立体旋转图.gif
OpenGL-ES-loadCubeImage
思路:
一.初始化
这里初始化一些展示相关的类:
- (void)commonInit {
//1.创建context
EAGLContext *context = [[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES3];
//设置当前context
[EAGLContext setCurrentContext:context];
//2.创建GLKView并设置代理
CGRect frame = CGRectMake(0, 100, self.view.frame.size.width, self.view.frame.size.width);
self.glkView = [[GLKView alloc] initWithFrame:frame context:context];
self.glkView.backgroundColor = [UIColor clearColor];
self.glkView.delegate = self;
//3.使用深度缓存
self.glkView.drawableDepthFormat = GLKViewDrawableDepthFormat24;
//默认是(0, 1)，这里用于翻转 z 轴，使正方形朝屏幕外
//glDepthRangef(1, 0);
//4.将GLKView 添加self.view 上
[self.view addSubview:self.glkView];
//5.获取纹理图片
NSString *imagePath = [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:@"miao.jpeg"];
UIImage *image = [UIImage imageWithContentsOfFile:imagePath];
//6.设置纹理参数
NSDictionary *options = @{GLKTextureLoaderOriginBottomLeft : @(YES)};
GLKTextureInfo *textureInfo = [GLKTextureLoader textureWithCGImage:[image CGImage]
options:options
error:NULL];
//7.使用baseEffect,这里可以把GLKBaseEffect理解为着色器
self.baseEffect = [[GLKBaseEffect alloc] init];
self.baseEffect.texture2d0.name = textureInfo.name;
self.baseEffect.texture2d0.target = textureInfo.target;
}
二.顶点数据
创建顶点数据,并把这些数据拷贝到缓冲的内存中,并且开通Attribute通道,默认是关闭的
-(void)vertexDataSetup
{
/*
解释一下:
这里我们不复用顶点，使用每 3 个点画一个三角形的方式，需要 12 个三角形，则需要 36 个顶点
以下的数据用来绘制以（0，0，0）为中心，边长为 1 的立方体
*/
//8. 开辟顶点数据空间(数据结构SenceVertex 大小 * 顶点个数kCoordCount)
self.vertices = malloc(sizeof(CCVertex) * kCoordCount);
// 前面
self.vertices[0] = (CCVertex){{-0.5, 0.5, 0.5}, {0, 1}};//前面左上角
self.vertices[1] = (CCVertex){{-0.5, -0.5, 0.5}, {0, 0}};//前面左下角
self.vertices[2] = (CCVertex){{0.5, 0.5, 0.5}, {1, 1}};//前面右上角
self.vertices[3] = (CCVertex){{-0.5, -0.5, 0.5}, {0, 0}};//前面左下角
self.vertices[4] = (CCVertex){{0.5, 0.5, 0.5}, {1, 1}};//前面右上角
self.vertices[5] = (CCVertex){{0.5, -0.5, 0.5}, {1, 0}};//前面右下角
// 上面
self.vertices[6] = (CCVertex){{0.5, 0.5, 0.5}, {1, 1}};
self.vertices[7] = (CCVertex){{-0.5, 0.5, 0.5}, {0, 1}};
self.vertices[8] = (CCVertex){{0.5, 0.5, -0.5}, {1, 0}};
self.vertices[9] = (CCVertex){{-0.5, 0.5, 0.5}, {0, 1}};
self.vertices[10] = (CCVertex){{0.5, 0.5, -0.5}, {1, 0}};
self.vertices[11] = (CCVertex){{-0.5, 0.5, -0.5}, {0, 0}};
// 下面
self.vertices[12] = (CCVertex){{0.5, -0.5, 0.5}, {1, 1}};
self.vertices[13] = (CCVertex){{-0.5, -0.5, 0.5}, {0, 1}};
self.vertices[14] = (CCVertex){{0.5, -0.5, -0.5}, {1, 0}};
self.vertices[15] = (CCVertex){{-0.5, -0.5, 0.5}, {0, 1}};
self.vertices[16] = (CCVertex){{0.5, -0.5, -0.5}, {1, 0}};
self.vertices[17] = (CCVertex){{-0.5, -0.5, -0.5}, {0, 0}};
// 左面
self.vertices[18] = (CCVertex){{-0.5, 0.5, 0.5}, {1, 1}};
self.vertices[19] = (CCVertex){{-0.5, -0.5, 0.5}, {0, 1}};
self.vertices[20] = (CCVertex){{-0.5, 0.5, -0.5}, {1, 0}};
self.vertices[21] = (CCVertex){{-0.5, -0.5, 0.5}, {0, 1}};
self.vertices[22] = (CCVertex){{-0.5, 0.5, -0.5}, {1, 0}};
self.vertices[23] = (CCVertex){{-0.5, -0.5, -0.5}, {0, 0}};
// 右面
self.vertices[24] = (CCVertex){{0.5, 0.5, 0.5}, {1, 1}};
self.vertices[25] = (CCVertex){{0.5, -0.5, 0.5}, {0, 1}};
self.vertices[26] = (CCVertex){{0.5, 0.5, -0.5}, {1, 0}};
self.vertices[27] = (CCVertex){{0.5, -0.5, 0.5}, {0, 1}};
self.vertices[28] = (CCVertex){{0.5, 0.5, -0.5}, {1, 0}};
self.vertices[29] = (CCVertex){{0.5, -0.5, -0.5}, {0, 0}};
// 后面
self.vertices[30] = (CCVertex){{-0.5, 0.5, -0.5}, {0, 1}};
self.vertices[31] = (CCVertex){{-0.5, -0.5, -0.5}, {0, 0}};
self.vertices[32] = (CCVertex){{0.5, 0.5, -0.5}, {1, 1}};
self.vertices[33] = (CCVertex){{-0.5, -0.5, -0.5}, {0, 0}};
self.vertices[34] = (CCVertex){{0.5, 0.5, -0.5}, {1, 1}};
self.vertices[35] = (CCVertex){{0.5, -0.5, -0.5}, {1, 0}};
//开辟缓存区 VBO 顶点缓冲对象(Vertex Buffer Objects)
//生成一个VBO对象
glGenBuffers(1, &_vertexBuffer);
//设置顶点缓冲对象的缓冲类型是GL_ARRAY_BUFFER，将创建的VBO对象绑定到当前的执行程序上，也可以理解为激活
glBindBuffer(GL_ARRAY_BUFFER, _vertexBuffer);
GLsizeiptr bufferSizeBytes = sizeof(CCVertex) * kCoordCount;
//将准备好的顶点数据复制到缓冲的内存中，vertices为顶点数据，GL_STATIC_DRAW表示数据不会改变和几乎不会改变。第三个参数一共有三个选择：GL_STATIC_DRAW 表示数据不会或几乎不会改变、GL_DYNAMIC_DRAW表示数据会被改变很多、GL_STREAM_DRAW 表示数据每次绘制时都会改变。
glBufferData(GL_ARRAY_BUFFER, bufferSizeBytes, self.vertices, GL_STATIC_DRAW);
//顶点数据
glEnableVertexAttribArray(GLKVertexAttribPosition);
glVertexAttribPointer(GLKVertexAttribPosition, 3, GL_FLOAT, GL_FALSE, sizeof(CCVertex), NULL + offsetof(CCVertex, positionCoord));
//纹理数据
glEnableVertexAttribArray(GLKVertexAttribTexCoord0);
glVertexAttribPointer(GLKVertexAttribTexCoord0, 2, GL_FLOAT, GL_FALSE, sizeof(CCVertex), NULL + offsetof(CCVertex, textureCoord));
}
三.渲染及更新
这里更新使用的是CADisplayLink,屏幕每次展示新的一帧时调用
渲染在GLKView的代理方法中进行
- (void)glkView:(GLKView *)view drawInRect:(CGRect)rect {
//1.开启深度测试
glEnable(GL_DEPTH_TEST);
//2.清除颜色缓存区&深度缓存区
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
//3.准备绘制
[self.baseEffect prepareToDraw];
//4.绘图
glDrawArrays(GL_TRIANGLES, 0, kCoordCount);
}
