Video Game Design and Coding · PLECK lesson

PLECK lesson 16 · suggested week 4, day 1

Replace free motion with a physics body

Objective. Use CharacterBody2D velocity and move_and_slide correctly.

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.

Physics bodies, visible walls, layers and collision diagnosis

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-L015.

A CharacterBody2D lets Godot resolve motion against solid geometry. Follow C-BODY to make a reusable Player scene. Its velocity is measured in pixels per second; move_and_slide applies the physics step internally, so do not multiply this velocity by delta again. Use _physics_process for physics movement. The CollisionShape2D defines where the actor is solid, while _draw defines how it looks. Place the player above the world origin so it is visible before diagnosing collision problems.

Worked example

A wall is a StaticBody2D with matching rectangle art and collider. A player standing next to it should be stopped by geometry, not by a special if statement checking the wall’s screen color. Scaffold C-BODY — Reusable top-down player with collision Setup: Create CharacterBody2D root Player at (80,180); add CollisionShape2D with CircleShape2D radius 14. Attach this script to Player and save Player.tscn. Use C-FREE-MOVE input actions. Root collision layer 1, mask 2. Create a separate StaticBody2D Wall on layer 2 mask 1 with RectangleShape2D collision and a Polygon2D rectangle as visible child. Instance both under an unscaled Node2D World. Do not put a body inside another physics body. ```gdscript extends CharacterBody2D @export var speed: float = 160.0 func _draw() -> void: draw_circle(Vector2.ZERO, 14.0, Color.CORNFLOWER_BLUE) draw_line(Vector2(-8, 0), Vector2(8, 0), Color.WHITE, 3.0) func _physics_process(_delta: float) -> void: velocity = Input.get_vector("move_left", "move_right", "move_up", "move_down") * speed move_and_slide() ```

Reusable top-down player with collision

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

Scene and node setup

Create CharacterBody2D root Player at (80,180); add CollisionShape2D with CircleShape2D radius 14. Attach this script to Player and save Player.tscn. Use C-FREE-MOVE input actions. Root collision layer 1, mask 2. Create a separate StaticBody2D Wall on layer 2 mask 1 with RectangleShape2D collision and a Polygon2D rectangle as visible child. Instance both under an unscaled Node2D World. Do not put a body inside another physics body.

extends CharacterBody2D
@export var speed: float = 160.0
func _draw() -> void:
    draw_circle(Vector2.ZERO, 14.0, Color.CORNFLOWER_BLUE)
    draw_line(Vector2(-8, 0), Vector2(8, 0), Color.WHITE, 3.0)
func _physics_process(_delta: float) -> void:
    velocity = Input.get_vector("move_left", "move_right", "move_up", "move_down") * 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.

Pocket Orchard starter, as text files. Open the files in Godot on the family computer. This page does not download a zip or run the project.

Replace free motion with a physics body — evidence task

  1. 1. Create Player.tscn with a circle collider and C-BODY.
  2. 2. Run it in a blank World and compare its movement with the earlier actor.

Deliverable. Player scene/script and a node-tree screenshot.

Acceptance checks

Understanding question. Why is delta absent from the velocity assignment in this recipe?

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 a single rectangle wall and C-BODY. Enable visible collision shapes in the Debug menu before redesigning the level. Start with the first assigned task and re-run its acceptance test before adding the remaining feature.

Optional extra. Compare two collider sizes and explain how perceived fairness changes. Document one changed parameter, your prediction, and the observed effect; optional, not required for completion.

Name ____________________ Date ____________________