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+title: Creating my Go Godot Jam 3 entry devlog 1
+author: David Luévano
+lang: en
+summary: Details on the implementation for the game I created for the Go Godot Jam 3, which theme is Evolution.
+tags: gamedev
+	godot
+	gamejam
+	english
+
+**IF YOU'RE SEEING THIS, THIS IS A WIP**
+
+The jam's theme is Evolution and all the details are listed [here](https://itch.io/jam/go-godot-jam-3). This time I'm logging as I go, so there might be some changes to the script or scenes along the way. Note that I'm not going to go into much details, the obvious will be ommitted.
+
+I wanted to do a *Snake* clone, and I'm using this jam as an excuse to do it and add something to it. The features include:
+
+- Snakes will pass their stats in some form to the next snakes.
+- Non-grid snake movement. I just hate the grid constraint, so I wanted to make it move in any direction.
+- Depending on the food you eat, you'll gain new mutations and the more you eat the more that mutation develops.
+- Procedural map creation.
+
+## Initial setup
+
+Again, similar to the [FlappyBird](https://blog.luevano.xyz/g/flappybird_godot_devlog_1.html) clone I developed, I'm using the structure I wrote about on [Godot project structure](https://blog.luevano.xyz/g/godot_project_structure.html) with slight modifications to test things out. Also using similar *Project settings* as those from the *FlappyBird* clone like the pixel art texture imports, keybindings, layers, etc..
+
+I've also setup [GifMaker](https://github.com/bram-dingelstad/godot-gifmaker), with slight modifications as the *AssetLib* doesn't install it correctly and contains unnecessry stuff: moved necessary files to the `res://addons` directory, deleted test scenes and files in general, and copied the license to the `res://docs` directory. Setting this up was a bit annoying because the tutorial it's bad (with all due respect). I might do a separate entry just to explain how to set it up, because I couldn't find it anywhere other than by inspecting some of the code/scenes.
+
+This time I'm also going to be using an [Event bus](https://www.gdquest.com/docs/guidelines/best-practices/godot-gdscript/event-bus/) singleton (which I'm going to just call *Event*) as managing signals was pretty annoying on my last project; as well as a *Global* singleton for essential stuff so I don't have to do as many cross references between nodes/scenes.
+
+## Assets
+
+This time I'll be creating my own assets in [Aseprite](https://www.aseprite.org/), wont be that good, but enough to prototype and get things going.
+
+## The snake
+
+This is the most challenging part in my opinion as making all the body parts follow the head in a user defined path it's kinda hard. I tried with like 4-5 options and the one I'm detailing here is the only one that worked as I wanted for me. This time the directory structure I'm using is the following:
+
+![FileSystem - Snake dir structure](images/g/gogodot_jam3/file_system_snake_dir_structure.png "FileSystem - Snake dir structure")
+
+### Basic movement
+
+The most basic thing is to move the head, this is what we have control of. Create a scene called `Head.tscn` and setup the basic *KinematicBody2D* with it's own *Sprite* and *CollisionShape2D* (I used a small circle for the tip of the head), and set the *Collision Layer/Mask* accordingly, for now just `layer = bit 1`. And all we need to do, is keep moving the snake forwards and be able to rotate left or right. Created a new script called `head.gd` attached to the root (*KinematicBody2D*) and added:
+
+```gdscript
+extends KinematicBody2D
+
+enum {
+	LEFT=-1,
+	RIGHT=1
+}
+
+var velocity: Vector2 = Vector2.ZERO
+var _direction: Vector2 = Vector2.UP
+
+
+func _physics_process(delta: float) -> void:
+	if Input.is_action_pressed("move_left"):
+		_rotate_to(LEFT)
+	if Input.is_action_pressed("move_right"):
+		_rotate_to(RIGHT)
+
+	velocity = _direction * Global.SNAKE_SPEED
+
+	velocity = move_and_slide(velocity)
+	_handle_time_elapsed(delta)
+
+
+func _rotate_to(direction: int) -> void:
+	rotate(deg2rad(direction * Global.SNAKE_ROT_SPEED * get_physics_process_delta_time()))
+	_direction = _direction.rotated(deg2rad(direction * Global.SNAKE_ROT_SPEED * get_physics_process_delta_time()))
+```
+
+After tunning all the necessary parameters you should get something like this:
+
+![Snake - Basic movement (left and right controls)](images/g/gogodot_jam3/snake_basic_movement.gif "Snake - Basic movement (left and right controls)")
+
+### Setting up path following
+
+To move other snake parts by following the snake head the only solution I found was to use the *Path2D* and *PathFollow2D* nodes. *Path2D* basically just handles the curve/path that *PathFollow2D* will use to move its child node; and I say "child node" in singular... as *PathFollow2D* can only handle one damn child, all the other ones will have weird transformations and/or rotations. So, the next thing to do is to setup a way to compute (and draw so we can validate) the snake's path/curve.
+
+Added `signal new_curve_point(coordinates)` to the *Event* singleton and then add the following to `head.gd`:
+
+```gdscript
+var _time_elapsed: float = 0.0
+
+# using a timer is not recommended for < 0.01
+func _handle_time_elapsed(delta: float) -> void:
+	if _time_elapsed >= Global.SNAKE_POSITION_UPDATE_INTERVAL:
+		Event.emit_signal("new_curve_point", global_position)
+		_time_elapsed = 0.0
+	_time_elapsed += delta
+```
+
+This will be pinging the current snake head position every `0.01` seconds (defined in *Global*). Now create a new scene called `Snake.tscn` which will contain a *Node2D*, a *Path2D* and an instance of *Head* as its childs. Create a new script called `snake.gd` attached to the root (*Node2D*) with the following content:
+
+```gdscript
+class_name Snake
+extends Node2D
+
+onready var path: Path2D = $Path
+
+func _ready():
+	Event.connect("new_curve_point", self, "_on_Head_new_curve_point")
+
+
+func _draw() -> void:
+	if path.curve.get_baked_points().size() >= 2:
+		draw_polyline(path.curve.get_baked_points(), Color.aquamarine, 1, true)
+
+
+func add_point_to_curve(coordinates: Vector2) -> void:
+	path.curve.add_point(coordinates)
+	# update call is to draw curve as there are new points to the path's curve
+	update()
+
+
+func _on_Head_new_curve_point(coordinates: Vector2) -> void:
+	add_point_to_curve(coordinates)
+```
+
+With this, we're now populating the *Path2D* curve points with the position of the snake head. You should be able to see it because of the `_draw` call. If you run it you should see something like this:
+
+![Snake - Basic movement with path](images/g/gogodot_jam3/snake_basic_movement_with_path.gif "Snake - Basic movement with path")
+
+### Define body parts for the snake
+
+At this point the only thing to do is to add the corresponding next body parts and tail of the snake. To do so, we need a *PathFollow2D* to use the live-generating *Path2D*, the only caveat is that we need one of these per body part/tail (this took me hours to figure out, *thanks documentation*).
+
+Create a new scene called `Body.tscn` with a *PathFollow2D* as its root and an *Area2D* as its child, then just add the necessary *Sprite* and *CollisionShap2D* for the *Area2D*, I'm using `layer = bit 2` for its collision. Create a new script called `generic_segment.gd` with the following code:
+
+```gdscript
+extends PathFollow2D
+
+export(String, "body", "tail") var TYPE: String = "body"
+
+
+func _physics_process(delta: float) -> void:
+	offset += Global.SNAKE_SPEED * delta
+```
+
+And this can be attached to the *Body*'s root node (*PathFollow2D*), no extra setup needed. Repeat the same steps for creating the `Tail.tscn` scene and when attaching the `generic_segment.gd` script just configure the `Type` parameter to `tail` in the GUI (by selecting the node with the script attached and editing in the *Inspector*).
+
+### Creating body parts on the fly
+
+Now it's just a matter of handling when to add new body parts in the `snake.gd` script. For now I've only setup the initial lenght of the snake. The extra code needed is the following:
+
+```gdscript
+export(PackedScene) var BODY_SEGMENT_NP: PackedScene
+export(PackedScene) var TAIL_SEGMENT_NP: PackedScene
+
+var current_body_segments: int = 0
+var max_body_segments: int = 1
+var body_segment_size: float = 16.0
+
+
+func add_point_to_curve(coordinates: Vector2) -> void:
+	path.curve.add_point(coordinates)
+	# update call is to draw curve as there are new points to the path's curve
+	update()
+
+	# add the following lines
+	if current_body_segments < max_body_segments:
+		add_snake_segment(BODY_SEGMENT_NP)
+	elif current_body_segments == max_body_segments:
+		add_snake_segment(TAIL_SEGMENT_NP)
+
+
+func add_snake_segment(type: PackedScene) -> void:
+	if path.curve.get_baked_length() >= (current_body_segments + 1.0) * body_segment_size:
+		var _temp_body_segment: PathFollow2D = type.instance()
+		path.add_child(_temp_body_segment)
+		current_body_segments += 1
+```
+
+Select the *Snake* node and add the *Body* and *Tail* scene to the parameters, respectively. Then when running you should see something like this:
+
+![Snake - Basic movement with all body parts](images/g/gogodot_jam3/snake_basic_movement_added_body_parts.gif "Snake - Basic movement with all body parts")
+
+## Brainstorm/To-do
+
+- Snake clone with evolution.
+	- Evolution on the snake itself?
+		- Evolve after eating X amount?
+		- Evolve after eating X type of food?
+			- Similar to Contra, where you can switch the food (not sure if this counts as evolution)
+	- Evolution on the world?
+		- Start with a small procedural generated map, then expand it?
+	- When snake dies, it passes the genes it collected by eating some food to the next snakes?
+		- Or similar to the Rogue Legacy system?
+
+- Snake clone
+	- Each snake has several attributes
+		- Health
+		- Time to live (before getting food?)
+	- Special food will unlock new attributes for subsequent snakes
+		- Jumping ability (need to level it up by eating more of the same food or by using it)
+		- Crawl up walls?
+
+## Resources
+
+- [Nuclear Throne Like Map Generation In Godot](https://www.youtube.com/watch?v=ppP2Doq3p7s)
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