通过简单封装理顺了一下思路的简单三角形绘制代码。

#import "ViewController.h"

static const GLKVector3 triangleVertices[3] = {
    {0.0f, 0.25f, 0.0f},
    {-0.5f, -0.25f, 0.0f},
    {0.5f, -0.25f, 0.0f}
};

static const GLKVector4 triangleColors[3] = {
    {1.0f, 0.0f, 0.0f, 1.0f},
    {0.0f, 1.0f, 0.0f, 1.0f},
    {0.0f, 0.0f, 1.0f, 1.0f}
};

@interface ViewController () <GLKViewDelegate>
{
    GLuint _triangle;
    GLuint _color;
}
@property (strong, nonatomic) GLKBaseEffect *baseEffect;
@end

@implementation ViewController
//创建VBO对象
- (GLuint)createVertexBuffer:(GLsizeiptr)stride         //顶点数据大小
            numberOfVertices:(GLsizei)count             //顶点数
                       bytes:(const GLvoid *)dataPtr    //数组地址
                       usage:(GLenum)usage {            //用途
    
    GLuint name = 0;
    glGenBuffers(1, &name);
    glBindBuffer(GL_ARRAY_BUFFER, name);
    glBufferData(GL_ARRAY_BUFFER, stride * count, dataPtr, usage);
    
    NSAssert(name != 0, @"没有正确产生缓存名称");
    
    return name;
}

//设置绘制对象的属性
- (void)prepareToDrawTarget:(GLuint)name
                     attrib:(GLuint)index
            numberOfCoordinates:(GLint)count
                         stride:(GLsizei)stride
                   attribOffset:(GLsizeiptr)offset
                         enable:(GLboolean)enable {
    glBindBuffer(GL_ARRAY_BUFFER, name);
    
    if (enable) {
        glEnableVertexAttribArray(index);
    }
    glVertexAttribPointer(index,            //属性类型
                          count,            //顶点数
                          GL_FLOAT,         //数据类型
                          GL_FALSE,         //是否归一化
                          stride,           //顶点数据大小
                          NULL + offset);   //数据偏移量
}

- (void)drawArrayWithMode:(GLenum)mode
               startIndex:(GLuint)index 
         numberOfVertices:(GLsizei)count {
    glDrawArrays(mode, index, count);
}

- (void)configOpenGL {
    //1. 配置OpenGL上下文
    GLKView *glkView = (GLKView *)self.view;
    glkView.context = [[EAGLContext alloc] initWithAPI: kEAGLRenderingAPIOpenGLES2];
    glkView.drawableDepthFormat = GLKViewDrawableDepthFormat24;
    glkView.delegate = self;
    
    [EAGLContext setCurrentContext:glkView.context];
    
    //2. 设置基本的环境参数
    self.baseEffect = [[GLKBaseEffect alloc] init];
    self.baseEffect.useConstantColor = GL_TRUE;
    self.baseEffect.constantColor = GLKVector4Make(1.0f, 0.0f, 0.0f, 1.0f);
}

- (void)testBgColor {
    glClearColor(1.0f, 1.0f, 1.0f, 1.0f);
}

- (void)viewDidLoad {
    [super viewDidLoad];
    
    [self configOpenGL];
    
    [self testBgColor];
    //分配缓存区
    _triangle = [self createVertexBuffer:sizeof(GLKVector3) 
                        numberOfVertices:3 
                                   bytes:triangleVertices 
                                   usage:GL_STATIC_DRAW];
    _color = [self createVertexBuffer:sizeof(GLKVector4) 
                     numberOfVertices:3 
                                bytes:triangleColors 
                                usage:GL_STATIC_DRAW];
}

- (void)glkView:(GLKView *)view drawInRect:(CGRect)rect {
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    
    [self.baseEffect prepareToDraw];
    
    //准备顶点数组
    [self prepareToDrawTarget:_triangle 
                       attrib:GLKVertexAttribPosition 
          numberOfCoordinates:3 
                       stride:sizeof(GLKVector3) 
                 attribOffset:0 
                       enable:GL_TRUE];
    //准备颜色数组
    [self prepareToDrawTarget:_color
                       attrib:GLKVertexAttribColor
          numberOfCoordinates:4 
                       stride:sizeof(GLKVector4) 
                 attribOffset:0
                       enable:GL_TRUE];
    //绘制形状
    [self drawArrayWithMode:GL_TRIANGLES 
                 startIndex:0 
           numberOfVertices:3];
}
@end