Added get_player_velocity() method. Fixes #1176

doc/lua_api.txt

@@ -2470,6 +2470,7 @@ This is basically a reference to a C++ `ServerActiveObject`
 
 ##### Player-only (no-op for other objects)
 * `get_player_name()`: returns `""` if is not a player
+* `get_player_velocity()`: returns `nil` if is not a player otherwise a table {x, y, z} representing the player's instantaneous velocity in nodes/s
 * `get_look_dir()`: get camera direction as a unit vector
 * `get_look_pitch()`: pitch in radians
 * `get_look_yaw()`: yaw in radians (wraps around pretty randomly as of now)

src/script/lua_api/l_object.cpp

@@ -945,6 +945,21 @@ int ObjectRef::l_get_player_name(lua_State *L)
 	return 1;
 }
 
+// get_player_velocity(self)
+int ObjectRef::l_get_player_velocity(lua_State *L)
+{
+	NO_MAP_LOCK_REQUIRED;
+	ObjectRef *ref = checkobject(L, 1);
+	Player *player = getplayer(ref);
+	if (player == NULL) {
+		lua_pushnil(L);
+		return 1;
+	}
+	// Do it
+	push_v3f(L, player->getSpeed() / BS);
+	return 1;
+}
+
 // get_look_dir(self)
 int ObjectRef::l_get_look_dir(lua_State *L)
 {
@@ -1706,6 +1721,7 @@ const luaL_reg ObjectRef::methods[] = {
 	luamethod(ObjectRef, is_player),
 	luamethod(ObjectRef, is_player_connected),
 	luamethod(ObjectRef, get_player_name),
+	luamethod(ObjectRef, get_player_velocity),
 	luamethod(ObjectRef, get_look_dir),
 	luamethod(ObjectRef, get_look_pitch),
 	luamethod(ObjectRef, get_look_yaw),

src/script/lua_api/l_object.h

@@ -183,6 +183,9 @@ private:
 	// get_player_name(self)
 	static int l_get_player_name(lua_State *L);
 
+	// get_player_velocity(self)
+	static int l_get_player_velocity(lua_State *L);
+
 	// get_look_dir(self)
 	static int l_get_look_dir(lua_State *L);