GLKBaseEffect让我们避开了写shader Language 着色器语言, 相当于对glsl的封装

typedef struct {

    GLKVector3 positonCoords;//顶点

    GLKVector2 textureCoords;//纹理

}SceneVertex;

@interface GLViewController ()

@property(nonatomic,strong)GLKBaseEffect *baseEffect;

@property(nonatomic,assign)GLuint vertexBufferID;//缓存ID属性

@end

@implementation GLViewController

- (void)viewDidLoad {

    [super viewDidLoad];

    // Do any additional setup after loading the view.

    //1.创建OpenGLE ES上下文

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

    view.context = [[EAGLContext alloc]initWithAPI:kEAGLRenderingAPIOpenGLES2];

    [EAGLContext setCurrentContext:view.context];

    //2.GLKBaseEffect属性, 使我们不需要编写shader language(着色器)代码就可以简单完成绘制

    self.baseEffect = [[GLKBaseEffect alloc]init];

    self.baseEffect.useConstantColor = GL_TRUE;//使用静态颜色绘制

    self.baseEffect.constantColor = GLKVector4Make(1.0f, 1.0f, 1.0f, 1.0f);//设置绘制颜色 rgba

    glClearColor(0.0f, 0.0f, 0.0f, 1.0f);//背景颜色

    //3.定点数据

    //矩形的六个顶点

    static const SceneVertex vertices[] = {

        {{, -, 0.0f,},{1.0f,0.0f}}, //右下

        {{, ,  0.0f},{1.0f,1.0f}}, //右上

        {{-, , 0.0f},{0.0f,1.0f}}, //左上

        {{, -, 0.0f},{1.0f,0.0f}}, //右下

        {{-, , 0.0f},{0.0f,1.0f}}, //左上

        {{-, -, 0.0f},{0.0f,0.0f}}, //左下

    };

    //4.生成缓存,并为缓存提供数据

    glGenBuffers(, &_vertexBufferID);//申请一个标识符

    glBindBuffer(GL_ARRAY_BUFFER, _vertexBufferID);//将标识符绑定到GL_ARRAY_BUFFER

    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);//复制定点数据从CPU 到 GPU

    glEnableVertexAttribArray(GLKVertexAttribPosition);//顶点缓存数据

    glVertexAttribPointer(GLKVertexAttribPosition, , GL_FLOAT, GL_FALSE, sizeof(SceneVertex), NULL + offsetof(SceneVertex, positonCoords));

    glEnableVertexAttribArray(GLKVertexAttribTexCoord0);

    glVertexAttribPointer(GLKVertexAttribTexCoord0, , GL_FLOAT, GL_FALSE, sizeof(SceneVertex), NULL + offsetof(SceneVertex, textureCoords));

    //5.生成纹理

    //使用GLkit中的GLKTextureInfo方便的生成图片纹理。

    CGImageRef imageRef = [[UIImage imageNamed:@"1.png"]CGImage];

    //GLKTextureInfo封装了纹理缓存的信息，包括是否包含MIP贴图

    //option 防止图片是倒立了，这个是因为CoreGraphics的坐标系问题

    NSDictionary* options = [NSDictionary dictionaryWithObjectsAndKeys:@(), GLKTextureLoaderOriginBottomLeft, nil];

    GLKTextureInfo *textureInfo = [GLKTextureLoader textureWithCGImage:imageRef options:options error:nil];

    self.baseEffect.texture2d0.name = textureInfo.name;

    self.baseEffect.texture2d0.target = textureInfo.target;

    //6.代理, 绘制

}

//系统给我们回调的绘制消息，该方法会一直被调用，和display方法一致

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

    //清除背景色

    glClearColor(0.0f,0.0f,0.0f,1.0f);

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    [self.baseEffect prepareToDraw];

    glDrawArrays(GL_TRIANGLES, , );

}

- (void)dealloc{

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

    [EAGLContext setCurrentContext:view.context];

    if (_vertexBufferID != ) {

        glDeleteBuffers(, &_vertexBufferID);

        _vertexBufferID = ;

    }

}

@end