Frame buffer objects seem to be messing with my computer
Post: #1
I've been working with OpenGL frame buffer objects recently. I had plain FBOs working for a while, and am now trying to build a class that can wrap around an FBO. However, when I run a program that binds to an FBO (through one of my FBO objects) while drawing for off-screen rendering, quitting the program causes the screen to either flicker black or freeze entirely. 
My frame buffer object code:
My program also uses a texture manager:
And finally, code from my NSOpenGLView subclass:
My frame buffer object code:
Code:
#import <Cocoa/Cocoa.h>
@interface FrameBuffer : NSObject
{
GLuint fbo;
GLuint depthRenderBuffer;
}
+ (void) unbind;
- (void) bind;
- (void) attachTexture: (GLuint) textureID;
- (void) setDepthBufferWidth: (int) width andHeight: (int) height;
- (void) checkStatus;
@endCode:
#import "FrameBuffer.h"
@implementation FrameBuffer
+ (void) unbind
{
glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
}
- (id) init
{
if (![super init])
{
return nil;
}
glGenRenderbuffersEXT(1, &depthRenderBuffer);
glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, depthRenderBuffer);
glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT, GL_DEPTH_COMPONENT,
0, 0);
glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, 0);
glGenFramebuffersEXT(1, &fbo);
glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, fbo);
glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT,
GL_DEPTH_ATTACHMENT_EXT, GL_RENDERBUFFER_EXT, depthRenderBuffer);
//glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
return self;
}
- (void) bind
{
glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, fbo);
}
- (void) attachTexture: (GLuint) textureID
{
glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT,
GL_TEXTURE_2D, textureID, 0);
}
- (void) setDepthBufferWidth: (int) width andHeight: (int) height
{
glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, depthRenderBuffer);
glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT, GL_DEPTH_COMPONENT,
width, height);
}
- (void) checkStatus
{
GLenum status = glCheckFramebufferStatusEXT(GL_FRAMEBUFFER_EXT);
if (status != GL_FRAMEBUFFER_COMPLETE_EXT)
{
NSException *exception;
switch (status)
{
case GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT_EXT:
exception = [NSException
exceptionWithName: @"FrameBufferIncompleteException"
reason: @"GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT_EXT"
userInfo:nil];
break;
case GL_FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT_EXT:
exception = [NSException
exceptionWithName: @"FrameBufferIncompleteException"
reason:
@"GL_FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT_EXT"
userInfo:nil];
break;
case GL_FRAMEBUFFER_INCOMPLETE_DIMENSIONS_EXT:
exception = [NSException
exceptionWithName: @"FrameBufferIncompleteException"
reason: @"GL_FRAMEBUFFER_INCOMPLETE_DIMENSIONS_EXT"
userInfo:nil];
break;
case GL_FRAMEBUFFER_INCOMPLETE_FORMATS_EXT:
exception = [NSException
exceptionWithName: @"FrameBufferIncompleteException"
reason: @"GL_FRAMEBUFFER_INCOMPLETE_FORMATS_EXT"
userInfo:nil];
break;
case GL_FRAMEBUFFER_INCOMPLETE_DRAW_BUFFER_EXT:
exception = [NSException
exceptionWithName: @"FrameBufferIncompleteException"
reason: @"GL_FRAMEBUFFER_INCOMPLETE_DRAW_BUFFER_EXT"
userInfo:nil];
break;
case GL_FRAMEBUFFER_INCOMPLETE_READ_BUFFER_EXT:
exception = [NSException
exceptionWithName: @"FrameBufferIncompleteException"
reason: @"GL_FRAMEBUFFER_INCOMPLETE_READ_BUFFER_EXT"
userInfo:nil];
break;
case GL_FRAMEBUFFER_UNSUPPORTED_EXT:
exception = [NSException
exceptionWithName: @"FrameBufferIncompleteException"
reason: @"GL_FRAMEBUFFER_UNSUPPORTED_EXT"
userInfo:nil];
break;
default:
exception = [NSException
exceptionWithName: @"FrameBufferIncompleteException"
reason: @"Unknown error"
userInfo:nil];
break;
}
@throw exception;
}
}
- (void) dealloc
{
glDeleteFramebuffersEXT(1, &fbo);
glDeleteRenderbuffersEXT(GL_RENDERBUFFER_EXT, &depthRenderBuffer);
[super dealloc];
}
@endMy program also uses a texture manager:
Code:
@interface TextureManager : NSObject
{
GLuint *textures;
int numTextures;
}
+ (void) unbind;
- (id) initWithNumTextures: (int) num;
- (GLuint) getTextureIDatIndex: (int) index;
- (void) bindTextureAtIndex: (int) index;
- (void) setMagFilter: (GLint) filter;
- (void) setMinFilter: (GLint) filter;
- (void) setWrapping: (GLint) wrap;
- (void) createTextureWithWidth: (int) width withHeight: (int) height;
@endCode:
#import "TextureManager.h"
@implementation TextureManager
+ (void) unbind
{
glBindTexture(GL_TEXTURE_2D, 0);
}
- (id) initWithNumTextures: (int) num
{
if (![super init])
{
return nil;
}
textures = calloc(num, sizeof(*textures));
numTextures = num;
glGenTextures(num, textures);
return self;
}
- (GLuint) getTextureIDatIndex: (int) index
{
return textures[index];
}
- (void) bindTextureAtIndex: (int) index
{
glBindTexture(GL_TEXTURE_2D, textures[index]);
}
- (void) setMagFilter: (GLint) filter
{
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, filter);
}
- (void) setMinFilter: (GLint) filter
{
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, filter);
}
- (void) setWrapping: (GLint) wrap
{
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, wrap);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, wrap);
}
- (void) createTextureWithWidth: (int) width withHeight: (int) height
{
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, width, height, 0, GL_BGRA,
GL_UNSIGNED_INT_8_8_8_8_REV, NULL);
}
- (void) dealloc
{
glDeleteTextures(numTextures, textures);
free(textures);
[super dealloc];
}
@endAnd finally, code from my NSOpenGLView subclass:
Code:
@interface MyOpenGLView : NSOpenGLView
{
...
TextureManager *textures;
FrameBuffer *fbo;
}
......
- (void) prepareOpenGL
{
...
textures = [[TextureManager alloc]
initWithNumTextures: NUM_SCENE_TEXTURES];
int i;
for (i = 0; i < NUM_SCENE_TEXTURES; ++i)
{
[textures bindTextureAtIndex: i];
[textures setMagFilter: GL_LINEAR];
[textures setMinFilter: GL_LINEAR];
[textures setWrapping: GL_CLAMP_TO_EDGE];
[textures createTextureWithWidth: 0 withHeight: 0];
}
[TextureManager unbind];
//-----
fbo = [[FrameBuffer alloc] init];
// Only bind the first texture for now
[fbo attachTexture: [textures getTextureIDatIndex: 0]];
[FrameBuffer unbind];
...
}
- (void) reshape
{
int width = [self bounds].size.width;
int height = [self bounds].size.height;
[scene resizeWithWidth: width withHeight: height];
int i;
for (i = 0; i < NUM_SCENE_TEXTURES; ++i)
{
[textures bindTextureAtIndex: i];
[textures createTextureWithWidth: width withHeight: height];
}
[fbo setDepthBufferWidth: width andHeight: height];
}
- (void) drawRect: (NSRect) bounds
{
// Setup stuff
...
// First pass - draw scene to texture
// I enable a shader here.
// If I comment out the next two likes I don't get any screen flickering or
// possible crashes when I exit the program.
[fbo bind];
[fbo checkStatus];
glLoadIdentity();
glClearColor(0.0, 0.0, 0.0, 1.0);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
[scene draw];
[FrameBuffer unbind];
glLoadIdentity();
glClearColor(1.0, 1.0, 1.0, 1.0);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
// I'm not doing anything with the new texture yet.
glFlush();
}
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