Barebone OpenGL ES initialization with iOS

bare_opengl_es.m

#import <UIKit/UIKit.h>
#import <QuartzCore/QuartzCore.h>
#import <OpenGLES/ES1/gl.h>
#import <OpenGLES/ES1/glext.h>

@interface OGLESView : UIView {
    EAGLContext * glContext;
    GLuint framebuffer;
    GLuint renderbuffer;
}

@end

@implementation OGLESView

// This will make ourself a CAEAGLLayer
+ (Class)layerClass
{
    return [CAEAGLLayer class];
}

- (id)initWithCoder:(NSCoder *)aDecoder
{
    if(!(self = [super initWithCoder:aDecoder]))
        return self;
    
    CAEAGLLayer * eaglLayer = (CAEAGLLayer *)self.layer;
    
    eaglLayer.opaque = YES;
    eaglLayer.drawableProperties = [NSDictionary dictionaryWithObjectsAndKeys:[NSNumber numberWithBool:NO], kEAGLDrawablePropertyRetainedBacking, kEAGLColorFormatRGBA8, kEAGLDrawablePropertyColorFormat, nil];
    
    glContext = [[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES1];
    [EAGLContext setCurrentContext:glContext];
    
    // A framebuffer is the "rendering destination"
    glGenFramebuffersOES(1, &framebuffer);
    glBindFramebufferOES(GL_FRAMEBUFFER_OES, framebuffer);
    
    // A rendering buffer is something that OpenGL needs
    glGenRenderbuffersOES(1, &renderbuffer);
    glBindRenderbufferOES(GL_RENDERBUFFER_OES, renderbuffer);
    
    // Assign our layer to OpenGL
    [glContext renderbufferStorage:GL_RENDERBUFFER_OES fromDrawable:(CAEAGLLayer *)self.layer];
    
    // Bind the framebuffer and the rendering layer
    glFramebufferRenderbufferOES(GL_FRAMEBUFFER_OES, GL_COLOR_ATTACHMENT0_OES, GL_RENDERBUFFER_OES, renderbuffer);
    
    glEnableClientState(GL_VERTEX_ARRAY);
    glEnableClientState(GL_COLOR_ARRAY);
    
    static const GLfloat vertices[] = {
        -0.5f, -0.33f,
        0.5f, -0.33f,
        -0.5f, 0.33f,
        0.5f, 0.33f
    };
    
    static const GLubyte colors[] = {
        255, 255, 0, 255,
        0, 255, 255, 255,
        0, 0, 0, 0,
        255, 0, 255, 255,
    };
    
    // Standard OpenGL goes on
    glClearColor(0.9f, 0.9f, 0.9f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT);
    
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glViewport(0, 0, 320, 480);
    
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    glVertexPointer(2, GL_FLOAT, 0, vertices);
    glColorPointer(4, GL_UNSIGNED_BYTE, 0, colors);
    glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
    
    [glContext presentRenderbuffer:GL_RENDERBUFFER_OES];
    
    return self;
}

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        // Initialization code
    }
    return self;
}

/*
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect
{
    // Drawing code
}
*/

- (void)dealloc
{
    glDeleteFramebufferOES(1, &framebuffer);
    glDeleteRenderbufferOES(1, &renderbuffer);

    [glContext release];
    
    [super dealloc];
}

@end