前面主要写了iPhone开发的一些基本知识,有iPhone设备的介绍,iPhoneSDK开发的流程和文件的组成等,下面就据上部分介绍EAGL文件的内容:EAGLView.h和EAGLView.m文件.

     EAGLView类的主要功能是完成UIView到EAGL的3D接口,并且渲染一个旋转的彩色矩形.

首先完成3D接口必须导入OpenGLES.framework,

     然后必须重载以下函数:

    + (Class)layerClass;

 

    - (void)layoutSubviews;

 

     下面是函数内容:

 

- (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;
}
}

另外,我们还忘了初始化是怎么弄的,EAGLView文件内容是存在了nib文件里面,所以我们用:initWithCode初始化如下:

//The GL view is stored in the nib file. When it's unarchived it's sent -initWithCoder:

- (id)initWithCoder:(NSCoder*)coder {

if ((self = [super initWithCoder:coder])) { // 重载

// Get the layer

CAEAGLLayer *eaglLayer = (CAEAGLLayer *)self.layer;

 

eaglLayer.opaque = YES; // 显示设置不透明

// 属性:(缓存颜色格式:kEAGLColorFormatRGBA8)

eaglLayer.drawableProperties = [NSDictionary dictionaryWithObjectsAndKeys:

  [NSNumber numberWithBool:NO], kEAGLDrawablePropertyRetainedBacking, kEAGLColorFormatRGBA8, kEAGLDrawablePropertyColorFormat, nil];

// 调用initWithAPI初始化 EAGLContext *context;

context = [[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES1];

// 设为当前画布

if (!context || ![EAGLContext setCurrentContext:context]) {

[self release];

return nil;

}

// 时间间隔

animationInterval = 1.0 / 60.0;

}

return self;

}

 

最终,我们要描绘一个彩色的方块:

使用到函数 : - (void)drawView;

 

- (void)drawView {

// Replace the implementation of this method to do your own custom drawing

const GLfloat squareVertices[] = { //顶点数据

-0.5f, -0.5f,

0.5f,  -0.5f,

-0.5f,  0.5f,

0.5f,   0.5f,

};

const GLubyte squareColors[] = { // 颜色数据

255, 255,   0, 255,

0,   255, 255, 255,

0,     0,   0,   0,

255,   0, 255, 255,

};

// 设为当前画布

[EAGLContext setCurrentContext:context];

// 绑定桢缓冲区

glBindFramebufferOES(GL_FRAMEBUFFER_OES, viewFramebuffer);

// 设置视图窗口大小

glViewport(0, 0, backingWidth, backingHeight);

// 投影变换

glMatrixMode(GL_PROJECTION);

glLoadIdentity(); // 设置为单位矩阵

glOrthof(-1.0f, 1.0f, -1.5f, 1.5f, -1.0f, 1.0f); //正投影,创建一个正交平行的可视空间

glMatrixMode(GL_MODELVIEW); // 模型变换

glRotatef(3.0f, 0.0f, 0.0f, 1.0f); // 围绕x轴旋转

 

glClearColor(0.5f, 0.5f, 0.5f, 1.0f); // 清屏颜色

glClear(GL_COLOR_BUFFER_BIT); // 清除颜色缓冲区

 

glVertexPointer(2, GL_FLOAT, 0, squareVertices); // 指定顶点数据指针

glEnableClientState(GL_VERTEX_ARRAY); // 开启顶点数组

glColorPointer(4, GL_UNSIGNED_BYTE, 0, squareColors); // 指定颜色数据数组指针

glEnableClientState(GL_COLOR_ARRAY); // 开启颜色数组

 

glDrawArrays(GL_TRIANGLE_STRIP, 0, 4); // 解引用一个数组元素序列,描绘

 

// 绑定到渲染缓冲区

glBindRenderbufferOES(GL_RENDERBUFFER_OES, viewRenderbuffer);

[context presentRenderbuffer:GL_RENDERBUFFER_OES]; // 渲染到设备

}

 

到此从建立接口到显示就这样完成了,另外在动态渲染的时候用到了一个定时器NSTimer,以下是它的方法:(这里不详细介绍)

- (void)startAnimation {

self.animationTimer = [NSTimer scheduledTimerWithTimeInterval: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];

}

}

 

在以后文章里面会建立一个EAGLView类,它的功能只是建立UIView到EAGL的接口,所以以后需要3D视图的类都可以通过继承它来完成,就像一个接口一样使用,这次就写到这.有的地方还不够详细,以后碰到了再介绍...(待续)

1 楼 bnb7xi 2011-08-01  

没看懂。楼主能不能稍微解释下。。或者梳理下。