Reserve space for both player and guard

Objective. Design generation constraints around the actual movement model.

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.

Constraints, bounded systems, seed testing and an AI assessment

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-L130.

A direct-steering guard cannot navigate arbitrary mazes. Reserve an open patrol lane separate from the required player route, and prevent random walls from appearing there. Keep the guard’s chase area in an open region or constrain the game so walls cannot trap it. Document this limitation rather than naming it navigation AI. A procedural generator should satisfy the needs of its actors; adding random geometry without considering movement is not a complete system design.

Worked example

A procedural bug report might say seed 17, build alpha2, start at entrance, move right, expected clear corridor, actual blocking wall. The seed makes reproduction practical. Scaffold C-GRID — A deterministic grid with a guaranteed clear route Setup: Attach to Node2D GridLab. This example draws, not physics, so the assignment adds matching wall collision only after validation. Grid is 8 columns by 6 rows at 40 pixels per cell. Row 0 and column 7 are a guaranteed clear route from (0,0) to (7,5). RNG seed is a nonpersonal integer. ```gdscript extends Node2D const COLS: int = 8 const ROWS: int = 6 const CELL: int = 40 var cells: Array = [] func _ready() -> void: var rng := RandomNumberGenerator.new() rng.seed = 2468 for y in range(ROWS): var row: Array[int] = [] for x in range(COLS): var blocked: bool = y != 0 and x != COLS - 1 and rng.randf() < 0.25 row.append(1 if blocked else 0) cells.append(row) queue_redraw() func _draw() -> void: for y in range(cells.size()): for x in range(cells[y].size()): var color := Color.DIM_GRAY if cells[y][x] == 1 else Color.BEIGE draw_rect(Rect2(x * CELL, y * CELL, CELL - 2, CELL - 2), color) ``` Scaffold C-GUARD-AI — A readable patrol/chase/return state machine Setup: Create CharacterBody2D Guard with visible circle or polygon and matching collider. Layer 4 mask 2 for walls. Attach script and assign target to your Player instance in Inspector. Level is one open rectangle; this is steering, not navigation around walls. Damage remains a separate sensor/manager event. Draw detection radii on a design diagram before tuning values. ```gdscript extends CharacterBody2D enum Mode { PATROL, CHASE, RETURN } @export var target: Node2D @export var speed: float = 70.0 var mode: Mode = Mode.PATROL var home: Vector2 var patrol_target: Vector2 func _ready() -> void: home = global_position patrol_target = home + Vector2(80, 0) func _physics_process(delta: float) -> void: if not is_instance_valid(target): velocity = Vector2.ZERO return var distance: float = global_position.distance_to(target.global_position) if mode != Mode.CHASE and distance < 120.0: mode = Mode.CHASE elif mode == Mode.CHASE and distance > 180.0: mode = Mode.RETURN var destination: Vector2 if mode == Mode.CHASE: destination = target.global_position elif mode == Mode.RETURN: destination = home if global_position.distance_to(home) <= maxf(3.0, speed * delta): mode = Mode.PATROL else: destination = patrol_target if global_position.distance_to(patrol_target) <= maxf(3.0, speed * delta): patrol_target = home if patrol_target != home else home + Vector2(80, 0) var offset := destination - global_position velocity = offset.normalized() * minf(speed, offset.length() / maxf(delta, 0.001)) move_and_slide() ```

A deterministic grid with a guaranteed clear route

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

Scene and node setup

Attach to Node2D GridLab. This example draws, not physics, so the assignment adds matching wall collision only after validation. Grid is 8 columns by 6 rows at 40 pixels per cell. Row 0 and column 7 are a guaranteed clear route from (0,0) to (7,5). RNG seed is a nonpersonal integer.

extends Node2D
const COLS: int = 8
const ROWS: int = 6
const CELL: int = 40
var cells: Array = []
func _ready() -> void:
    var rng := RandomNumberGenerator.new()
    rng.seed = 2468
    for y in range(ROWS):
        var row: Array[int] = []
        for x in range(COLS):
            var blocked: bool = y != 0 and x != COLS - 1 and rng.randf() < 0.25
            row.append(1 if blocked else 0)
        cells.append(row)
    queue_redraw()
func _draw() -> void:
    for y in range(cells.size()):
        for x in range(cells[y].size()):
            var color := Color.DIM_GRAY if cells[y][x] == 1 else Color.BEIGE
            draw_rect(Rect2(x * CELL, y * CELL, CELL - 2, CELL - 2), color)

Checks to run in the editor

Same seed and version produce same grid.
All cells on top row and rightmost column are empty.

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 readable patrol/chase/return state machine

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

Scene and node setup

Create CharacterBody2D Guard with visible circle or polygon and matching collider. Layer 4 mask 2 for walls. Attach script and assign target to your Player instance in Inspector. Level is one open rectangle; this is steering, not navigation around walls. Damage remains a separate sensor/manager event. Draw detection radii on a design diagram before tuning values.

extends CharacterBody2D
enum Mode { PATROL, CHASE, RETURN }
@export var target: Node2D
@export var speed: float = 70.0
var mode: Mode = Mode.PATROL
var home: Vector2
var patrol_target: Vector2
func _ready() -> void:
    home = global_position
    patrol_target = home + Vector2(80, 0)
func _physics_process(delta: float) -> void:
    if not is_instance_valid(target):
        velocity = Vector2.ZERO
        return
    var distance: float = global_position.distance_to(target.global_position)
    if mode != Mode.CHASE and distance < 120.0:
        mode = Mode.CHASE
    elif mode == Mode.CHASE and distance > 180.0:
        mode = Mode.RETURN
    var destination: Vector2
    if mode == Mode.CHASE:
        destination = target.global_position
    elif mode == Mode.RETURN:
        destination = home
        if global_position.distance_to(home) <= maxf(3.0, speed * delta):
            mode = Mode.PATROL
    else:
        destination = patrol_target
        if global_position.distance_to(patrol_target) <= maxf(3.0, speed * delta):
            patrol_target = home if patrol_target != home else home + Vector2(80, 0)
    var offset := destination - global_position
    velocity = offset.normalized() * minf(speed, offset.length() / maxf(delta, 0.001))
    move_and_slide()

Checks to run in the editor

Far player: guard patrols 80 pixels from home.
Within 120 pixels: chase.
Beyond 180 pixels: return, then patrol.
Missing target stops safely rather than throwing an invalid-instance error.

Reserve space for both player and guard — evidence task

1. Mark player route, guard lane, spawn and goal as reserved cells.
2. Update generation conditions and test ten seeds.

Deliverable. Reserved-space map, generator update and ten-seed checks.

Acceptance checks

VGC-L131-T1. All required actor spaces remain open.
VGC-L131-T2. Guard patrol endpoints are not inside walls.

Understanding question. Why is an open reserved lane appropriate for this guard?

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. Keep guard patrol in a reserved open lane and the player route guaranteed. Avoid adding maze pathfinding to this project. Start with the first assigned task and re-run its acceptance test before adding the remaining feature.

Optional extra. Add one optional guard route only if the generator can prove its lane remains clear. Document one changed parameter, your prediction, and the observed effect; optional, not required for completion.

Your first 2D game
Free public tutorial; no account; external asset download is optional, not used by this course.
· Opening this link does not submit the lesson.

Name ____________________ Date ____________________