Only white images by PPM export about gource HOT 15 CLOSED

Very strange. When this happens, is the screen white too?

Nope, although insanely slow (and seems to miss updates if you pull another 
window in
front) it shows the start of the sequence just fine.

It sounds like glReadPixels() is returning all white for some reason, like its
pointing at the wrong buffer, somehow.

Could you try and replace the glReadPixels call in src/ppm.cpp with:

glReadBuffer(GL_BACK);
glPixelStorei(GL_PACK_ALIGNMENT, 1);
glReadPixels(0, 0, display.width, display.height,
        GL_RGB, GL_UNSIGNED_BYTE, next_pixel_ptr);

And see if that helps.

Nope, that didn't do it. Still the same result. I have re-verified and after the
initial ASCII header there are only 0xFF values.

I guess another thing would be to check if glReadPixels is in fact setting 
values to
0xFF (ie next_pixel_ptr[0] == 0xFF after call but not initially or something 
like
that) and if glReadPixels() is setting an error so that glGetError() returns a 
non
zero value.

It could also be that 'char' arrays (pixel1, pixel2, pixels_shared_ptr and
next_pixel_ptr) need to be changed to be 'unsigned char'.

Can you provide some patch to try? I have also tried the (new) Fedora package, 
no
success either. I have asked the package for more info, e.g. if the problem 
appears
also on his box and on 32-bit 
(https://bugzilla.redhat.com/show_bug.cgi?id=567559).

Ok I wrote a patch to try:

This test patch changes char to unsigned char and will print some debugging to 
STDERR
each time we call glReadPixels().

This will tell us (hopefully):

- was an error set by glReadPixels(), and what was it.
- did glReadPixels() modify the input array or leave it the same.
- did glReadPixels() modify the input array to 0xFF.

Tried it. Still the same result, prints the following on the screen:

glReadPixels(0, 0, 1024, 768, 6407, 5121, next_pixel_ptr)
next_pixel_ptr[0] == 0xFF (changed to 0xFF)

Anything else you want me to try?
Maybe you can also try it with the F-12 x86_64 Live CD from
http://download.fedoraproject.org/pub/fedora/linux/releases/12/Live/x86_64/Fedor
a-12-x86_64-Live.iso
on your system?

[deleted comment]

I've got the same issue on a WinXP box.
BUT: when runned without --output-framerate the program window is just white.

Case 1) gource.exe some_log_file

Everything is just fine.

Case 2) gource.exe some_log_file --output-ppm-stream some_file 
--output-framerate 25

I can see the animation in the program window, but it runs much much slower 
than in
case 1, and it seems to be displaying a single white frame for a fraction of 
second
every second or so.

The stream is all white frames.

Case 3) gource.exe some_log_file --output-ppm-stream some_file

The program window is all white.

Can you try commenting out these 3 lines in FrameExporter::dump():

display.renderToTexture(screentex, display.width, display.height, GL_RGBA);
display.fullScreenQuad(true);

...

display.fullScreenQuad(false);

If this fixes it, you will see upside down images in the ppm file.

Also if this doesn't work, could you try version 0.23 from the Downloads 
section as I
made a lot of changes between 0.23 and 0.24 and it may be one of those.

Cheers

It's upside down but otherwise it contains the expected output! So how do we 
get it
flipped without loosing content again?

Great, I wasn't sure if we were going to figure this out.

Can you apply this patch to the original source. It does the flip in software 
now.

The patch works just fine. Thank you! Will you put out a new release? Would 
make the
life much easier for packagers.

Now in 0.25