Fun with the Tools and Beginning Scripting

• Main Camera: Projection Orthographic, Size 50.
• The world therefore spans y = −50 to +50 (a total height of 100). The width depends on the Game window's aspect ratio.

Four sprite objects, each created from an image and each of size 1 (Transform Scale (1, 1, 1)), at:

Any image works, for example Egg.png (the one in my solution) or GreenUp.PNG from the Module 1 self-exercise. Give each object a different color through its SpriteRenderer's Color (a tint), so each one is easy to tell apart.

Speed and time: Time.smoothDeltaTime

Update() runs once per frame, and different computers run at different frame rates: 60, 144 or more frames per second. If you move an object by a fixed amount every frame, it moves more than twice as fast on a 144 Hz machine as on a 60 Hz one. To make speed mean the same thing everywhere, express it in units per second, and multiply by the time the last frame took. Unity provides that as Time.deltaTime, and Time.smoothDeltaTime is a smoothed (averaged) version that avoids jitter when one frame happens to take longer than the others. So each frame, an object moving at 10 units/second moves 10 * Time.smoothDeltaTime units, and a scale changing at 0.75 per second changes by 0.75f * Time.smoothDeltaTime. After one second of frames, those add up to about 10 units and 0.75, whatever the frame rate.

float dt = Time.smoothDeltaTime;           // seconds the last frame took (smoothed)
float distance = kMoveSpeed * dt;          // kMoveSpeed = 10f units per second
float growth   = kScaleRate * dt;          // kScaleRate = 0.75f per second

We'll use this idea in every example from Module 2 on.

Reading the keyboard

Use the Input System, exactly as in Module 1's GreenArrowBehavior.cs:

using UnityEngine;
using UnityEngine.InputSystem;

// ... inside your MonoBehaviour:
void Update()
{
    float direction = 0f;                   // +1 away from origin, -1 toward it
    if (Keyboard.current.upArrowKey.isPressed)
        direction += 1f;
    if (Keyboard.current.downArrowKey.isPressed)
        direction -= 1f;

    if (Keyboard.current.qKey.wasPressedThisFrame)
        Application.Quit();

    // Your code: move and scale the four objects using
    // direction and Time.smoothDeltaTime, then clamp.
}

Finished early? Try one of these:

• Space resets all four objects to their starting positions and size 1.
• ←/→ rotate all four objects, at a rate given in degrees per second.

Your submission has two parts:

1. A zip file named YourNameEX1.zip containing your entire project: every file in Assets, Packages and ProjectSettings, and nothing more.
2. A separate folder with your PC EXE build. We'll double-click the EXE to run your project.

Self-check before you submit

• I unzipped my zip into a new, empty folder and opened it in Unity 6000.3.11f1. It opens and runs.
• The zip has only Assets, Packages and ProjectSettings. No UserSettings, Library, Temp, Logs, obj or .vs.
• Double-clicking the EXE in my build folder runs the game.
• Q quits the EXE.
• My four objects are sprites made from an image, not built-in shapes.
• Holding ↑ stops at the corners (±50) and at size 6; holding ↓ stops at (±1, ±1) and size 1.
• My script has the 2–3 sentence explanation comment at the top.