Allow place_param2 = 0 node placement predictions (#13787)

The placement prediction value 0 was accidentally ignored
and made the clients fall back to automatic rotation based
on the node paramtype2 value.

This now changes the internal representation to properly
indicate the disabled state (e.g. 'nil' in Lua).

src/client/game.cpp

@@ -3627,10 +3627,10 @@ bool Game::nodePlacement(const ItemDefinition &selected_def,
 	// Compare core.item_place_node() for what the server does with param2
 	MapNode predicted_node(id, 0, 0);
 
-	const u8 place_param2 = selected_def.place_param2;
+	const auto place_param2 = selected_def.place_param2;
 
 	if (place_param2) {
-		predicted_node.setParam2(place_param2);
+		predicted_node.setParam2(*place_param2);
 	} else if (predicted_f.param_type_2 == CPT2_WALLMOUNTED ||
 			predicted_f.param_type_2 == CPT2_COLORED_WALLMOUNTED) {
 		v3s16 dir = nodepos - neighborpos;

src/client/wieldmesh.cpp

@@ -443,7 +443,8 @@ void WieldMeshSceneNode::setItem(const ItemStack &item, Client *client, bool che
 		default: {
 			// Render non-trivial drawtypes like the actual node
 			MapNode n(id);
-			n.setParam2(def.place_param2);
+			if (def.place_param2)
+				n.setParam2(*def.place_param2);
 
 			mesh = createSpecialNodeMesh(client, n, &m_colors, f);
 			changeToMesh(mesh);
@@ -638,7 +639,8 @@ void getItemMesh(Client *client, const ItemStack &item, ItemMesh *result)
 		default: {
 			// Render non-trivial drawtypes like the actual node
 			MapNode n(id);
-			n.setParam2(def.place_param2);
+			if (def.place_param2)
+				n.setParam2(*def.place_param2);
 
 			mesh = createSpecialNodeMesh(client, n, &result->buffer_colors, f);
 			scaleMesh(mesh, v3f(0.12, 0.12, 0.12));

src/itemdef.cpp

@@ -123,7 +123,7 @@ void ItemDefinition::reset()
 	sound_use_air = SoundSpec();
 	range = -1;
 	node_placement_prediction.clear();
-	place_param2 = 0;
+	place_param2.reset();
 }
 
 void ItemDefinition::serialize(std::ostream &os, u16 protocol_version) const
@@ -169,10 +169,20 @@ void ItemDefinition::serialize(std::ostream &os, u16 protocol_version) const
 
 	os << serializeString16(short_description);
 
-	os << place_param2;
+	if (protocol_version <= 43) {
+		// Uncertainity whether 0 is the specified prediction or means disabled
+		if (place_param2)
+			os << *place_param2;
+		else
+			os << (u8)0;
+	}
 
 	sound_use.serializeSimple(os, protocol_version);
 	sound_use_air.serializeSimple(os, protocol_version);
+
+	os << (u8)place_param2.has_value(); // protocol_version >= 43
+	if (place_param2)
+		os << *place_param2;
 }
 
 void ItemDefinition::deSerialize(std::istream &is, u16 protocol_version)
@@ -226,10 +236,21 @@ void ItemDefinition::deSerialize(std::istream &is, u16 protocol_version)
 	try {
 		short_description = deSerializeString16(is);
 
-		place_param2 = readU8(is); // 0 if missing
+		if (protocol_version <= 43) {
+			place_param2 = readU8(is);
+			// assume disabled prediction
+			if (place_param2 == 0)
+				place_param2.reset();
+		}
 
 		sound_use.deSerializeSimple(is, protocol_version);
 		sound_use_air.deSerializeSimple(is, protocol_version);
+
+		if (is.eof())
+			throw SerializationError("");
+
+		if (readU8(is)) // protocol_version >= 43
+			place_param2 = readU8(is);
 	} catch(SerializationError &e) {};
 }
 

src/itemdef.h

@@ -23,6 +23,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "irrlichttypes_extrabloated.h"
 #include <string>
 #include <iostream>
+#include <optional>
 #include <set>
 #include "itemgroup.h"
 #include "sound.h"
@@ -87,7 +88,7 @@ struct ItemDefinition
 	// Server will update the precise end result a moment later.
 	// "" = no prediction
 	std::string node_placement_prediction;
-	u8 place_param2;
+	std::optional<u8> place_param2;
 
 	/*
 		Some helpful methods

src/network/networkprotocol.h

@@ -217,6 +217,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 		[scheduled bump for 5.7.0]
 	PROTOCOL VERSION 43:
 		"start_time" added to TOCLIENT_PLAY_SOUND
+		place_param2 type change u8 -> optional<u8>
 		[scheduled bump for 5.8.0]
 */
 

src/script/common/c_content.cpp

@@ -133,7 +133,9 @@ void read_item_definition(lua_State* L, int index,
 	getstringfield(L, index, "node_placement_prediction",
 			def.node_placement_prediction);
 
-	getintfield(L, index, "place_param2", def.place_param2);
+	int place_param2;
+	if (getintfield(L, index, "place_param2", place_param2))
+		def.place_param2 = rangelim(place_param2, 0, U8_MAX);
 }
 
 /******************************************************************************/