思维导图

渲染金字塔的思维导图已经描述的很清楚了，这里我就不做过多的赘述了。

GLKit-金字塔.png

代码

粘出主要代码，经供参考

//1、初始化上下文
- (void)setupContext
{
    //初始化上下文
    self.myContext = [[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES2];
    
    //设置GLKView的上下文
    GLKView *view = (GLKView *)self.view;
    view.context = self.myContext;
    
    //设置绘制属性
    view.drawableColorFormat = GLKViewDrawableColorFormatRGBA8888;
    view.drawableDepthFormat = GLKViewDrawableDepthFormat24;
    
    //设置当前上下文
    [EAGLContext setCurrentContext:self.myContext];
    
    //开启深度测试
    glEnable(GL_DEPTH_TEST);
    
}

//绘制金字塔
- (void)renderPyramid
{
    //1.顶点数据
    //1.顶点数据
    //前3个元素，是顶点数据xyz；中间3个元素，是顶点颜色值rgb，最后2个是纹理坐标st
    GLfloat attrArr[] =
    {
        -0.5f, 0.5f, 0.0f,      0.0f, 0.0f, 0.5f,       0.0f, 1.0f,//左上
        0.5f, 0.5f, 0.0f,       0.0f, 0.5f, 0.0f,       1.0f, 1.0f,//右上
        -0.5f, -0.5f, 0.0f,     0.5f, 0.0f, 1.0f,       0.0f, 0.0f,//左下
        0.5f, -0.5f, 0.0f,      0.0f, 0.0f, 0.5f,       1.0f, 0.0f,//右下
        
        0.0f, 0.0f, 1.0f,       1.0f, 1.0f, 1.0f,       0.5f, 0.5f,//顶点
    };
    
    //2.绘图索引
    GLuint indices[] =
    {
        0, 3, 2,
        0, 1, 3,
        0, 2, 4,
        0, 4, 1,
        2, 3, 4,
        1, 4, 3,
    };
    
    //3.顶点个数
    self.count = sizeof(indices) / sizeof(GLuint);
    
    //4.把顶点数据放到缓存区
    GLuint vertixBuffer;
    glGenBuffers(1, &vertixBuffer);
    glBindBuffer(GL_ARRAY_BUFFER, vertixBuffer);
    glBufferData(GL_ARRAY_BUFFER, sizeof(attrArr), attrArr, GL_STATIC_DRAW);
    
    //5.把索引数据放到缓冲区
    GLuint elementBuffer;
    glGenBuffers(1, &elementBuffer);
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, elementBuffer);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
    
    //6.使用顶点数据
    glEnableVertexAttribArray(GLKVertexAttribPosition);
    glVertexAttribPointer(GLKVertexAttribPosition, 3, GL_FLOAT, GL_FALSE, sizeof(GLfloat) * 8, (GLfloat *)NULL + 0);
    
    //7.使用颜色数据
    glEnableVertexAttribArray(GLKVertexAttribColor);
    glVertexAttribPointer(GLKVertexAttribColor, 3, GL_FLOAT, GL_FALSE, sizeof(GLfloat) * 8, (GLfloat *)NULL + 3);
    
    //8.使用纹理数据
    glEnableVertexAttribArray(GLKVertexAttribTexCoord0);
    glVertexAttribPointer(GLKVertexAttribTexCoord0, 2, GL_FLOAT, GL_FALSE, sizeof(GLfloat) * 8, (GLfloat *)NULL + 6);
    
    //9.获取纹理
    NSString *filePath = [[NSBundle mainBundle] pathForResource:@"cTest" ofType:@"jpg"];
    
    NSDictionary *options = @{
                              GLKTextureLoaderOriginBottomLeft : @(true),
                              };
    
    //10.通过GLKTextureLoader加载纹理
    NSError *error = nil;
    GLKTextureInfo *textureInfo = [GLKTextureLoader textureWithContentsOfFile:filePath options:options error:&error];
    if (error)
    {
        NSLog(@"加载纹理: %@", error.description);
        return;
    }
    
    
    //11.初始化Effect
    self.myEffect = [[GLKBaseEffect alloc] init];
    self.myEffect.texture2d0.enabled = GL_TRUE;
    self.myEffect.texture2d0.name = textureInfo.name;
    
    //12.设置投射投影
    GLfloat aspect = self.view.bounds.size.width / self.view.bounds.size.height;
    
    GLKMatrix4 projectionMatrix = GLKMatrix4MakePerspective(GLKMathDegreesToRadians(90.0), aspect, 0.01, 100.0);
    projectionMatrix = GLKMatrix4Scale(projectionMatrix, 1, 1, 1);
    self.myEffect.transform.projectionMatrix = projectionMatrix;
    
    //13.设置模型矩阵
    GLKMatrix4 modelViewMatrix = GLKMatrix4Translate(GLKMatrix4Identity, 0.0f, 0.0f, -2.0f);
    self.myEffect.transform.modelviewMatrix = modelViewMatrix;
    
    //14.定时器
    timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, dispatch_get_main_queue());
    dispatch_source_set_timer(timer, DISPATCH_TIME_NOW, 0.1 * NSEC_PER_SEC, 0);
    dispatch_source_set_event_handler(timer, ^{
        
        self.xDegree = self.XB * 0.1;
        self.yDegree = self.YB * 0.1;
        self.zDegree = self.ZB * 0.1;
    });
    dispatch_resume(timer);

}

- (void)glkView:(GLKView *)view drawInRect:(CGRect)rect
{
    glClearColor(0.3f, 0.4f, 0.5f, 1.0f);
    
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    
    [self.myEffect prepareToDraw];
    
    //2.绘图索引
    const static GLuint indices[] =
    {
        0, 3, 2,
        0, 1, 3,
        0, 2, 4,
        0, 4, 1,
        2, 3, 4,
        1, 4, 3,
    };

//    glDrawElements(GL_TRIANGLES, self.count, GL_UNSIGNED_INT, (GLvoid *)indices);
    glDrawElements(GL_TRIANGLES, self.count, GL_UNSIGNED_INT, NULL);
}

- (void)update
{
    GLKMatrix4 modelViewMatrix = self.myEffect.transform.modelviewMatrix;
    
    modelViewMatrix = GLKMatrix4RotateX(modelViewMatrix, self.xDegree);

    modelViewMatrix = GLKMatrix4RotateY(modelViewMatrix, self.yDegree);

    modelViewMatrix = GLKMatrix4RotateZ(modelViewMatrix, self.zDegree);
    
    self.myEffect.transform.modelviewMatrix = modelViewMatrix;
}

Demo下载地址

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