PLECK lesson 8 · suggested week 2, day 3

Calculate resources and clamp boundaries

Objective. Trace arithmetic and preserve a valid range.

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.

Values, types, expressions, branches and repeatable experiments

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-L007.

Games need limits: a courier cannot have negative energy or exceed a bag’s capacity. Write an expression before adding input. For capacity five and current cargo three, accepting four parcels should produce five rather than seven. GDScript’s clampi(value, minimum, maximum) confines an integer. Arithmetic happens before the function checks limits. Make a small trace table with starting value, change, raw result and bounded result. Predict lower-bound, ordinary and upper-bound cases so a single successful example does not hide a mistake.

Worked example

A counter lab can store parcels as an int and route_title as a String. print exposes intermediate values; a function such as double_points(n) returns n*2 without needing any artwork. Scaffold C-TESTS — A tiny pure-function test harness Setup: Attach to Node TestLab. If using command line, create a separate SceneTree harness rather than running this Node script with --script. Run current TestLab scene in editor; assert reports a failed condition in Debugger. No external test framework or package is needed. ```gdscript extends Node func bounded_score(old_score: int, change: int) -> int: return clampi(old_score + change, 0, 999) func _ready() -> void: assert(bounded_score(10, 2) == 12) assert(bounded_score(0, -3) == 0) assert(bounded_score(998, 9) == 999) print("3 score checks passed") ```

A tiny pure-function test harness

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

Scene and node setup

Attach to Node TestLab. If using command line, create a separate SceneTree harness rather than running this Node script with --script. Run current TestLab scene in editor; assert reports a failed condition in Debugger. No external test framework or package is needed.

extends Node
func bounded_score(old_score: int, change: int) -> int:
    return clampi(old_score + change, 0, 999)
func _ready() -> void:
    assert(bounded_score(10, 2) == 12)
    assert(bounded_score(0, -3) == 0)
    assert(bounded_score(998, 9) == 999)
    print("3 score checks passed")

Checks to run in the editor

All three assertions pass.
Intentionally change expected 12 to 13 and observe a failure, then restore.

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.

Calculate resources and clamp boundaries — evidence task

1. Write bounded cargo calculations using clampi for (3,+1), (3,+4) and (0,-2), range 0 to 5.
2. Print predicted and observed results.

Deliverable. Lab project and three-case trace table.

Acceptance checks

VGC-L008-T1. Results are 4, 5 and 0.
VGC-L008-T2. A middle case is not incorrectly forced to a boundary.

Understanding question. Why test the middle value as well as the two limits?

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. Return to C-HELLO and change one value per run. Write the expected output before running. Start with the first assigned task and re-run its acceptance test before adding the remaining feature.

Optional extra. Create another small numeric example and predict the result without executing it first. Document one changed parameter, your prediction, and the observed effect; optional, not required for completion.

Turn in typed notes and a JPEG, PNG, or WebP screenshot. One https address is stored as text and is not opened, extracted, or run. An MP3, WAV, M4A, MP4, or WebM file up to 4 MB can show a demo. The demo does not replace editable source. Zip and code files are refused. If there is no private link, keep the project on the family computer and review the code in person.

Godot 4.7.2 stable archive and platform downloads
Free public page; download required once for offline desktop use; no account required.
· Opening this link does not submit the lesson.
Godot step by step: nodes, scenes, GDScript, input, signals
Free public documentation, no account. Same class help is available within the desktop editor.
· Opening this link does not submit the lesson.

This is a preview. A parent assigns the lesson and chooses the due date after the student is enrolled. The answer key is not on this page.

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