158 lines
4.2 KiB
Org Mode
158 lines
4.2 KiB
Org Mode
#+title: Section 03 - Lesson 30 | Section Review
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#+HTML_HEAD: <link rel="stylesheet" type="text/css" href="../../_share/media/css/godot.css" />
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* Links
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- [[../../toc.org][TOC - Godot Notes]]
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- [[https://www.udemy.com/course/jumpstart-to-2d-game-development-godot-4-for-beginners/learn/lecture/45070537#overview][S03:L42.30 - Section Review]]
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* Notes
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** paddle scene
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*** node composition
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- root: Area2D
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- Sprite2D
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- CollisionShape2D
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*** script view: paddle.gd
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- extends Area2D
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**** use *@export* to create speed variable
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- can be modified in Inspector
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- give default value
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**** override _process function
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- check if =Input.is_action_pressed=
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- is 'left'
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- is 'right'
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- move paddle
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- get the Node2D.position property
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- multiply speed by delta and add or subtract it from position.x
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- delta is number of seconds that elapsed since the previous frame
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** gem scene
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*** node composition
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- root: Area2D
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- Sprite2D
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- CollisionShape2D
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*** script view: gem.gd
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- extends Area2D
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**** set class name
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- =class_name Gem=
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- this allows us to instantiate Gem objects in scripts
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**** set a signal property
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- =signal on_gem_off_screen=
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- allows us to attach listeners who will be notified when we emit a signal
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**** set export property
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- =@export var speed=
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- lets us set the speed in the Inspector
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*** modify _process
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**** determine if the gem has gone out of bounds
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- this is going to be the edge of the viewport
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- check position property against the viewport rect property
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#+begin_src gdscript
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if position.y > get_viewport_rect().size.y
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#+end_src
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**** if gem went out of bounds
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***** emit signal
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#+begin_src gdscript
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on_gem_off_screen.emit()
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#+end_src
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***** stop the gem and remove it from the node tree
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- stop going through the process function
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- delete node at the end of the current frame
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#+begin_src gdscript
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set_process(false)
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queue_free()
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#+end_src
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** Game scene
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*** preload assets
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- using const to set builtin preload function
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#+begin_src gdscript
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const EXPLOSDE = preload("res://assets/explode.wav")
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#+end_src
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*** add a PackedScene variable
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- allows us to instantiate gem scenes
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- export allows us to drag and drop the scene we want into the inspector
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#+begin_src gdscript
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@export var gem_scene: PackedScene
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# when time comes to use it
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gem_scene.instantiate()
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add_child(gem_scene)
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#+end_src
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- otherwise we would have to preload it
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#+begin_src gdscript
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gem_scene = preload("res://somescene.tscn").instantiate()
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add_child(gem_scene)
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#+end_src
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*** use onready to add nodes in tree scene
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#+begin_src gdscript
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@onready var label: Label = $Label
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@onready var timer: Timer = $Timer
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@onready var audio_stream_player_2d: AudioStreamPlayer2D = $AudioStreamPlayer2D
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#+end_src
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- these are all scenes in the Game tree
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- use onready to attach them to variables for use in game script
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- onready makes sure it's available so we dont end up with a null reference
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*** spawn gem at _ready
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- in the ready function immediately call spawn_gem
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- spawn Gem instantiates a gem scene and type casts it to a Gem class
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- connect any signals
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- set it's position
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- add it as a child
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#+begin_src gdscript
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var new_gem: Gem = gem_scene.instantiate()
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new_gem.on_gem_off_screen.connect(game_over)
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new_gem.position = Vector2(xpos, ypos)
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add_child(new_gem)
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#+end_src
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*** stop all function
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- stop the timer
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- run through all children and set process to false
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#+begin_src gdscript
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timer.stop()
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for child in get_children():
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child.set_process(false)
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#+end_src
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*** turn off audio
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- get references to audio and call 'stop' function
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- you can also set another sound for ending and play that
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#+begin_src gdscript
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audio_stream_player_2d.stop()
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audio_stream_player_2d.stream = EXPLODE
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audio_stream_player_2d.play()
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#+end_src
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*** whenever timer times out spawn a gem
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- we attached the timer to a signal to call a function that calls spawn gem
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*** when the paddle gets hit by a gem
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- increase score
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- set the position of where the paddle got hit to the audio and play a sound
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- free up the hit object (the gem)
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#+begin_src gdscript
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func _on_padd_area_entered(area: Area2D) -> void:
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_score += 1
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label.text = "%05d" % _score
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audio_stream_player_2d.position = area.position
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audio_stream_player_2d.play()
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area.queue_free()
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#+end_src
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