OpenGL的简单示例

EAGLView.h

 

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

@interface EAGLView : UIView {
	
@private
	/* The pixel dimensions of the backbuffer */
	GLint backingWidth;
	GLint backingHeight;
	
	EAGLContext *context;
	
	/* OpenGL names for the renderbuffer and framebuffers used to render to this view */
	GLuint viewRenderbuffer, viewFramebuffer;
	
	/* OpenGL name for the depth buffer that is attached to viewFramebuffer, if it exists (0 if it does not exist) */
	GLuint depthRenderbuffer;
	
	NSTimer *animationTimer;
	NSTimeInterval animationInterval;
}

@property NSTimeInterval animationInterval;

- (void)startAnimation;
- (void)stopAnimation;
- (void)drawView;

@end

 

EAGLView.m

 

#import <QuartzCore/QuartzCore.h>
#import <OpenGLES/EAGLDrawable.h>
#import "EAGLView.h"

#define USE_DEPTH_BUFFER 0

// A class extension to declare private methods
@interface EAGLView ()

@property (nonatomic, retain) EAGLContext *context;
@property (nonatomic, assign) NSTimer *animationTimer;

- (BOOL) createFramebuffer;
- (void) destroyFramebuffer;

@end

@implementation EAGLView

@synthesize context;
@synthesize animationTimer;
@synthesize animationInterval;

+ (Class)layerClass {
	return [CAEAGLLayer class];
}

- (id)initWithCoder:(NSCoder*)coder {
	if ((self = [super initWithCoder:coder])) {
		CAEAGLLayer *eaglLayer = (CAEAGLLayer *)self.layer;
		eaglLayer.opaque = YES;
		eaglLayer.drawableProperties =
        [NSDictionary dictionaryWithObjectsAndKeys:
         [NSNumber numberWithBool:NO], kEAGLDrawablePropertyRetainedBacking,
         kEAGLColorFormatRGBA8, kEAGLDrawablePropertyColorFormat, nil];
		context = [[EAGLContext alloc]
                   initWithAPI:kEAGLRenderingAPIOpenGLES1];
		
		if (!context || ![EAGLContext setCurrentContext:context]) {
			[self release];
			return nil;
		}
		
		self.animationInterval = 1.0 / 60.0;
	}
	return self;
}

- (void)drawView {
	const GLfloat squareVertices[] = {
		-0.5f, -0.5f,
		0.5f,  -0.5f,
		-0.5f,  0.5f,
		0.5f,   0.5f,
	};
	const GLubyte squareColors[] = {
		255, 255,   0, 255,
		0,   255, 255, 255,
		0,     0,   0,   0,
		255,   0, 255, 255,
	};
	
	[EAGLContext setCurrentContext:context];
	
	glBindFramebufferOES(GL_FRAMEBUFFER_OES, viewFramebuffer);
	glViewport(0, 0, backingWidth, backingHeight);
	
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	glOrthof(-1.0f, 1.0f, -1.5f, 1.5f, -1.0f, 1.0f);
	glMatrixMode(GL_MODELVIEW);
	glRotatef(3.0f, 0.0f, 0.0f, 1.0f);
	
	glClearColor(0.5f, 0.5f, 0.5f, 1.0f);
	glClear(GL_COLOR_BUFFER_BIT);
	
	glVertexPointer(2, GL_FLOAT, 0, squareVertices);
	glEnableClientState(GL_VERTEX_ARRAY);
	glColorPointer(4, GL_UNSIGNED_BYTE, 0, squareColors);
	glEnableClientState(GL_COLOR_ARRAY);
	glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
	
	glBindRenderbufferOES(GL_RENDERBUFFER_OES, viewRenderbuffer);
	[context presentRenderbuffer:GL_RENDERBUFFER_OES];
}

- (void)layoutSubviews {
	[EAGLContext setCurrentContext:context];
	[self destroyFramebuffer];
	[self createFramebuffer];
	[self drawView];
}

- (BOOL)createFramebuffer {
	glGenFramebuffersOES(1, &viewFramebuffer);
	glGenRenderbuffersOES(1, &viewRenderbuffer);
	
	glBindFramebufferOES(GL_FRAMEBUFFER_OES, viewFramebuffer);
	glBindRenderbufferOES(GL_RENDERBUFFER_OES, viewRenderbuffer);
	[context renderbufferStorage:GL_RENDERBUFFER_OES fromDrawable:(CAEAGLLayer*)self.layer];
	glFramebufferRenderbufferOES(GL_FRAMEBUFFER_OES, GL_COLOR_ATTACHMENT0_OES, GL_RENDERBUFFER_OES, viewRenderbuffer);
	
	glGetRenderbufferParameterivOES(GL_RENDERBUFFER_OES, GL_RENDERBUFFER_WIDTH_OES, &backingWidth);
	glGetRenderbufferParameterivOES(GL_RENDERBUFFER_OES, GL_RENDERBUFFER_HEIGHT_OES, &backingHeight);
	
	if (USE_DEPTH_BUFFER) {
		glGenRenderbuffersOES(1, &depthRenderbuffer);
		glBindRenderbufferOES(GL_RENDERBUFFER_OES, depthRenderbuffer);
		glRenderbufferStorageOES(GL_RENDERBUFFER_OES, GL_DEPTH_COMPONENT16_OES, backingWidth, backingHeight);
		glFramebufferRenderbufferOES(GL_FRAMEBUFFER_OES, GL_DEPTH_ATTACHMENT_OES, GL_RENDERBUFFER_OES, depthRenderbuffer);
	}
    
	if(glCheckFramebufferStatusOES(GL_FRAMEBUFFER_OES) != GL_FRAMEBUFFER_COMPLETE_OES) {
		NSLog(@"failed to make complete framebuffer object %x", glCheckFramebufferStatusOES(GL_FRAMEBUFFER_OES));
		return NO;
	}
	
	return YES;
}

- (void)destroyFramebuffer {
	glDeleteFramebuffersOES(1, &viewFramebuffer);
	viewFramebuffer = 0;
	glDeleteRenderbuffersOES(1, &viewRenderbuffer);
	viewRenderbuffer = 0;
	
	if(depthRenderbuffer) {
		glDeleteRenderbuffersOES(1, &depthRenderbuffer);
		depthRenderbuffer = 0;
	}
}

- (void)startAnimation {
	self.animationTimer =
    [NSTimer scheduledTimerWithTimeInterval:self.animationInterval
                                     target:self selector:@selector(drawView)
                                   userInfo:nil repeats:YES];
}

- (void)stopAnimation {
	self.animationTimer = nil;
}

- (void)setAnimationTimer:(NSTimer *)newTimer {
	[animationTimer invalidate];
	animationTimer = newTimer;
}

- (void)setAnimationInterval:(NSTimeInterval)interval {
	animationInterval = interval;
	if (animationTimer) {
		[self stopAnimation];
		[self startAnimation];
	}
}

- (void)dealloc {
	[self stopAnimation];
	
	if ([EAGLContext currentContext] == context) {
		[EAGLContext setCurrentContext:nil];
	}
	
	[context release];
	[super dealloc];
}

@end