ContentCAO: Fix broken attachments on join (#8701)

What happened:
1) Object data is received. Client begins to read the data
2) Client initializes all its children (gob_cmd_update_infant)
3) Children try to attach to parent (yet not added)
4) Parent initializes, is added to the environment

And somewhere in between, Irrlicht wrecks up the attachments due to the missing matrix node.

The solution here is to:
1) Use the same structure as ServerActiveObject
2) Attach all children after the parent is really initialized

1 files changed, 112 insertions, 89 deletions

diff --git a/src/client/content_cao.cpp b/src/client/content_cao.cpp
index 388a71873..d2ab0631a 100644
--- a/src/client/content_cao.cpp
+++ b/src/client/content_cao.cpp
@@ -17,36 +17,35 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */
 
+#include "content_cao.h"
+#include <IBillboardSceneNode.h>
 #include <ICameraSceneNode.h>
 #include <ITextSceneNode.h>
-#include <IBillboardSceneNode.h>
 #include <IMeshManipulator.h>
 #include <IAnimatedMeshSceneNode.h>
-#include "content_cao.h"
-#include "util/numeric.h" // For IntervalLimiter & setPitchYawRoll
-#include "util/serialize.h"
-#include "util/basic_macros.h"
+#include "client/client.h"
+#include "client/renderingengine.h"
 #include "client/sound.h"
 #include "client/tile.h"
-#include "environment.h"
+#include "util/basic_macros.h"
+#include "util/numeric.h" // For IntervalLimiter & setPitchYawRoll
+#include "util/serialize.h"
+#include "camera.h" // CameraModes
 #include "collision.h"
-#include "settings.h"
-#include "serialization.h" // For decompressZlib
-#include "clientobject.h"
-#include "mesh.h"
-#include "itemdef.h"
-#include "tool.h"
 #include "content_cso.h"
-#include "sound.h"
-#include "nodedef.h"
+#include "environment.h"
+#include "itemdef.h"
 #include "localplayer.h"
 #include "map.h"
-#include "camera.h" // CameraModes
-#include "client.h"
+#include "mesh.h"
+#include "nodedef.h"
+#include "serialization.h" // For decompressZlib
+#include "settings.h"
+#include "sound.h"
+#include "tool.h"
 #include "wieldmesh.h"
 #include <algorithm>
 #include <cmath>
-#include "client/renderingengine.h"
 
 class Settings;
 struct ToolCapabilities;
@@ -305,6 +304,7 @@ void TestCAO::processMessage(const std::string &data)
 */
 
 #include "genericobject.h"
+#include "clientobject.h"
 
 GenericCAO::GenericCAO(Client *client, ClientEnvironment *env):
 		ClientActiveObject(0, client, env)
@@ -372,6 +372,7 @@ void GenericCAO::processInitData(const std::string &data)
 	m_position = readV3F32(is);
 	m_rotation = readV3F32(is);
 	m_hp = readU16(is);
+
 	const u8 num_messages = readU8(is);
 
 	for (int i = 0; i < num_messages; i++) {
@@ -443,7 +444,7 @@ scene::IAnimatedMeshSceneNode* GenericCAO::getAnimatedMeshSceneNode()
 
 void GenericCAO::setChildrenVisible(bool toset)
 {
-	for (u16 cao_id : m_children) {
+	for (u16 cao_id : m_attachment_child_ids) {
 		GenericCAO *obj = m_env->getGenericCAO(cao_id);
 		if (obj) {
 			obj->setVisible(toset);
@@ -451,43 +452,79 @@ void GenericCAO::setChildrenVisible(bool toset)
 	}
 }
 
-void GenericCAO::setAttachments()
+void GenericCAO::setAttachment(int parent_id, const std::string &bone, v3f position, v3f rotation)
 {
+	int old_parent = m_attachment_parent_id;
+	m_attachment_parent_id = parent_id;
+	m_attachment_bone = bone;
+	m_attachment_position = position;
+	m_attachment_rotation = rotation;
+
+	ClientActiveObject *parent = m_env->getActiveObject(parent_id);
+
+	if (parent_id != old_parent) {
+		if (auto *o = m_env->getActiveObject(old_parent))
+			o->removeAttachmentChild(m_id);
+		if (parent)
+			parent->addAttachmentChild(m_id);
+	}
+
 	updateAttachments();
 }
 
-ClientActiveObject* GenericCAO::getParent() const
+void GenericCAO::getAttachment(int *parent_id, std::string *bone, v3f *position,
+	v3f *rotation) const
+{
+	*parent_id = m_attachment_parent_id;
+	*bone = m_attachment_bone;
+	*position = m_attachment_position;
+	*rotation = m_attachment_rotation;
+}
+
+void GenericCAO::clearChildAttachments()
 {
-	ClientActiveObject *obj = NULL;
+	// Cannot use for-loop here: setAttachment() modifies 'm_attachment_child_ids'!
+	while (!m_attachment_child_ids.empty()) {
+		int child_id = *m_attachment_child_ids.begin();
 
-	u16 attached_id = m_env->attachement_parent_ids[getId()];
+		if (ClientActiveObject *child = m_env->getActiveObject(child_id))
+			child->setAttachment(0, "", v3f(), v3f());
 
-	if ((attached_id != 0) &&
-			(attached_id != getId())) {
-		obj = m_env->getActiveObject(attached_id);
+		removeAttachmentChild(child_id);
 	}
-	return obj;
 }
 
-void GenericCAO::removeFromScene(bool permanent)
+void GenericCAO::clearParentAttachment()
 {
-	// Should be true when removing the object permanently and false when refreshing (eg: updating visuals)
-	if((m_env != NULL) && (permanent))
-	{
-		for (u16 ci : m_children) {
-			if (m_env->attachement_parent_ids[ci] == getId()) {
-				m_env->attachement_parent_ids[ci] = 0;
-			}
-		}
-		m_children.clear();
+	if (m_attachment_parent_id)
+		setAttachment(0, "", m_attachment_position, m_attachment_rotation);
+	else
+		setAttachment(0, "", v3f(), v3f());
+}
 
-		m_env->attachement_parent_ids[getId()] = 0;
+void GenericCAO::addAttachmentChild(int child_id)
+{
+	m_attachment_child_ids.insert(child_id);
+}
 
-		LocalPlayer* player = m_env->getLocalPlayer();
-		if (this == player->parent) {
-			player->parent = nullptr;
-			player->isAttached = false;
-		}
+void GenericCAO::removeAttachmentChild(int child_id)
+{
+	m_attachment_child_ids.erase(child_id);
+}
+
+ClientActiveObject* GenericCAO::getParent() const
+{
+	return m_attachment_parent_id ? m_env->getActiveObject(m_attachment_parent_id) :
+			nullptr;
+}
+
+void GenericCAO::removeFromScene(bool permanent)
+{
+	// Should be true when removing the object permanently
+	// and false when refreshing (eg: updating visuals)
+	if (m_env && permanent) {
+		clearChildAttachments();
+		clearParentAttachment();
 	}
 
 	if (m_meshnode) {
@@ -711,6 +748,7 @@ void GenericCAO::addToScene(ITextureSource *tsrc)
 		updateTextures(m_current_texture_modifier);
 
 	scene::ISceneNode *node = getSceneNode();
+
 	if (node && !m_prop.nametag.empty() && !m_is_local_player) {
 		// Add nametag
 		v3f pos;
@@ -736,7 +774,7 @@ void GenericCAO::updateLight(u8 light_at_pos)
 	updateLightNoCheck(light_at_pos);
 
 	// Update light of all children
-	for (u16 i : m_children) {
+	for (u16 i : m_attachment_child_ids) {
 		ClientActiveObject *obj = m_env->getActiveObject(i);
 		if (obj) {
 			obj->updateLightNoCheck(light_at_pos);
@@ -871,12 +909,8 @@ void GenericCAO::step(float dtime, ClientEnvironment *env)
 
 		// Attachments, part 1: All attached objects must be unparented first,
 		// or Irrlicht causes a segmentation fault
-		for (auto ci = m_children.begin(); ci != m_children.end();) {
-			if (m_env->attachement_parent_ids[*ci] != getId()) {
-				ci = m_children.erase(ci);
-				continue;
-			}
-			ClientActiveObject *obj = m_env->getActiveObject(*ci);
+		for (u16 cao_id : m_attachment_child_ids) {
+			ClientActiveObject *obj = m_env->getActiveObject(cao_id);
 			if (obj) {
 				scene::ISceneNode *child_node = obj->getSceneNode();
 				// The node's parent is always an IDummyTraformationSceneNode,
@@ -884,18 +918,16 @@ void GenericCAO::step(float dtime, ClientEnvironment *env)
 				if (child_node)
 					child_node->getParent()->setParent(m_smgr->getRootSceneNode());
 			}
-			++ci;
 		}
 
 		removeFromScene(false);
 		addToScene(m_client->tsrc());
 
 		// Attachments, part 2: Now that the parent has been refreshed, put its attachments back
-		for (u16 cao_id : m_children) {
-			// Get the object of the child
+		for (u16 cao_id : m_attachment_child_ids) {
 			ClientActiveObject *obj = m_env->getActiveObject(cao_id);
 			if (obj)
-				obj->setAttachments();
+				obj->updateAttachments();
 		}
 	}
 
@@ -916,7 +948,6 @@ void GenericCAO::step(float dtime, ClientEnvironment *env)
 		{
 			LocalPlayer *player = m_env->getLocalPlayer();
 			player->overridePosition = getParent()->getPosition();
-			m_env->getLocalPlayer()->parent = getParent();
 		}
 	} else {
 		rot_translator.translate(dtime);
@@ -1296,6 +1327,14 @@ void GenericCAO::updateBonePosition()
 void GenericCAO::updateAttachments()
 {
 	ClientActiveObject *parent = getParent();
+
+	m_attached_to_local = parent && parent->isLocalPlayer();
+
+	if (!parent && m_attachment_parent_id) {
+		//m_is_visible = false; maybe later. needs better handling
+		return;
+	}
+
 	if (!parent) { // Detach or don't attach
 		if (m_matrixnode) {
 			v3f old_pos = m_matrixnode->getAbsolutePosition();
@@ -1303,10 +1342,6 @@ void GenericCAO::updateAttachments()
 			getPosRotMatrix().setTranslation(old_pos);
 			m_matrixnode->updateAbsolutePosition();
 		}
-		if (m_is_local_player) {
-			LocalPlayer *player = m_env->getLocalPlayer();
-			player->isAttached = false;
-		}
 	}
 	else // Attach
 	{
@@ -1325,10 +1360,11 @@ void GenericCAO::updateAttachments()
 			getPosRotMatrix().setRotationDegrees(m_attachment_rotation);
 			m_matrixnode->updateAbsolutePosition();
 		}
-		if (m_is_local_player) {
-			LocalPlayer *player = m_env->getLocalPlayer();
-			player->isAttached = true;
-		}
+	}
+	if (m_is_local_player) {
+		LocalPlayer *player = m_env->getLocalPlayer();
+		player->isAttached = parent;
+		player->parent = parent;
 	}
 }
 
@@ -1488,31 +1524,15 @@ void GenericCAO::processMessage(const std::string &data)
 		updateBonePosition();
 	} else if (cmd == GENERIC_CMD_ATTACH_TO) {
 		u16 parent_id = readS16(is);
-		u16 &old_parent_id = m_env->attachement_parent_ids[getId()];
-		if (parent_id != old_parent_id) {
-			if (GenericCAO *old_parent = m_env->getGenericCAO(old_parent_id)) {
-				old_parent->m_children.erase(std::remove(
-					m_children.begin(), m_children.end(),
-					getId()), m_children.end());
-			}
-			if (GenericCAO *new_parent = m_env->getGenericCAO(parent_id))
-				new_parent->m_children.push_back(getId());
-
-			old_parent_id = parent_id;
-		}
+		std::string bone = deSerializeString(is);
+		v3f position = readV3F32(is);
+		v3f rotation = readV3F32(is);
 
-		m_attachment_bone = deSerializeString(is);
-		m_attachment_position = readV3F32(is);
-		m_attachment_rotation = readV3F32(is);
+		setAttachment(parent_id, bone, position, rotation);
 
 		// localplayer itself can't be attached to localplayer
-		if (!m_is_local_player) {
-			m_attached_to_local = getParent() != NULL && getParent()->isLocalPlayer();
-			// Objects attached to the local player should be hidden by default
+		if (!m_is_local_player)
 			m_is_visible = !m_attached_to_local;
-		}
-
-		updateAttachments();
 	} else if (cmd == GENERIC_CMD_PUNCHED) {
 		u16 result_hp = readU16(is);
 
@@ -1539,6 +1559,12 @@ void GenericCAO::processMessage(const std::string &data)
 					m_reset_textures_timer += 0.05 * damage;
 				updateTextures(m_current_texture_modifier + "^[brighten");
 			}
+		} else {
+			// Same as 'Server::DiePlayer'
+			clearParentAttachment();
+			// Same as 'ObjectRef::l_remove'
+			if (!m_is_player)
+				clearChildAttachments();
 		}
 	} else if (cmd == GENERIC_CMD_UPDATE_ARMOR_GROUPS) {
 		m_armor_groups.clear();
@@ -1561,13 +1587,10 @@ void GenericCAO::processMessage(const std::string &data)
 		}
 	} else if (cmd == GENERIC_CMD_SPAWN_INFANT) {
 		u16 child_id = readU16(is);
-		u8 type = readU8(is);
+		u8 type = readU8(is); // maybe this will be useful later
+		(void)type;
 
-		if (GenericCAO *childobj = m_env->getGenericCAO(child_id)) {
-			childobj->processInitData(deSerializeLongString(is));
-		} else {
-			m_env->addActiveObject(child_id, type, deSerializeLongString(is));
-		}
+		addAttachmentChild(child_id);
 	} else {
 		warningstream << FUNCTION_NAME
 			<< ": unknown command or outdated client \""