AeThex-Engine-Core/docs/GDSCRIPT_BASICS.md

# Your First AeThex Game - Multiplayer Pong

Build a simple multiplayer Pong game in 30 minutes. Learn core AeThex features: multiplayer, cloud saves, and the Studio IDE.

**What you'll build:** Real-time multiplayer Pong where 2 players compete, with automatic cloud save of high scores.

**Time required:** 30 minutes  
**Difficulty:** Beginner

---

## Prerequisites

- AeThex Engine installed
- Text editor or Studio IDE
- Basic programming knowledge (any language)

---

## Part 1: Project Setup (5 min)

### 1. Create New Project

In Studio IDE:
1. Click **File → New Project**
2. Name: `MultiplayerPong`
3. Location: Choose folder
4. Click **Create & Open**

<function_calls>
<invoke name="create_file">
<parameter name="content"># GDScript Basics

Quick reference for developers new to GDScript.

## What is GDScript?

GDScript is Python-like scripting language designed for game development. Easy to learn, powerful for games.

## Basic Syntax

### Variables
```gdscript
var health = 100          # Integer
var speed = 5.5           # Float
var name = "Player"       # String
var is_alive = true       # Boolean
var position = Vector2(0, 0)  # Object
```

### Constants
```gdscript
const MAX_HEALTH = 100
const GRAVITY = 980
```

### Functions
```gdscript
func take_damage(amount):
    health -= amount
    if health <= 0:
        die()

func die():
    print("Game Over")
    queue_free()
```

### If Statements
```gdscript
if health > 50:
    print("Healthy")
elif health > 20:
    print("Low health")
else:
    print("Critical")
```

### Loops
```gdscript
# For loop
for i in range(10):
    print(i)

# While loop
while health > 0:
    take_damage(10)

# Iterate array
for item in inventory:
    print(item.name)
```

### Arrays
```gdscript
var fruits = ["apple", "banana", "orange"]
fruits.append("grape")
print(fruits[0])  # "apple"
print(fruits.size())  # 4
```

### Dictionaries
```gdscript
var player = {
    "name": "Alex",
    "level": 5,
    "health": 100
}

print(player["name"])  # "Alex"
player.health = 90
```

## Common Lifecycle Functions

### _ready()
Called when node is added to scene.
```gdscript
func _ready():
    print("Node is ready")
    health = MAX_HEALTH
```

### _process(delta)
Called every frame.
```gdscript
func _process(delta):
    # delta = time since last frame (seconds)
    position.x += speed * delta
```

### _physics_process(delta)
Called every physics frame (fixed timestep).
```gdscript
func _physics_process(delta):
    velocity.y += gravity * delta
    move_and_slide(velocity)
```

### _input(event)
Called on input events.
```gdscript
func _input(event):
    if event is InputEventKey:
        if event.pressed and event.keycode == KEY_SPACE:
            jump()
```

## Node Management

### Get child nodes
```gdscript
var player = $Player  # Direct child
var health_bar = $UI/HealthBar  # Nested
var enemy = get_node("Enemy")  # Alternative
```

### Create nodes
```gdscript
var bullet = preload("res://bullet.tscn").instantiate()
bullet.position = global_position
get_parent().add_child(bullet)
```

### Remove nodes
```gdscript
queue_free()  # Remove this node
$Bullet.queue_free()  # Remove child
```

## Signals

### Define signal
```gdscript
signal health_changed(new_health)
signal died

func take_damage(amount):
    health -= amount
    health_changed.emit(health)
    if health <= 0:
        died.emit()
```

### Connect signal
```gdscript
func _ready():
    $Player.connect("died", self, "_on_player_died")

func _on_player_died():
    print("Player died!")
```

## Classes

```gdscript
class_name Player extends CharacterBody2D

var health = 100
var speed = 200

func _ready():
    print("Player ready")

func move(direction: Vector2):
    velocity = direction * speed
    move_and_slide()
```

## Exports (Inspector Variables)

```gdscript
@export var max_health = 100
@export var speed = 5.0
@export var player_name = "Hero"
@export var sprite: Texture2D
```

These appear in the Inspector and can be edited visually.

## Common Types

```gdscript
# Numbers
var integer: int = 5
var floating: float = 3.14

# Vectors
var pos2d: Vector2 = Vector2(10, 20)
var pos3d: Vector3 = Vector3(1, 2, 3)

# Colors
var red = Color.RED
var custom = Color(1.0, 0.5, 0.0)  # RGB

# Nodes
var player: CharacterBody2D
var sprite: Sprite2D
```

## Tips for Beginners

1. **Use typed variables** for better autocomplete:
   ```gdscript
   var speed: float = 5.0
   var player: Node2D
   ```

2. **$ is shorthand** for get_node():
   ```gdscript
   $Player == get_node("Player")
   ```

3. **Connect signals in Inspector** or code - both work

4. **Use @export** to expose variables to Inspector

5. **Always null-check** before using nodes:
   ```gdscript
   if player != null:
       player.take_damage(10)
   ```

6. **Use preload** for resources:
   ```gdscript
   const Bullet = preload("res://bullet.tscn")
   var bullet = Bullet.instantiate()
   ```

## Next Steps

- [Your First AeThex Game](tutorials/FIRST_GAME_TUTORIAL.md)
- [GDScript Official Docs](https://docs.godotengine.org/en/stable/tutorials/scripting/gdscript/index.html)
- [AeThex API Reference](API_REFERENCE.md)