效果图如下：
GLKit.gif
首先，使用GLKit绘制图形分为以下两个步骤
- 初始化上下文
- 使用GLKBaseEffect渲染图形
初始化上下文
- 新建OpenGL ES上下文，EAGLContext是苹果iOS平台下实现OpenGL ES渲染层
- 新建GLKView
- 设置view的上下文为步骤1中创建的上下文
- 设置GLKView代理（GLKViewDelegate）
- 设置颜色、深度缓冲格式
- 设置渲染层的当前上下文为步骤1中新建的上下文
- 开启深度测试
//1.新建图层
-(void)setupContext
{
//1.新建OpenGL ES上下文
self.mContext = [[EAGLContext alloc]initWithAPI:kEAGLRenderingAPIOpenGLES2];
GLKView *view = (GLKView *)self.view;
view.context = self.mContext;
view.delegate = self;
//设置颜色缓冲格式
view.drawableColorFormat = GLKViewDrawableColorFormatRGBA8888;
//设置深度缓冲格式
view.drawableDepthFormat = GLKViewDrawableDepthFormat24;
[EAGLContext setCurrentContext:self.mContext];
glEnable(GL_DEPTH_TEST);
}
绘制图形
- 顶点、索引数据和GLSL综合案例中的顶点、索引数据相同
- 将顶点数组放入数组缓冲区中 GL_ARRAY_BUFFER
- 将索引数组存储到索引缓冲区 GL_ELEMENT_ARRAY_BUFFER
- 使用顶点、颜色数据，GLKBaseEffect使用命名顶点属性，因此当配置/启用/绑定要与GLKBaseEffect一起使用的顶点属性数据时，客户端应用程序可以引用以下顶点属性名称：
GLKVertexAttribPosition
GLKVertexAttribNormal
GLKVertexAttribColor
GLKVertexAttribTexCoord0
GLKVertexAttribTexCoord1
请注意，GLKVertexAttribNormal的法线总是标准化。- 新建GLKBaseEffect着色器： 一种简单的光照/着色系统，用于基于着色器的OpenGL渲染
- 设置着色器的投影、模型视图
- 开启定时器，让图形随时间旋转
//2.渲染图形
-(void)render
{
//1.顶点数据
//前3个元素，是顶点数据；后面3个元素，是顶点颜色值
GLfloat attrArr[] =
{
-0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 1.0f, //左上
0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 1.0f, //右上
-0.5f, -0.5f, 0.0f, 1.0f, 1.0f, 1.0f, //左下
0.5f, -0.5f, 0.0f, 1.0f, 1.0f, 1.0f, //右下
0.0f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, //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,
};
//顶点个数
self.count = sizeof(indices) /sizeof(GLuint);
//将顶点数组放入数组缓冲区中 GL_ARRAY_BUFFER
GLuint buffer;
glGenBuffers(1, &buffer);
glBindBuffer(GL_ARRAY_BUFFER, buffer);
glBufferData(GL_ARRAY_BUFFER, sizeof(attrArr), attrArr, GL_STATIC_DRAW);
//将索引数组存储到索引缓冲区 GL_ELEMENT_ARRAY_BUFFER
GLuint index;
glGenBuffers(1, &index);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, index);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
//使用顶点数据
glEnableVertexAttribArray(GLKVertexAttribPosition);
glVertexAttribPointer(GLKVertexAttribPosition, 3, GL_FLOAT, GL_FALSE, sizeof(GLfloat) * 6, NULL);
//使用颜色数据
glEnableVertexAttribArray(GLKVertexAttribColor);
glVertexAttribPointer(GLKVertexAttribColor, 3, GL_FLOAT, GL_FALSE, sizeof(GLfloat) * 6, (GLfloat *)NULL + 3);
//着色器
self.mEffect = [[GLKBaseEffect alloc]init];
//投影视图
CGSize size = self.view.bounds.size;
float aspect = fabs(size.width / size.height);
GLKMatrix4 projectionMatrix = GLKMatrix4MakePerspective(GLKMathDegreesToRadians(90.0), aspect, 0.1f, 100.0);
projectionMatrix = GLKMatrix4Scale(projectionMatrix, 1.0f, 1.0f, 1.0f);
self.mEffect.transform.projectionMatrix = projectionMatrix;
//模型视图
GLKMatrix4 modelViewMatrix = GLKMatrix4Translate(GLKMatrix4Identity, 0.0f, 0.0f, -2.0f);
self.mEffect.transform.modelviewMatrix = modelViewMatrix;
//定时器
double seconds = 0.1;
timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, dispatch_get_main_queue());
dispatch_source_set_timer(timer, DISPATCH_TIME_NOW, seconds * NSEC_PER_SEC, 0.0);
dispatch_source_set_event_handler(timer, ^{
self.XDegree += 0.1f * self.XB;
self.YDegree += 0.1f * self.YB;
self.ZDegree += 0.1f * self.ZB ;
});
dispatch_resume(timer);
}
GLKViewDelegate代理方法- (void)glkView:(GLKView *)view drawInRect:(CGRect)rect
- (void)glkView:(GLKView *)view drawInRect:(CGRect)rect {
glClearColor(0.3f, 0.3f, 0.3f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
[self.mEffect prepareToDraw];
glDrawElements(GL_TRIANGLES, self.count, GL_UNSIGNED_INT, 0);
}
GLKViewControllerDelegate代理方法- (void)glkViewControllerUpdate:(GLKViewController *)controller;
- (void)glkViewControllerUpdate:(GLKViewController *)controller{
GLKMatrix4 modelViewMatrix = GLKMatrix4Translate(GLKMatrix4Identity, 0.0f, 0.0f, -2.5);
modelViewMatrix = GLKMatrix4RotateX(modelViewMatrix, self.XDegree);
modelViewMatrix = GLKMatrix4RotateY(modelViewMatrix, self.YDegree);
modelViewMatrix = GLKMatrix4RotateZ(modelViewMatrix, self.ZDegree);
self.mEffect.transform.modelviewMatrix = modelViewMatrix;
}
控制X、Y、Z轴方向变化方法
#pragma mark -XYZClick
- (IBAction)XClick:(id)sender {
_XB = !_XB;
}
- (IBAction)YClick:(id)sender {
_YB = !_YB;
}
- (IBAction)ZClick:(id)sender {
_ZB = !_ZB;
}
Demo：
GLKitDemo
