Create branches and resolve merge conflicts

In collaborative game development, your project will grow and evolve over time, one commit at a time. It’s important to keep your changes organized and separated from the main project. This is done by creating branches. A branch is a collection of commits that represents a parallel or alternate timeline of your project's development. A feature branch, for example, allows you to develop a new feature without affecting the stable main branch.

However, when multiple team members work on different branches and modify the same parts of a file, merge conflicts can occur. A merge conflict happens when Git cannot automatically combine changes from two branches because it doesn't know which version of the conflicting lines to keep.

In this tutorial, you'll do the following:

• Create a new feature branch to work on a specific part of the project.
• Make and commit changes on your isolated branch.
• Simulate a scenario where another team member makes conflicting changes on the main branch.
• Attempt to merge your feature branch into main, trigger a merge conflict, and learn how to resolve it using GitHub Desktop.

A feature branch isolates your changes, allowing you to work on new features or bug fixes without disrupting the main project. Clear branch names help your team understand what each branch is for. In this step, you'll create a new branch dedicated to developing boss fight functionality.

Instructions

1. Create a new branch

• In Github Desktop, go to Branch > New Branch... in the top menu, or open the Current branch dropdown and select New Branch.

2. Name your branch

• Name your branch “feature/bossfight-function”.

Note: Best practice for naming branches is to use lowercase and describe the branch purpose clearly. You can also use prefixes like feature/, bugfix/, or hotfix/ when needed.

3. Create the branch

• Select Create Branch.
• GitHub Desktop automatically switches you to the new branch.

Your feature branch for the boss fight system has been created, providing an isolated workspace for your new functionality.

Now that you’re on your feature branch, you'll make specific changes related to the boss fight functionality. This simulates you working independently on a new feature, making changes to GameObjects and scripts that will later be integrated into the main project. These changes will introduce the first part of a potential merge conflict.

Instructions

1. Open Unity and make changes to the Boss GameObject

• Open the Unity project. If prompted, select Reload to ensure you’re viewing the current state of your feature/bossfight-functions branch.
• In the Hierarchy window, select the BossCharacter GameObject.
• In the Inspector window, open the Tag property dropdown and select Boss.
• Drag the Yellow material from Assets > Materials folder onto the BossCharacter GameObject to apply it.
• Save the scene.

2. Test the changes

• Press the Play button to test the scene. Now that the BossCharacter GameObject has the tag that the script expects, shooting it with projectiles should damage and destroy it after four hits.

3. Commit your changes to the feature branch

• Open GitHub Desktop. The Changes tab will show your updated scene.
• In the Summary box, enter “ Update Boss tag to Boss and apply yellow material”.
• Select Commit to feature/bossfight-functions.

4. Push your changes to GitHub

• Select Publish branch to upload your changes to GitHub.com.

Your feature/bossfight-functions branch now contains unique committed changes related to the boss fight, which are isolated from the main branch.

To understand merge conflicts, you need to simulate a scenario where another team member has made different changes to the same part of the project on the main branch. This step represents a common situation where parallel development leads to conflicting edits.

Instructions

1. Switch to the main branch

• In GitHub Desktop, switch to the main branch by opening the Current Branch dropdown and selecting main.

2. Open Unity and make conflicting changes

• Open the Unity project. When prompted, select Reload to update to the main branch version.

Note: You'll observe that the BossCharacter material is red again. This is because you’re now working in the main branch, where your previous changes from the feature/bossfight-functions branch have not been applied.

• In the Hierarchy window, select the BossCharacter GameObject.
• In the Inspector window, open the Tag property dropdown and select Enemy.
• Drag the Orange material from the Assets > Materials folder onto the BossCharacter GameObject.
• Save the scene.

3. Commit the conflicting changes to the main branch

• Return to GitHub Desktop. The Changes tab will show your updated scene.
• In the Summary box, enter “Change Boss tag to Enemy and update material on main”.
• Select Commit to main.

4. Push the changes to GitHub

• Select Push origin to upload the updated main branch to GitHub.com.

The main branch now contains a committed change to the BossCharacter tag and material that directly conflicts with the changes you made on your feature/bossfight-functions branch.

Now that both your feature/bossfight-functions branch and the main branch have conflicting changes to the same GameObject, Git will detect this when you attempt to merge them. You'll now initiate the merge and resolve the conflict.

Instructions

1. Start the merge process

• In GitHub Desktop, ensure you’re on the main branch.
• Go to Branch > Merge into current branch.
• In the Merge a branch into the current branch dialog, select your feature/bossfight-functions branch from the dropdown.

2. Handle the merge conflict warning

• A warning will appear, indicating that this merge will create a conflict. Select Create a merge commit.
• A new dialog will prompt you to resolve the conflict. The conflicting file (your scene file) will be listed.

3. Resolve the conflict

• Next to the conflicting file, open the dropdown menu and select Use modified file from feature/bossfight-functions. This means you’re deciding to keep the changes you made on your feature branch (Boss tag, yellow material) over the changes made on the main branch (Enemy tag, orange material).

Important: Before resolving real-world merge conflicts, always discuss the change with your team. Agree on which version should be kept, or how to combine the changes, to ensure no valuable work is lost.

4. Complete the merge

• Select Continue merge.
• GitHub Desktop will then present a commit message for the merge. You can modify it if needed, then select Commit merge (for example, Merge branch 'feature/bossfight-functions' into main).
• Select Push origin to upload the merged changes to GitHub.com.

The conflict is now resolved, and your main branch reflects the chosen changes from your feature branch.

In this tutorial, you learned the critical skills of creating isolated branches for feature development, including making and committing changes within those branches. Most importantly, you gained practical experience in triggering and resolving merge conflicts, a common and essential task in collaborative development.

In the next tutorial, you’ll clone a repository, creating a local copy of an existing online repo.