每当我尝试在Yosemite 10.10.4上安装rgl包时，都会收到此消息
Error : .onLoad failed in loadNamespace() for 'rgl', details:
call: dyn.load(file, DLLpath = DLLpath, ...)
error: unable to load shared object '/Library/Frameworks/R.framework/Versions/3.2/Resources/library/rgl/libs/rgl.so':
dlopen(/Library/Frameworks/R.framework/Versions/3.2/Resources/library/rgl/libs/rgl.so, 6): Library not loaded: /opt/X11/lib/libGLU.1.dylib
Referenced from: /Library/Frameworks/R.framework/Versions/3.2/Resources/library/rgl/libs/rgl.so
Reason: image not found
Error: package or namespace load failed for ‘rgl’
我该如何解决这个问题？