本文介绍在iOS下通过OpenGL ES简单渲染一个视图出来。
OpenGLView.h
#import <UIKit/UIKit.h>
#import <QuartzCore/QuartzCore.h>
#include <OpenGLES/ES2/gl.h>
#include <OpenGLES/ES2/glext.h>
@interface OpenGLView : UIView {
EAGLContext *context;
GLuint colorRenderBuffer;
GLuint framebuffer;
}
@end
OpenGLView.m
#import "OpenGLView.h"
@implementation OpenGLView
//设置OpenGLView 的layer层为CAEAGLLayer
+ (Class)layerClass {
return [CAEAGLLayer class];
}
- (void)setup {
// 创建一个管理上下文
context = [[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES2];
// 设置其为当前OpenGL 渲染的管理上下文
[EAGLContext setCurrentContext:context];
// 创建渲染缓冲区
glGenRenderbuffers(1, &colorRenderBuffer);
glBindRenderbuffer(GL_RENDERBUFFER, colorRenderBuffer);
// 创建帧缓冲区
glGenFramebuffers(1, &framebuffer);
glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
// 将渲染缓冲区和帧缓冲区关联
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, colorRenderBuffer);
// 将渲染缓冲区和layer关联在一起(OpenGL ES渲染缓存对象绑定到layer上)
[context renderbufferStorage:GL_RENDERBUFFER fromDrawable:(CAEAGLLayer*)self.layer];
// 检测帧对象是否创建成功
if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE) {
NSLog(@"Failed to make complete framebuffer object %x", glCheckFramebufferStatus(GL_FRAMEBUFFER));
}
// 清除颜色缓冲区
glClearColor(1, 1, 0, 1.0);
glClear(GL_COLOR_BUFFER_BIT);
// 将渲染缓冲区呈现出来
[context presentRenderbuffer:GL_RENDERBUFFER];
}
- (void)didMoveToSuperview {
[super didMoveToSuperview];
[self setup];
}
@end
ViewController.m
#import "ViewController.h"
#import "OpenGLView.h"
@interface ViewController ()
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
OpenGLView *view = [[OpenGLView alloc] initWithFrame:CGRectMake(100, 100, 100, 100)];
[self.view addSubview:view];
}
@end
