Add an activeobject manager to hold active objects (#7939)

* Add an activeobject manager to hold active objects
* Add unittests

src/client/activeobjectmgr.cpp

@@ -0,0 +1,106 @@
+/*
+Minetest
+Copyright (C) 2010-2018 nerzhul, Loic BLOT <loic.blot@unix-experience.fr>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#include <log.h>
+#include "profiler.h"
+#include "activeobjectmgr.h"
+
+namespace client
+{
+
+void ActiveObjectMgr::clear()
+{
+	// delete active objects
+	for (auto &active_object : m_active_objects) {
+		delete active_object.second;
+	}
+}
+
+void ActiveObjectMgr::step(
+		float dtime, const std::function<void(ClientActiveObject *)> &f)
+{
+	g_profiler->avg("Client::ActiveObjectMgr: num of objects",
+			m_active_objects.size());
+	for (auto &ao_it : m_active_objects) {
+		f(ao_it.second);
+	}
+}
+
+// clang-format off
+bool ActiveObjectMgr::registerObject(ClientActiveObject *obj)
+{
+	assert(obj); // Pre-condition
+	if (obj->getId() == 0) {
+		u16 new_id = getFreeId();
+		if (new_id == 0) {
+			infostream << "Client::ActiveObjectMgr::registerObject(): "
+					<< "no free id available" << std::endl;
+
+			delete obj;
+			return false;
+		}
+		obj->setId(new_id);
+	}
+
+	if (!isFreeId(obj->getId())) {
+		infostream << "Client::ActiveObjectMgr::registerObject(): "
+				<< "id is not free (" << obj->getId() << ")" << std::endl;
+		delete obj;
+		return false;
+	}
+	infostream << "Client::ActiveObjectMgr::registerObject(): "
+			<< "added (id=" << obj->getId() << ")" << std::endl;
+	m_active_objects[obj->getId()] = obj;
+	return true;
+}
+
+void ActiveObjectMgr::removeObject(u16 id)
+{
+	verbosestream << "Client::ActiveObjectMgr::removeObject(): "
+			<< "id=" << id << std::endl;
+	ClientActiveObject *obj = getActiveObject(id);
+	if (!obj) {
+		infostream << "Client::ActiveObjectMgr::removeObject(): "
+				<< "id=" << id << " not found" << std::endl;
+		return;
+	}
+
+	m_active_objects.erase(id);
+
+	obj->removeFromScene(true);
+	delete obj;
+}
+
+// clang-format on
+void ActiveObjectMgr::getActiveObjects(const v3f &origin, f32 max_d,
+		std::vector<DistanceSortedActiveObject> &dest)
+{
+	for (auto &ao_it : m_active_objects) {
+		ClientActiveObject *obj = ao_it.second;
+
+		f32 d = (obj->getPosition() - origin).getLength();
+
+		if (d > max_d)
+			continue;
+
+		dest.emplace_back(obj, d);
+	}
+}
+
+} // namespace client