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Screen Dark working with FBOs

Note: This was originally posted on 7th November 2010 at http://forums.arm.com

Hi Guys,

Trying to port an akready well running Sw from Fedora PC to the Mali400 on ST7108 chip, with GLES-2.0, I got a problem working with Framebuffer Objects.
Everything is ok, debugging ok, framebuffer objects completes, no errors, but the screen remains completely dark.
My environment on Mali/ST7108 is OK, other applications can run nicely.

But I think to have not completely understood (or better: not understood at all) how to set display and surfaces while working woth FBOs (maybe the problem could be also found somewhere else)

Basic setting is more or less as below, where I have put only the relevant setting and call for Display and Surfaces.

In does seem that the eglSwapBuffers does't work at all while working with FBOs
(even a monocolor screen cannot be seen...).
In contrast, while working out of FBOs, everything seems to be ok.

After binding with glBindFramebuffer(GL_FRAMEBUFFER,0), then everything is working and can be displayed.

In contrast, after glBindFramebuffer(GL_FRAMEBUFFER, framebuffer), I cannot see anything after he eglSwapBuffers, even if the debug seems to be ok.

Could someone pls help me in giving me suggestions on how to properly set Display and Surfaces?
Does there is a running examples while using FBOs on ST7108 chip?
Thanks a lot in advance for this
(here below I have just put a rough skeleton of the used code)

"
EGLDisplay eglDisplay = 0;
EGLSurface eglSurface = 0;
EGLint major, minor, num_configs;

..........
eglDisplay = eglGetDisplay(EGL_DEFAULT_DISPLAY));

eglInitialize(eglDisplay, &major, &minor);
eglBindAPI(EGL_OPENGL_ES_API);

eglChooseConfig(eglDisplay, configAttribs, &eglConfig, 1, &num_configs);

eglSurface = eglCreateWindowSurface(eglDisplay, eglConfig, NULL, NULL);
eglContext = eglCreateContext(eglDisplay, eglConfig, NULL, contextAttribs)));
eglMakeCurrent(eglDisplay, eglSurface, eglSurface, eglContext);
...........
...........

egl_setup(&eglDisplay,&eglSurface);

GLuint framebuffer;
GLuint depthRenderbuffer;
GLuint texture;

.....

glGenFramebuffers(1, &framebuffer);
glGenRenderbuffers(1, &depthRenderbuffer);
glGenTextures(1, &texture);
glBindTexture(GL_TEXTURE_2D, texture);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, texWidth, texHeight, 0, GL_RGB, GL_UNSIGNED_SHORT_5_6_5, NULL);

glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);

glBindRenderbuffer(GL_RENDERBUFFER, depthRenderbuffer);
glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT16, texWidth, texHeight);

glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);

glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, texture, 0);

glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, depthRenderbuffer);

Switch (glCheckFramebufferStatus(GL_FRAMEBUFFER))
{
case GL_FRAMEBUFFER_COMPLETE:
fprintf(stdout, "\n o Framebuffer Complete");
break;
......
}

GLCheckError(glClearColor(1.0f, 0.0f, 0.0f, 1.0f));
.....
eglSwapBuffers(eglDisplay, eglSurface);

// glBindFramebuffer(GL_FRAMEBUFFER,0);
.........

eglSwapBuffers(eglDisplay, eglSurface);
""

Many Thanks

Parents

Ericsson Broadbent over 11 years ago

Note: This was originally posted on 9th August 2011 at http://forums.arm.com

Stacy - I'm fairly new to OpenGL and have been trying to learn exactly this kind of overall usage model for when to use FBOs and how they can improve either graphics or memory performance (or both). My application will essentially be operating on textures - with a background texture surface filling the "window" and a number of smaller textures being "animated" on top of that - potentially with changes in alpha as well as of course position, rotation, size, etc. This functionality represents only a small portion of the OpenGL|ES functionality, and yet I still haven't found a good resource to learn from on how to optimize this kind of drawing.
The kinds of questions I have range from some basics such as how to account for the number of texture units when optimizing (i.e. is it better to use only one?), to understanding when the underlying memory transfers between application and GPU occur (in terms of APIs or other evolutions) and what the performance implications of these are, etc. I have also heard that some kinds of ops (e.g. DEPTH testing) will slow down texture processing, so I'd like to understand if there are things like this that I should stay away from - given more than one way to do what I need to do. Any general advice for a newbie trying to get up to speed on these sorts of topics?
Thanks very much.
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Ericsson Broadbent over 11 years ago

Note: This was originally posted on 9th August 2011 at http://forums.arm.com

Stacy - I'm fairly new to OpenGL and have been trying to learn exactly this kind of overall usage model for when to use FBOs and how they can improve either graphics or memory performance (or both). My application will essentially be operating on textures - with a background texture surface filling the "window" and a number of smaller textures being "animated" on top of that - potentially with changes in alpha as well as of course position, rotation, size, etc. This functionality represents only a small portion of the OpenGL|ES functionality, and yet I still haven't found a good resource to learn from on how to optimize this kind of drawing.
The kinds of questions I have range from some basics such as how to account for the number of texture units when optimizing (i.e. is it better to use only one?), to understanding when the underlying memory transfers between application and GPU occur (in terms of APIs or other evolutions) and what the performance implications of these are, etc. I have also heard that some kinds of ops (e.g. DEPTH testing) will slow down texture processing, so I'd like to understand if there are things like this that I should stay away from - given more than one way to do what I need to do. Any general advice for a newbie trying to get up to speed on these sorts of topics?
Thanks very much.
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