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 OpenGL FrameBuffer Object 101
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Reply Quoting This MessageEdit Message MENTAL    Member since: 4/8/2000  From: Herne Bay, United Kingdom
 Posted - 11/24/2006 7:52:39 AM
Oh
My
God

Rate++++++++++++++++++++++++++++++++++++++++++++++++
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Reply Quoting This MessageEdit Message Pipo DeClown    Member since: 2/16/2002  From: Amsterdam, Netherlands
 Posted - 11/24/2006 10:14:08 AM
You sing very well. Nice voice!
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Reply Quoting This MessageEdit Message elFarto    Member since: 10/21/2006
 Posted - 11/24/2006 1:40:41 PM
Quote:
Original post by MENTAL
Oh
My
God

Rate++++++++++++++++++++++++++++++++++++++++++++++++


Indeed, It was a very clear article.

Regards
elFarto
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Reply Quoting This MessageEdit Message iNsAn1tY    Member since: 12/18/2001  From: Guildford
 Posted - 11/25/2006 5:31:35 PM
Excellent. I've been using FBOs for a while, and I learnt something new :)

My opinion is a recombination and regurgitation of the opinions of those around me. I bring nothing new to the table, and as such, can be safely ignored.
[ Useful things - Firefox | GLee | Boost | DevIL ]
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Reply Quoting This MessageEdit Message Aph3x  GDNet+  Member since: 1/7/2004  From: UK
 Posted - 11/28/2006 3:37:04 PM
Yep - very nice article - cheers Rob!
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Reply Quoting This MessageEdit Message cyrfer    Member since: 12/9/2006  From: Monterey, CA, United States
 Posted - 12/9/2006 3:35:35 PM
Well, my experience with this tutorial was not as good. It reads very well, but the code doesn't work on my machine. So, I'm wondering if I typed up something wrong or if I have a bug in my graphics driver. I've been trying to get past this issue for a while, even before the tutorial came out. It looks like it samples the code available in MOGP text. I liked the part that tells you to add a depth buffer, which wasn't obvious from reading MOGP.

I'd like to know if anyone typed up this code and saw it working? I tried and I see that my FBO is unhappy when I try to attach the depth buffer.
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Reply Quoting This MessageEdit Message Kwizatz  GDNet+  Member since: 4/7/2000  From: San Jose, Costa Rica
 Posted - 12/9/2006 4:35:36 PM
Looks good, now I may actually add FBOs to my shadowmaps and video to texture code , just one thing:

Quote:

The example program requires some form of GLUT to be compiled and run (I used FreeGLUT)


Where is the link to said example program?
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Reply Quoting This MessageEdit Message cyrfer    Member since: 12/9/2006  From: Monterey, CA, United States
 Posted - 12/10/2006 3:46:51 PM
The tutorial is working well for me. I had a setting on my display that prevented any FBO code to work. Watch out that someone doesn't change your antialiasing settings behind your back!
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Reply Quoting This MessageEdit Message henrym    Member since: 2/12/2002  From: Christchurch, New Zealand
 Posted - 12/12/2006 4:37:18 PM
Quote:
Original post by Kwizatz
...

Where is the link to said example program?

Took me a while to find it too... It's in the right sidebar; the link is 'Source Code'.
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Reply Quoting This MessageEdit Message Kwizatz  GDNet+  Member since: 4/7/2000  From: San Jose, Costa Rica
 Posted - 12/12/2006 5:10:22 PM
Quote:
Original post by henrym
Quote:
Original post by Kwizatz
...

Where is the link to said example program?

Took me a while to find it too... It's in the right sidebar; the link is 'Source Code'.


Thanks!
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Reply Quoting This MessageEdit Message CyberSlag5k  GDNet+  Member since: 4/25/2003  From: Blue Ash, OH, United States
 Posted - 3/7/2007 3:20:50 PM
Hmm... I'm still not seeing it. Is this side bar in the actual article itself?


Without order nothing can exist - without chaos nothing can evolve.
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Reply Quoting This MessageEdit Message fasthazard    Member since: 3/18/2007  From: Raleigh, NC, United States
 Posted - 3/18/2007 2:02:45 PM
I too had trouble initally getting this stuff to work (compiling's the easy part). I'm using the glx_base code from the main nehe.gamedev site. I couldn't find the example code for the article, so I copied and pasted line by line.

I'm running linux, so the following may be most interesting to other linux users. Here are the most important fixes:

1- use libglew (the "GL extension wrangler) to manage checking for hardware/driver support for extensions, and mapping the appropriate pointers. If you know the extension you want to use is supported, you can use glewInit() to do the rest of the setup.

2- It's important that you complete setting up the target texture. Specifically, you can't just call glTexImage2D(...). You must also have something like:
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);

If these parameters aren't set, the glCheckFrameBufferStatus(...) will give error 0x8cdd (unsupported). For the meaning of other errors, see http://www.nvidia.com/dev_content/nvopenglspecs/GL_EXT_framebuffer_object.txt .

Good luck,

Matt
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Reply Quoting This MessageEdit Message BradDaBug    Member since: 5/2/2001  From: Cuba, MS, United States
 Posted - 4/16/2007 12:47:03 AM
Here's the link to the source if anyone else is having trouble finding it: clicky
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Reply Quoting This MessageEdit Message Oxidative    Member since: 4/26/2007  From: Darmstadt, Germany
 Posted - 6/4/2007 8:25:00 AM
Has anyone else noticed a general performance problem with the FBO extension?

The first time I start the example I get a pretty good framerate (~25fps), but after restarting the program the frames drop to 2-3fps! I thought it might be a cleanup problem, but it does call glDeleteFramebuffersEXT, glDeleteRenderbuffersEXT and glDeleteTextures at the end. Is there something missing?

I'm having the same problem with my own program. Maybe a driver problem? I'm using a Nvidia Quadro FX 4500 X2 with the ForceWare 96.02 driver.
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Reply Quoting This MessageEdit Message EonStrife    Member since: 10/28/2003
 Posted - 10/2/2007 5:38:42 AM
Hi, sorry for this silly question...But how can I access per-pixel data (color, or depth, etc.) of a renderbuffer object or texture object bound with FBO ?
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Reply Quoting This MessageEdit Message taby    Member since: 2/10/2005  From: Regina, Canada
 Posted - 10/2/2007 2:58:47 PM
The following code reads from the FBO's 0th attached floating point texture in GPU RAM and copies that data to an array in CPU RAM:

vector<float> entry_points(4*width*height); // 4 channels per pixel

glReadBuffer(GL_COLOR_ATTACHMENT0_EXT);
glReadPixels(0, 0, width, height, GL_RGBA, GL_FLOAT, &entry_points[0]);

// Print array
for(long unsigned int i = 0; i < width*height; i++)
{
cout << "R: " << entry_points[i*4 + 0] << endl;
cout << "G: " << entry_points[i*4 + 1] << endl;
cout << "B: " << entry_points[i*4 + 2] << endl;
cout << "A: " << entry_points[i*4 + 3] << endl;
}
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Reply Quoting This MessageEdit Message EonStrife    Member since: 10/28/2003
 Posted - 10/3/2007 2:58:18 AM
@taby

Thanks :)
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Reply Quoting This MessageEdit Message jhondoe    Member since: 4/29/2008  From: paris, France
 Posted - 4/29/2008 6:48:57 PM
Hi,

I am looking for the source code of the example exposed in this tutorial. It it has made with freeglut.

I did not see anywhere a link to download it.

Thx

John
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Reply Quoting This MessageEdit Message jhondoe    Member since: 4/29/2008  From: paris, France
 Posted - 4/30/2008 10:28:09 PM
Oh yeah I see now

(I was on this one http://www.gamedev.net/reference/articles/article2331.asp)
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Reply Quoting This MessageEdit Message jhondoe    Member since: 4/29/2008  From: paris, France
 Posted - 5/3/2008 6:58:46 PM
Correct page: here

A related question : here

[Edited by - jhondoe on May 4, 2008 6:58:52 AM]
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Reply Quoting This MessageEdit Message vodoo    Member since: 10/19/2008  From: Gainesville, FL, United States
 Posted - 7/7/2009 4:59:24 PM
The concept does not work for me.

My situation is slightly different, where I am calling a shader program on textures attached to the FBO.

This is the rough idea:

//MFC and OpenGL
OnPaint()
{
//context set up. RC , DC etc.

//get data from video frame and render
glDrawPixels(x,y, data..);

//bind to a FBO
glBindFrameBufferEXT(GL_FRAMEBUFFER_EXT, fb);

glPushAttrib(GL_COLOR_BIT | GL_VIEWPORT);

glClearColor(..); //clear screen

Myfunction(); //that internally calls my shader program

glPopAttrib();

//at this stage I expect the viewport and color settings restored, but not so

glBindFrameBufferEXT(GL_FRAMEBUFFER_EXT, 0);

setViewPort(0,0,W,H); //need to do it again.

..

}//This function is called again till number of available frames



Here is what is going on in MyFunction()

MyFunction()
{
setViewPort(0, 0, w, h); //W > w and H > h

//take two textures and attach them to FBO
a. set texture 1 with id tex[0] and other with id tex[1]
b. Internal type : GL_RGBA_FLOAT32_ATI
Pixel Data Format : RGBA
Data Type: GL_FLOAT
The pixel data is not related to video frame data.
c. glBindFrameBufferTexture2DEXT(..)

Shader(); //computes and produces yellow color
}


Shader()
{
//set up shader
..

//read source files
..

//compile
..

//link
..

//execute
glProgramExecute(..)


glDrawBuffers(2, buffers);

//pass on any uniform data
..

//render on quad
drawQuad(w, h); //same size as that of view port

}



As you can see the shader computes yellow color.

After coming out of shader the portion of the MFC screen where the first frame was drawn remains there but when it is the turn for the second frame to be drawn, insteead of next frame's data, the area is painted with color given out by shader.

Any comments???? Need any other info ??? Help required.Thank you.







}
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