iPhone OpenGL ES上下文和帧缓冲

Question

我正在尝试正确设置帧缓冲，以支持深度和正确的视角。我在XCode中使用OpenGL ES应用程序模板，我一直遵循OpenGL ES Programming Guide中的指南。

我手动将渲染器设置为ES1，因为我只想使用FFP进行深度渲染。

这是我目前的代码：

#import "ES1Renderer.h"
#import "water.h"
//#import "EAGLError.h"
#define PRINT_GLERR(error) ((error == GL_NO_ERROR) ? NSLog(@"No error") : NSLog(@"GL Error: %d", (error)))
//#define GLE(X) {X; eglGetError(); }

@implementation ES1Renderer

// Create an OpenGL ES 1.1 context
- (id)init
{
    if ((self = [super init]))
    {
        context = [[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES1];

        if (!context || ![EAGLContext setCurrentContext:context])
        {
            [self release];
            return nil;
        }

  glGenFramebuffersOES(1, &framebuffer);
  glBindFramebufferOES(GL_FRAMEBUFFER_OES, framebuffer);

  glGenRenderbuffersOES(1, &colorRenderbuffer);
  glBindRenderbufferOES(GL_RENDERBUFFER_OES, colorRenderbuffer);
  glFramebufferRenderbufferOES(GL_FRAMEBUFFER_OES, GL_COLOR_ATTACHMENT0_OES, GL_RENDERBUFFER_OES, colorRenderbuffer);


  glViewport(0, 0, backingWidth, backingHeight);

  // Start in projection mode.
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();

  double xmin, xmax, ymin, ymax;
  ymax = NEAR_PLANE * tanf(DEGREES_TO_RADIANS(FOV) / 2.0f);
  ymin = -ymax;
  xmin = ymin * ((float)backingWidth / (float)backingHeight);
  xmax = ymax * ((float)backingWidth / (float)backingHeight);
  glFrustumf(xmin, xmax, ymin, ymax, NEAR_PLANE, FAR_PLANE);
  glViewport(0, 0, backingWidth, backingHeight);

  glEnable(GL_DEPTH_TEST);
  glDepthFunc(GL_LESS);
  glDepthRangef(0.0f, 1.0f);
  glDepthMask(TRUE);
     glClearColor(0.0f, 0.0f, 0.0f, 1.0f);

  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();
    }

    return self;
}

- (void)render
{
    static const GLfloat squareVertices[] = {
        -0.5f,  -0.33f, -1.0f,
  0.5f,  -0.33f, -1.0f,
        -0.5f,   0.33f, -1.0f,
  0.5f,   0.33f, -1.0f,
    };

    static const GLubyte squareColors[] = {
        255, 255,   0, 255,
        0,   255, 255, 255,
        0,     0,   0,   0,
        255,   0, 255, 255,
    };

    static float transY = 0.0f;

    [EAGLContext setCurrentContext:context];

    glBindFramebufferOES(GL_FRAMEBUFFER_OES, framebuffer);

    glViewport(0, 0, backingWidth, backingHeight);

    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    glTranslatef(0.0f, (GLfloat)(sinf(transY)/2.0f), 0.0f);
    transY += 0.075f;

    glClearColor(0.5f, 0.5f, 0.5f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT);

    glVertexPointer(3, 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, colorRenderbuffer);
    [context presentRenderbuffer:GL_RENDERBUFFER_OES];
}

- (BOOL)resizeFromLayer:(CAEAGLLayer *)layer
{
 glGenFramebuffersOES(1, &framebuffer);
 glGenRenderbuffersOES(1, &colorRenderbuffer);

 glBindFramebufferOES(GL_FRAMEBUFFER_OES, framebuffer);
 glBindRenderbufferOES(GL_RENDERBUFFER_OES, colorRenderbuffer);

 [context renderbufferStorage:GL_RENDERBUFFER_OES fromDrawable:layer];
 glFramebufferRenderbufferOES(GL_FRAMEBUFFER_OES, GL_COLOR_ATTACHMENT0_OES, GL_RENDERBUFFER_OES, colorRenderbuffer);

 glGetRenderbufferParameterivOES(GL_RENDERBUFFER_OES, GL_RENDERBUFFER_WIDTH_OES, &backingWidth);
 glGetRenderbufferParameterivOES(GL_RENDERBUFFER_OES, GL_RENDERBUFFER_HEIGHT_OES, &backingHeight);

 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)dealloc
{
    if (framebuffer)
    {
        glDeleteFramebuffersOES(1, &framebuffer);
        framebuffer = 0;
    }

    if (colorRenderbuffer)
    {
        glDeleteRenderbuffersOES(1, &colorRenderbuffer);
        colorRenderbuffer = 0;
    }

 if (depthRenderbuffer) 
 {
  glDeleteRenderbuffersOES(1, &depthRenderbuffer);
  depthRenderbuffer = 0;
 }

    if ([EAGLContext currentContext] == context)
        [EAGLContext setCurrentContext:nil];

    [context release];
    context = nil;

    [super dealloc];
}

@end

当我推荐这部分代码时：

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);

我得到一个上下弹跳的四边形并正确呈现。任何关于深度问题的帮助都会很棒！