Add First Person Attachments (#10360)

Fixes some other third person camera specific attachments.
Implements a single new flag for entities to be forced visible in first person mode.
Old mods do not need to be updated to use the new flag and are fully backwards compatible.

doc/lua_api.txt

@@ -6167,12 +6167,14 @@ object you are working with still exists.
   `frame_loop`.
 * `set_animation_frame_speed(frame_speed)`
     * `frame_speed`: number, default: `15.0`
-* `set_attach(parent, bone, position, rotation)`
+* `set_attach(parent, bone, position, rotation, forced_visible)`
     * `bone`: string
     * `position`: `{x=num, y=num, z=num}` (relative)
     * `rotation`: `{x=num, y=num, z=num}` = Rotation on each axis, in degrees
-* `get_attach()`: returns parent, bone, position, rotation or nil if it isn't
-  attached.
+    * `forced_visible`: Boolean to control whether the attached entity 
+       should appear in first person.
+* `get_attach()`: returns parent, bone, position, rotation, forced_visible, 
+    or nil if it isn't attached.
 * `set_detach()`
 * `set_bone_position(bone, position, rotation)`
     * `bone`: string

src/activeobject.h

@@ -120,9 +120,9 @@ public:
 
 
 	virtual void setAttachment(int parent_id, const std::string &bone, v3f position,
-			v3f rotation) {}
+			v3f rotation, bool force_visible) {}
 	virtual void getAttachment(int *parent_id, std::string *bone, v3f *position,
-			v3f *rotation) const {}
+			v3f *rotation, bool *force_visible) const {}
 	virtual void clearChildAttachments() {}
 	virtual void clearParentAttachment() {}
 	virtual void addAttachmentChild(int child_id) {}

src/client/content_cao.cpp

@@ -456,7 +456,8 @@ void GenericCAO::setChildrenVisible(bool toset)
 	for (u16 cao_id : m_attachment_child_ids) {
 		GenericCAO *obj = m_env->getGenericCAO(cao_id);
 		if (obj) {
-			obj->setVisible(toset);
+			// Check if the entity is forced to appear in first person.
+			obj->setVisible(obj->isForcedVisible() ? true : toset);
 		}
 	}
 }
@@ -477,8 +478,6 @@ void GenericCAO::setAttachment(int parent_id, const std::string &bone, v3f posit
 		if (parent)
 			parent->addAttachmentChild(m_id);
 	}
-
-
 	updateAttachments();
 }
 
@@ -498,7 +497,7 @@ void GenericCAO::clearChildAttachments()
 		int child_id = *m_attachment_child_ids.begin();
 
 		if (ClientActiveObject *child = m_env->getActiveObject(child_id))
-			child->setAttachment(0, "", v3f(), v3f());
+			child->setAttachment(0, "", v3f(), v3f(), false);
 
 		removeAttachmentChild(child_id);
 	}
@@ -800,6 +799,7 @@ void GenericCAO::addToScene(ITextureSource *tsrc)
 	updateBonePosition();
 	updateAttachments();
 	setNodeLight(m_last_light);
+	updateMeshCulling();
 }
 
 void GenericCAO::updateLight(u32 day_night_ratio)
@@ -1411,6 +1411,9 @@ void GenericCAO::updateTextures(std::string mod)
 				setMeshColor(mesh, m_prop.colors[0]);
 		}
 	}
+	// Prevent showing the player after changing texture
+	if (m_is_local_player)
+		updateMeshCulling();
 }
 
 void GenericCAO::updateAnimation()
@@ -1739,12 +1742,25 @@ void GenericCAO::processMessage(const std::string &data)
 		std::string bone = deSerializeString16(is);
 		v3f position = readV3F32(is);
 		v3f rotation = readV3F32(is);
+		m_force_visible = readU8(is); // Returns false for EOF
 
 		setAttachment(parent_id, bone, position, rotation);
 
+		// Forcibly show attachments if required by set_attach
+		if (m_force_visible)
+			m_is_visible = true;
 		// localplayer itself can't be attached to localplayer
-		if (!m_is_local_player)
-			m_is_visible = !m_attached_to_local;
+		else if (!m_is_local_player) {
+			// Objects attached to the local player should be hidden in first
+			// person provided the forced boolean isn't set.
+			m_is_visible = !m_attached_to_local ||
+				m_client->getCamera()->getCameraMode() != CAMERA_MODE_FIRST;
+			m_force_visible = false;
+		} else {
+			// Local players need to have this set,
+			// otherwise first person attachments fail.
+			m_is_visible = true;
+		}
 	} else if (cmd == AO_CMD_PUNCHED) {
 		u16 result_hp = readU16(is);
 
@@ -1858,5 +1874,33 @@ std::string GenericCAO::debugInfoText()
 	return os.str();
 }
 
+void GenericCAO::updateMeshCulling()
+{
+	if (!m_is_local_player)
+		return;
+
+	// Grab the active player scene node so we know there's
+	// at least a mesh to occlude from the camera.
+	irr::scene::ISceneNode *node = getSceneNode();
+	if (!node)
+		return;
+
+	if (m_client->getCamera()->getCameraMode() == CAMERA_MODE_FIRST) {
+		// Hide the mesh by culling both front and
+		// back faces. Serious hackyness but it works for our
+		// purposes. This also preserves the skeletal armature.
+		node->setMaterialFlag(video::EMF_BACK_FACE_CULLING,
+			true);
+		node->setMaterialFlag(video::EMF_FRONT_FACE_CULLING,
+			true);
+	} else {
+		// Restore mesh visibility.
+		node->setMaterialFlag(video::EMF_BACK_FACE_CULLING,
+			m_prop.backface_culling);
+		node->setMaterialFlag(video::EMF_FRONT_FACE_CULLING,
+			false);
+	}
+}
+
 // Prototype
 GenericCAO proto_GenericCAO(NULL, NULL);

src/client/content_cao.h

@@ -124,6 +124,7 @@ private:
 	float m_step_distance_counter = 0.0f;
 	u8 m_last_light = 255;
 	bool m_is_visible = false;
+	bool m_force_visible = false;
 	s8 m_glow = 0;
 	// Material
 	video::E_MATERIAL_TYPE m_material_type;
@@ -215,6 +216,11 @@ public:
 		m_is_visible = toset;
 	}
 
+	inline bool isForcedVisible() const
+	{
+		return m_force_visible;
+	}
+
 	void setChildrenVisible(bool toset);
 	void setAttachment(int parent_id, const std::string &bone, v3f position, v3f rotation);
 	void getAttachment(int *parent_id, std::string *bone, v3f *position,
@@ -275,4 +281,6 @@ public:
 	{
 		return m_prop.infotext;
 	}
+
+	void updateMeshCulling();
 };

src/client/game.cpp

@@ -2950,7 +2950,8 @@ void Game::updateCamera(u32 busy_time, f32 dtime)
 
 		camera->toggleCameraMode();
 
-		playercao->setVisible(camera->getCameraMode() > CAMERA_MODE_FIRST);
+		// Make the player visible depending on camera mode.
+		playercao->updateMeshCulling();
 		playercao->setChildrenVisible(camera->getCameraMode() > CAMERA_MODE_FIRST);
 	}
 

src/clientiface.cpp

@@ -80,10 +80,11 @@ LuaEntitySAO *getAttachedObject(PlayerSAO *sao, ServerEnvironment *env)
 	int id;
 	std::string bone;
 	v3f dummy;
-	sao->getAttachment(&id, &bone, &dummy, &dummy);
+	bool force_visible;
+	sao->getAttachment(&id, &bone, &dummy, &dummy, &force_visible);
 	ServerActiveObject *ao = env->getActiveObject(id);
 	while (id && ao) {
-		ao->getAttachment(&id, &bone, &dummy, &dummy);
+		ao->getAttachment(&id, &bone, &dummy, &dummy, &force_visible);
 		if (id)
 			ao = env->getActiveObject(id);
 	}

src/script/lua_api/l_camera.cpp

@@ -63,7 +63,8 @@ int LuaCamera::l_set_camera_mode(lua_State *L)
 		return 0;
 
 	camera->setCameraMode((CameraMode)((int)lua_tonumber(L, 2)));
-	playercao->setVisible(camera->getCameraMode() > CAMERA_MODE_FIRST);
+	// Make the player visible depending on camera mode.
+	playercao->updateMeshCulling();
 	playercao->setChildrenVisible(camera->getCameraMode() > CAMERA_MODE_FIRST);
 	return 0;
 }

src/script/lua_api/l_object.cpp

@@ -664,7 +664,7 @@ int ObjectRef::l_get_bone_position(lua_State *L)
 	return 2;
 }
 
-// set_attach(self, parent, bone, position, rotation)
+// set_attach(self, parent, bone, position, rotation, force_visible)
 int ObjectRef::l_set_attach(lua_State *L)
 {
 	GET_ENV_PTR;
@@ -687,7 +687,8 @@ int ObjectRef::l_set_attach(lua_State *L)
 	std::string bone;
 	v3f position = v3f(0, 0, 0);
 	v3f rotation = v3f(0, 0, 0);
-	co->getAttachment(&parent_id, &bone, &position, &rotation);
+	bool force_visible;
+	co->getAttachment(&parent_id, &bone, &position, &rotation, &force_visible);
 	if (parent_id) {
 		ServerActiveObject *old_parent = env->getActiveObject(parent_id);
 		old_parent->removeAttachmentChild(co->getId());
@@ -702,7 +703,8 @@ int ObjectRef::l_set_attach(lua_State *L)
 	rotation = v3f(0, 0, 0);
 	if (!lua_isnil(L, 5))
 		rotation = read_v3f(L, 5);
-	co->setAttachment(parent->getId(), bone, position, rotation);
+	force_visible = readParam<bool>(L, 6, false);
+	co->setAttachment(parent->getId(), bone, position, rotation, force_visible);
 	parent->addAttachmentChild(co->getId());
 	return 0;
 }
@@ -722,7 +724,8 @@ int ObjectRef::l_get_attach(lua_State *L)
 	std::string bone;
 	v3f position = v3f(0, 0, 0);
 	v3f rotation = v3f(0, 0, 0);
-	co->getAttachment(&parent_id, &bone, &position, &rotation);
+	bool force_visible;
+	co->getAttachment(&parent_id, &bone, &position, &rotation, &force_visible);
 	if (!parent_id)
 		return 0;
 	ServerActiveObject *parent = env->getActiveObject(parent_id);
@@ -731,7 +734,8 @@ int ObjectRef::l_get_attach(lua_State *L)
 	lua_pushlstring(L, bone.c_str(), bone.size());
 	push_v3f(L, position);
 	push_v3f(L, rotation);
-	return 4;
+	lua_pushboolean(L, force_visible);
+	return 5;
 }
 
 // set_detach(self)

src/server/luaentity_sao.cpp

@@ -238,9 +238,9 @@ std::string LuaEntitySAO::getClientInitializationData(u16 protocol_version)
 	msg_os << serializeString32(generateUpdateAnimationCommand()); // 3
 	for (const auto &bone_pos : m_bone_position) {
 		msg_os << serializeString32(generateUpdateBonePositionCommand(
-			bone_pos.first, bone_pos.second.X, bone_pos.second.Y)); // m_bone_position.size
+			bone_pos.first, bone_pos.second.X, bone_pos.second.Y)); // 3 + N
 	}
-	msg_os << serializeString32(generateUpdateAttachmentCommand()); // 4
+	msg_os << serializeString32(generateUpdateAttachmentCommand()); // 4 + m_bone_position.size
 
 	int message_count = 4 + m_bone_position.size();
 

src/server/player_sao.cpp

@@ -122,10 +122,10 @@ std::string PlayerSAO::getClientInitializationData(u16 protocol_version)
 	msg_os << serializeString32(generateUpdateAnimationCommand()); // 3
 	for (const auto &bone_pos : m_bone_position) {
 		msg_os << serializeString32(generateUpdateBonePositionCommand(
-			bone_pos.first, bone_pos.second.X, bone_pos.second.Y)); // m_bone_position.size
+			bone_pos.first, bone_pos.second.X, bone_pos.second.Y)); // 3 + N
 	}
-	msg_os << serializeString32(generateUpdateAttachmentCommand()); // 4
-	msg_os << serializeString32(generateUpdatePhysicsOverrideCommand()); // 5
+	msg_os << serializeString32(generateUpdateAttachmentCommand()); // 4 + m_bone_position.size
+	msg_os << serializeString32(generateUpdatePhysicsOverrideCommand()); // 5 + m_bone_position.size
 
 	int message_count = 5 + m_bone_position.size();
 
@@ -569,7 +569,8 @@ bool PlayerSAO::checkMovementCheat()
 			int parent_id;
 			std::string bone;
 			v3f attachment_rot;
-			getAttachment(&parent_id, &bone, &attachment_pos, &attachment_rot);
+			bool force_visible;
+			getAttachment(&parent_id, &bone, &attachment_pos, &attachment_rot, &force_visible);
 		}
 
 		v3f parent_pos = parent->getBasePosition();

src/server/unit_sao.cpp

@@ -121,8 +121,8 @@ void UnitSAO::sendOutdatedData()
 }
 // clang-format on
 
-void UnitSAO::setAttachment(
-		int parent_id, const std::string &bone, v3f position, v3f rotation)
+void UnitSAO::setAttachment(int parent_id, const std::string &bone, v3f position,
+		v3f rotation, bool force_visible)
 {
 	// 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.
@@ -137,6 +137,7 @@ void UnitSAO::setAttachment(
 	m_attachment_bone = bone;
 	m_attachment_position = position;
 	m_attachment_rotation = rotation;
+	m_force_visible = force_visible;
 	m_attachment_sent = false;
 
 	if (parent_id != old_parent) {
@@ -145,13 +146,14 @@ void UnitSAO::setAttachment(
 	}
 }
 
-void UnitSAO::getAttachment(
-		int *parent_id, std::string *bone, v3f *position, v3f *rotation) const
+void UnitSAO::getAttachment(int *parent_id, std::string *bone, v3f *position,
+		v3f *rotation, bool *force_visible) const
 {
 	*parent_id = m_attachment_parent_id;
 	*bone = m_attachment_bone;
 	*position = m_attachment_position;
 	*rotation = m_attachment_rotation;
+	*force_visible = m_force_visible;
 }
 
 void UnitSAO::clearChildAttachments()
@@ -159,7 +161,7 @@ void UnitSAO::clearChildAttachments()
 	for (int child_id : m_attachment_child_ids) {
 		// Child can be NULL if it was deleted earlier
 		if (ServerActiveObject *child = m_env->getActiveObject(child_id))
-			child->setAttachment(0, "", v3f(0, 0, 0), v3f(0, 0, 0));
+			child->setAttachment(0, "", v3f(0, 0, 0), v3f(0, 0, 0), false);
 	}
 	m_attachment_child_ids.clear();
 }
@@ -169,9 +171,9 @@ void UnitSAO::clearParentAttachment()
 	ServerActiveObject *parent = nullptr;
 	if (m_attachment_parent_id) {
 		parent = m_env->getActiveObject(m_attachment_parent_id);
-		setAttachment(0, "", m_attachment_position, m_attachment_rotation);
+		setAttachment(0, "", m_attachment_position, m_attachment_rotation, false);
 	} else {
-		setAttachment(0, "", v3f(0, 0, 0), v3f(0, 0, 0));
+		setAttachment(0, "", v3f(0, 0, 0), v3f(0, 0, 0), false);
 	}
 	// Do it
 	if (parent)
@@ -245,6 +247,7 @@ std::string UnitSAO::generateUpdateAttachmentCommand() const
 	os << serializeString16(m_attachment_bone);
 	writeV3F32(os, m_attachment_position);
 	writeV3F32(os, m_attachment_rotation);
+	writeU8(os, m_force_visible);
 	return os.str();
 }
 

src/server/unit_sao.h

@@ -64,9 +64,9 @@ public:
 	ServerActiveObject *getParent() const;
 	inline bool isAttached() const { return getParent(); }
 	void setAttachment(int parent_id, const std::string &bone, v3f position,
-			v3f rotation);
+			v3f rotation, bool force_visible);
 	void getAttachment(int *parent_id, std::string *bone, v3f *position,
-			v3f *rotation) const;
+			v3f *rotation, bool *force_visible) const;
 	void clearChildAttachments();
 	void clearParentAttachment();
 	void addAttachmentChild(int child_id);
@@ -133,4 +133,5 @@ private:
 	v3f m_attachment_position;
 	v3f m_attachment_rotation;
 	bool m_attachment_sent = false;
+	bool m_force_visible = false;
 };