Complete the attachment framework.

The child ID can now be checked against the parent ID in content_cao.cpp so the parent can be detected. Actual attachment code to come

Divide attachment system between server attachments and client attachments, neither coded right now. As explained in the code comment:

// Attachments need to be handled on both the server and client.
// If we attach only on the server, models (which are client-side)
// can't be read so we don't know the origin and orientation of bones.
// If we attach only on the client, the real position of attachments is
// not updated and you can't click them for example.

src/content_cao.cpp

@@ -581,6 +581,10 @@ private:
 	int m_frame_speed;
 	int m_frame_blend;
 	std::map<std::string, core::vector2d<v3f> > m_bone_posrot;
+	ClientActiveObject* m_attachment_parent;
+	std::string m_attachment_bone;
+	v3f m_attacmhent_position;
+	v3f m_attachment_rotation;
 	int m_anim_frame;
 	int m_anim_num_frames;
 	float m_anim_framelength;
@@ -615,6 +619,14 @@ public:
 		m_tx_basepos(0,0),
 		m_initial_tx_basepos_set(false),
 		m_tx_select_horiz_by_yawpitch(false),
+		m_frames(v2f(0,0)),
+		m_frame_speed(15),
+		m_frame_blend(0),
+		// Nothing to do for m_bone_posrot
+		m_attachment_parent(NULL),
+		m_attachment_bone(""),
+		m_attacmhent_position(v3f(0,0,0)),
+		m_attachment_rotation(v3f(0,0,0)),
 		m_anim_frame(0),
 		m_anim_num_frames(1),
 		m_anim_framelength(0.2),
@@ -906,6 +918,9 @@ public:
 
 	void updateNodePos()
 	{
+		if(m_attachment_parent != NULL)
+			return;
+
 		if(m_meshnode){
 			m_meshnode->setPosition(pos_translator.vect_show);
 			v3f rot = m_meshnode->getRotation();
@@ -933,9 +948,10 @@ public:
 			addToScene(m_smgr, m_gamedef->tsrc(), m_irr);
 			updateAnimations();
 			updateBonePosRot();
-			updateAttachment();
 		}
 
+		if(m_attachment_parent == NULL) // Attachments should be glued to their parent by Irrlicht
+		{
 			if(m_prop.physical){
 				core::aabbox3d<f32> box = m_prop.collisionbox;
 				box.MinEdge *= BS;
@@ -980,6 +996,7 @@ public:
 					m_gamedef->sound()->playSoundAt(spec, false, getPosition());
 				}
 			}
+		}
 
 		m_anim_timer += dtime;
 		if(m_anim_timer >= m_anim_framelength){
@@ -1194,9 +1211,37 @@ public:
 		}
 	}
 	
-	void updateAttachment()
+	void updateAttachments()
 	{
-		// Code for attachments goes here
+		// REMAINING ATTACHMENT ISSUES:
+		// We get to this function when the object is an attachment that needs to
+		// be attached to its parent. If a bone is set we attach it to that skeletal
+		// bone, otherwise just to the object's origin. Attachments should not copy parent
+		// position as that's laggy... instead the Irrlicht function(s) to attach should
+		// be used. If the parent object is NULL that means this object should be detached.
+		// This function is only called whenever a GENERIC_CMD_SET_ATTACHMENT message is received.
+		
+		// We already attach our entity on the server too (copy position). Reason we attach
+		// to the client as well is first of all lag. The server sends the position
+		// of the child separately than that of the parent, so even on localhost
+		// you'd see the child lagging behind. Models are also client-side, so this is
+		// needed to read bone data and attach to joints.
+		
+		// Functions:
+		// - m_attachment_parent is ClientActiveObject* for the parent entity.
+		// - m_attachment_bone is std::string of the bone, "" means none.
+		// - m_attachment_position is v3f and represents the position offset of the attachment.
+		// - m_attachment_rotation is v3f and represents the rotation offset of the attachment.
+		
+		// Implementation information:
+		// From what I know, we need to get the AnimatedMeshSceneNode of m_attachment_parent then
+		// use parent_node->addChild(m_animated_meshnode) for position attachment. For skeletal
+		// attachment I don't know yet. Same must be used to detach when a NULL parent is received.
+
+		//Useful links:
+		// http://irrlicht.sourceforge.net/forum/viewtopic.php?t=7514
+		// http://www.irrlicht3d.org/wiki/index.php?n=Main.HowToUseTheNewAnimationSystem
+		// Irrlicht documentation: http://irrlicht.sourceforge.net/docu/
 	}
 
 	void processMessage(const std::string &data)
@@ -1225,6 +1270,8 @@ public:
 		}
 		else if(cmd == GENERIC_CMD_UPDATE_POSITION)
 		{
+			// Not sent by the server if the object is an attachment
+			
 			m_position = readV3F1000(is);
 			m_velocity = readV3F1000(is);
 			m_acceleration = readV3F1000(is);
@@ -1287,12 +1334,18 @@ public:
 		}
 		else if(cmd == GENERIC_CMD_SET_ATTACHMENT)
 		{
-			// Part of the attachment structure, not used yet!
+			ClientActiveObject *obj;
+			int parent_id = readS16(is);
+			if(parent_id > 0)
+				obj = m_env->getActiveObject(parent_id);
+			else
+				obj = NULL;
+			m_attachment_parent = obj;
+			m_attachment_bone = deSerializeString(is);
+			m_attacmhent_position = readV3F1000(is);
+			m_attachment_rotation = readV3F1000(is);
 
-			// Get properties here.
+			updateAttachments();
-
-			updateAttachment();
-			expireVisuals();
 		}
 		else if(cmd == GENERIC_CMD_PUNCHED)
 		{

src/content_sao.cpp

@@ -218,6 +218,7 @@ public:
 
 		if(pos_f.getDistanceFrom(m_last_sent_position) > 0.05*BS)
 		{
+			// TODO: We shouldn't be sending this when the object is attached, but we can't check m_parent here
 			setBasePosition(pos_f);
 			m_last_sent_position = pos_f;
 
@@ -383,6 +384,7 @@ void LuaEntitySAO::addedToEnvironment(u32 dtime_s)
 	// Create entity from name
 	lua_State *L = m_env->getLua();
 	m_registered = scriptapi_luaentity_add(L, m_id, m_init_name.c_str());
+	m_parent = NULL;
 	
 	if(m_registered){
 		// Get properties
@@ -442,6 +444,16 @@ void LuaEntitySAO::step(float dtime, bool send_recommended)
 
 	m_last_sent_position_timer += dtime;
 	
+	if(m_parent != NULL)
+	{
+		// REMAINING ATTACHMENT ISSUES:
+		// This is causing a segmentation fault, investigate why!
+		//m_base_position = m_parent->getBasePosition();
+		m_velocity = v3f(0,0,0);
+		m_acceleration = v3f(0,0,0);
+	}
+	else
+	{
 		if(m_prop.physical){
 			core::aabbox3d<f32> box = m_prop.collisionbox;
 			box.MinEdge *= BS;
@@ -465,6 +477,7 @@ void LuaEntitySAO::step(float dtime, bool send_recommended)
 					* dtime * m_acceleration;
 			m_velocity += dtime * m_acceleration;
 		}
+	}
 
 	if(m_registered){
 		lua_State *L = m_env->getLua();
@@ -552,6 +565,10 @@ int LuaEntitySAO::punch(v3f dir,
 		return 0;
 	}
 
+	// It's best that attachments cannot be punched 
+	if(m_parent != NULL)
+		return 0;
+	
 	ItemStack *punchitem = NULL;
 	ItemStack punchitem_static;
 	if(puncher){
@@ -601,12 +618,16 @@ void LuaEntitySAO::rightClick(ServerActiveObject *clicker)
 
 void LuaEntitySAO::setPos(v3f pos)
 {
+	if(m_parent != NULL)
+		return;
 	m_base_position = pos;
 	sendPosition(false, true);
 }
 
 void LuaEntitySAO::moveTo(v3f pos, bool continuous)
 {
+	if(m_parent != NULL)
+		return;
 	m_base_position = pos;
 	if(!continuous)
 		sendPosition(true, true);
@@ -661,14 +682,21 @@ void LuaEntitySAO::setBonePosRot(std::string bone, v3f position, v3f rotation)
 	m_messages_out.push_back(aom);
 }
 
-// Part of the attachment structure, not used yet!
 void LuaEntitySAO::setAttachment(ServerActiveObject *parent, std::string bone, v3f position, v3f rotation)
 {
-	// Parent should be translated from a ServerActiveObject into something
+	// Attachments need to be handled on both the server and client.
-	// the client will recognize (as a ClientActiveObject) then sent in
+	// If we just attach on the server, we can only copy the position of the parent. Attachments
-	// gob_cmd_set_attachment that way.
+	// are still sent to clients at an interval so players would see them following the parent
+	// instead of sticking to it, plus we can't read and attach to skeletal bones.
+	// If we just attach on the client, the server still sees the child at its original location.
+	// This can break some things, so we also give the server the most accurate representation
+	// even if players will only see the client changes since they override server-sent position.
 
-	std::string str = gob_cmd_set_attachment(); // <- parameters here
+	// Server attachment:
+	m_parent = parent;
+
+	// Client attachment:
+	std::string str = gob_cmd_set_attachment(parent->getId(), bone, position, rotation);
 	// create message and add to list
 	ActiveObjectMessage aom(getId(), true, str);
 	m_messages_out.push_back(aom);
@@ -748,6 +776,9 @@ std::string LuaEntitySAO::getPropertyPacket()
 
 void LuaEntitySAO::sendPosition(bool do_interpolate, bool is_movement_end)
 {
+	if(m_parent != NULL)
+		return;
+	
 	m_last_sent_move_precision = m_base_position.getDistanceFrom(
 			m_last_sent_position);
 	m_last_sent_position_timer = 0;
@@ -843,6 +874,7 @@ void PlayerSAO::addedToEnvironment(u32 dtime_s)
 {
 	ServerActiveObject::addedToEnvironment(dtime_s);
 	ServerActiveObject::setBasePosition(m_player->getPosition());
+	m_parent = NULL;
 	m_player->setPlayerSAO(this);
 	m_player->peer_id = m_peer_id;
 	m_last_good_position = m_player->getPosition();
@@ -906,6 +938,8 @@ void PlayerSAO::step(float dtime, bool send_recommended)
 	m_time_from_last_punch += dtime;
 	m_nocheat_dig_time += dtime;
 
+	if(m_parent == NULL)
+	{
 		if(m_is_singleplayer || g_settings->getBool("disable_anticheat"))
 		{
 			m_last_good_position = m_player->getPosition();
@@ -960,16 +994,25 @@ void PlayerSAO::step(float dtime, bool send_recommended)
 				m_last_good_position_age = 0;
 			}
 		}
+	}
 
 	if(send_recommended == false)
 		return;
 
-	if(m_position_not_sent)
+	// If the object is attached client-side, don't waste bandwidth and send its position to clients
+	if(m_position_not_sent && m_parent == NULL)
 	{
 		m_position_not_sent = false;
 		float update_interval = m_env->getSendRecommendedInterval();
+		v3f pos;
+		// REMAINING ATTACHMENT ISSUES:
+		// This is causing a segmentation fault, investigate why!
+		if(m_parent != NULL)
+			pos = m_parent->getBasePosition();
+		else
+			pos = m_player->getPosition() + v3f(0,BS*1,0);
 		std::string str = gob_cmd_update_position(
-			m_player->getPosition() + v3f(0,BS*1,0),
+			pos,
 			v3f(0,0,0),
 			v3f(0,0,0),
 			m_player->getYaw(),
@@ -1000,12 +1043,16 @@ void PlayerSAO::step(float dtime, bool send_recommended)
 
 void PlayerSAO::setBasePosition(const v3f &position)
 {
+	if(m_parent != NULL)
+		return;
 	ServerActiveObject::setBasePosition(position);
 	m_position_not_sent = true;
 }
 
 void PlayerSAO::setPos(v3f pos)
 {
+	if(m_parent != NULL)
+		return;
 	m_player->setPosition(pos);
 	// Movement caused by this command is always valid
 	m_last_good_position = pos;
@@ -1016,6 +1063,8 @@ void PlayerSAO::setPos(v3f pos)
 
 void PlayerSAO::moveTo(v3f pos, bool continuous)
 {
+	if(m_parent != NULL)
+		return;
 	m_player->setPosition(pos);
 	// Movement caused by this command is always valid
 	m_last_good_position = pos;
@@ -1029,6 +1078,10 @@ int PlayerSAO::punch(v3f dir,
 	ServerActiveObject *puncher,
 	float time_from_last_punch)
 {
+	// It's best that attachments cannot be punched 
+	if(m_parent != NULL)
+		return 0;
+
 	if(!toolcap)
 		return 0;
 
@@ -1126,10 +1179,21 @@ void PlayerSAO::setBonePosRot(std::string bone, v3f position, v3f rotation)
 	m_messages_out.push_back(aom);
 }
 
-// Part of the attachment structure, not used yet!
 void PlayerSAO::setAttachment(ServerActiveObject *parent, std::string bone, v3f position, v3f rotation)
 {
-	std::string str = gob_cmd_set_attachment(); // <- parameters here
+	// Attachments need to be handled on both the server and client.
+	// If we just attach on the server, we can only copy the position of the parent. Attachments
+	// are still sent to clients at an interval so players would see them following the parent
+	// instead of sticking to it, plus we can't read and attach to skeletal bones.
+	// If we just attach on the client, the server still sees the child at its original location.
+	// This can break some things, so we also give the server the most accurate representation
+	// even if players will only see the client changes since they override server-sent position.
+
+	// Server attachment:
+	m_parent = parent;
+
+	// Client attachment:
+	std::string str = gob_cmd_set_attachment(parent->getId(), bone, position, rotation);
 	// create message and add to list
 	ActiveObjectMessage aom(getId(), true, str);
 	m_messages_out.push_back(aom);

src/content_sao.h

@@ -99,6 +99,7 @@ private:
 	float m_last_sent_position_timer;
 	float m_last_sent_move_precision;
 	bool m_armor_groups_sent;
+	ServerActiveObject *m_parent;
 };
 
 /*
@@ -235,6 +236,7 @@ private:
 	bool m_position_not_sent;
 	ItemGroupList m_armor_groups;
 	bool m_armor_groups_sent;
+	ServerActiveObject *m_parent;
 	bool m_properties_sent;
 	struct ObjectProperties m_prop;
 	// Cached privileges for enforcement

src/genericobject.cpp

@@ -104,17 +104,6 @@ std::string gob_cmd_set_animations(v2f frames, float frame_speed, float frame_bl
 	return os.str();
 }
 
-// Part of the attachment structure, not used yet!
-std::string gob_cmd_set_attachment() // <- parameters here
-{
-	std::ostringstream os(std::ios::binary);
-	// command 
-	writeU8(os, GENERIC_CMD_SET_ATTACHMENT);
-	// parameters
-	// Parameters go here
-	return os.str();
-}
-
 std::string gob_cmd_set_bone_posrot(std::string bone, v3f position, v3f rotation)
 {
 	std::ostringstream os(std::ios::binary);
@@ -127,6 +116,19 @@ std::string gob_cmd_set_bone_posrot(std::string bone, v3f position, v3f rotation
 	return os.str();
 }
 
+std::string gob_cmd_set_attachment(int parent_id, std::string bone, v3f position, v3f rotation)
+{
+	std::ostringstream os(std::ios::binary);
+	// command 
+	writeU8(os, GENERIC_CMD_SET_ATTACHMENT);
+	// parameters
+	writeS16(os, parent_id);
+	os<<serializeString(bone);
+	writeV3F1000(os, position);
+	writeV3F1000(os, rotation);
+	return os.str();
+}
+
 std::string gob_cmd_punched(s16 damage, s16 result_hp)
 {
 	std::ostringstream os(std::ios::binary);

src/genericobject.h

@@ -61,7 +61,7 @@ std::string gob_cmd_set_animations(v2f frames, float frame_speed, float frame_bl
 
 std::string gob_cmd_set_bone_posrot(std::string bone, v3f position, v3f rotation);
 
-std::string gob_cmd_set_attachment(); // <- parameters here
+std::string gob_cmd_set_attachment(int parent_id, std::string bone, v3f position, v3f rotation);
 
 std::string gob_cmd_punched(s16 damage, s16 result_hp);
 

src/scriptapi.cpp

@@ -2737,7 +2737,7 @@ private:
 		return 0;
 	}
 
-	// setboneposrot(std::string bone, v3f position, v3f rotation)
+	// setboneposrot(self, std::string bone, v3f position, v3f rotation)
 	static int l_set_bone_posrot(lua_State *L)
 	{
 		ObjectRef *ref = checkobject(L, 1);
@@ -2758,8 +2758,7 @@ private:
 		return 0;
 	}
 
-// Part of the attachment structure, not used yet!
+	// set_attachment(self, parent, bone, position, rotation)
-	// set_attachment() // <- parameters here
 	static int l_set_attachment(lua_State *L)
 	{
 		ObjectRef *ref = checkobject(L, 1);
@@ -2779,8 +2778,6 @@ private:
 			rotation = read_v3f(L, 5);
 		// Do it
 
-//lua_pushnumber(L, cobj->getId()); // Push id
-
 		co->setAttachment(parent, bone, position, rotation);
 		return 0;
 	}