OpenGL ES 学习笔记一之清空屏幕

新建Xcode工程初始化问题:

- (EAGLContext *)glContext

{

      if (!_glContext) {

      _glContext = [[EAGLContext alloc]  initWithAPI:kEAGLRenderingAPIOpenGLES2];

      }

      return _glContext;

}

- (void)viewDidLoad {

      [super viewDidLoad];

     GLKView * viewGl = (GLKView *)self.view;

     self.glView = viewGl;

     self.glView.context = self.glContext;

    viewGl.drawableColorFormat = GLKViewDrawableColorFormatRGBA8888;  //颜色缓冲区格式

    [EAGLContext setCurrentContext:self.glContext];

}

/**

*  渲染场景代码

*/

- (void)glkView:(GLKView *)view drawInRect:(CGRect)rect {

//启动着色器

     glClearColor(0.3f, 0.6f, 1.0f, 1.0f);

     glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); 

}

崩溃问题:'-[UIView setContext:]: unrecognized selector sent to instance 0x7fcd35609a10'

解决办法:ViewController 为UIViewController对象,并不是GLKViewController,导致属性context的setter找不到,导致崩溃。将StoryBoard里的ViewController类型改为GLKViewController,此时运行,屏幕为黑色,因为Xib继承的还是GLKViewController,并没有运行在ViewController里面写的初始化代码,因此需要将GLKViewController改成ViewController,再次运行,屏幕会变成紫色。


将ViewController修改成GLKViewController之后,继续崩溃。

崩溃问题:'-[GLKViewController loadView] loaded the "BYZ-38-t0r-view-8bC-Xf-vdC" nib but didn't get a GLKView.'

解决办法:将StoryBoard里ViewController Xib下的View改成GLKView类型


如果Xib用不惯则可以自己创建一个LearnGLViewController会避免以上的问题。

#import

@interface LearnGLViewController : GLKViewController

@end

#import "LearnGLViewController.h"

@interface LearnGLViewController ()

@property (nonatomic,strong)EAGLContext *glContext;

@property (nonatomic,strong)GLKView *glView;

@end

@implementation LearnGLViewController

- (void)viewDidLoad {

[super viewDidLoad];

[self configContext];

// Do any additional setup after loading the view.

}

- (void)didReceiveMemoryWarning {

[super didReceiveMemoryWarning];

// Dispose of any resources that can be recreated.

}

- (EAGLContext *)glContext

{

if (!_glContext) {

_glContext = [[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES2];

}

return _glContext;

}

- (void)configContext

{

GLKView * viewGl = (GLKView *)self.view;

self.glView = viewGl;

self.glView.context = self.glContext;

viewGl.drawableColorFormat = GLKViewDrawableColorFormatRGBA8888;  //颜色缓冲区格式

[EAGLContext setCurrentContext:self.glContext];

}

/**

*  渲染场景代码

*/

- (void)glkView:(GLKView *)view drawInRect:(CGRect)rect {

//启动着色器

glClearColor(0.3f, 0.6f, 1.0f, 1.0f);

glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

}

@end

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