# Print out broken symbolic links find -L . -type l
Note to self: Move this to a useful Linux tips post.
Find Broken Symbolic Links
malloc double free/non- aligned pointer being freed set a breakpoint in malloc_error_break to debug
malloc: *** error for object 0x3874a0: double free ***set a breakpoint in malloc_error_break to debug malloc: *** error for object 0x18a138: Non- aligned pointer being freed *** set a breakpoint in malloc_error_break to debug
So basically something in your code is screwing around with memory.
Either releasing something that has already been released:
int* x = new x[10]; delete [] x; delete [] x;
Or releasing something that is not pointing to the start of an allocated block of memory:
int* x = new int[10]; x++; delete [] x;
The error message isn’t very clear if you have no experience with GDB. GDB is a debugger for your binaries. It allows you to set break points at the start of a function and any time that function is called your application will pause and allow you to debug in GDB. We can then get valuable information back by executing commands to get the backtrace, registers state and disassembly. The advantage of using GDB over Xcode/KDevelop is being able to break into any function, not just functions in your source code. Anyway, this is how I got the backtrace to find out where in my sourcecode I was making a mistake:
gdb file myapplication break malloc_error_break run backtrace
Now whenever a double free or non- aligned pointer is freed it will break into gdb and we can type in “backtrace” and work out what our code did to trigger this.
Cannot open /dev/sda1: Device or resource busy
After an update (Upgrade?) a while ago I couldn’t boot into Fedora, it had the text mode bar graph and after getting to 100% it failed with this error message:
Cannot open /dev/sda1: Device or resource busy
It turned out that this was a dmraid problem. It would appear that something changed when updating and added or enabled dmraid. So I had to find a way to remove or disable it, the simplest solution I found that worked was disabling it via the arguments to the kernel in GRUB.
Edit menu.lst (Or grub.conf, my menu.lst is a symbolic link to grub.conf)
su gedit /boot/grub/menu.lst
Find the entry that you are currently booting into and add “nodmraid” to the end of the “kernel” line:
kernel /vmlinuz-2.6.31.6-166.fc12.x86_64 ro root=UUID=7129c2cc-03c5-4b7a-8472-bb9d314446b3 LANG=en_US.UTF-8 SYSFONT=latarcyrheb-sun16 KEYBOARDTYPE=pc KEYTABLE=us rhgb quiet nodmraid
I also like to add a timeout and remove hiding of the menu (This is in the general entry at the top of the file):
timeout=10 #hiddenmenu
My final menu.lst/grub.conf file looks like this:
default=0 timeout=10 splashimage=(hd0,1)/grub/splash.xpm.gz #hiddenmenu title Fedora (2.6.31.6-166.fc12.x86_64) root (hd0,1) kernel /vmlinuz-2.6.31.6-166.fc12.x86_64 ro root=UUID=7129c2cc-03c5-4b7a-8472-bb9d314446b3 LANG=en_US.UTF-8 SYSFONT=latarcyrheb-sun16 KEYBOARDTYPE=pc KEYTABLE=us rhgb quiet initrd /initramfs-2.6.31.6-166.fc12.x86_64.img
Why Chris, your grub.conf is so puny, only one entry in it. Leave me alone, I only just reinstalled.
When Good Customers Go Bad
class Customer; class CustomerEx; // Added 20.03.2006 class CustomerEx2; // Added 05.10.2006 class CustomerEx2B; // Added 13.07.2008
How to Find and Remove Folders Recursively in Linux/Unix Because I Always Forget This
# Recursively search for folders called .svn and delete them (Even if not empty) find . -name .svn -type d -print | xargs rm -rf # Recursively search for files called *~ (gedit creates these for temporarily saving to) and delete them find . -name \*~ -print | xargs rm -rf # Recursively search for files called *.h or *.cpp and print them find -name '*.h' -o -name '*.cpp' -print
Blender Export OBJ Python Script
First of all I’d like to state that I’m definitely a Blender n00b and I have never touched Python in my life.
Baby steps, textured sphere loaded from an obj file
In my game engine I basically have this sort of layout:
sphere/
sphere.obj
sphere.mat
sphere.pngThe .obj points to the .mat file which points to the .png file. So in Blender I would set the material name to “sphere” and ideally in the .obj file it would have a line like this, “usemtl sphere”, I would then get the sphere part and append “.mat” and load the material. I’m not sure if this is standard practice for Blender export scripts, but when exporting to the obj file format, Blender adds the texture name to the material like so, “usemtl sphere_sphere.png”, not cool. Anyway I thought, hey, the export script is written in Python, I wonder if I can fix this?
1) Locate the script. I read somewhere on the Blender site that scripts are in “/usr/share/blender/scripts/”. “export_obj.py” is there, along side “export_obj.pyc” and “export_obj.pyo”.
2) Edit the script.
gedit /usr/share/blender/scripts/export_obj.py
3) The script is pretty well documented. I knew that I should search for “usemtl” as that is the only constant part of the string (Apart from “_” which is much harder to search for). There are two in the file and we want the second one:
mat_data= MTL_DICT.get(key) if not mat_data: # First add to global dict so we can export to mtl # Then write mtl # Make a new names from the mat and image name, # converting any spaces to underscores with fixName. # If none image dont bother adding it to the name if key[1] == None: mat_data = MTL_DICT[key] = ('%s'%fixName(key[0])), materialItems[f_mat], f_image else: mat_data = MTL_DICT[key] = ('%s_%s' % (fixName(key[0]), fixName(key[1]))), materialItems[f_mat], f_image if EXPORT_GROUP_BY_MAT: file.write('g %s_%s_%s\n' % (fixName(ob.name), fixName(ob.getData(1)), mat_data[0]) ) # can be mat_image or (null) file.write('usemtl %s\n' % mat_data[0]) # can be mat_image or (null)
mat_data is a dictionary that is filled out and then written the file with “usemtl”. I replaced the offending line:
mat_data = MTL_DICT[key] = ('%s_%s' % (fixName(key[0]), fixName(key[1]))), materialItems[f_mat], f_image
with this:
mat_data = MTL_DICT[key] = ('%s'%fixName(key[0])), materialItems[f_mat], f_image
And then I realised that it was exactly the same as the line from the “if key[1] == None:” so you could probably remove the branch etc. if you want, I didn’t bother.
If you are exporting groups by material you may also need to edit the “if EXPORT_GROUP_BY_MAT:” branch also, again I didn’t bother. Anyway, save and you’re good to go.
4) I was worried that I would have to compile into bytecode or something for Blender to be able to use this, nope, either restart Blender or hit “Update Menu”. Actually as it is an export script, I’m not sure you even need to do that, it probably gets reloaded when you hit “File > Export > Wavefront (.obj)”?
This is the entirety of my Python knowledge, oh, I also know that whitespace is important or something, woo.
PS. I’m loving git, I can’t believe I didn’t switch earlier!
I Love the Idea of a New Smart Phone
The list of awesome phones:
HTC Phones
OpenMoko
Palm Pre
However, a new hotness has just been born.
The Nokia n900.
32 GB internal storage
Expandable to up to 48 GB with external microSD card
3.5G mobile network
Quadband GSM with GPRS and EDGE
Data transfers over a cellular network 10/2Mbps
Data transfers over Wi-Fi 54Mbps
Flash 9.4 support (In your face iPhone users, Nokia loves me)
5-megapixel (2584 × 1938 resolution) digital camera (iPhone is up to 3.2-megapixel)
800 × 480 resolution video recording
Dual LED flash
800 × 480 resolution screen
Tactile and onscreen QWERTY keyboards (Yes, none of this onscreen keyboard rubbish)
Removable battery (That probably won’t explode)
Assisted-GPS receiver
Ovi Maps pre-installed
TV out (PAL/NTSC) with Nokia Video Connectivity Cable (CA-75U, included in box) or WLAN/UPnP
Wide aspect ratio 16:9 (WVGA)
Video recording file format: .mp4; codec: MPEG-4
Video recording at up to 848 × 480 pixels (WVGA) and up to 25fps
Video playback file formats: .mp4, .avi, .wmv, .3gp; codecs: H.264, MPEG-4, Xvid, WMV, H.263
Music playback file formats: .wav, .mp3, .AAC, .eAAC, .wma, .m4a
The important part:
Development in C and Python are supported, using GTK.
Unfortunately it looks like C++ is not supported so anyone wanting to do any OOP will have to do it in Python.
That is great that Nokia are supporting open standards, releasing a mobile phone running Linux. It would be nice if they supported C++ too, but that is just my personal preference, and it may come in the future, I know all the C++ jazz is quite complex and definitely non-trivial.
I’d still rather use Python than C. I certainly hope that Windows Mobile dies and the highly overrated iPhone becomes less popular, not completely die, just put in its place. I would love to see the world embrace open standards, open source software and a rise in DRM free, happy, feel good devices, gain popularity and eventually dominate the market and warm people’s hearts.
Posted in linux, nokia n900, smartphone
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Moving from SVN to GIT
So I have a few projects on SourceForge, but they’re all hosted via SVN. With all this distributed version control going on I thought I would like to get in on the action. I thought about moving to github, but what happens in 5 or 10 years when I want to move on to another revision control software? The name has a limited life expectancy. Anyway so I wanted to switch so I researched alot, this is the best information I found and this blog entry is basically a rehash specific to SourceForge (Because I didn’t find any good SourceForge specific information).
Note: For this tutorial you will want to change all occurrences of USERNAME to your user name for example “pilkch”, PROJECTNAME to your project name for example “breathe” and YOURFULLNAME to your full name for example “Chris Pilkington”.
First of all we need to download git and git-svn:
su yum install git git-svn
Now we are going to create our repo directory for holding our repositories:
cd ~ mkdir repo
Create a users.txt file to map our subversion users to git users:
users.txt
USERNAME = YOURFULLNAME <USERNAME@PROJECTNAME.git.sourceforge.net>
As the other article says, we basically check out a svn directory as a git repository:
cd repo mkdir PROJECTNAME_from_svn cd PROJECTNAME_from_svn git svn init http://PROJECTNAME.svn.sourceforge.net/svnroot/PROJECTNAME --no-metadata git config svn.authorsfile ../users.txt git svn fetch
Check that worked (Just read the last few changes to make sure svn history is present, you can hit spacebar to scroll back a page of history or two just to make sure):
git log
From now on we can use git commands, first of all want to create a copy of the git-svn repository:
cd ..
git clone PROJECTNAME_from_svn PROJECTNAMEPROJECTNAME/ now contains our “clean” repository and PROJECTNAME_from_svn can be deleted if you like. We now just need to add and push our local repository to the remote location:
cd PROJECTNAME git config user.name "YOURFULLNAME" git config user.email "USERNAME@users.sourceforge.net" git remote rm origin # This may not be necessary for you git remote add origin ssh://USERNAME@PROJECTNAME.git.sourceforge.net/gitroot/PROJECTNAME/PROJECTNAME git config branch.master.remote origin git config branch.master.merge refs/heads/master git push origin master
Now to check that this is working you can browse to the git page of your SourceForge project and there should be data in your repository. And we can clone our repository back again to check that everything is working.
git clone ssh://USERNAME@PROJECTNAME.git.sourceforge.net/gitroot/PROJECTNAME/PROJECTNAME
You may also want to ignore certain types of files, place a file called .gitignore in the root directory of your project and fill it with the patterns you want ignored:
.gitignore
.DS_Store .svn ._* ~$* .*.swp Thumbs.db
Now when we want to update we can do:
git commit -a -m "This is my commit message." # All changes to the local repository need to be committed before we try merging new changes git pull # Grab any changes from the main repository
Committing is slightly different:
git add .gitignore # For example we might want to add our new .gitignore file git commit -a -m "This is my commit message." # Note: Your commit has now only been staged, it is not in the main repository yet git push # Now it is pushed into the main repository
That last step is to remove your svn repository which for SourceForge is as simple as unchecking a checkbox on the Admin->Features page.
Symbols/Characters Returned by ls -l
$ ls -l total 24 drwxrwxr-x ... thisisadirectory -rw-rw-r-- ... thisisafile lrwxrwxrwx. ... thisisalink -> /media/data
We know what the rwx fields are but what about d, – and l? Ok, those are pretty obvious too, here is a list of the more obscure ones because I always forget.
d Directory.
l Symbolic link.
- Regular file.
b Block buffered device special file.
c Character unbuffered device special file.
s Socket link.
p FIFO pipe.
. indicates a file with an SELinux security context, but no other alternate access method.
s setuid – This is only found in the execute field.
If there is a “-” in a particular location, there is no permission. This may be found in any field whether read, write, or execute field.
The file permissions bits include an execute permission bit for file owner, group and other. When the execute bit for the owner is set to “s” the set user ID bit is set.
This causes any persons or processes that run the file to have access to system resources as though they are the owner of the file. When the execute bit for the group is set to “s”,
the set group ID bit is set and the user running the program is given access based on access permission for the group the file belongs to.
libxdgmm
I think the Portland Project from freedesktop.org, is a great idea and
everyone should be supporting it in their applications.
I’ve just created a very small C++ wrapper (libxdgmm) for accessing XDG more easily. To use it, you need libxdgmm.h and libxdgmm.cpp. Just add these to your project and then use them like so:
#include <libxdgmm/libxdg.h> int main(int argc, char** argv) { if (!xdg::IsInstalled()) std::cout<<"XDG is not installed"<<std::endl; else { std::string data; xdg::GetDataHome(data); std::cout<<"data=\""<<data<<"\""<<std::endl; std::string config; xdg::GetConfigHome(config); std::cout<<"config=\""<<config<<"\""<<std::endl; // Obviously these have to exist to work. You can translate the error code returned by calling xdg::GetOpenErrorString(int result); xdg::OpenFile("/home/chris/dev/cMd3Loader.cpp"); xdg::OpenFolder("/home/chris/"); xdg::OpenURL("http://chris.iluo.net"); } return EXIT_SUCCESS; }
I still have to wrap some of the other functionality, such as XDG_DESKTOP_DIR, XDG_DOCUMENTS_DIR, XDG_MUSIC_DIR, desktop-file-utils, xdg-desktop-menu and xdg-desktop-icon etc. I will wrap these as I need them (Or at special request). I don’t think I will be supporting xdg-screensaver or xdg-mime as I don’t have a use for them right now.
C++0x compiling with gcc
Gcc has some early support for C++0x. You can enable it with -std=c++0x (Note: You can already use Boost without enabling this flag). Enabling this flag broke boost::filesystem for me, but this has already been reported and fixed:
boost/filesystem/operations.hpp
661 661 inline bool is_empty( const path & ph ) 662 - { return is_empty<path>( ph ); } 662 + { return boost::filesystem::is_empty<path>( ph ); } 663 663 inline bool is_empty( const wpath & ph ) 664 - { return is_empty<wpath>( ph ); } 664 + { return boost::filesystem::is_empty<wpath>( ph ); }
The full patch is much longer, but this seemed to be all I needed to get it to work (Note: You will need to su and then gedit /usr/include/boost/filesystem/operations.hpp).
Anyway, you will want to test it out:
enum A { A_1, A_2 }; enum B { B_1, B_2 }; void Test() { B b = 0; b = true; b = 1; b = A_1; b = A::A_1; b = B_1; b = B::B_1; }
The only lines of Test that compile are “b = B_1;” and “b = B::B_1;”. Under C++98/C++03 this would 100% compile, which could easily create bugs where the code compiles but may not be what is intended. We can also get slightly tighter restrictions again, by defining “enum B” as “enum class B”. This restricts the correct lines of Test to “b = B::B_1″, meaning the enum must be fully qualified which should lead to less ambiguous code. In a real situation you will also want to actually initialise b to a decent value initially as well: “B b = B::B_1″ for example.
Anyway, this is a pretty trivial example, just a tidy up of the language really, you will want to delve deeper. Variadic templates, Initializer lists, Lambda expressions and closures, New character types, Unicode string literals, Raw string literals and Universal character name literals look good. Extern templates, Inheriting constructors, nullptr, __func__, C99 preprocessor, long long, Extended integral types can’t get here soon enough.
Posted in c++0x
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AHGotoPage Doesn’t Work Argh!
It looks like AHGotoPage is broken with Mac OS X 10.5.7 and later (It was also broken on 10.3.9 and earlier). Probably the easiest way around this for the moment is to open your help documentation in a web browser using LSOpenCFURLRef instead. Hope this helps someone.
Upgraded Linux Kernel not recognising ext3 partitions and the solution
Unable to access resume device (/dev/dm-1) mount: error mounting /dev/root on /sysroot as ext3: No such file or directory
Being a Linux noob, I found this solution
Create mkinitrd.new
chmod +x mkinitrd.new su cd /boot sudo ./mkinitrd.new -f initrd-2.6.27.24-170.2.68.fc10.x86_64.img 2.6.27.24-170.2.68.fc10.x86_64
“Error: glXCreateContext failed” After Updating Video Drivers
After updating video drivers I couldn’t run 3d applications, for example glxinfo:
Error: glXCreateContext failed
The following needs to be present in the xorg.conf file:
Section "Files"
ModulePath "/usr/lib64/xorg/modules/extensions/nvidia"
ModulePath "/usr/lib64/xorg/modules"
EndSection
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Yearly Update :)
Skysytem background, testing wireframe grid, TombRaider MD3 model, testing material boxes, particle systems, frames per second messages, pegs, shocks, all the necessary elements of a Sudoku game.
It’s been a while, I have like 20 draft entries in WordPress ranging from 1 paragraph comments up to 10 paragraph full on entries that still need that final once over and edit before going live. Actually it might be cool if there was (There probably is) a plugin so that people could optionally go to a page on my blog where they can see everything that hasn’t been published yet, like tagged with “draft” or something and comment on which ones I should flesh out and which ones I should ditch before they are even finished.
Anyway, so I have been working (Getting side tracked while working on) my Sudoku game.
Basically in Sudoku mode you get to select a number from the “palette” at the top and then click on all the places you want it on the board. The solver I have coded up can solve about 80% of Sudoku boards with “human solvable” methods and the remaining 20% can be solved with a combination of human solvable and then resorting to brute force for anything it can’t find. A valid board should not need brute forcing which means that I need to implement more rules for my human solving methods first. I should be doing something like this:
if (solve_human_methods()) ... solved
else ... this board is invalid as it could not possibly be solved by a human without resorting to brute force
However I haven’t implemented all human methods of solving yet, only about 4 or 5 simple ones, actually probably less, there are about 2 or 3 real rules and then 4 or 5 extrapolated rules that are just combinations of the first ones.
Anyway, in First Person mode there is flying around (No clip mode) as well as moving Lara Croft around (Optionally other MD3 models) with sort of appropriate animations based on velocity (But not facing direction yet). One thing I have noticed is that half of the MD3 models I download have different file naming conventions, so at some stage I want to break out some Quake 3 action and see what file names it uses and use that as my standard.
Why all this other stuff in a Sudoku game? Whichever game I am working at the time becomes my test bed application for whatever I feel like implementing when bored. I really need to make a dedicated test bed that does nothing else but demonstrate stuff. I’ve also split my game engine into Spitfire and Breathe portions, which splits the library into two halves, the generic tools for any application (string, math, xml, md5 hashes etc.) and game specific features (OpenGL rendering, audio, physics, MD3 animation, etc.) respectively.
Posted in c++, gamedev, linux
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x86_64 Linux C/C++ Test
I use:
gcc
cmake
KDevelop
RapidSVN
Meld
However, don’t go the websites, all of these are available in the (Default?) repositories, so you can either install them via yum, PackageKit or apt-get. Also note: RapidSVN and Meld are only needed if you want to use SVN. Even KDevelop is not required if you have another text editor that you prefer such as gedit/vi/emacs. If you want to create your provide your own make file then you don’t need cmake either.
Anyway, so a simple application that just tests that you can do a 64 bit compile is pretty straight forward.
1) Create your main.cpp file with a int main(int argc, char* argv[]); in it.
# Set the minimum cmake version cmake_minimum_required (VERSION 2.6) # Set the project name project (size_test) # Add executable called "size_test" that is built from the source file # "main.cpp". The extensions are automatically found. add_executable (size_test main.cpp)
2) Create a CMakeLists.txt that includes your main.cpp.
#include <iostream> int main(int argc, char* argv[]) { int *int_ptr; void *void_ptr; int (*funct_ptr)(void); std::cout<<"sizeof(char): "<<sizeof(char)<<" bytes"<<std::endl; std::cout<<"sizeof(short): "<<sizeof(short)<<" bytes"<<std::endl; std::cout<<"sizeof(int): "<<sizeof(int)<<" bytes"<<std::endl; std::cout<<"sizeof(long): "<<sizeof(long)<<" bytes"<<std::endl; std::cout<<"sizeof(long long): "<<sizeof(long long)<<" bytes"<<std::endl; std::cout<<"------------------------------"<<std::endl; std::cout<<"sizeof(float): "<<sizeof(float)<<" bytes"<<std::endl; std::cout<<"sizeof(double): "<<sizeof(double)<<" bytes"<<std::endl; std::cout<<"sizeof(long double): "<<sizeof(long double)<<" bytes"<<std::endl; std::cout<<"------------------------------"<<std::endl; std::cout<<"sizeof(*int): "<<sizeof(int_ptr)<<" bytes"<<std::endl; std::cout<<"sizeof(*void): "<<sizeof(void_ptr)<<" bytes"<<std::endl; std::cout<<"sizeof(*function): "<<sizeof(funct_ptr)<<" bytes"<<std::endl; std::cout<<"------------------------------"<<std::endl; std::cout<<"Architecture: "<<sizeof(void_ptr)<<" bit"<<std::endl; return 0; }
3) cd to the directory of your CMakeLists.txt and run “cmake .” and then “make”
4) ./size_test output:
sizeof(char): 1 bytes sizeof(short): 2 bytes sizeof(int): 4 bytes sizeof(long): 8 bytes sizeof(long long): 8 bytes ------------------------------ sizeof(float): 4 bytes sizeof(double): 8 bytes sizeof(long double): 16 bytes ------------------------------ sizeof(*int): 8 bytes sizeof(*void): 8 bytes sizeof(*function): 8 bytes ------------------------------ Architecture: 64 bit
As you can see this is specific to x86_64. The beauty of gcc is that by default it compiles to the architecture it is being run on. I had previously thought that it would be a world of pain, making sure that my compiler built the right executable code and linked in the correct libaries. I know this project doesn’t use any special libraries, but (because of cmake?) the process is exactly the same as using cmake under 32 bit to make 32 bit executables. You just make sure that they are there using Find*.cmake and then add them to the link step:
SET(LIBRARIES ALUT OpenAL GLU SDL SDL_image SDL_net SDL_ttf ) # Some of the libraries have different names than their Find*.cmake name SET(LIBRARIES_LINKED alut openal GLU SDL SDL_image SDL_net SDL_ttf ) FOREACH(LIBRARY_FILE ${LIBRARIES}) Find_Package(${LIBRARY_FILE} REQUIRED) ENDFOREACH(LIBRARY_FILE) # Link our libraries into our executable TARGET_LINK_LIBRARIES(${PROJECT_NAME} ${LIBRARIES_LINKED})
Note that we don’t actually have to specify the architecture for each package or even the whole executable. This is taken care of by cmake. Anyway, it is not some mysterious black magic, it is exactly the same as you’ve always been doing. Cross compiling is slightly different, but basically you would just specify -m32 and make sure that you link against the 32 bit libraries instead. If I actually bother creating another 32 bit executable in my life I’ll make sure that I document right here exactly how to do a cross compile from 64 bit.
The advantages of 64 bit are mmm, not so great unless you deal with really big files/memory ie. more than 4 GB. Perhaps more practical are the extra and upgraded to 64 bit registers so you may see an increase in speed or parallelisation of 64 bit operations, for example a game may want to use 64 bit colours (ie. 4x 16 bit floats instead of 4x 8 bit ints to represent an rgba pixel.
Things to watch out for:
int is still 32 bit! If I were implementing the x86_64 version of C++ standard/gcc/in a perfect world this would have been changed to 64 bit, ie. “int” would be your native int size, it’s logical, it makes sense. However, I do understand that this would have broken a lot of code. The problem is, if int != architecture bits, then why have it at all, why not drop it from the standard and just have int32_t and int64_t and be done with it. Then if a program chooses it can have:
typedef int32_t int;
or
typedef int64_t int;
as it sees fit. Anyway.
Pointers are now 64 bit! So you can use them with size_t but cannot use them with int
Under linux x86_64 gcc sizeof(int*) == sizeof(function*), however, this is not guaranteed anywhere. It may change on a certain platform/compiler. Don’t do stuff like this:
int address = &originalvariable;
gcc should warn you (you may need to turn on these warnings -Wformat -Wconversion).
All in all, if you have been writing standard code and using make/cmake it should be relatively pain free to upgrade to 64 bit.
Linux x86_64
I have been dipping my toe into x86_64 waters sporadically over the last couple of years. On each of the previous occasions it always seemed too immature, packages were way to hard to come by (I prefer precompiled binaries), half my hardware didn’t work, strange crashes etc. Seeing as this episode has been 100% successful, I thought this time I would document it.
Fedora
My favourite distribution is Fedora due to it’s rapid development and ease of use. I downloaded via BitTorrent. (Obviously) make sure you get the x86_64 version. I always like to run the sha checksum to rule out that as the problem if something does arise later. I also make sure that my DVD verifies in my burning program after it has been burnt.
Now we are ready to install. Unless you have something really exotic you should not need any special drivers or anything (At least not until after the install), it should just work. The important parts of my hardware are:
Asus A8V-E SE (Not awesome, my awesome motherboard blew up causing me to downgrade to this one I had lying around) AMD Socket 939
AMD Athlon 64 X2 4800+ CPU
nVidia GeForce 8600 GT 256MB PCIe
I use the onboard LAN and sound card, as well as 2 SATA drives, an IDE drive and an IDE CDROM.
So I installed Fedora from the DVD. You can again choose to verify the media, weirdly (And in previous versions as well) this check always seems to fail even though the sha check and burning software verification succeed, so either the check is broken or the motherboard/drive is broken. I have never seen this verification succeed in my life. Anyway, I skip it now and the options I select (At appropriate times) are fresh install onto a blank drive, “Software Development” profile/packages (You can probably turn off the other profiles, you can install any required packages individually later on when you are in the OS anyway). Next time I do an install I would love to try an upgrade install.
That should all install (You don’t have to get too serious about selecting the right packages right now, I find it easier to install “generally” what I need (“Software Development”) and then customise later) and you should now be logging into a fresh install of Fedora 10.
Initially I had some problems with an additional PCI sound card I had present due out of habit because I had never gotten my on board sound to work for any motherboard under Linux. Some programs were using the onboard and some where then using the PCI one, so I rebooted and went into the bios to disable the onboard one. Both still get detected. Apparently this is a common problem with this motherboard. I went to update the bios and wouldn’t you believe it, the bios updater is Windows only. Anyway, because the onboard sound card was being detected I just removed the PCI one and enabled the onboard one again. That fixed it up awesomely and I had audio, yay. Also removing PulseAudio can “unconfuse” applications and force them to use ALSA,
yum remove alsa-plugins-pulseaudio
I then noticed that I had some issues with audio playback stuttering, cycling through normal speed and then fast for a second and then normal again. I fixed it by following this tutorial.
Add the Livna repo by downloading and running the add repo rpm, it is not linked to on the main page, but the url can be built from the other releases. Add the RPMFusion repo by downloading and running both the free and non-free add repo rpm.
For my information:
RPMFusion provides additional packages that are not in the base Fedora repos.
Livna provides the same packages as RPMFusion, but also provides the libdvdcss package for watching DVDs.
I have never had much luck with ATI drivers for Linux. I had heard the nVidia ones were easier to install and configure and apparently faster to boot. Before you install drivers, you might want to get a benchmark of your FPS in glxgears before installation:
glxgears
I downloaded and installed the nVidia (Binary, proprietary) driver:
sudo yum install kmod-nvidia
Now reboot (It’s the easiest way to restart X). Test that hardware accelerate rendering is happening by looking for in the output of this command:
glxinfo | grep direct
And your glxgears FPS should be above 2000:
glxgears
Adobe recently released an x86_64 Linux version of Flash so we don’t have to mess around with nswrapper etc. any more. I downloaded it from here, extracted, su, cp ./libflashplayer.so /usr/lib64/mozilla/plugins, restarted Firefox. You may want to test it also.
Nexuiz
For my benefit for next time, I also like:
Neverball and Neverputt
VDrift
Torcs
Nexuiz
Open Arena
Urban Terror
XMoto
Transmission
Thunderbird
Rhythmbox
VLC
K3B
Wine
CMake
KDevelop
I have not provided any links to these as they are all present in PackageKit which comes with Fedora 10.
Also for my information:
Firefox Add Ons
Adblock Plus
Flashblock
NoScript
PDF Download
FireBug
Nightly Tools
Net Usage Item
Open links in Firefox in the background
Type about:config into the address bar in Firefox, then look for the line browser.tabs.loadDivertedInBackground and set it to true.
Automatic Login
su gedit /etc/gdm/custom.conf
And adding this text:
[daemon]
# http://live.gnome.org/GDM/2.22/Configuration
TimedLoginEnable=true
TimedLogin=yourusername
TimedLoginDelay=30
NTFS Drives
Gnome automatically finds and mounts NTFS drives/partitions, however in Fedora 9 and later, ownership is now broken. Each partition (And every sub folder and file) seems to default to ownership so even though some operations work such as moving files around, even adding and deleting, some programs will complain (I found this problem through RapidSVN not working). Nautilus reports that you are not the owner and even if you run Nautilus as root you cannot change to owner to anything other than root. The way I solved this was to install ntfs-config and run with:
sudo ntfs-config
You should now have valid entries in /etc/fstab:
sudo cp /etc/fstab /etc/fstab.bak
gksudo gedit /etc/fstab
Something like this (One for each partition, the ones you are interested in are any with ntfs-3g):
UUID=A2D4DF1DD4DEF291 /media/DUMP ntfs-3g defaults,nosuid,nodev,locale=en_AU.UTF-8 0 0
I then edited each ntfs-3g line like so:
UUID=A2D4DF1DD4DEF291 /media/DUMP ntfs-3g defaults,rw,user,uid=500,gid=500,umask=0022,nosuid,nodev,locale=en_AU.UTF-8 0 0
Where uid=youruserid and gid=yourgroupid. You can find these out via System->Administration->Users and Groups (There is probably a command to find this out, actually I would say there is definitely a command for finding this out, but I’m pretty lazy). If you log in with different users perhaps changing to a common group would be better? Reboot to let these settings take effect. If you now to view your partition in Nautilus, File->Properties->Permissions should now list you as the owner with your group.
You now have a pretty well set up Fedora 10 installation. These steps should be pretty similar for future versions. I will probably refer back these when I install Fedora 11 or 12 in a year or two. I love Fedora because it is the total opposite of Windows. With Vista, Microsoft stagnated, waiting a year or two longer than they should have to release a product that by that time was out of touch with the target audience. In contrast, I had been planning to install Fedora 9 this time around after installing 8 only 6-12 months ago, but I was pleasantly surprised to find that 10 had been released. I would also like to try Ubuntu as I haven’t really used it much apart from at work, so I might give that a shot next time. x86_64 has certainly matured over the last 2 or 3 years, I would say it is definitely production server ready and probably has been for at least a year. The quality and variety of packages available for Linux is amazing, the community just keeps on giving. Fedora just keeps on amazing me. The future is bright, I can’t wait.
Covers!
Last night we went to The Pheonix (Where I met Christina almost 3 years ago!) and they had The Ellis Collective playing with two other bands. The girl on the violin was the highlight, reminding Sam and I of Fourplay. It would have been good if there were more violin solos, also the songs on their site just don’t do the violin justice.
I heart covers. No wait, I heart covers more than everyone in the world put together. YouTube is awesome for finding covers, it can be quite patchy, but basically everyone votes down the worst ones so you only view the gold.
Johnny from Australia.
Kina Grannis
Johnny sings Exit Music (from a Film) by Radiohead (And he does drums as well, awesome (Well not at the same time, but still awesome)).
Kina sings 1234 by Fiest
Johnny sings Waltz #2 by Elliot Smith
Kina sings New Soul by Yael Naïm
Johnny sings Mad World by Gary Jules
Johnny sings Karma Police by Radiohead
Kina sings Hallelujah by Leonard Cohen
Johnny sings Hallelujah by Leonard Cohen
No one is as awesome as Hallelujah Jesus himself though.
I also heart mashups.
Jack Conte specialises in both covering and mashing up songs, some of them are downloadable at.
Jack Conte – Radiohead/Chopin mashup/cover
Jack Conte – Gorillaz – Feel Good Inc. cover watch this if only for the ending hilarious.
Jack Conte – Aphex Twin/Bright Eyes mashup/cover
This wouldn’t be a blog entry by Chris if it didn’t include:
Johnny sings *cough* Britney *cough*
Yael Naïm New Soul and Toxic
const int vs. enum vs. #define
Example A:
int GetValue0() { return 10; } int GetValue1() { return 10 + 10; } int GetValue2() { return 10 * 10; }
So if all of the values 10 represent a common magic number then you are going to want to extract that value to one location instead of the 5 that it is in at the moment. How do we do this?
Say we call the value MAGIC_NUMBER (Of course, in a real life situation you would use a better name than this, wouldn’t you? Something like PI, GST_PERCENTAGE, NUMBER_OF_CLIENTS, etc.) we would then have this code.
Example B:
int GetValue0() { return MAGIC_NUMBER; } int GetValue1() { return MAGIC_NUMBER + MAGIC_NUMBER; } int GetValue2() { return MAGIC_NUMBER * MAGIC_NUMBER; }
Great. The problem now is, how do we tell our program about MAGIC_NUMBER?
If you originally started programming C then your first instinct may be to use:
#define MAGIC_NUMBER 10The main problem here is that the compiler may not realise that all of the places you use MAGIC_NUMBER are linked so it may not realise that it can factor it out. The other problem with this method is the lack of type safety. You can use MAGIC_NUMBER with sign/unsigned ints, char, bool etc. The compiler may not warn you about converting between these types. For an int this isn’t really a problem, but const float PI = 3.14…f should give you a warning when you try to initialise an int to it. This is good news as it requires you to cast if you really want to do it, which then shows other programmers than you have actually thought about what you are doing and what is happening to the value as it passes through each variable.
You might be tempted to use:
int MAGIC_NUMBER = 10;
This is much better as it adds type safety, however you can do even better than that,
const int MAGIC_NUMBER = 10;
This way it isn’t “just” a global variable, when you declare it as const you are telling the compiler that it will never change in value which means that it can make all sorts of assumptions about how it will be used. Your compiler may or may not factor out/in this value, it may or may not insert 10 + 10 and 10 * 10 into those functions for you at compile time. Using a const int means that the compiler gets the choice of using either the value directly or using a variable containing that value, and I trust the compiler more than myself to make that decision. Because it knows the value of MAGIC_NUMBER at compile time and knows that it will never change at runtime it can actually do the calculation and insert that value instead.
int GetValue0() { return 10; } int GetValue1() { return 20; } int GetValue2() { return 100; }
The other magic number container is enum. It varies slightly to const int as it is more for collections of values where you want to identify something by what type it is.
enum RESULT { RESULT_FILE_DOWNLOADED, RESULT_CONNECTION_FAILED, RESULT_FILE_NOT_FOUND, RESULT_DISCONNECTED }; RESULT DownloadFile(const std::string& url) { // Pseudocode if (could not connect) return RESULT_CONNECTION_FAILED; if (file not found) return RESULT_FILE_NOT_FOUND; if (disconnected) return RESULT_DICONNECTED; return RESULT_FILE_DOWNLOADED; }
In this way we can get rid of magic numbers and (In C++0x at least with enum class) get some type safety, your compiler will hopefully complain if you try and return an integer instead of a RESULT.
Posted in c++
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Crank very early testing of heightmap and basic physics
This is what I have been working on in my spare time. I think it is going alright. I still have to do:
The brakes can’t be locked up at the moment, they always give a little so you can’t for example lean on the front wheel and hold the brakes and expect to stay in the same place.
Create the level editor, at the moment the level is just a bunch of sin waves added together.
Add a little bit of parallax scrolling to add a bit of interest and depth.
Create better artwork for example shocks and rider.
Add dynamic bike bits such as suspension that compresses and a rider that leans forwards and backwards and has a weight (At the moment I fake weight transfer by just rotating the bike).
Posted in crank, gamedev
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