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pepi55
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Joined: 28 Oct 2013
Posts: 37
Location: The Internet
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 Posted: Sat Mar 18, 2017 8:57 pm Post subject: [Solved] Rendering things in C++ using dispmanX on RPi3 |
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Hello,
I need help with a very weird problem that I don't know how to solve or where to look for a solution.
The thing I'm trying to do is get a cube and terrain on screen in C++, but for some reason all I'm seeing on screen is a solid color, the color is an average hue of the textures I am trying to draw.
Now here is the problem, I know this is a Gentoo specific problem because I have raspbian and archlinux arm on 2 separate SD cards and on those 2 systems the scene renders fine:
http://imgur.com/ylz5xqH
First I thought it might be a library problem, one of the systems uses either outdated or newer vc libraries which causes this anomaly but after I ran rpi-update on both the Gentoo system and Raspbian, the problem persists.
I am very certain that both systems now use the same version of the proprietary VC libraries.
Now my imagination runs short so I have no clue where to look next. I am hopeful someone here might be able to point me in the right direction at the very least.
Thanks in advance!
EDIT: Here is a picture of how the same scene looks on Gentoo:
http://imgur.com/kgSjSyT
And here is an image of how it looks when I try to screenshot it the same way I screenshot it on Archlinux:
http://imgur.com/1OoBgnD
Using this
| Code: | void Screenshot(GLint endX, GLint endY, GLint startX, GLint startY, std::string filename)
{
GLubyte *pixels = new GLubyte[3 * endX * endY];
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
glReadPixels(startX, startY, endX, endY, GL_RGB, GL_UNSIGNED_BYTE, pixels);
stbi_write_png(filename.c_str(), endX, endY, 3, pixels, endX * 3);
delete[] pixels;
} |
EDIT2: Wrong gentoo screenshot image.
Last edited by pepi55 on Mon Mar 20, 2017 10:19 am; edited 1 time in total |
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pepi55
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Joined: 28 Oct 2013
Posts: 37
Location: The Internet
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| Posted: Sat Mar 18, 2017 11:54 pm Post subject: |
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Something like progress:
The same project built on Archlinux runs on Gentoo, and vice versa.
When I run an Arch-build executable, I get an error saying that GLIBCXX_3.4.21 was not found in libstdc++.so.6. I fixed this by putting the libstdc++ from arch into the program's folder.
Then if I run it, the program runs and the scene is rendered perfectly fine.
When I run the Gentoo built version of this program on Archlinux, it runs without copying any libs and the scene is not rendered, just like on Gentoo itself.
I think this narrows down the problem to gcc itself. However, I am still not sure how to proceed. Is it an issue with the Gentoo version of gcc? Am I missing some kind of useflag? Is it related to ld?
Since this might be related to how I compile the program, here are the makefile settings I have set:
http://imgur.com/BOk4fzL
If there is a need for the makefile itself, please tell me I will post it.
I will try compiling gcc with the vanilla useflag, maybe that will help. |
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pepi55
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Joined: 28 Oct 2013
Posts: 37
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| Posted: Mon Mar 20, 2017 12:28 am Post subject: |
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The vanilla useflag for gcc fixed my issue.
Where can I find what patches are applied to the gentoo version of GCC? |
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R0b0t1
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Joined: 05 Jun 2008
Posts: 264
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| Posted: Mon Mar 20, 2017 4:08 pm Post subject: |
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| Run `ebuild /usr/portage/sys-devel/gcc/gcc-4.9.4.ebuild prepare` or substitute the version of your choice. |
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John R. Graham
Administrator
Joined: 08 Mar 2005
Posts: 10657
Location: Somewhere over Atlanta, Georgia
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| Posted: Mon Mar 20, 2017 5:47 pm Post subject: |
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| pepi55 wrote: | | The vanilla useflag for gcc fixed my issue. ... |
This is definitely worth a bug report on Gentoo Bugzilla. Are you planning to work through the applied patches to see what the real culprit is?
- John
_________________
I can confirm that I have received between 0 and 499 National Security Letters. |
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pepi55
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Joined: 28 Oct 2013
Posts: 37
Location: The Internet
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| Posted: Mon Mar 20, 2017 9:56 pm Post subject: |
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I want to take a look to see what could cause the issue but I would like to work from the top down. As in: see what is patched and enable patches one by one to see which causes the problem.
For that I would need to know where I can see what patches are applied to the gentoo version of gcc, which I don't.
Also, please note that I am using gcc 4.9.4 which is the latest stable release. I have not tested newer versions of gcc in which the problem may not appear.
Since I am busy most of the time I cannot guarantee that I will find the culprit quickly, if ever.
EDIT: Missed R0b0t1's comment, I will look at it when possible and then file the bug report. |
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pepi55
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Joined: 28 Oct 2013
Posts: 37
Location: The Internet
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| Posted: Mon Mar 20, 2017 11:48 pm Post subject: |
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This was way easier to find than I thought...
The very first patch "09_all_default-ssp.patch" causes the issue as far as I can see.
When this patch is applied it changes the default behaviour to -fstack-protector-striog from what I understood, and sure enough, if I compile with -fstack-protector-strong, nothing renders anymore.
Considering that this is the issue, I don't think this is bug worthy. I think I should fix my code to compile and work properly even with -fstack-protector-strong as an option. |
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Gentoo on ARM
