Implement client node dig prediction

sofar · sfan5 · commit 5b3fbf9cf75f · 2017-09-11T20:54:20.000+02:00
Dig prediction allows clients to remove dug nodes without
waiting for server acknowledgement.
This patch allows mods to override dig prediction,
it can either be turned off or a different "prediction node"
can be selected.
diff --git a/doc/lua_api.txt b/doc/lua_api.txt
@@ -4240,6 +4240,13 @@ Definition tables
           on ground when the player places the item. Server will always update
           actual result to client in a short moment.
         ]]
+        node_dig_prediction = "air",
+        --[[
+        ^ if "", no prediction is made
+        ^ if "air", node is removed
+        ^ Otherwise should be name of node which the client immediately places
+          upon digging. Server will always update actual result shortly.
+        ]]
         sound = {
             breaks = "default_tool_break", -- tools only
             place = --[[<SimpleSoundSpec>]],
diff --git a/src/game.cpp b/src/game.cpp
@@ -4104,7 +4104,17 @@ void Game::handleDigging(const PointedThing &pointed, const v3s16 &nodepos,
 			    		client->getScript()->on_dignode(nodepos, wasnode)) {
 				return;
 			}
-			client->removeNode(nodepos);
+
+			const ContentFeatures &f = client->ndef()->get(wasnode);
+			if (f.node_dig_prediction == "air") {
+				client->removeNode(nodepos);
+			} else if (!f.node_dig_prediction.empty()) {
+				content_t id;
+				bool found = client->ndef()->getId(f.node_dig_prediction, id);
+				if (found)
+					client->addNode(nodepos, id, true);
+			}
+			// implicit else: no prediction
 		}
 
 		client->interact(2, pointed);
diff --git a/src/nodedef.cpp b/src/nodedef.cpp
@@ -335,6 +335,7 @@ void ContentFeatures::reset()
 	color = video::SColor(0xFFFFFFFF);
 	palette_name = "";
 	palette = NULL;
+	node_dig_prediction = "air";
 }
 
 void ContentFeatures::serialize(std::ostream &os, u16 protocol_version) const
@@ -422,6 +423,8 @@ void ContentFeatures::serialize(std::ostream &os, u16 protocol_version) const
 	// legacy
 	writeU8(os, legacy_facedir_simple);
 	writeU8(os, legacy_wallmounted);
+
+	os << serializeString(node_dig_prediction);
 }
 
 void ContentFeatures::correctAlpha(TileDef *tiles, int length)
@@ -530,6 +533,10 @@ void ContentFeatures::deSerialize(std::istream &is)
 	// read legacy properties
 	legacy_facedir_simple = readU8(is);
 	legacy_wallmounted = readU8(is);
+
+	try {
+		node_dig_prediction = deSerializeString(is);
+	} catch(SerializationError &e) {};
 }
 
 #ifndef SERVER
diff --git a/src/nodedef.h b/src/nodedef.h
@@ -324,6 +324,8 @@ struct ContentFeatures
 	// Player cannot build to these (placement prediction disabled)
 	bool rightclickable;
 	u32 damage_per_second;
+	// client dig prediction
+	std::string node_dig_prediction;
 
 	// --- LIQUID PROPERTIES ---
 
diff --git a/src/script/common/c_content.cpp b/src/script/common/c_content.cpp
@@ -737,6 +737,10 @@ ContentFeatures read_content_features(lua_State *L, int index)
 	}
 	lua_pop(L, 1);
 
+	// Node immediately placed by client when node is dug
+	getstringfield(L, index, "node_dig_prediction",
+		f.node_dig_prediction);
+
 	return f;
 }
 
@@ -861,6 +865,8 @@ void push_content_features(lua_State *L, const ContentFeatures &c)
 	lua_setfield(L, -2, "legacy_facedir_simple");
 	lua_pushboolean(L, c.legacy_wallmounted);
 	lua_setfield(L, -2, "legacy_wallmounted");
+	lua_pushstring(L, c.node_dig_prediction.c_str());
+	lua_setfield(L, -2, "node_dig_prediction");
 }
 
 /******************************************************************************/

Original file line number	Diff line number	Diff line change
`@@ -737,6 +737,10 @@ ContentFeatures read_content_features(lua_State *L, int index)`
`737`	`737`	`}`
`738`	`738`	`lua_pop(L, 1);`
`739`	`739`
	`740`	`+ // Node immediately placed by client when node is dug`
	`741`	`+ getstringfield(L, index, "node_dig_prediction",`
	`742`	`+ f.node_dig_prediction);`
	`743`	`+`
`740`	`744`	`return f;`
`741`	`745`	`}`
`742`	`746`
`@@ -861,6 +865,8 @@ void push_content_features(lua_State *L, const ContentFeatures &c)`
`861`	`865`	`lua_setfield(L, -2, "legacy_facedir_simple");`
`862`	`866`	`lua_pushboolean(L, c.legacy_wallmounted);`
`863`	`867`	`lua_setfield(L, -2, "legacy_wallmounted");`
	`868`	`+ lua_pushstring(L, c.node_dig_prediction.c_str());`
	`869`	`+ lua_setfield(L, -2, "node_dig_prediction");`
`864`	`870`	`}`
`865`	`871`
`866`	`872`	`/******************************************************************************/`