or_add_cb(orig_points, [&]() {
+      auto geometry = bke::GeometrySet::from_pointcloud(BKE_pointcloud_copy_for_eval(orig_points));
+      return instances.add_new_reference(std::move(geometry));
+    });
+  }
+
+  bke::GeometrySet realized_geometry = geometry::realize_instances(
+      bke::GeometrySet::from_instances(&instances, bke::GeometryOwnershipType::ReadOnly),
+      geometry::RealizeInstancesOptions());
+
+  PointCloud *realized_points =
+      realized_geometry.get_component_for_write<bke::PointCloudComponent>().release();
+  BKE_pointcloud_nomain_to_pointcloud(realized_points, &active_pointcloud);
+
+  for (Object *object : objects.as_span().drop_front(1)) {
+    object::base_free_and_unlink(bmain, scene, object);
+  }
+
+  DEG_relations_tag_update(bmain);
+  DEG_id_tag_update(&active_object->id, ID_RECALC_TRANSFORM | ID_RECALC_GEOMETRY);
+  DEG_id_tag_update(&scene->id, ID_RECALC_SELECT);
+  WM_event_add_notifier(C, NC_SCENE | ND_OB_ACTIVE, scene);
+  WM_event_add_notifier(C, NC_SCENE | ND_LAYER_CONTENT, scene);
+
+  return OPERATOR_FINISHED;
+}
+
+}  // namespace blender::ed::point_cloud