Debugging Tasks in Godot | Kodeco

It’d come as a shock, however not all code works on the primary attempt. (Insert shocked copyright-safe yellow electrical rodent right here)

For that reason, most built-in growth environments (IDEs) embody a debugger that permits the developer to identify and clear up points throughout the a number of growth iterations. That is illustrated by the next pseudocode:

whereas growing == true:
    code
    take a look at
    debug

When growing a sport, nonetheless, there are different points to consider, comparable to sport steadiness or verifying behaviors that is perhaps too quick or refined to note throughout gameplay.

Give it some thought. You rigorously crafted your sport’s problem stage, so that you wish to make certain it’s as much as the problem. However how will you rely the variety of enemies in a sport once they’re transferring round and taking pictures at you?
You may wish to verify the sport steadiness. Is the variety of enemies spawned at a given instantaneous what you count on? Did the power-up add the harm enhance you anticipated?

These are only a few of the questions you may wish to reply whereas testing your sport. That is the place Godot’s debug instruments come in useful, serving to you take a look at and confirm all that.

Getting Began

The instance challenge is similar from the Publishing Your Godot Challenge to itch.io tutorial. Nonetheless, for this text, the code was modified to reinforce the gameplay expertise. Sadly, the sport broke within the course of and you could discover what’s incorrect with it utilizing the debug instruments. How handy! :]

You’ll be able to obtain the challenge utilizing the Obtain supplies hyperlinks on the high and backside of this text. Word that this challenge requires Godot 4.3 or newer to run.

The beginning challenge has the identical construction as within the earlier article, however three information have modified: projectile.gd, enemy_ship.gd, and main_game.gd.

Now is an efficient time to obtain and run the challenge to evaluate the way it’s working and see how the bugs affect the sport. The primary problem you’ll discover is that it’s unattainable to destroy the enemy ships, though they’ll destroy your ship, so it’s debugging time!

Overview of the Debug Instruments

Godot has a set of highly effective debug instruments you should use to evaluate code for logic errors, or graphics for efficiency points, and even to get an x-ray of how the sport is utilizing its processing time.

Though there’s a Debug menu on the high of the display screen, this text will deal with the instruments accessible via the Debugger panel on the backside of the display screen, as a result of these are the instruments that collect data when executing the challenge via the Run the challenge button.

Debugger Panel

The debugger panel, positioned on the backside of the display screen by default, is accessible from the Debugger possibility on the backside of the window, to the best of the Output possibility. The next image reveals the debug panel:

On the panel’s high, you’ll be able to see a number of tabs. From left to proper, the tabs are:

1. Stack hint: Reveals the execution stack, the context and its variables, and permits for controlling how the sport executes throughout the debug session. You’ll be taught extra about this tab later on this article.
2. Errors: Reveals the error and warning messages throughout the sport execution.
3. Profiler: Reveals which code is operating and the way it impacts the sport efficiency. You’ll be taught extra about this tab later on this article.
4. Visible profiler: Shows a graph exhibiting which code is operating and the way a lot time it takes for execution. You’ll be taught extra about this tab later on this article.
5. Displays: Comprises graphs of sport data, comparable to frames per second (fps), reminiscence utilization, scene nodes, and extra. The info from the debug session is saved even after the session is over, so it’s attainable to evaluate it even after execution.
6. Video RAM: Reveals an inventory of sources and the way a lot video RAM they use whereas operating, in addition to the grand whole on the high of the panel.
7. Misc: Displays and identifies the management nodes clicked throughout runtime.
8. Community Profiler: Comprises the listing of all nodes speaking over Godot’s multiplayer API and the way a lot knowledge every one in every of them obtained or despatched throughout the debug session.

This text focuses on tabs 1, 2, 3, 4 and 5. Nonetheless, be at liberty to look at the others utilizing the identical challenge. A few of them, comparable to Community Profiler received’t have any fascinating data, although, as the sport doesn’t use the multiplayer API in any level.

Utilizing Breakpoints

After executing the sport, you need to have seen that the principle problem is that it’s unattainable to destroy the enemy ships. So, logically, there have to be an issue with the perform invoked when damaging the enemy ships — possibly the ships don’t take harm when they need to?

To check if that is true, study the perform that offers harm to the enemies: open projectile.gd and discover the damage_body perform. The perform code is:

func damage_body(physique: Node2D) -> void:
    # 1
    physique.take_damage(3)
    # 2
    create_explosion() 
    # 3
    queue_free()       

This code does the next:

1. When the bullet collides with the enemy ship, it reduces the ship’s well being by 3 factors;
2. An explosion seems on the purpose the place the collision occurred;
3. The bullet is faraway from reminiscence;

It is a simple perform, and its logic appears to be right. How can it not be working? Wouldn’t or not it’s nice if there was a method of getting a deeper have a look at how the code is working? That’s the place breakpoints are available in, permitting you to halt the code execution and dig deeper to find the issue.

Breakpoints

When analyzing code, the error won’t be apparent simply by wanting on the code; you may want to take a look on the code throughout runtime. To just do that, you’ll want to make use of breakpoints and watches, which work collectively to help and confirm what the code is doing.

Once you outline a breakpoint, Godot is aware of it might want to execute the challenge usually as much as that time. After that, it halts execution and lets you management how briskly the code ought to execute, and allows you to see which code executes in case of conditionals or loops.

The outline ought to be type of summary now, however you’ll see that in follow it’s quite simple and helpful!