OpenGL行为异常

-prepareOpenGL 方法:

- (void)prepareOpenGL {
 GLfloat lightAmbient[] = { 0.5f, 0.5f, 0.5f, 1.0f };
 GLfloat lightDiffuse[] = { 1.0f, 1.0f, 1.0f, 1.0f };
 GLfloat lightPosition[] = { 0.0f, 0.0f, 2.0f };

 quality = 0;
 zCoord = -6;

 [self loadTextures];

 glEnable(GL_LIGHTING);
 glEnable(GL_TEXTURE_2D);
 glShadeModel(GL_SMOOTH);
 glClearColor(0.2f, 0.2f, 0.2f, 0.0f);
 glClearDepth(1.0f);
 glEnable(GL_DEPTH_TEST);
 glDepthFunc(GL_LEQUAL);
 glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);

 glLightfv(GL_LIGHT1, GL_AMBIENT, lightAmbient);
 glLightfv(GL_LIGHT1, GL_DIFFUSE, lightDiffuse);
 glLightfv(GL_LIGHT1, GL_POSITION, lightPosition);
 glEnable(GL_LIGHT1);

 gameState = kGameStateRunning;
 int i = 0; // HERE ********
 [NSTimer scheduledTimerWithTimeInterval:0.03f target:self
           selector:@selector(processKeys) userInfo:nil repeats:YES];

 // Synchronize buffer swaps with vertical refresh rate
 GLint swapInt = 1;
 [[self openGLContext] setValues:&swapInt forParameter:NSOpenGLCPSwapInterval];
 // Setup and start displayLink
 [self setupDisplayLink];
}

int i = 0; (制造) // HERE ******* ),这使得灯光无法工作!当我把它拿走的时候,一切都很好,但是当我把它放回去的时候,一切都是黑暗的。有人能对此给出合理的解释吗?只需创建任何变量就可以做到这一点,即使已经声明了几个变量。

谢谢。