linux桌面游戏,刚开始加了个类就出现链接错误

Cocos2d-x
#1

0%] Built target tinyxml2
0%] Built target MyGame_CORE_PRE_BUILD
MyGame_PRE_BUILD …
0%] Built target MyGame_PRE_BUILD
1%] Built target xxhash
1%] Built target unzip
98%] Built target cocos2d
Linking CXX executable bin/MyGame
CMakeFiles/MyGame.dir/Classes/HelloWorldScene.cpp.o: In function Edge::Edge()': /home/zeek/Documents/cocos2dx/MyGame/Classes/Edge.h:15: undefined reference to vtable for Edge’
collect2: error: ld returned 1 exit status
make: *** Error 1
make: *** Error 2
make: *** Error 2

#2

/Edge.h:15: undefined reference to `vtable for Edge’

Do you know what’s meaning?