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2018年6月29日 (金) 06:05時点における最新版

Preliminaries

You have checked out the Blender repository and you have claimed write access to the repository. You find the basics in the Git for developers document.

I am using windows and i have created my repository at D:\blendergit\blender this is my "working directory". Of course you will have to use your own path.

+ Update your repository to the newest revision

To ensure you have the most recent version of the blender repository you will want to update your repository as follows:

cd D:\blendergit\blender
git checkout master
git pull --rebase
git submodule update --recursive --remote

First ensure that you are in your working directory (the initial cd command does just that).
The first git command ensures that you are now in the main development branch of Blender.
The 2nd git command fetches all changes from the blender repository and applies these changes to your repository.
And the last git command does the same for all submodules.


+ Create a branch for your specific issue

Lets assume you want to fix a specific Bug report, like for example the report T36395 collada skinning: vertex weights are not read from indices It probably makes sense to do this fix in a "local area" which is sort of parallel to the main development. So we will create a branch and name it according to the report ID:

cd D:\blendergit\blender
git checkout -b T36395

The git statement creates the branch and checks it out in one step. However you also can create a branch and check it out separately:

cd D:\blendergit\blender
git branch T36395
git checkout T36395

Both approaches will create the exact same result: You have a new branch and you can go ahead with your work without "disturbing" the main branch.

Hint for svn users: "checkout" does not fetch anything from the blender repository! Remind that you have a full copy of the blender repository on your computer. So the checkout fetches all data from your local disk. furthermore a checkout does only ensure that all files in your "working directory"


+ Creating snapshots (commit)

Once in a while you may want to conserve (commit) your work results, even if your patch is not yet ready for pushing it to the blender main branch. This will allow you to revert back to a previous state of your work. For example when you messed up something then you can revert to the last snapshot easily and restart from there. You conserve your work as follows:

Lets say you have changed the file D:\blendergit\blender\source\blender\collada\collada.cpp Then you will go ahead as follows:

cd D:\blendergit\blender\source\blender\collada
git add collada.cpp
git status
git commit -m "Fixed a call to bmesh API"

The first git command tells git that collada.cpp should be added to the next commit.
The second git command tells you what files you may have added previously and before you committed the last time.
The 3rd git command Creates the snapshot.

Now you have saved a local snapshot of the added files. And whenever you have to revert your work, you just can go back to this snapshot (see below how this can be done)

Note how this is different from svn add! In git this command does only prepare a file for committing it. Also the commit is performed only in your local repository. Blender's repository is not yet affected in any way by now.

Tips for working with commit

Since commit is a local task you actually can commit as often as you like without affecting blender's repository. However when you finally push your work back into the repository, then all your tiny commits will be sent along... unless you take some precautions.

fix a fix (Adding to the last commit)

Assume you detected that your last commit contains an error and the fix would be a small change only. Now you may want to "fix the commit" instead of adding another commit. Git allows you to amend a commit as follows:

git add collada.cpp
git commit -amend -m "Fixed my previous fix"

Thus you can achieve that you get only one commit containing your fix.

Squash a commit chain

assume you have worked on a medium sized fix or feature. Maybe you have done several commits in a line but it makes not much sense (for whichever reason) to preserve the entire commit history of your branch. Git allows you to squash all your commits together into one single "summary commit":

git checkout master
git merge --squash T36395
git commit -m 'T36395: Fixed reading vertex weights.'


+ See the commit history of your work

You may want to scroll back in time and see some of your previous commits. actually you can jump around to any of your committed versions. But you will need to know the commit revision number to tell git where to step. For this purpose there is git log:

git log

By default you will get a verbose log which displays the log messages of all commits. Each commit is reported with its commit revision number (the commit hash) in the first row. Followed by Author, Date, and the commit comment:

commit 50fbebe0a443d10b3b5525c9a7e152acc32b4527
Author: Sergey Sharybin <sergey.vfx@gmail.com>
Date:   Tue Nov 19 22:01:43 2013 +0600

    Buildinfo fixes

    - Use -M suffix if working tree does have uncommitted
      modifications.
    - Local commits are considered local changes as well
tricks & Tips

git log has a wast amount of options which allow you to format the log output and restrict the output to certain commit versions. here are 2 tricks:

You can tell git to only print one line per commit:

git log --oneline

Note that the commit hash is now truncated and displayed in the first column of your list. However this truncated hash is sufficient to address the related commit (see next chapter)

1ea47c9 Code Cleanup: style, spelling and pep8 edits
780459e Extra unwanted change from the previous commit
50fbebe0 Buildinfo fixes
5743a6e Code Cleanup: move trans-verts out of snap code...
035d864 Fix: tab completing a filepath name in file brow...
0c0bed3 Fix: Game Engine regression drawing text from re...
2d8d3f3 Buildbot: update configuration file
000312a Remove Surface modifier when removing force fiel...
c566e40 Cleanup: Renamed compositor executePixel functio...
3c662ef Buildbot: fix path got pack step

And you can tell git to only report the last n commits (10 in the example below):

git log --oneline -n 10


+ Updating your branch from the main repository

While you work on your issue, other developers may have pushed their recent work to the main branch. You may occasionally (or frequently) want to add these changes to your branch as well. You want to do this to keep your working environment up to date with current development. here is what you will have to do:

git checkout master; 
git pull;
git rebase master T36395;

The first term will bring you back to the blender master branch.
The second term gets the most recent changes from the Blender master repository.
The third term moves all changes on master to your own branch and also beams you back into your branch.

By now your branch has all recent changes applied and you can go ahead with your work.


+ Reverting to a previous status of your work

Actually you can step to any commit that was ever made in the repository. All you need to know is the commit hash value which you can get from gitlog (see above). Once you have the correct has, you can simply check it out:

git checkout 50fbebe0;

Now your directory contains the status of Blender when the requested commit was ...well ...committed


to be completed...

moving your work into the main branch

Pushing your work to the Blender repository

when something goes wrong (resolving conflicts)

+ arc patch: Get a Differential for review

git checkout master
git pull --rebase
arc patch Dxxx;

The arc command will create a new branch arcpatch-Dxxx and apply the Dxxx to that branch and checkout the branch.


+ arc land: Accept a patch ...

After you have tested a branch that was created with arc patch, you can accept the patch and push it to the master branch in one step:

arc land

However, sometimes arc land may fail with a message like this:

Landing current branch 'arcpatch-Dxxx'.
Switched to branch master. Updating branch...
The following commit(s) will be landed:

a0a1f2e Fix for Txxxxx

Switched to branch arcpatch-Dxxx. Identifying and merging...
Usage Exception: arc can not identify which revision exists 
on branch 'arcpatch-Dxxx'. Update the revision with recent 
changes to synchronize the branch name and hashes, 
or use 'arc amend' to amend the commit message at HEAD, 
or use '--revision <id>' to select a revision explicitly.

Here is a workaround for this situation:

git branch master
git pull --rebase
git branch arcpatch-Dxxx
arc land --hold --revision Dxxx
git push

actually you only need the last 2 commands. The first 3 commands are just to be sure you commit on the most recent version of master