Category: Informatique

As a little post-it, here’s a script to amend author’s name and email of all commits of a repository. Use with care, it will override all commits, no matter what the original author is.

Credit: https://stackoverflow.com/a/750191/913135

#!/bin/sh

if [ "$#" -ne 2 ]; then
	echo "usage: amend 'name' 'email'"
	exit 1
fi

git filter-branch -f --env-filter "
	GIT_AUTHOR_NAME='$1'
	GIT_AUTHOR_EMAIL='$2'
	GIT_COMMITTER_NAME='$1'
	GIT_COMMITTER_EMAIL='$2'
" HEAD

Visual Studio Code is an open source and multiplatform IDE for code editing (and compiling, debugging, etc.) available here : https://code.visualstudio.com/

I wanted to see if I could build, run and debug Blender using this IDE, and the anwser is : yes. Here is how to do it.

Get Blender’s sources and dependencies

Based on : https://wiki.blender.org/index.php/Dev:Doc/Building_Blender/Linux/Generic_Distro/CMake. Here are the commands I used :

mkdir blender-git
cd blender-git
git clone --recursive https://git.blender.org/blender.git

This will get the main Blender sources. It’s quite fast, but depending on your internet connection speed, it can take a few minutes.

The next part is a lot longer : it will retrieve everything needed to build the third party libraries, and then build them. Depending on your computer it can be very long, so be patient. And check regularly, because it might ask for your password more than once !

cd ..
mkdir -p deps/src
mkdir -p deps/install
./blender/build_files/build_environment/install_deps.sh --with-all --source <path_to_blender-git>/deps/src --install <path_to_blender-git>/deps/install

<path_to_blender-git> must be an absolute path to your blender-git folder. Note that you must also create the deps/src and deps/install folders prior to calling install_deps.sh, or else you might have some errors telling you that you don’t have the rights to create folders.

Install Visual Studio Code

Once you’ve installed Visual Studio Code, install the following addons :

• C/C++ (Microsoft) – C/C++ support. Required
• CMake (twxs) – CMake syntax coloring, code completion, etc. Optional but useful if you have to modify a CMake script file
• CMake Tools (vector-of-bool) – Add Configure/Build features based on CMake. Required

Note that CMake Tools plugin requires CMake version 3.7.1 or greater, with server mode enabled (if you installed a recent prebuilt version from the CMake website, it should be enabled by default. But if you build your own, make sure it’s enabled)

Configure Blender’s project

Now, open Visual Studio Code, and open the blender-git/blender folder. If CMake Tools worked correctly, the status bar should look like this:

Before going further, we will setup the project to configure CMake to use the dependencies. Open the Preferences, then select “Workspace Settings” to only modify the Blender’s project settings. In this settings file, add the following options (there are comments in case you’re wondering what they do) :

// Place your settings in this file to overwrite default and user settings.
{
    //
    // This is where the build system will create intermediate files
    // I like to keep this out of my source folder to avoid
    // unintentionally commiting them :)
    //
    "cmake.buildDirectory": "${workspaceRoot}/../build", 

    //
    // This will setup the install path path. This option is needed
    // because Blender needs to deploy all its scripts files, and
    // this is not done during building, but during install.
    // So we need to setup this, and run CMake: Install once
    // before being able to debug. Note that this little complexity
    // is due to the way Blender is built/deployed
    //
    "cmake.installPrefix": "${workspaceRoot}/../build/bin",

    //
    // Options sent to CMake when it's configured. Those are the
    // options found in BUILD_NOTES.txt, converted to JSON format.
    // I didn't put all of them here, so copy from your own file.
    //
    "cmake.configureSettings": {
        "WITH_CODEC_SNDFILE": "ON",
        "PYTHON_VERSION": "3.5",
        "PYTHON_ROOT_DIR": "<blender-git>/deps/install/python-3.5",
        "WITH_OPENCOLORIO": "ON",
        "OPENCOLORIO_ROOT_DIR": "<blender-git>/deps/install/ocio"
.
        //
        // The rest of the options.
        // Don't forget to copy them !!
        //
    }
}

"OPENCOLLADA_ROOT_DIR": "<blender-git>/deps/install/opencollada",

{
    "version": "0.2.0",
    "configurations": [
        {
            //
            // the name of this configuration. Choose what you want
            //
            "name": "Debug",
            "type": "cppdbg",
            "request": "launch",
            //
            // Point to Blender's executable.
            //
            "program": "${workspaceRoot}/../build/bin/blender",
            "args": [],
            "stopAtEntry": false,
            //
            // Execute in the same folder as Blender's executable.
            //
            "cwd": "${workspaceRoot}/../build/bin",
            "environment": [],
            "externalConsole": true,
            "MIMode": "gdb",
            "setupCommands": [
             {
             "description": "Enable pretty-printing for gdb",
             "text": "-enable-pretty-printing",
             "ignoreFailures": true
             }
            ]
        }
    ]
}

A small post-it on how to change the default location of intellisense databases for Visual Studio. By default, those huge .sdf files (which get updated again and again) are stored next to your project location.

If you’re working on an SSD, or on a slow USB drive, you might want to avoid storing those databases at their usual location (or just to avoid having huge files around, or whatever other reason)

To do that, just go to Tools > Options then on the Text Editor > C/C++ > Advanced tab, locate the section Fallback Location. Here, Always use Fallback Location will need to be set to true to tell Visual Studio to always use the Fallback Location (which you can then set to any folder you want, or leave empty if you want to use the windows temp folder)

You can now close Visual Studio, remove your sdf files, launch it again. It will prompt you about your fallback location, but you just have to click OK and don’t forget to check the Don’t Prompt Me Again checkbox to avoid this at every launch. Tadaaa, no more sdf files next to your projects !

[Source]

In my previous post on how to build Qt on Windows, I explained how to build Qt for Windows, using Visual Studio 2010 and prebuilt ICU libraries. If we want to build Qt with Visual Studio 2013, we’ll need to build ICU ourself, and here’s how :

• Download ICU sources from here : http://site.icu-project.org/download
• Unzip in C:\ (you will have a C:\icu folder with C:\icu\readme.html (among others))
• Go into C:\icu\source\common\unicode, edit platform.h and add the following somewhere at the beginning. It’s needed if you want to build Qt :

#define U_CHARSET_IS_UTF8 1

• Go into C:\icu and create a build.bat file, with the following content and run it :

@echo off

::
:: setup Visual Studio 2013 environment for x64 builds
::
call "C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\vcvarsall.bat" x86_amd64

::
:: build
::
msbuild source\allinone\allinone.sln /m /target:Build /property:Configuration=Release;Platform=x64
msbuild source\allinone\allinone.sln /m /target:Build /property:Configuration=Debug;Platform=x64

This will build ICU in x64. You can run the same script again and remove the “x86_amd64” argument to the vcvarsall.bat script, and change the Platform property to Win32 to build ICU in x86.

Imagine the following peace of code (which is really simple for the sake of the example :)

for (entity in entities)
{
    glPushMatrix();

    // do some stuff

    glPopMatrix();
}

The basic idea here is that you need to maintain the integrity of a states’ stack in a loop. But what happens if you have some tests that allow to break, continue or return :

for (entity in entities)
{
    glPushMatrix();

    // do some stuff

    if (entity->NeedToDoOtherStuff() == false)
    {
        continue;
    }

    // do some other stuff

    glPopMatrix();
}

Wrong. You didn’t pop the matrix, everything gets corrupted. You need to add a glPopMatrix() right before continue. And the more of those special cases, the more glPopMatrix you need to add. And if you have more states to push / pop, you need to duplicate those too.

This scenario happens a lot in real applications. If you allocate some temporary data to work with, you need to cleanup before exiting the function, and if you have many exit points (error checks, etc.) you end up duplicating cleanup code everywhere, which is error prone and fastidious. You can also use goto’s :)

Here is a little templated class which solves this problem using 2 features of C++11 : lambdas and functional.

class Cleanup
{
public:
    template< typename T >
    Cleanup(const T & code)
        : m_Code(code)
    {
    }
    ~Cleanup(void)
    {
        m_Code();
    }
private:
    std::function< void (void) > m_Code;
};

This class can be used like this :

for (entity in entities)
{
    glPushMatrix();
    Cleanup popMatrix([]() { glPopMatrix(); });

    // do your stuff
    // make some tests, continue or break depending on the reults
    // do other stuff
}

As soon as the Cleanup instance goes out of scope (which happens after an iteration is done, or when we break or continue) it will execute the code that you gave it. I find this particularly useful :

• no longer crashes when you add an exit point, special case, etc. and forget to copy / paste the cleanup code.
• the cleanup code is defined right at the top of the scope, which in my experience makes it really hard to forget updating it, if you need to add more states, more intermediate data that need cleanup, etc.

If you’re using Visual Studio 2012 or 2013 Express with Qt, you can’t use the Qt Addin, but you might still want to have user friendly Qt types showing in your debugger. Luckily this is quite easily achieved :

1. Download the qt5.natvis file from the Qt Git repository.
2. Make sure you have the following folder : <MyDocuments>\Visual Studio 2013\Visualizers and if not, create it.
3. Copy the qt5.natvis file in it, and restart Visual Studio.
4. Done.

Following is a small script that I use to build a few static Boost libraries in 64 bits for Visual Studio 2012, and with iterator debugging turned off.

:: build the bjam and b2 exe
if not exist "b2.exe" (
    bootstrap.bat
)

:: build boost with visual 2012 toolset.
::   - static lib
::   - multithreaded shared runtime
::
:: it only builds signals and filesystem
b2.exe -a -d0 -j4 toolset=msvc-11.0 address-model=64 variant=debug link=static threading=multi runtime-link=shared define=_HAS_ITERATOR_DEBUGGING=0 --with-signals --with-filesystem
b2.exe -a -d0 -j4 toolset=msvc-11.0 address-model=64 variant=release link=static threading=multi runtime-link=shared define=_HAS_ITERATOR_DEBUGGING=0 --with-signals --with-filesystem

A little note on the build system integrated in Sublime. If you have multiple commands to execute during a build (for instance minifying your js code, and generating the documentation) your can do it quite easily on Windows, but it took me a while to find the equivalent on Mac, so here is the relevent (simplified version) part of my build system:

"windows": {
    "shell": true,
    "cmd": [
        "python", "build.py", "compress", "&;"
        "python", "build.py", "doc"
    ]
},
"osx": {
    "shell": false,
    "cmd": [
        "sh", "-c", "python build.py compress && python build.py doc"
    ]
}

Notice the difference between Windows and OSX. On Windows, you simply add an additional “&;” parameter which will separate the commands, but on OSX (I guess it would be the same on Linux) it doesn’t work. The only way I found to execute multiple commands was to directly call sh with the -c option and put all my commands in a single string. The commands are then separated by a && sequence.

Oh and also shell must be true on Windows, but false on OSX, else nothing runs.