objective-c - 不使用 Interface Builder 创建 OpenGL View

Question

所以我正在尝试创建一个 openGL View (在我的窗口中)。我正在制作一个 Cocoa 应用程序。我设法通过 Interface Builder 创建了一个，但出于教育目的，我想继续并在没有它的情况下创建一个。就在纸上。

这就是我告诉你我正在努力解决的问题。所以到目前为止我基本上做过的尝试是这样的:我创建了一个继承自 NSOpenGLView 的新类“MyOpenGLView.h/m”。我没有向它添加任何私有(private)变量或方法，只是类名。我唯一做的就是重写 initWithFrame:(在里面添加一个 self = [super initWithFrame:pixelFormat:]。)我在网上读到过，你必须先用这样的东西实例化它，然后才能使用它)。这是代码:

- (id) initWithFrame:(NSRect)frameRect
{
 NSOpenGLPixelFormat *pixelFormat = [[NSOpenGLPixelFormat alloc]
                                    initWithAttributes:(NSOpenGLPixelFormatAttribute[])
                                    {
                                    NSOpenGLPFAWindow,
                                    NSOpenGLPFADoubleBuffer,
                                    NSOpenGLPFADepthSize, 32,
                                    nil
                                    }];
 self = [super initWithFrame:frameRect pixelFormat:pixelFormat];
 [[self openGLContext] makeCurrentContext];
}

所以我有另一个名为“MyViewController.h/m”的类来处理我的 View ？那里有我的 MyOpenGLView *myView。在 .m 文件中，我使用类似这样的内容:

myView = [[MyOpenGLView alloc] initWithFrame:CGRectMake(0,0,100.0,100.0)];
if (!myView) { NSLog(@"ERROR"); }

当然，我会出错。

我的窗口应用程序中没有移植 openGL View 。我猜它与被调用方法的层次结构有关，但话又说回来..我不确定。你能帮我吗？

Answer 1

他们让这个工作的方式是我没有在我看来实现 init 方法。然后在我的 Controller 或应用程序委托(delegate)中。

@implementation AppDelegate

@synthesize window = _window;
@synthesize view = _view;

- (void)applicationDidFinishLaunching:(NSNotification *)aNotification {
    NSRect mainDisplayRect = [[NSScreen mainScreen] frame]; // I'm going to make a full screen view.

    NSOpenGLPixelFormatAttribute attr[] = {
        NSOpenGLPFAOpenGLProfile, NSOpenGLProfileVersion3_2Core, // Needed if using opengl 3.2 you can comment this line out to use the old version.
        NSOpenGLPFAColorSize,     24,
        NSOpenGLPFAAlphaSize,     8,
        NSOpenGLPFAAccelerated,
        NSOpenGLPFADoubleBuffer,
        0
    };

    NSOpenGLPixelFormat *pix = [[NSOpenGLPixelFormat alloc] initWithAttributes:attr];
    self.view = [[OpenGLViewCoreProfile alloc] initWithFrame:mainDisplayRect pixelFormat:pix];

    // Below shows how to make the view fullscreen. But you could just add to the contact view of any window.
    self.window = [[NSWindow alloc] initWithContentRect:mainDisplayRect
                                              styleMask:NSBorderlessWindowMask 
                                                backing:NSBackingStoreBuffered 
                                                  defer:YES];

    self.window.opaque = YES;
    self.window.hidesOnDeactivate = YES;
    self.window.level = NSMainMenuWindowLevel + 1; // Show window above main menu.
    self.window.contentView = self.view;
    [self.window makeKeyAndOrderFront:self]; // Display window.
}

@end

可以在-prepareOpenGl 方法中调用-makeCurrentContext。我在下面写的所有内容都不是必需的，但出于性能原因很好。我已经开始使用 CVDisplayLink 将帧绘制与屏幕刷新率同步，所以我的 openGLview 看起来像

// This is the callback function for the display link.
static CVReturn OpenGLViewCoreProfileCallBack(CVDisplayLinkRef displayLink,
                                              const CVTimeStamp* now, 
                                              const CVTimeStamp* outputTime, 
                                              CVOptionFlags flagsIn, 
                          CVOptionFlags *flagsOut, 
                                              void *displayLinkContext) {
    @autoreleasepool {
        OpenGLViewCoreProfile *view = (__bridge OpenGLViewCoreProfile*)displayLinkContext;
        [view.openGLContext makeCurrentContext];
        CGLLockContext(view.openGLContext.CGLContextObj); // This is needed because this isn't running on the main thread.
        [view drawRect:view.bounds]; // Draw the scene. This doesn't need to be in the drawRect method.
        CGLUnlockContext(view.openGLContext.CGLContextObj);
        CGLFlushDrawable(view.openGLContext.CGLContextObj); // This does glFlush() for you.

        return kCVReturnSuccess;
    }
}

- (void)reshape {
    [super reshape];
    CGLLockContext(self.openGLContext.CGLContextObj);

    ... // standard opengl reshape stuff goes here.

    CGLUnlockContext(self.openGLContext.CGLContextObj);
}

- (void)prepareOpenGL {
    [super prepareOpenGL];

    [self.openGLContext makeCurrentContext];
    GLint swapInt = 1;
    [self.openGLContext setValues:&swapInt forParameter:NSOpenGLCPSwapInterval];

    CGLLockContext(self.openGLContext.CGLContextObj);

    ... // all opengl prep goes here

    CGLUnlockContext(self.openGLContext.CGLContextObj);

    // Below creates the display link and tell it what function to call when it needs to draw a frame.
    CVDisplayLinkCreateWithActiveCGDisplays(&_displayLink);
    CVDisplayLinkSetOutputCallback(self.displayLink, &OpenGLViewCoreProfileCallBack, (__bridge void *)self);
    CVDisplayLinkSetCurrentCGDisplayFromOpenGLContext(self.displayLink, 
                                                      self.openGLContext.CGLContextObj, 
                                                      self.pixelFormat.CGLPixelFormatObj);
    CVDisplayLinkStart(self.displayLink);
}