Cocoa練習帳

避けてきた分野に3Dがある。でも、まったく避けていただけでは進歩がないので、理解できていないながらも、簡単な何かをやろうと思う。三角形を描画するだけに挑戦する。

プロジェクトにGLKit.frameworkとOpenGLES.frameworkを追加する。

GLKViewControllerのサブクラスを作成する。

#import <UIKit/UIKit.h>
#import <GLKit/GLKit.h>
 
@interface PrimitiveViewController : GLKViewController
 
@end

書籍を読みながら、理解していないながらもなんとか記述。

#import "PrimitiveViewController.h"
 
@interface PrimitiveViewController ()
 
@property (strong, nonatomic) EAGLContext   *context;
@property (assign, nonatomic) GLuint        defaultFramebuffer;
@property (assign, nonatomic) GLuint        colorRenderbuffer;
@property (assign, nonatomic) GLuint        depthRenderbuffer;
 
- (void)setupGL;
- (void)tearDownGL;
 
@end
 
@implementation PrimitiveViewController
 
@synthesize context = _context;
@synthesize defaultFramebuffer = _defaultFramebuffer;
@synthesize colorRenderbuffer = _colorRenderbuffer;
@synthesize depthRenderbuffer = _depthRenderbuffer;
 
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
        self.defaultFramebuffer = 0;
        self.colorRenderbuffer = 0;
        self.depthRenderbuffer = 0;
    }
    return self;
}
 
- (void)viewDidLoad
{
    [super viewDidLoad];
     
    self.context = [[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES1];
    
    if (!self.context) {
        NSLog(@"Failed to create ES context");
    }
    
    GLKView *view = (GLKView *)self.view;
    view.context = self.context;
    view.drawableDepthFormat = GLKViewDrawableDepthFormat24;
    
    [self setupGL];
}
 
- (void)viewDidUnload
{
    [self tearDownGL];
    
    if ([EAGLContext currentContext] == self.context) {
        [EAGLContext setCurrentContext:nil];
    }
    self.context = nil;
    
    [super viewDidUnload];
}
 
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    return (interfaceOrientation == UIInterfaceOrientationPortrait);
}
 
- (void)setupGL
{
    [EAGLContext setCurrentContext:self.context];
    
    glGenFramebuffersOES(1, &_defaultFramebuffer);
    glBindFramebufferOES(GL_FRAMEBUFFER_OES, self.defaultFramebuffer);
    
    glGenRenderbuffersOES(1, &_colorRenderbuffer);
    glBindRenderbufferOES(GL_RENDERBUFFER_OES, self.colorRenderbuffer);
    glRenderbufferStorageOES(GL_RENDERBUFFER_OES,
                             GL_RGBA8_OES,
                             self.view.bounds.size.width,
                             self.view.bounds.size.height);
    glFramebufferRenderbufferOES(GL_FRAMEBUFFER_OES,
                                 GL_COLOR_ATTACHMENT0_OES,
                                 GL_RENDERBUFFER_OES,
                                 self.colorRenderbuffer);
 
    glGenRenderbuffersOES(1, &_depthRenderbuffer);
    glBindRenderbufferOES(GL_RENDERBUFFER_OES, self.depthRenderbuffer);
    glRenderbufferStorageOES(GL_RENDERBUFFER_OES,
                             GL_DEPTH_COMPONENT16_OES,
                             self.view.bounds.size.width,
                             self.view.bounds.size.height);
    glFramebufferRenderbufferOES(GL_FRAMEBUFFER_OES,
                                 GL_DEPTH_ATTACHMENT_OES,
                                 GL_RENDERBUFFER_OES,
                                 self.depthRenderbuffer);
    
    GLenum status = glCheckFramebufferStatusOES(GL_FRAMEBUFFER_OES) ;
    if (status != GL_FRAMEBUFFER_COMPLETE_OES) {
        DBGMSG(@"failed to make complete framebuffer object %x", status);
    }
}
 
- (void)tearDownGL
{
    [EAGLContext setCurrentContext:self.context];
 
    if (self.defaultFramebuffer) {
        glDeleteFramebuffersOES(1, &_defaultFramebuffer);
        self.defaultFramebuffer = 0;
    }
    
    if (self.colorRenderbuffer) {
        glDeleteRenderbuffersOES(1, &_colorRenderbuffer);
        self.colorRenderbuffer = 0;
    }
    
    if (self.depthRenderbuffer) {
        glDeleteRenderbuffersOES(1, &_depthRenderbuffer);
        self.depthRenderbuffer = 0;
    }
}
 
#pragma mark - GLKView and GLKViewController delegate methods
 
/*
- (void)update
{
}
*/
 
- (void)glkView:(GLKView *)view drawInRect:(CGRect)rect
{
    glClear(GL_COLOR_BUFFER_BIT);
    
    /* 頂点の定義 */
    GLfloat vertices[] = {
        -0.5f, -0.5f,
        0.5f, -0.5f,
        0.0f, 0.5f,
    };
    
    /* カラー（RGBA）の定義 */
    GLubyte colors[] = {
        255, 0, 0, 255,
        255, 0, 0, 255,
        255, 0, 0, 255,
    };
 
    /* 頂点配列とカラー配列を有効 */
    glEnableClientState(GL_VERTEX_ARRAY);
    glEnableClientState(GL_COLOR_ARRAY);
    
    /* 頂点配列とカラー配列を設定 */
    glVertexPointer(2 , GL_FLOAT , 0 , vertices);
    glColorPointer(4, GL_UNSIGNED_BYTE, 0, colors);
    
    /* 描画 */
    glDrawArrays(GL_TRIANGLES, 0, 3);
    
    glDisableClientState(GL_COLOR_ARRAY);
    glDisableClientState(GL_VERTEX_ARRAY);
}
 
@end

実行。

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