Video Game Design and Coding · PLECK lesson

PLECK lesson 65 · suggested week 13, day 5

Reset safely after a fall

Objective. Implement a fall-zone trigger and a deliberate spawn point.

Godot Engine Standard desktop editor 4.7.2-stable, GDScript (Godot 4), Compatibility renderer. Headless Godot 4.7.2.stable.official.ed1daf0bf passed 106 assertions on the supplied scaffolds, including malformed JSON saves. Audio used the Dummy driver and a synthetic WAV, not a speaker. The visual editor, browser export, and signed-in submission were not tested. The desk still does not run a student's own upload.

About 55 minutes. The due date is chosen by a parent.

Gravity, jumps, floor checks and safe geometry

Suggested pace: Recall and predict 5 min; Read instruction and scaffold 12 min; Build or design the assigned artifact 25 min; Run acceptance tests 8 min; Explain and checkpoint 5 min.

Materials: Godot Standard 4.7.2 desktop editor (GDScript, Compatibility renderer), Local course folder and prior checkpoint, No paid assets or public account required.

Comes after VGC-L064.

A fall should return the player to a valid point rather than leave them outside the level. Place an Area2D fall zone below the platforms, with a wide rectangle collider and mask for Player. Its body_entered handler checks the player group and calls the level’s respawn method. C-CHECKPOINT defers the actual move and clears velocity. Put the spawn above a safe floor with enough collider clearance. Do not put it inside the fall zone or another hazard, which creates a reset loop.

Worked example

A ball thrown upward begins with negative y velocity. Gravity adds a positive amount each physics step, slowing the rise and eventually producing downward motion. Scaffold C-CHECKPOINT — A safe checkpoint respawn Setup: Add this pattern to a separate Node2D level root with child Player using C-PLATFORM. Call set_checkpoint with a safe global position when a player reaches a checkpoint Area2D; call respawn when entering a fall zone. This code does not connect Area2D automatically; select the area body_entered signal in editor and call these methods from its handler after checking the player group. Respawn is deferred because a physics callback may be active. ```gdscript extends Node2D @onready var player: CharacterBody2D = $Player var checkpoint: Vector2 func _ready() -> void: checkpoint = player.global_position func set_checkpoint(safe_position: Vector2) -> void: checkpoint = safe_position func respawn() -> void: _apply_respawn.call_deferred() func _apply_respawn() -> void: player.global_position = checkpoint player.velocity = Vector2.ZERO ``` Scaffold C-PLATFORM — A gravity-and-jump platform player Setup: CharacterBody2D root Player, child CollisionShape2D RectangleShape2D size (24,32), no scale changes. Layer 1 mask 2. StaticBody2D floor layer 2 mask 1 with rectangular collider. Add Input Map move_left, move_right and jump bound to Space. Place player above floor, not intersecting it. Coordinates use positive y downward. Attach script to Player. ```gdscript extends CharacterBody2D @export var speed: float = 160.0 @export var gravity: float = 900.0 @export var jump_speed: float = 340.0 func _draw() -> void: draw_rect(Rect2(-12, -16, 24, 32), Color.SKY_BLUE) draw_line(Vector2(-8, -4), Vector2(8, -4), Color.BLACK, 2.0) func _physics_process(delta: float) -> void: velocity.x = Input.get_axis("move_left", "move_right") * speed if not is_on_floor(): velocity.y += gravity * delta if Input.is_action_just_pressed("jump") and is_on_floor(): velocity.y = -jump_speed move_and_slide() ```

A safe checkpoint respawn

GDScript (Godot 4, not Scratch, Python, JavaScript or C#). Scaffold C-CHECKPOINT. Copy starts from this text. The desk does not run it.

Scene and node setup

Add this pattern to a separate Node2D level root with child Player using C-PLATFORM. Call set_checkpoint with a safe global position when a player reaches a checkpoint Area2D; call respawn when entering a fall zone. This code does not connect Area2D automatically; select the area body_entered signal in editor and call these methods from its handler after checking the player group. Respawn is deferred because a physics callback may be active.

extends Node2D
@onready var player: CharacterBody2D = $Player
var checkpoint: Vector2
func _ready() -> void:
    checkpoint = player.global_position
func set_checkpoint(safe_position: Vector2) -> void:
    checkpoint = safe_position
func respawn() -> void:
    _apply_respawn.call_deferred()
func _apply_respawn() -> void:
    player.global_position = checkpoint
    player.velocity = Vector2.ZERO

Checks to run in the editor

Native Godot 4.7.2.stable.official.ed1daf0bf headless compile and representative node-tree/runtime tests passed; see native-qa-results.json. Visual UI, audible output, exports and website submission still need separate checks.

A gravity-and-jump platform player

GDScript (Godot 4, not Scratch, Python, JavaScript or C#). Scaffold C-PLATFORM. Copy starts from this text. The desk does not run it.

Scene and node setup

CharacterBody2D root Player, child CollisionShape2D RectangleShape2D size (24,32), no scale changes. Layer 1 mask 2. StaticBody2D floor layer 2 mask 1 with rectangular collider. Add Input Map move_left, move_right and jump bound to Space. Place player above floor, not intersecting it. Coordinates use positive y downward. Attach script to Player.

extends CharacterBody2D
@export var speed: float = 160.0
@export var gravity: float = 900.0
@export var jump_speed: float = 340.0
func _draw() -> void:
    draw_rect(Rect2(-12, -16, 24, 32), Color.SKY_BLUE)
    draw_line(Vector2(-8, -4), Vector2(8, -4), Color.BLACK, 2.0)
func _physics_process(delta: float) -> void:
    velocity.x = Input.get_axis("move_left", "move_right") * speed
    if not is_on_floor():
        velocity.y += gravity * delta
    if Input.is_action_just_pressed("jump") and is_on_floor():
        velocity.y = -jump_speed
    move_and_slide()

Checks to run in the editor

Native Godot 4.7.2.stable.official.ed1daf0bf headless compile and representative node-tree/runtime tests passed; see native-qa-results.json. Visual UI, audible output, exports and website submission still need separate checks.

Reset safely after a fall — evidence task

  1. 1. Add the fall zone and C-CHECKPOINT respawn pattern.
  2. 2. Fall while moving sideways and test the restored velocity and position.

Deliverable. Respawn-capable level and fall test note.

Acceptance checks

Understanding question. Why clear velocity during respawn?

Include a downloadable project ZIP with project.godot, .tscn, .gd and original asset files when code changes. A private, teacher-accessible download link to that ZIP is equivalent. Screenshots or a playthrough do not replace editable source.

If this is still shaky. Use C-PLATFORM with one wide floor and no hazards. Verify floor contact before adding platforms. Start with the first assigned task and re-run its acceptance test before adding the remaining feature.

Optional extra. Compare two gravity/jump-speed pairs while keeping horizontal speed fixed. Document one changed parameter, your prediction, and the observed effect; optional, not required for completion.

Name ____________________ Date ____________________