场景完全显示不出来
__glView = [EAGLView viewWithFrame:window.bounds
pixelFormat: kEAGLColorFormatRGBA8
depthFormat: GL_DEPTH_COMPONENT16_OES
preserveBackbuffer: YES
sharegroup: nil
multiSampling: NO
numberOfSamples: 0 ];
```
用xcode5编译没问题
xcode6就不行了